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The biology-material hybrid method for chemical-electricity conversion via microbial fuel cells (MFCs) has garnered significant attention in addressing global energy and environmental challenges. However, the efficiency of these systems remains unsatisfactory due to the complex manufacturing process and limited biocompatibility. To overcome these challenges, here, we developed a simple bio-inorganic hybrid system for bioelectricity generation in Shewanella oneidensis (S. oneidensis) MR-1. A biocompatible surface display approach was designed, and silver-binding peptide AgBP2 was expressed on the cell surface. Notably, the engineered Shewanella showed a higher electrochemical sensitivity to Ag + , and a 60 % increase in power density was achieved even at a low concentration of 10 μM Ag + . Further analysis revealed significant upregulations of cell surface negative charge intensity, ATP metabolism, and reducing equivalent (NADH/NAD + ) ratio in the engineered S. oneidensis-Ag nanoparticles biohybrid. This work not only provides a novel insight for electrochemical biosensors to detect metal ions, but also offers an alternative biocompatible surface display approach by combining compatible biomaterials with electricity-converting bacteria for advancements in biohybrid MFCs., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this work, a reusable DNA sensing microchip was developed for detection of vomitoxin (deoxynivalenol, DON) in sorghum using Cd-based core-shell CdSe@CdS quantum dots (QDs) as promising electrochemiluminescence (ECL) emitter. The size-adjustable aqueous phase CdSe@CdS QDs were prepared through homogeneous method, exhibiting strong cathodic ECL emission with a central wavelength of 520 nm in S 2 O 8 2- coreactant. And gold nanoparticles-modified iron cobalt cyanide hydrate (Fe-Co-Au) was introduced as an accelerator to amplify the ECL signal. ECL signal was quenched after the formation of a double-stranded (dsDNA) S1-S2 by generating an electron transfer system between the emitter and ferrocene (Fc), which are modified on the aptamer (ssDNA S1) and its complement sequence (ssDNA S2), respectively. When the target DON is presence, the aptamer ssDNA S1 will bind to the DON and trigger the unbinding of double strands DNA and the release of the ssDNA S2, thus the signal can be generated. This approach offers a feasible method for the detection of DON within the range of 1 ng/mL to 200 ng/mL., 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.)

Background: Carcinoembryonic antigen (CEA) is a significant glycosylated protein, and the unusual expression of CEA in human serum is used as a tumor marker in the clinical diagnosis of many cancers. Although scientists have reported many ways to detect CEA in recent years, such as electrochemistry, photoelectrochemistry, and fluorescence, their operation is complex and sensitivity is average. Therefore, finding a convenient method to accurately detect CEA is significance for the prevention of malignant tumors. With high sensitivity, quick reaction, and low background, electrochemiluminescence (ECL) has emerged as an essential method for the detection of tumor markers in blood., Results: In this work, a "signal on-off" ECL immunosensor for sensitive analysis of CEA ground on the ternary extinction effects of CuFe 2 O 4 @PDA-MB towards a self-enhanced Ru(dcbpy) 3 2+ functionalized metal-organic layer [(Hf)MOL-Ru-PEI-Pd] was prepared. The high ECL efficiency of (Hf)MOL-Ru-PEI-Pd originated from the dual intramolecular self-catalysis, including intramolecular co-reaction between polyethylenimine (PEI) and Ru(dcbpy) 3 2+ . At the same time, loading Pd NPs onto (Hf)MOL-Ru-PEI could not only improve the electron transfer ability of (Hf)MOL-Ru-PEI, but also provide more active sites for the reaction of Ru(dcbpy) 3 2+ and PEI. In the presence of CEA, CuFe 2 O 4 @PDA-MB-Ab 2 efficiently quenches the excited states of (Hf)MOL-Ru-PEI-Pd by PDA, Cu 2+ , and methylene blue (MB) via energy and electron transfer, leading to an ECL signal decrease. Under optimal conditions, the proposed CEA sensing strategy showed satisfactory properties ranging from 0.1 pg mL -1 to 100 ng mL -1 with a detection limit of 20 fg mL -1 ., Significance: The (Hf)MOL-Ru-PEI-Pd and CuFe 2 O 4 @PDA-MB were prepared in this work might open up innovative directions to synthesize luminescence-functionalized MOLs and effective quencher. Besides, the ECL quenching mechanism of Ru(dcbpy) 3 2+ by MB was successfully explained by the inner filter effect (ECL-IFE). At last, the proposed immunosensor exhibits excellent repeatability, stability, and selectivity, and may provide an attractive way for CEA and other disease markers determination., 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 Elsevier B.V. All rights reserved.)

Silver nanoparticles (Ag·NPs) show promising advantages in electrochemiluminescence (ECL) owing to their favorable optical properties and biocompatibility. However, their susceptibility to oxidation and degradation in the presence of air adversely affects ECL intensity. In this study, we employed a sandwich sensing platform using silica-coated silver nanoparticles (Ag@SiO 2 ) as a novel luminescent material and cerium dioxide (CeO 2 ) as an ECL signal quencher for sensitive neuro-specific enolase (NSE) detection. The core-shell structure protected Ag NPs within the silica (SiO 2 ) layer, enhancing their ECL luminescence properties by reducing external environmental influence and preventing Ag NPs aggregation. Amino-functionalized CeO 2 efficiently diminished Ag@SiO 2 ECL emission through electron transfer, resulting in a "signal-off" detection mode with high sensitivity and accuracy. The detection limit reached 1.66 fg/mL, and the detection range spanned from 100 fg/mL to 500 ng/mL, showcasing a powerful biomolecule detection strategy., 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 Elsevier B.V. All rights reserved.)

A photoelectrochemical (PEC) immunosensor was designed based on MgIn 2 S 4 -decorated inorganic halide perovskite CsPbBr 3 combined with the signal polarity conversion strategy for neuron-specific enolase (NSE) detection. CsPbBr 3 was applied as the basic photoactive material owing to its excellent optical and electronic properties, which provide a good PEC performance for sensor construction. In order to improve the stability of this perovskite, the three-dimensional flower-like MgIn 2 S 4 with a desirable direct band gap was applied to enhance the PEC response. Also, the excellent structure of MgIn 2 S 4 provides large surface-active sites for CsPbBr 3 loaded. For enhancing the detection sensitivity of PEC immunosensor, p-type CuInS 2 was used as a signal probe which fixed on detection antibody (Ab 2 ). When the target NSE was present, the photogenerated electrons produced by CuInS 2 were transferred to the test solution, and the polarity of PEC signal changes. Based on the above photosensitive materials and signal conversion strategy, the proposed PEC immunosensor showed favorable detection performance, and the linear detection range is 0.0001 ~ 100 ng/mL with a 38 fg/mL of detection limit. The proposed strategy improved the adhibition of CsPbBr 3 in the analytical chemistry field as well as provided a reference method for other protein detections., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

MicroRNAs (miRNA) are the potential biomarker for breast cancer, a biosