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Background: Patulin (PAT) is a mycotoxin, usually found in fruit and their products, that can potentially be harmful to human health. In order to achieve rapid detection of mycotoxins and ensure the safety of food. This study reported a novel ratiometric fluorescent aptasensor for PAT detection. In this study, we used aptamer as the recognition element, Hybrid double stranded modified with fluorescent substances as the fluorescent donor, and AuNCs@CGO as the fluorescent acceptor. After the addition of PAT, the ratiometric fluorescence "turn on" response was exhibited., Results: The AuNCs@CGO are obtained by amide reaction between BSA-AuNCs and carboxylated graphene oxide (CGO). The prepared AuNCs@CGO can shorten the time of FRET effect and exhibit highly efficient quenching ability by adsorption effects (π-π stacking and electrostatic gravity) on the Aptamer-modified CDs. When the target PAT bound specifically to the CDs-apt, the fluorescence of the CDs-apt would recover, while the fluorescence of ROX modified cDNA remained unchanged. This ratiometric fluorescence response improved the accuracy of PAT detection. In addition, the proposed had good linearity for PAT in the range of 0.1-50 ng/mL with a limit of detection 0.16 ng/mL. The recovery of standard addition in grapes were 95.9%-105.4 %., Significance: An effective fluorescent detection method for PAT was constructed based on aptamer and nanomaterials. This new fluorescent biosensor has the characteristics of simple synthesis, easy operation, high sensitivity, strong selectivity and a low LOD, which may be a promising idea and platform for the detection of food safety hazard factors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Rapid and accurate diagnosis of tuberculosis (TB) is of great significance to control the spread of this devastating infectious disease. In this work, a sensitive and low-cost point-of-care testing (POCT) detection platform for TB was developed based on recombinase polymerase amplification (RPA)-catalytic hairpin assembly (CHA)-assisted dual signal amplification strategy. This platform could achieve homogeneous fluorescent and visual diagnosis of TB by using CdTe quantum dots (QDs) signal reporter. In the presence of target DNA (IS1081 gene fragment), RPA amplicons blocked by short oligonucleotide strands could trigger CHA signal amplification, leading to the Ag + releasing from C-Ag + -C structure and the fluorescence quenching of CdTe QDs by the released Ag + . Furthermore, the detection performance of CdTe QDs modified by 3-mercaptopropionic acid (MPA) or thiomalic acid (TMA) (MPA-capped QDs and TMA-capped QDs) was systematically compared. Experimental results demonstrated that TMA-capped QDs exhibited better detection sensitivity due to their stronger interaction with Ag + . The limits of detection (LODs) of fluorescence and visual analysis were as low as 0.13 amol L -1 and 0.33 amol L -1 . This method was successfully applied to the clinical sputum samples from 36 TB patients and 20 healthy individuals, and its quantitative results were highly consistent with those obtained by real-time fluorescent quantitative polymerase chain reaction (RT-qPCR). The proposed approach has the advantages of high sensitivity and specificity, simple operation and low cost, and is expected to be applied in clinical TB screening and diagnosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Due to the complexity of regulatory networks of disease-related biomarkers, developing simple, sensitive, and accurate methods has remained challenging for precise diagnosis. Herein, an "AND" logic gates DNA molecular machine (LGDM) was constructed, which was powered by the catalytic hairpin assembly (CHA). It was coupled with dual-emission CdTe quantum dots (QDs)-based cation exchange reaction (CER) for label-free, sensitive, and ratiometric fluorescence detection of APE1 and miRNA biomarkers. Benefiting from synergistic signal amplification strategies and a ratiometric fluorometric output mode, this LGDM enables accurate logic computing with robust and significant output signals from weak inputs. It offers improved sensitivity and selectivity even in cell extracts. Using dual-emission spectra CdTe QDs, with a ratiometric signal output mode, ensured good stability and effectively prevented false-positive signals from intrinsic biological interferences compared to the approach relying on a single signal output mode, which enabled the LGDM to achieve rapid, efficient, and accurate natural drug screening against APE1 inhibitors in vitro and cells. The developed method provides impetus to streamline research related to miRNA and APE1, offering significant promise for widespread application in drug development and clinical analysis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

The study of biomimetic self-assembly is crucial for scientists aiming to understand the origin of life and construct biomimetic functional structures. In our endeavor to create a biomimetic photosynthetic assembly, we discover a self-inflation behavior that drives the components, MPA-CdSe quantum dots (QDs) and a solid cationic polyelectrolyte, CPPA , to form a giant-vesicle-like (GVL) architecture, termed GVL-QDs@CPPA . The in situ generation of osmotic pressure during the self-assembly of QDs onto swollen CPPA in water was found to cause this self-inflation process. The resulting vesicle-like structure exhibits spatial characteristics similar to those of natural photosynthetic cells, with QDs acting as pigments uniformly distributed on the CPPA membranes, which have embedded cobalt catalytic centers. This architecture ensures optimal absorption of visible light and facilitates efficient electron transfer between the QDs and catalytic centers. As a result, GVL-QDs@CPPA assemblies efficiently harness photogenerated electrons and holes to convert protons and isopropanol into hydrogen (H 2 ) and acetone, respectively, achieving a nearly 1:1 ratio of the reduction product (H 2 ) to the oxidation product (acetone).

Paper-based cultural relics often undergo acidification and deterioration during long-term preservation. Accurate detection of paper acidity is of great significance to assess aging status and extend the preservation lifetime of paper-based cultural relics. Rapid identification of the acidification degree and acid distribution across multiple regions of paper is essential. Inspired by fluorescent sensing technology, pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) and rhodamine B (RB) fluorescent probes are synthesized and incorporated onto the nanofibers of a bacterial cellulose (BC) membrane to enable visual acidity detection of paper. Due to the complementary pH detection range of CdTe QDs and RB probes, the composite BC membrane exhibits a clear pH response across an acidic to neutral range (pH 3.0-7.5). Notably, the contrasting fluorescent colors of the two probes within the BC membrane allow for easy visualization of paper pH and acidity distribution with the naked eyes. A distinct color transition from red to green was observed on the fluorescent BC membrane when it is applied to a model paper with a gradient pH distribution. The feasibility of this method was verified by using the flat-headed pH electrode method. Additionally, common metal ions in most paper fillers, inks, pigments, as well as some sugars and amino acids showed minimal interference with the pH response of the composite BC membrane, highlighting its potential and broad applicability for visual acidity detection in paper-based cultural relics.

A ratiometric electrochemiluminescence (ECL) aptamer-based sensing platform was fabricated for prostate-specific antigen (PSA) determination. Activated CdS nanocrystals/multi-walled carbon nanotubes (CdS/MCNTs) and luminol-Pt/PAMAM nanocomposites (L-Pt/PAMAM NCs) were synthesized and used as cathodic and anodic ECL emitters, respectively. Amino group-modified aptamers were assembled on carboxylated magnetic beads, followed by hybridization with probe DNA functionalized L-Pt/PAMAM NCs. In the presence of PSA, the aptamer would bind specifically to the target PSA, thereby releasing L-Pt/PAMAM NCs. After magnetic separation, the separated L-Pt/PAMAM NCs would hybridize with capture DNA on CdS/MCNTs coated on glassy carbon electrode. This binding would lead to a decrease in cathodic ECL signal of CdS/MCNTs, due to the efficient energy transfer from CdS/MCNTs to L-Pt/PAMAM NCs. Meanwhile, L-Pt/PAMAM brought the anodic ECL signal from luminol. With the increase of PSA concentration, the ECL emission from luminol increased and the ECL emission from CdS/MCNTs decreased. The ratio of ECL intensity of luminol at 0.55 V and CdS/MCNTs at - 1.25 V could be used to quantify the concentration of PSA. This method enables sensitive and reliable detection of PSA over a wide range from 0.05 to 200 ng mL -1 , and the detection limit is 0.02 ng mL -1 ., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.)

In this study, a ratiometric fluorescent sensor CdTe QDs@ZIF-8 with butterfly spectra is successfully constructed by in situ encapsulating mercaptopropionic acid-modified CdTe quantum dots in zeolitic imidazolate framework-8 (ZIF-8) with a simple strategy, and used for the detection of tetracycline in fluorescence/smartphone colorimetry dual-mode. ZIF-8 not only reduces the agglomeration of the quantum dots but also surprisingly generates a new green fluorescence signal at 524 nm while the red fluorescence of the CdTe quantum dots at 650 nm quenches when tetracycline is added. The two opposing fluorescence signals create a butterfly-shaped fluorescence spectrum, allowing the sensor to detect tetracycline over a linear range of 0-70 μM with the detection limit (LOD) of 0.0155 μM by using a ratiometric fluorescence technique. What is more, based on the obvious color change of the fluorescent sensor gradually from red to green under UV light, a highly stable point-of-care testing sensor has been developed for on-site detection of tetracycline through color recognition by smartphones, which can be used for real-time detection of this antibiotic in the range of 0-1000 μM with the LOD of 0.0249 μM. This work provides a simple and efficient method for the on-site detection of tetracycline., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.)

Florfenicol (F), an antimicrobial agent exclusive to veterinary use within the chloramphenicol class, is extensively applied as a broad-spectrum remedy for animal diseases. Despite its efficacy, concerns arise over potential deleterious residues in animal-derived edibles, posing threats to human health. This study pioneers an innovative approach, introducing a quantum dot fluorescence-based immunoassay (FLISA) for the meticulous detection of F residues in animal-derived foods and feeds. This method demonstrates heightened sensitivity, with a detection limit of 0.3 ng/mL and a quantitative detection range of 0.6-30.4 ng/mL. Method validation, applied to diverse food sources, yields recoveries from 90.4 % to 109.7 %, featuring RSDs within 1.3 % to 8.7 %, the results showed high consistency with the national standard HPLC-MS/MS detection method. These findings underscore the method's accuracy and precision, positioning it as a promising tool for swift and reliable F residue detection, with substantial implications for fortifying food safety monitoring., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Obtaining stable electrochemiluminescence (ECL) emissions from a hydrophobic luminophore in aqueous solutions and designing a method without the use of an exogenous coreactant are promising for ECL biosensing. Here, a highly sensitive signal-on ECL immunoassay for the SARS-CoV-2 N protein was developed using micelles as an ECL tag. The micelles were prepared by coencapsulating the luminophore hydrophobic CdSe/ZnS quantum dots and coreactant dibenzoyl peroxide within the hydrophobic core of micelles. The ECL probe was obtained by covalently bonding a SARS-CoV-2 N protein-binding aptamer onto the micelle surface. The construction of the immunosensor was initiated by the immobilization of the anti-SARS-CoV-2 N protein antibody onto the screen-printed carbon electrode (SPCE) with a -COOH-functionalized surface. The surface functionalization of SPCEs was achieved through paste-exfoliated graphene, which was modified with a -COOH group through supramolecular-covalent scaffolds on SPCE. Upon achieving sandwich complexes on the immunosensor, an efficient ECL signal response at -1.4 V versus Ag/AgCl was obtained in phosphate buffer solution. The ECL assay was used for the sensitive determination of SARS-CoV-2 N protein with the linear range from 0.01 to 50 ng mL -1 , and the detection limit was 3.0 pg mL -1 . The immunosensor showed good reproducibility and stability, and the ECL immunoassay was used to determine the SARS-CoV-2 N protein in serum samples. The proposed approach to obtain micelles is versatile for the preparation of stable ECL luminophores by using hydrophobic materials, and the strategy provides an alternative for ECL bioassays based on the coreactant route.

Modulating the migration of interfacial carriers in heterojunctions is critical for driving the signal response of high-performance optical biosensors. In this study, a polarity-switchable photoelectrochemical (PEC) and nanozyme-enabled colorimetric dual-modal biosensor is designed to modulate the interfacial carrier migration of the zeolitic imidazolate framework (ZIF)-based heterojunction by exploiting stem-loop DNA and the CRISPR/Cas12a system. Specifically, ZIF-hemin (ZIF-Hemin) is assembled at the CdSe/NH 2 -rGO interface via stem-loop DNA to form a ZIF-based heterojunction. Stem-loop DNA with a reinforcing rib effect enhances binding and accelerates the interfacial carrier migration of the heterojunction. In the presence of the target Cry1Ab, the CRISPR/Cas12a system is activated to shear the ZIF-based heterojunction, resulting in the disintegration of the heterojunction and the disappearance of interfacial carrier migration. At this point, ZIF-Hemin is released from the CdSe/NH 2 -rGO interface, with the photocurrent switching from the anode to the cathode. Meanwhile, due to its rich accessible active sites, the released ZIF-Hemin nanosheet shows high peroxidase-like catalytic activity and generates colorimetric signals. The dual-modal biosensor demonstrates excellent performance in selectivity and sensitivity, with low detection limits of 0.05 pg mL -1 (PEC) and 0.4 pg mL -1 (colorimetric). This work provides a general strategy to improve the performance of optical biosensors by modulating the migration of interfacial carriers in heterojunctions.

The photochemical generation of nicotinamide cofactor 1,4-NADH, facilitated by inorganic photosensitizers, emerges as a promising model system for investigating charge transfer phenomena at the interface of semiconductors and bacteria, with implications for enhancing photosynthetic biohybrid systems (PBSs). However, extant semiconductor nanocrystal model systems suffer from achieving optimal conversion efficiency under visible light. This study investigates quasi-one-dimensional CdS nanorods as superior light absorbers, surface modified with catalyst Cp*Rh(4,4'-COOH-bpy)Cl 2 to produce enzymatically active NADH. This model subsystem facilitates easy product isolation and achieves a turnover frequency (TOF) of 175 h -1 , one of the highest efficiencies reported for inorganic photosensitizer-based nicotinamide cofactor generation. Charge transfer kinetics, fundamental for catalytic solar energy conversion, range from 10 6 to 10 8 s -1 for this system highlighting the superior electron transfer capabilities of NRs. This model ensures efficient cofactor production and offers critical insights into advancing systems that mimic natural photosynthesis for sustainable solar-to-chemical synthesis.

Multiplexed fluorescence in vivo imaging remains challenging due to the attenuation and scattering of visible and traditional near infrared (NIR-I, 650-950 nm) wavelengths. Fluorescence imaging using shortwave infrared (SWIR, 1000-1700 nm, a.k.a. NIR-II) light enables deeper tissue penetration due to reduced tissue scattering as well as minimal background autofluorescence. SWIR-emitting semiconductor quantum dots (QDs) with tunable emission peaks and optical stability are powerful contrast agents, yet few imaging demonstrations exclusively use SWIR emission beyond two-color imaging schemes. In this study, we engineered three high quality lead sulfide/cadmium sulfide (PbS/CdS) core/shell QDs with distinct SWIR emission peaks ranging from 1100-1550 nm for simultaneous three-color imaging in mice. We first use the exceptional photostability of QDs to non-invasively track lymphatic drainage with longitudinal imaging, highlighting the detailed networks of lymphatic vessels with widefield imaging over a 2 hr period. We then perform multiplexed imaging with all three QDs to distinctly visualize the lymphatic system and spatially overlapping vasculature networks, including clearly distinguishing the liver and spleen. This work establishes optimized SWIR QDs for next generation multiplexed and longitudinal preclinical imaging, unlocking numerous opportunities for preclinical studies of disease progression, drug biodistribution, and cell trafficking dynamics in living organisms., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A spatial-resolved and self-calibrated photoelectrochemical (PEC) biosensor has been fabricated by a multifunctional CeO 2 /CdS heterostructure, achieving portable and sensitive detection of carcinoembryonic antigen (CEA) using a homemade 3D printing device. The CeO 2 /CdS heterostructure with matched band structure is prepared to construct the dual-photoelectrodes to improve the PEC response of CeO 2 . In particular, as the photoactive nanomaterial, the CeO 2 also plays the role of peroxidase mimetic nanozymes. Therefore, the catalytic performance of CeO 2 with different morphologies (e.g., nano-cubes, nano-rods and nano-octahedra) have been studied, and CeO 2 nano-cubes (c-CeO 2 ) achieve the optimal catalytic activity. Upon introducing CEA, the sandwich-type immunocomplex is formed in the microplate using GOx-AuNPs-labeled second antibody as detection antibody. As a result, H 2 O 2 can be produced from the catalytic oxidization of glucose substrate by GOx, which is further catalyzed by CeO 2 to form •OH, thus in situ etching CdS and decreasing the photocurrents. The self-calibration is achieved by the dual-channel photoelectrodes on the homemade 3D printing device to obtain the photocurrents ratio, thus effectively normalizing the fluctuations of external factors to enhance the accuracy. This integrated biosensor with a detection limit as low as 0.057 ng mL -1 provides a promising way for ultrasensitive immunoassay in clinic application in complex environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

This study investigates the utilization of carbon dots (CDs) from neem leaves (Azadirachta indica) decorated onto cadmium sulfide (CdS) for the photocatalytic degradation of ciprofloxacin. A comparative study of ciprofloxacin degradation with pristine CdS and CD decorated CdS demonstrated high degradation of ∼ 75 % with CD/CdS when compared to bare CdS (∼68 %). Process optimization studies were further carried out with CD/CdS catalysts at different solution pH (4-10), feed concentrations (10-50 mg/L), catalyst loadings (25-125 mg/L), temperatures (10 - 30 °C), and lamp power (25, 50, 250 W and sunlight). Higher temperatures, combined with a solution pH of 7 and catalyst loading of 100 mg/L favored the enhanced degradation of 20 mg/L of ciprofloxacin. The ciprofloxacin degradation rate increased linearly with temperature with an apparent activation energy of 27 kJ mol -1 . The CD/CdS photocatalyst demonstrated maximum degradation rates with higher lamp powers while it also showed remarkable performance under natural sunlight achieving the same degradation within 3 h., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Organophosphorus pesticides (OPPs) constitute the most widely employed class of pesticides. However, the prevalent use of OPPs, while advantageous, raises concerns due to their toxicity, posing serious threats to food safety. Chemical sensors utilizing quantum dots (QDs) demonstrate promising applications in rapidly detecting OPPs residues, thereby facilitating efficient inspection of agricultural products. In this study, we employ an aqueous synthesis approach to prepare low toxic CdTe@ZnS QDs with stable fluorescence properties. To mitigate the risk of imprecise measurements stemming from the inherent susceptibility of fluorescence to quenching, we have adopted the principle of fluorescence resonance energy transfer (FRET) for the construction of the turn-on quantum dot sensor. With a detection limit for chlorpyrifos as low as 10 ppb (10 μg/L), the QDs sensor exhibits notable resistance to interference from various pesticides. Application of this system to detect organophosphorothioate pesticides in apples produced results consistent with those obtained from high-performance liquid chromatography (HPLC) detection, affirming the promising application prospects of this sensing system for the rapid detection of OPPs residues., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Deoxynivalenol (DON), a mycotoxin produced by Fusarium, poses a significant risk to human health and the environment. Therefore, the development of a highly sensitive and accurate detection method is essential to monitor the pollution situation. In response to this imperative, we have devised an advanced split-type photoelectrochemical (PEC) sensor for DON analysis, which leverages self-shedding MOF-nanocarriers to modulate the photoelectric response ability of PEC substrate. The PEC sensing interface was constructed using CdS/MoSe 2 heterostructures, while the self-shedding copper peroxide nanodots@ZIF-8 (CPNs@ZIF-8) served as the Cu 2+ source for the in-situ ion exchange reaction, which generated a target-related signal reduction. The constructed PEC sensor exhibited a broad linear range of 0.1 pg mL -1 to 500 ng mL -1 with a low detection limit of 0.038 pg mL -1 , demonstrating high stability, selectivity, and proactivity. This work not only introduces innovative ideas for the design of photosensitive materials, but also presents novel sensing strategies for detecting various environmental pollutants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Although circulating tumor cells (CTCs) have demonstrated considerable importance in liquid biopsy, their detection is limited by low concentrations and complex sample components. Herein, we developed a homogeneous, simple, and high-sensitivity strategy targeting breast cancer cells. This method was based on a non-immunological stepwise centrifugation preprocessing approach to isolate CTCs from whole blood. Precise quantification is achieved through the specific binding of aptamers to the overexpressed mucin 1 (MUC1) and human epidermal growth factor receptor 2 (HER2) proteins of breast cancer cells. Subsequently, DNAzyme cleavage and parallel catalytic hairpin assembly (CHA) reactions on the cholesterol-stacking DNA machine were initiated, which opened the hairpin structures T-Hg 2+ -T and C-Ag + -C, enabling multiple amplifications. This leads to the fluorescence signal reduction from Hg 2+ -specific carbon dots (CDs) and CdTe quantum dots (QDs) by released ions. This strategy demonstrated a detection performance with a limit of detection (LOD) of 3 cells/mL and a linear range of 5-100 cells/mL. 42 clinical samples have been validated, confirming their consistency with clinical imaging, pathology findings and the folate receptor (FR)-PCR kit results, exhibiting desirable specificity of 100% and sensitivity of 80.6%. These results highlight the promising applicability of our method for diagnosing and monitoring breast cancer., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

DNA hydrogel represents a noteworthy biomaterial. The preparation of biosensors by combining DNA hydrogel with electrochemiluminescence can simplify the modification process and raise the experimental efficiency. In this study, an electrochemiluminescence (ECL) biosensor based on DNA hydrogel was fabricated to detect adenosine triphosphate (ATP) simply and quickly. CdTe-Ru@SiO 2 nanospheres capable of ECL resonance energy transfer (RET) were synthesized and encapsulated CdTe-Ru@SiO 2 in the DNA hydrogel to provide strong and stable ECL signals. DNA hydrogel avoided the labeling of ECL signal molecules. The aptamer of ATP as the linker of the hydrogel for the specificity of ATP detection. The cross-linked structure of the aptamer and the polymer chains was opened by ATP, and then the decomposition of the DNA hydrogel initiated the escape of CdTe-Ru@SiO 2 to generate an ECL signal. The designed biosensor detected ATP without too much modification and complex experimental steps on the electrode surface, with good specificity and stability, and a wide linear range. The detection range was 10-5000 nM, and the detection limit was 6.68 nM (S/N = 3). The combination of DNA hydrogel and ECL biosensor provided a new way for clinical detection of ATP and other biomolecule., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Accurate and sensitive determination of human immunoglobulin G (HIgG) level is critical for diagnosis and treatment of various diseases, including rheumatoid arthritis, humoral immunodeficiencies, and infectious disease. In this study, versatile tri-signal probes were developed by preparing CdS@SiO 2 nanorods that integrate photoluminescence (PL), multi-phonon resonant Raman scattering (MRRS) and infrared absorption (IRA) properties. Through the coating of multiple CdS nanoparticles as cores within SiO 2 shells, the PL and MRRS properties of CdS were improved, resulting in a significantly lowered limit of detection (LOD), with the lowest LOD of 12.37 ag mL -1 . Integration with the distinctive IRA property of SiO 2 shells widened the detection range towards higher concentrations, establishing a final linear range of 50 ag mL -1 to 10 μg mL -1 . The remarkable consistency among the three signals highlighted the robust internal verification capability for accurate detection. This approach enhances flexibility in selecting detection methodologies to suit diverse scenarios, facilitating HIgG detection. The tri-signal nanoprobes also exhibited excellent detection selectivity, specificity and repeatability. This study presents a fresh idea for developing high-performance detection strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A ratiometric self-powered photoelectrochemical sensor based on laser direct writing technology was constructed to address the problem that the conventional single-signal detection mode was susceptible to the influence of instrumentation and environmental factors, which interfered with the detection results. Laser-induced CdS/TiO 2 /Graphene was prepared as dual photoanodes (PA1 and PA2), which were controlled by multiplexed switches to form a photocatalytic fuel cell with Pt cathode. By modifying the aptamer of aflatoxin B1 (AFB1) on the photoanode surface, the target was specifically captured to the electrode surface to form a biological complex, which increased the steric hindrance and affected the electron transfer, thus reducing the output signal of the sensor. Targets with different concentrations were incubated on the surface of PA1, and targets with fixed concentrations were incubated on the surface of PA2. Under the control of the multiplex switch, the output signals of the two photoanodes were recorded, and the ratio of these two signals was used as the basis for the quantitative detection of AFB1. The sensor output was linearly increasing with the logarithm of AFB1 concentration from 1.0 to 150 ng mL -1 and the detection limit was 0.0974 ng mL -1 . Additionally, this method had good stability, fast response, and good selectivity to real samples, providing an effective method for food safety monitoring., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Dopamine (DA) is a widely present, calcium cholinergic neurotransmitter in the body, playing important roles in the central nervous system and cardiovascular system. Developing fast and sensitive DA detection methods is of great significance. Fluorescence-based methods have attracted much attention due to their advantages of easy operation, a fast response speed, and high sensitivity. This study prepared hydrophilic and high-performance CdS/ZnS quantum dots (QDs) for DA detection. The waterborne CdS/ZnS QDs were synthesized in one step using the amphiphilic polymer PEI-g-C14, obtained by grafting tetradecane (C14) to polyethyleneimine (PEI), as a template. The polyacrylonitrile nanofiber membrane (PAN-NFM) was prepared by electrospinning (e-spinning), and a metal organic frame (ZIF-8) was deposited in situ on the surface of the PAN-NFM. The CdS/ZnS QDs were loaded onto this substrate (ZIF-8@PAN-NFM). The results showed that after the deposition of ZIF-8, the water contact angle of the hydrophobic PAN-NFM decreased to within 40°. The nanofiber membrane loaded with QDs also exhibited significant changes in fluorescence in the presence of DA at different concentrations, which could be applied as a fast detection method of DA with high sensitivity. Meanwhile, the fluorescence on this PAN-NFM could be visually observed as it transitioned from a blue-green color to colorless, making it suitable for the real-time detection of DA.

A nanoemulsion containing CdTe quantum dots (NE-CdTe-QD) was developed to shield cells from cadmium toxicity and shown to be a promising candidate for brain tumor diagnosis. CdTe-QD was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. CdTe-QD exhibited high luminescence emission at 700 nm, and their stability was maintained when encapsulated in lipidic/polymeric nanoemulsions (198 ± 2.0 nm; PDI = 0.174; - 49.0 mV). The biological effects of free and nanoemulsified CdTe-QD were tested in normal cells (NHF) and glioblastoma cell lines (U87-MG and T98G). Membrane colocalization of NE-CdTe-QD by T98G cells was observed. Instead, intracellular endoplasmic reticulum localization of NE-CdTe-QD was verified in U87-MG cells. Cell viability was reduced only when NE-CdTe-QD permeated the membrane of GBM cells, as observed in U87-MG cells, whereas no cytotoxic effects were observed in normal fibroblasts. Incorporating quantum dots directly into the brain cells is difficult. However, the nanoemulsions reduced the toxicity of CdTe-QD in zebrafish larvae and increased their circulation time, and direct injection into the zebrafish brain did not affect neural cell viability. This validates the potential application of these nanomaterials as diagnostic agents and satisfies the necessary criteria for their use as photosensitizers in photodynamic therapy., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Convenient and accurate quantification of disease-relevant multitargets is essential for community disease screening. However, in the field of photoelectrochemical (PEC) sensors for multisubstance detection, research on the continuous detection of multiple targets using a polarity-switching mode is scarce. In this study, a multiplexed PEC bioassay was developed based on a target-triggered "anodic-cathodic-anodic" multiple-polarity-switchable mode. Employing miRNA-21 and miRNA-141 as model analytes, the photosensitive material combinations of Cu 2 O/gold nanoparticles (AuNPs)/TiO 2 and CdS/AuNPs/TiO 2 were successively formed through the specific binding of different whisker branches of Whisker-DNA to Cu 2 O-H1 and the CdS-tripod DNA ring, respectively. This process reverses the photocurrent polarity from anodic to cathodic and then back to anodic upon detecting different targets, resulting in the high-sensitivity quantification of various biological targets with reduced interference. To enhance the device's utility and affordability in community disease screening, integrating a capacitor and a multimeter-smartphone connection simplifies the assembly and reduces costs. In developing the PEC sensor, the device demonstrated linear detection ranges for miRNA-21 and miRNA-141 from 0.01 fM to 10 nM. Detection limits for miRNA-21 and miRNA-141 were established at 3.2 and 4.3 aM, respectively. The innovative target-triggered multiple-polarity-switchable mode offers adaptability for other multitarget detections by simply modifying the structure of the whisker branches and the combination of photosensitive materials.

Excessive use of food coloring agents in the food industry to make the food more attractive or improve the taste has caused various health and ecological problems. Therefore, it is necessary to develop a reliable, sensitive, and selective sensing probe to detect food dyes in different food products for future industrial processing and biosafety. In recent decades, surface-functionalized quantum dots (QDs), owing to their unique optical properties, have gained tremendous interest for a wide range of applications, including biomedical, bioimaging and sensing applications. Herein, we have reported the synthesis of excellent colloidal stable and highly luminescent CdTe core and CdTe@ZnTe core-shell QDs using dual functionalizing agents, polyvinyl pyrrolidone and vitamin C. The synthesized QDs were explored as excellent sensing probes for the food dyes carmoisine, Ponceau 4R and tartrazine with limit of detection (LOD) values of 0.097 ± 0.006, 0.147 ± 0.001 and 0.044 ± 0.001 μM for CdTe-PVP QDs and 0.079 ± 0.001, 0.114 ± 0.002 and 0.042 ± 0.001 μM for CdTe@ZnTe-PVP QDs, respectively. The sensitivity of the synthesized QDs for the food dyes was also investigated in real samples (soft drinks and medications). Moreover, considering the potential effects of QDs as therapeutics or nano-drug carriers, the interactions between the synthesized QDs and carrier protein human serum albumin (HSA) were investigated. The binding affinity was observed to be in the order of 10 4 M -1 . QDs were found to quench the intrinsic fluorescence of HSA, and both types of quenching (static and dynamic) occur via electrostatic interactions in association with hydrophobic forces without any significant alteration in the protein structure.

In this work, we explored the potential of thiol-capped CdZnTe quantum dots (QDs) as an exceptional signal tag for fluorescence aptasensing applications. Employing a one-pot hydrothermal approach, we modulated the terminal functional groups of CdZnTe QDs using l-cysteine (Lcys), 3-mercaptopropionic acid (MPA), and N-acetyl-l-cysteine (NAC) as ligands. Our comparative analysis revealed that NAC-capped CdZnTe QDs (NAC-CdZnTe QDs) exhibited superior anti-interference capabilities and storage stability across various temperatures, pH levels, and storage durations. Encouraged by these promising results, we further optimized the use of ultrastable NAC-CdZnTe QDs encapsulated in dendritic mesoporous silica nanoparticles (DMSN@QDs) as an exceptional tag for the development of an advanced anti-interference fluorescence aptasensor for aflatoxin B1 (AFB1) detection. The developed aptasensor using DMSN@QDs as signal tags achieved a remarkable signal amplification of approximately 10.2 fold compared to the NAC-CdZnTe QDs coated silica (SiO 2 @QDs) labeled fluorescence aptasensor. This aptasensor was able to detect AFB1 within a wide range of 1 pg mL -1 to 200 ng mL -1 , achieving a limit of detection as low as 0.41 pg mL -1 (S/N = 3). Crucially, the specific binding affinity between the aptamer and the target enabled the aptasensor to be easily customized for various targets by simply replacing the aptamer sequence with the desired one. The exceptional potential of NAC-CdZnTe QDs, particularly when encapsulated in DMSNs, leads to the development of highly sensitive and selective anti-interference fluorescence aptasensors for various targets, thereby, paving the way for advancements in a diverse range of applications.

Loofah sponge-like carbon nanofibers (LF-Co,N/CNFs) were utilized as a carrier for Ru(bpy) 3 2+ , and then combined with CdS to create a novel solid-state electrochemiluminescence sensor capable of detecting trace amounts of fenpropathrin. LF-Co,N/CNFs, obtained through the high-temperature pyrolysis of ZIF-67 coaxial electrospinning fibers, were characterized by a loofah-like morphology and exhibited a significant specific surface area and porosity. Apart from serving as a carrier, LF-Co,N/CNFs also functioned as a luminescence accelerator, enhancing the system's luminescence efficiency by facilitating electron transmission and reducing the transmission distance. The inclusion of CdS in the luminescence reaction, in conjunction with Ru(bpy) 3 2+ , further boosted the sensor's luminescence signal. The resulting sensor demonstrated a satisfactory signal, with fenpropathrin causing significant quenching of the ECL signal. Under optimized conditions, a linear relationship between the signal quench value and fenpropathrin concentration in the range 1 × 10 -12 to 1 × 10 -6  M was observed, with a detection limit of 3.3 × 10 -13  M (S/N = 3). This developed sensor is characterized by its simplicity, sensitivity, and successful application in detecting fenpropathrin in real samples. The study not only presents a straightforward detection platform for fenpropathrin but also introduces new avenues for the rapid determination of various food contaminants, thereby expanding the utility of carbon fibers in electrochemiluminescence sensors., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The capped CdS-ZnS quantum dots (QDs) were synthesized with various thiol capping agents of glycolic acid (TGA), mercaptosuccinic acid (MSA), and L-cysteine (LCY) and used as fluorescence probe for determination of Cu (II) ions. The method of two-level three-factor full-factorial experiment design was used to achieve the best optical fluorescence emission. Results revealed that Cu (II) ions can effectively quench the emission of QDs, and the fluorescence intensity is linearly decreased with increasing Cu (II) ion concentration. The limit of detection for CdS-ZnS@ QDs capped with TGA, MSA, and LCY was obtained at 1.15 × 10 -7 , 1.32 × 10 -7 , and 2.19 × 10 -7  mol L -1 , respectively, with linear dynamic range of 3.13 × 10 -6 to 1.41 × 10 -4  mol L -1 . Luminescence quantum yields of CdS-ZnS@LCY, CdS-ZnS@MSA, and CdS-ZnS@TGA were obtained at 4.17, 1.92, and 2.47, respectively. Results indicated that no significant quenching occurred in the presence of the other metal ions. The binding constant (K b ) of capped CdS-ZnS@ QDs with Cu 2+ and the other metal ions was also investigated and discussed. The K b value for Cu 2+ was obtained considerably more than that the other ions. This work presents a new and sensitive method for determination of Cu 2+ ion., (© 2024 John Wiley & Sons Ltd.)

The pathogenic bacteria induced foodborne disease has been detrimental to public health worldwide. Herein, the peroxidase (POD)-like Fe 3 O 4 /MWCNTs@Mo-CDs (FMMC) nanozyme was applied for the detection of Escherichia coli (E. coli). The E. coli aptamer was conjugated with the surface of the FMMC, which effectively enhanced the POD-like activity attributing to the higher affinity to the substrate, and then specific capture of E. coli in food matrices, leading to the reduction of POD-like activity. Therefore, a robust and facile colorimetric aptasensor was developed for detecting E. coli with a wide linear range of 10 1 -10 6  CFU/mL, low LOQ of 10 1  CFU/mL and LOD of 0.978 CFU/mL. The aptasensor demonstrated the satisfied selectivity for E. coli compared to the other strains. This method possessed the potential application for fast in situ screening of foodborne pathogens in food products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Black phosphorus nanosheets (BPNs)/CdS heterostructure was successfully synthesized via hydrothermal method. The experimental results indicated that BPNs modified the surface of CdS nanoparticles uniformly. Meanwhile, the BPNs/CdS heterostructure exhibited a distinguished high rate of photocatalytic activity for Tetrabromobisphenol A (TBBPA) degradation under visible light irradiation (λ > 420 nm), the kinetic constant of TBBPA degradation reached 0.0261 min -1 was approximately 5.68 and 9.67 times higher than that of CdS and P25, respectively. Moreover, superoxide radical (•O 2 - ) is the main active component in the degradation process of TBBPA (the relative contribution is 91.57%). The photocatalytic mechanism and intermediates of the TBBPA was clarified, and a suitable model and pathway for the degradation of TBBPA were proposed. The results indicated that the toxicities of some intermediates were higher than the parent pollutant. This research provided an efficient approach by a novel photocatalyst for the removal of TBBPA from wastewater, and the appraisal methods for the latent risks from the intermediates were reported in this paper., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Exploring the construction of an interface with bright emission, fabulous stability, and good function to develop high-performance electrochemiluminescence (ECL) biosensors for tumor biomarkers is in high demand but faces a huge challenge. Herein, we report an oriented attachment and in situ self-assembling strategy for one-step fabrication of CdTe QD-encapsulated Hf polymer membrane onto an ITO surface (Hf-CP/CdTe QDs/APS/ITO). Hf-CP/CdTe QDs/APS/ITO is fascinating with excellent stability, high ECL emission, and specific adsorption toward ssDNA against dsDNA and mononucleotides (mNs). These interesting properties make it an ideal interface to rationally develop an immobilization-free ECL biosensor for cancer antigen 125 (CA125), used as a proof-of-concept analyte, based on target-aptamer recognition-promoted exonuclease III (Exo III)-assisted digestion. The recognition of ON by CA125 leads to the formation of CA125@ON, which hybridizes with Fc-ssDNA to switch Exo III-assisted digestion, decreasing the amount of Fc groups anchored onto the electrode's surface and blocking electron transfer. As compared to the case where CA125 was absent, significant ECL emission recovery is determined and relies on CA125 concentration. Thus, highly sensitive analysis of CA125 against other biomarkers was achieved with a limit of detection down to 2.57 pg/mL. We envision this work will provide a new path to develop ECL biosensors with excellent properties, which shows great potential for early and accurate diagnosis of cancer., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.)

Quantum dots (QDs) are widely utilized semiconductor nanocrystal materials with both nanotoxicity and composition-related toxicity. To determine the toxicological impacts and underlying mechanisms of QDs with different compositions on microalgae, carbon QDs (CQDs) and CdSe QDs were used in the present study. Results showed that QDs composed of CdSe were more toxic than QDs composed of carbon, which inhibited cell growth, with reductions in chl b content, chlorophyll fluorescence parameters, and increases in lipids and starch (two major storage substances). In addition, CdSe QDs elevated reactive oxygen species (ROS), resulting in oxidative damage, while CQDs had little effect on antioxidants. Comparative transcriptome analysis showed that gene expression was accelerated by CdSe QDs, and there was a compensatory upregulation of porphyrin metabolism, potentially to support chlorophyll synthesis. In addition, an MYB transcription factor was predicted by weighted gene co-expression network analysis (WGCNA) to serve as regulator in nanoparticle toxicity, while glutathione peroxidase (GPX) and dual-specificity tyrosine phosphorylation regulated kinases 2/3/4 (DYRK2/3/4) may be key mediators of the composition-related toxicity of CdSe QDs. This study highlights the critical role of QDs' composition in determining their impacts on aquatic microalgae, providing a theoretical reference for selecting appropriate QDs materials for various industrial applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A rational design of heterojunctions with high-quality contacts is essential for efficiently separating photogenerated charge carries and boosting the solar-driven harvesting capability. Herein, we fabricated a novel heterojunction of SnO 2 quantum dots-anchored CdS-CdCO 3 with g-C 3 N 4 nanosheets as a superior photocatalyst. SnO 2 quantum dots (SQDs) with positively charged surfaces were tightly anchored on the negatively charged surface of CdS nanosheets (NSs). The resulting CdS@SnO 2 was finally decorated with g-C 3 N 4 NSs, and a new crystalline phase of CdS-CdCO 3 was formed during the hydrothermal decoration process, g-C 3 N 4 decorated CdS-CdCO 3 @SnO 2 (CdS-CdCO 3 @SnO 2 @g-C 3 N 4 ). The as-synthesized photocatalysts were evaluated for the degradation of methyl orange dye under solar light conditions. The CdS-CdCO 3 @SnO 2 @g-C 3 N 4 exhibited 7.7-fold and 2.3-fold enhancements in photocatalytic activities in comparison to those of the bare CdS and CdS@SnO 2 NSs, respectively. The optimal performance of CdS-CdCO 3 @SnO 2 @g-C 3 N 4 is primarily attributed to the cascade-type conduction band alignments between 2D/0D/2D heterojunctions, which can harvest maximum solar light and effectively separate photoexcited charge carriers. This work provides a new inspiration for the rational design of 2D/0D/2D heterojunction photocatalyst for green energy generation and environmental remediation applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Sulfide biomineralization is a microorganism-induced process for transforming the environmentally hazardous cadmium into useful resource utilization. This study successfully constructed cadmium sulfide nanoparticles-Rhodopseudomonas palustris (Bio-CdS NPs-R. palustris) hybrids. For the self-assembling hybrids, Bio-CdS NPs were treated as new artificial-antennas to enhance photosynthesis, especially under low light (LL). Bacterial physiological results of hybrids were significantly increased, particularly for cells under LL, with higher enhancement photon harvesting ability. The enhancement included the pigment contents, and the ratio of the peripheral light-harvesting complex Ⅱ (LH2) to light-harvesting Ⅰ (1.33 ± 0.01 under LL), leading to the improvements of light-harvesting, transfer, and antenna conversion efficiencies. Finally, the stimulated electron chain of hybrids improved bacterial metabolism with increased nicotinamide adenine dinucleotide (NADH, 174.5% under LL) and adenosine triphosphate (ATP, 41.1% under LL). Furthermore, the modified photosynthetic units were induced by the up-regulated expression of fixK, which was activated by reduced oxygen tension of the medium for hybrids. fixK up-regulated genes encoding pigments (crt, and bch) and complexes (puf, pucAB, and pucC), leading to improved light-harvesting and transfer, and transform ability. This study provides a comprehensive understanding of the solar energy utilization mechanism of in-situ semiconductor-phototrophic microbe hybrids, contributing to further theoretical insight into their practical application., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

An innovative method for carbendazim (CBZ) detection was developed, consisting of an electrochemical-fluorescence dual-mode biosensor based on magneto-fluorescent composite M-CDs. M-CDs, as the fluorescent probe of this sensor, could combine the electrical signal-ferrocene to achieve the "signal switching" by specifically recognizing CBZ through aptamers, of which magnetic property was used to quickly separate from complex substrates without interference. The dual-mode sensor based on M-CDs demonstrated excellent linear responses in both electrochemical and fluorescence assays. It achieved detection ranges of 10 fg/mL - 300 ng/mL and 60 fg/mL - 100 ng/mL with detection limits (LODs) of 1.4 fg/mL and 2.3 fg/mL. The sensor exhibited exceptional detection performance, stability and anti-interference. In addition, the results of the sensor in actual samples were consistent with those of enzyme-linked immunosorbent assay (ELISA), which further demonstrated that the sensor could accurately trace detecting CBZ in real samples and had a certain application prospect., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A novel fluorometric method for the determination of L-asparaginase, an enzyme crucial in cancer therapy and food industry applications, is presented. This sensitive and selective approach utilizes L-asparagine and two pH-sensitive carbon dots (blue-N-CDs and red-N-CDs) as probes. The interaction between L-asparagine and L-asparaginase liberates ammonia, causing an increase in pH. This pH change simultaneously decreases the fluorescence of blue-N-CDs while enhancing the emission of red-N-CDs, enabling ratiometric detection of L-asparaginase. Comprehensive characterization of both carbon dots and investigation of their response mechanism towards L-asparaginase were conducted using ultraviolet-visible spectrophotometry, fluorescence spectroscopy, and transmission electron microscopy (TEM) imaging techniques. The designed approach demonstrates outstanding linearity (20 to 2000 U L -1 ) and a low detection limit (6.95 U L -1 ) for L-asparaginase quantification. Moreover, when tested to human serum samples, the detection system exhibits outstanding selectivity and high recovery rates (96.15% to 99.75%) with low standard deviation, underscoring its suitability for practical implementation in clinical diagnostics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, the interaction of the human hemoglobin with cost effective and chemically fabricated CdS quantum dots (QDs) (average sizes ≈3nm) has been investigated. The semiconductor QDs showed maximum visible absorption at 445 nm with excitonic formation and band gap of ≈ 2.88 eV along with hexagonal crystalline phase. The binding of QDs-Hb occurs through corona formation to the ground sate complex formation. The life time of the heme pocket binding and reorganization were found to be t 1  = 43 min and t 2  = 642 min, respectively. The emission quenching of the Hb has been indicated large energy transfer between CdS QDs and Hb with tertiary deformation of Hb. The binding thermodynamics showed highly exothermic nature. The ultrafast decay during corona formation was studied from TCSPC. The results showed that the energy transfer efficiency increases with the increase of the QDs concentration and maximum ≈71.5 % energy transfer occurs and average ultrafast lifetime varies from 5.45 ns to1.51 ns. The deformation and unfolding of the secondary structure of Hb with changes of the α-helix (≈74 % to ≈51.07 %) and β-sheets (≈8.63 % to ≈10.25 %) have been observed from circular dichroism spectrum. The SAXS spectrum showed that the radius of gyration of CdS QDs-Hb bioconjugate increased (up to 23 ± 0.45 nm) with the increase of the concentration of QDs compare with pure Hb (11 ± 0.23 nm) and Hb becoming more unfolded., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Here, a photoelectrochemical (PEC) immunosensor based on the FJU-200@CdSe heterostructure was developed for epidermal growth factor receptor (EGFR) detection. This is the first application of FJU-200 in PEC. After modification using CdSe quantum dots (QDs), FJU-200 and CdSe QDs formed an S-scheme heterostructure due to the interleaved energy band structure and the difference in Fermi energy (Ef) levels, which generated an efficient and stable PEC signal. When EGFR bound specifically to the antibody, a large spatial site resistance was generated, which hindered the electron transfer at the interface and the PEC signal was quenched. The proposed PEC sensing platform exhibited excellent detection performance for EGFR, with a good linear relationship with the photocurrent change value (ΔI) in the detection range of 10 fg/mL-100 ng/mL, and the detection limit was as low as 1.08 fg/mL. This work illustrates the potential electron transfer pathway between FJU-200 and CdSe QDs and creatively applies to the construction of PEC immunosensors, providing a new option for the detection of EGFR as well as other substances to be tested., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The advancement of pragmatic and highly-sensitive electrochemiluminescence (ECL) biosensors depends upon signal tags with high and stable signal intensity. Herein, enhanced ECL emission was obtained by encapsulating the dual-stabilizer-capped CdS QDs in a metal-organic framework (MOF), which served as a valid ECL signal tag for detecting biomarkers. Dual-stabilizer-capped CdS QDs reduce dangling bonds on the surface and improved the ECL emission. Furthermore, functionalized isoreticular metal-organic framework-3 (IRMOF-3) can not only load a large quantity of CdS QDs through the encapsulation capability but also serves as a co-reaction accelerator to promote the formation of more SO 4 •- from the S 2 O 8 2- , further improving the ECL emission of QDs, while the integrated design of IRMOF-3 co-reaction accelerator and CdS QDs effectively shortens the electron transfer pathway and reduces the energy consumption in ECL system. Using human epithelial protein 4 (HE4) as the model of analysis, the biosensor demonstrated a broad linear range (50 fg mL -1 ∼50 ng mL -1 ) and a low detection limit (9.89 fg mL -1 ) under optimal operating conditions. The study provides an effective and alternative method to improve the ECL efficiency of QDs, significantly broadening their potential applications in sensing analysis, medical diagnostics, and bioimaging., Competing Interests: Declaration of competing interest We have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Accurately differentiating respiratory diseases caused by viruses is challenging because of the similarity in their early or clinical symptoms. Moreover, different infection sources require different treatments. However, the current diagnostic methods have limited differentiating efficiency and sensitivity. We developed a dual-system immunosensor with a bilayer fluorescent label as a signal amplifier for the on-site, sensitive, and accurate identification of multiple respiratory viruses (RVs). The nanomaterial, comprising a polystyrene (PS) nanosphere core encapsulated by two layers of CdSe@ZnS-COOH quantum dots (QDs), outperforms the conventional color and fluorescent labels in RV detection. The dual-system detection platform, comprising a PS@DQD-based lateral flow immunoassay (LFIA) and a PS@DQD-based homogeneous sensor, enables qualitative and quantitative screening of multiple respiratory viruses within 10 and 30 min, respectively, depending on the specific detection requirements for different application scenarios. This remarkable method provides 51.2 to 1000 times sensitivity improvement over commercial antigen detection kits and greater than 12.5 to 100 times improvement over QD-based immunosensors. Furthermore, we comprehensively evaluated the specificity, reproducibility, and stability of the integrated dual-system detection platform, demonstrating its reliability. Remarkably, the respiratory viral testing was validated using biological samples, thus illustrating its promise and convenience in the detection of respiratory viruses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The highly sensitive detection method for porcine epidemic diarrhea virus (PEDV) is crucial for promptly identify infected pigs and effectively control the spread of the virus. In this study, the sensitization enhancement of organic photoactive material was combined with near zero background noise strategy for PEDV sensitive detection. A novel sensitized signal probe CdS quantum dots-doxycycline complex (CdS QDs-Dox) was prepared serving as a photoelectrochemical (PEC) probe embedded in dsDNA. Subsequently, a thiol-modified upstream inner primer (SH-FIP) was immobilized on the surface of electrode modified with gold nanoparticles (Au NPs) via Au-S bonding, enabling the loop-mediated isothermal amplification (LAMP) of PEDV on the electrode surface. The PEC probe (CdS QDs-Dox) embedded in the amplified dsDNA groove showed an increasing photocurrent signal with the rise of PEDV concentration, establishing a near-zero background LAMP-PEC sensing platform for PEDV detection. Under optimized conditions, the photocurrent intensity of this platform exhibited a good linear relationship with PEDV concentrations ranging from 0.0005 pg/μL to 10 pg/μL, achieving a detection limit as low as 0.17 fg/μL. This platform demonstrates outstanding specificity and sensitivity, thereby enabling precise quantitative detection of diverse pathogens., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A novel photoelectrochemical (PEC) biosensor was developed incorporating a specifically designed RNA aptamer for the detection of theophylline (TP). This involved utilizing two nucleotide base aptamers with tailored sequences designed to target TP. The 3' end of a single-stranded RNA sequence (5'-GGAUACCA-(CH 2 ) 6 -SH-3') and the 5' end of a complementary stranded RNA sequence (5'-HS-(CH 2 ) 6 -CCUUGGAAGCC-3') were linked to gold nanoparticles (AuNPs) and CdS quantum dots (QDs), respectively. These two single-stranded RNAs (ssRNA) formed a double-stranded RNA (dsRNA) capable of recognizing TP. This major structural change altered the spacing between QDs and NPs, which signaled the presence and concentration of TP. TP was photoelectrochemical catalytic oxidation by the hole of CdS QDs under illumination, then anode photocurrent was generated. Due to the increase in surface impedance and the effect of exciton energy transfer (EET) between QDs and AuNPs, the photocurrent would undergo varying degrees of change. TP was detected by changes in photocurrent. PEC detection of TP was achieved in the range of 0.1 μM-200 μM. The detection limit was 0.033 μM. The method exhibited commendable reproducibility and remarkable selectivity. The biosensor was used to measure TP content in tea, beverages and blood samples, resulting in satisfactory recovery rates., Competing Interests: Declaration of competing interest There are no conflicts that need to be declared., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Photocurrent-polarity conversion strategies are typically realized by constructing complex photovoltaic electrodes or changing the relevant conditions, but most involve poor photogenerated carrier transfer efficiency and cumbersome experimental steps. To this end, a photoelectrochemical (PEC) biosensor by utilizing ascorbic acid (AA)-induced photocurrent-polarity-switching was proposed for the detection of carcinoembryonic antigen (CEA). Under light excitation, the electron donor AA was oxidized by the photogenerated holes of photoactive material Co-NC/CdS, resulting in the conversion of cathodic photocurrent to the anodic direction. In the presence of the target CEA, alkaline phosphatase (ALP) was introduced into the microplates by the sandwiched immunoreaction, which then catalyzed the production of AA from ascorbic acid-2-phosphate (AAP). Finally, the catalytic product AA was transferred onto Co-NC/CdS-modified screen-printed carbon electrode, thus activating photocurrent-polarity-switching platform. The anodic photocurrent values gradually increased with increasing CEA concentration in the range of 0.02-80 ng mL -1 and reached a limit of detection (LOD) of 8.47 pg mL -1 (S/N = 3). In addition, the results of actual sample detection prove the reliability of the constructed PEC biosensor. Importantly, this work relies on a mobile smartphone wireless Bluetooth device coupled with the PEC biosensor for immediate detection, providing another idea for detecting CEA in clinical diagnosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this work, a photoelectrochemical (PEC) immunosensor was constructed for the ultrasensitive detection of lung cancer marker neuron-specific enolase (NSE) based on a microflower-like heterojunction of cadmium indium sulfide and magnesium indium sulfide (CdIn 2 S 4 /MgIn 2 S 4 , CMIS) as photoactive material. Specifically, the well-matched energy level structure and narrow energy level gradients between CdIn 2 S 4 and MgIn 2 S 4 could accelerate the separation of electron-hole (e - -h + ) pairs in the CMIS heterojunction to enhance the photocurrent of CMIS, which was increased 5.5 and 80 times compared with that of single CdIn 2 S 4 and MgIn 2 S 4 , respectively. Meanwhile, using CMIS as photoactive material, increasing the biocompatibility by dropping Pt NPs on the surface of CMIS to immobilize the antibody through Pt-N bond. Fe 3 O 4 -Ab 2 , acting as the quencher, competitively consumes electron donors and absorbs light, leading to photocurrent quenching. With the increasing of quencher, the photocurrent decreased. Hence, the developed "signal-off" PEC immunosensor realized the trace detection of NSE within the range from 1.0 fg/mL to 10 ng/mL with a low detection limit of 0.34 fg/mL. This strategy provided a new perspective for establishing ternary metal sulfide heterojunction to construct PEC immunosensor for sensitive detection of disease biomarkers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

As artificial receptors for protein recognition, epitope-imprinted polymers combined with fluorescence sensing based on quantum dots (QDs) can be potentially used for biological analysis and disease diagnosis. However, the usual way for fabrication of QD sensors through unoriented epitope imprinting is confronted with the problems of disordered imprinting sites and low template utilization. In this context, a facile and efficient oriented epitope surface imprinting was put forward based on immobilization of the epitope templates via thiol-disulfide exchange reactions. With N-succinimidyl 3-(2-pyridyldithio)-propionate (SPDP) as a heterobifunctional reagent, cysteine-modified epitopes of cytochrome c were anchored on the surface of pyridyl disulfide functionalized silica nanoparticles sandwiching CdTe QDs. After surface imprinting via a sol-gel process, the epitope templates were removed from the surface-imprinted layers simply by reduction of the thiol-disulfide, affording oriented epitope-imprinted sites. By this method, the amount of epitope templates was only 1/20 of traditionally unoriented epitopes. The resulting sensors demonstrated significantly enhanced imprinting performance and high sensitivity, with the imprinting factor increasing from 2.6 to 3.9, and the limit of detection being 91 nM. Such epitope-oriented surface-imprinted method may offer a new design strategy for the construction of high-affinity protein recognition nanomaterials with fluorescence sensing., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Anticancer theranostic nanocarriers have the potential to enhance the efficacy of pharmaceutical evaluation of drugs. Semiconductor nanocrystals, also known as quantum dots (QDs), are particularly promising components of drug carrier systems due to their small sizes and robust photoluminescence properties. Herein, bright CdZnSeS quantum dots were synthesized in a single step via the hot injection method. The particles have a quasi-core/shell structure as evident from the high quantum yield (85 %), which decreased to 41 % after water solubilization. These water solubilized QDs were encapsulated into gallic acid / alginate (GA-Alg) matrices to fabricate imaging QDs@mod-PAA/GA-Alg particles with enhanced stability in aqueous media. Cell viability assessments demonstrated that these nanocarriers exhibited viability ranging from 63 % to 83 % across all tested cell lines. Furthermore, the QDs@mod-PAA/GA-Alg particles were loaded with betulinic acid (BA) and ceranib-2 (C2) for in vitro drug release studies against HL-60 leukemia and PC-3 prostate cancer cells. The BA loaded QDs@mod-PAA/GA-Alg had a half-maximal inhibitory concentration (IC 50 ) of 8.76 μg/mL against HL-60 leukemia cells, which is 3-fold lower than that of free BA (IC 50  = 26.55 μg/mL). Similar enhancements were observed with nanocarriers loaded with C2 and simultaneously with both BA and C2. Additionally, BA:C2 loaded QDs@mod-PAA/GA-Alg nanocarriers displayed a similar enhancement (IC50 = 3.37 μg/mL compared against IC50 = 11.68 μg/mL for free BA:C2). The C2 loaded QDs@mod-PAA/GA-Alg nanocarriers had an IC50 = 2.24 μg/mL against HL-60 cells. C2 and BA loaded QDs@mod-PAA/GA-Alg NCr had IC50 values of 7.37 μg/mL and 24.55 μg/mL against PC-3 cells, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

This study employed an innovative copper oxide/cuprous oxide (CuO/Cu 2 O) polyhedron‑cadmium sulphide quantum dots (CdS QDs) double Z-scheme heterostructure as a matrix for the cathodic PEC determination of mercury ions (Hg 2+ ). First, the CuO/Cu 2 O polyhedral composite was prepared by calcining a copper-based metal organic framework (Cu-MOF). Subsequently, the amino-modified CuO/Cu 2 O was integrated with mercaptopropionic acid (MPA)-capped CdS QDs to form a CuO/Cu 2 O polyhedron-CdS QDs double Z-scheme heterostructure, producing a strong cathodic photocurrent. Importantly, this heterostructure exhibited a specifically reduced photocurrent for Hg 2+ when using CdS QDs as Hg 2+ -recognition probe. This was attributed to the extreme destruction of the double Z-scheme heterostructure and the in situ formation of the CuO/Cu 2 O-CdS/HgS heterostructure. Besides, p-type HgS competed with the matrix for electron acceptors, further decreasing the photocurrent. Consequently, Hg 2+ was sensitively assayed, with a low detection limit (0.11 pM). The as-prepared PEC sensor was also used to analyse Hg 2+ in food and the environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Background: The importance of multi-target simultaneous detection lies in its ability to significantly boost detection efficiency, making it invaluable for rapid and cost-effective testing. Photoelectrochemical (PEC) sensors have emerged as promising candidates for detecting harmful substances and biomarkers, attributable to their unparalleled sensitivity, minimal background signal, cost-effectiveness, equipment simplicity, and outstanding repeatability. However, designing an effective multi-target detection strategy remains a challenging task in the PEC sensing field. Consequently, there is a pressing need to address the development of PEC sensors capable of simultaneously detecting multiple targets., Results: CdIn 2 S 4 /V-MoS 2 heterojunctions were successfully prepared via a hydrothermal method. These heterojunctions exhibited a high photocurrent intensity, representing a 1.53-fold enhancement compared to CdIn 2 S 4 alone. Next, we designed a multi-channel aptasensing chip using ITO as the substrate. Three working electrodes were created via laser etching and subsequently modified with CdIn 2 S 4 /V-MoS 2 heterojunctions. Thiolated aptamers were then self-assembled onto the CdIn 2 S 4 /V-MoS 2 heterojunctions via covalent bonds, serving as recognition tool. By empolying the CdIn 2 S 4 /V-MoS 2 heterojunctions as the sensing platform and aptamers as recognition tool, we successfully developed a disposable aptasensing chip for the simultaneous PEC detection of three typical mycotoxins (aflatoxin B1 (AFB1), ochratoxin A (OTA), and zearalenone (ZEN)). This aptasensing chip exhibited wide detection range for AFB1 (0.05-50 ng/mL), OTA (0.05-500 ng/mL), and ZEN (0.1-250 ng/mL). Furthermore, it demonstrated ultra-low detection limits of 0.017 ng/mL for AFB1, 0.016 ng/mL for OTA, and 0.033 ng/mL for ZEN., Significance and Novelty: The aptasensing chip stands out for its cost-effectiveness, simplicity of fabrication, and multi-channel capabilities. The versatility and practicality enable it to serve as a powerful platform for designing multi-channel PEC aptasensors. With its ability to detect multiple targets with high sensitivity and specificity, the aptasensing chip holds immense potential for applications across diverse fields, such as environmental monitoring, clinical diagnostics, and food safety monitoring, where multi-target detection is crucial., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

BRCA1 gene and carcinoembryonic antigen (CEA) are important markers of breast cancer, so accurate detection of them is significant for early detection and diagnosis of breast cancer. In this study, a potential-resolved ratio electrochemiluminescence (ECL) biosensor using perylene diimide (PDI)-metal-organic framework and DNA nanoflowers (NFs)-CdS quantum dots (QDs) was constructed for detection of BRCA1 and CEA. Specifically, PDI-MOF and CdS QDs can generate potential-resolved intense ECL signals only using one coreactant, so the detection procedure can be effectively simplified. PDI-MOF was first attached to the electrode by graphene oxide, and the dopamine (DA) probe was linked to quench the ECL signal by DNA hybridization. In the presence of target BRCA1, it can form a bipedal DNA walker, so the quenching molecules (DA) were detached from the electrode via the walker amplification process aided by Mg 2+ , so that the PDI signal at -0.25 V was restored for the BRCA1 assay. Moreover, CdS QDs@DNA NFs as amplified signal probes were formed by self-assembly, and the target CEA-amplified product introduced the CdS QDs@DNA NFs to the electrode, so the QD ECL signal at -1.42 V was enhanced, while the ECL signal of PDI is unchanged; thus, CEA detection was achieved by the ratio value between them. Therefore, the detection accuracy is guaranteed by detection of two cancer markers and a ratio value. This biosensor has a great contribution to the development of new ECL materials and a novel ECL technique for fast and efficient multitarget assays, showing great significance for the early monitoring and diagnosis of breast cancer.

Abnormal expression in long noncoding RNAs (lncRNAs) is closely associated with cancers. Herein, a novel CRISPR/Cas13a-enhanced photocurrent-polarity-switching photoelectrochemical (PEC) biosensor was engineered for the joint detection of dual lncRNAs, using deep learning (DL) to assist in cancer diagnosis. After target lncRNA-activated CRISPR/Cas13a cleaves to induce DNAzyme bidirectional walkers with the help of cofactor Mg 2+ , nitrogen-doped carbon-Cu/Cu 2 O octahedra are introduced into the biosensor, producing a photocurrent in the opposite direction of CdS quantum dots (QDs). The developed PEC biosensor shows high specificity and sensitivity with limits of detection down to 25.5 aM for lncRNA HOTAIR and 53.1 aM for lncRNA MALAT1. More importantly, this platform for the lncRNA joint assay in whole blood can successfully differentiate cancers from healthy people. Furthermore, the DL model is applied to explore the potential pattern hidden in data of the established technology, and the accuracy of DL cancer diagnosis can acquire 93.3%. Consequently, the developed platform offers a new avenue for lncRNA joint detection and early intelligent diagnosis of cancer.

Staphylococcus aureus ( S. aureus ) is abundant in nature and frequently leads to various health issues. Bacteriophages as obligate intracellular parasites of bacteria have the ability to specifically identify and infect S. aureus , causing bacterial lysis and the release of endogenous catalase (CAT). The released CAT triggers the conversion of H 2 O 2 into O 2 and H 2 O, resulting in a notable decrease in UV absorption at 570 nm and a concurrent surge in photocurrent. On the basis of this, a photoelectrochemical/colorimetric dual-mode biosensor for the detection of S. aureus was developed. In the photoelectric detection mode, the reactions involving endogenous enzymes occur directly in the solution, requiring only the simple drop-coating of TiO 2 @CdS onto the indium tin oxide (ITO) electrode surface. There was no need for immobilizing additional biomolecules, thereby significantly minimizing nonspecific adsorption and improving the biosensor's stability and reproducibility. For colorimetry, we utilized a cost-effective and operationally simple approach based on KI and starch. Remarkably, this photoelectrochemical/colorimetry exhibited a linear range of 10 2 -10 9 CFU/mL for S. aureus , achieving detection limits of 7 and 10 CFU/mL, respectively. Herein, phage identification ensures the specific detection of live S. aureus , thereby effectively mitigating the potential for false signals. The dual-signal readout mode improves the detection accuracy and reliability. In conclusion, this present method offers numerous advantages, including simplicity, time-efficiency, cost-effectiveness, high specificity, and therefore excellent accuracy.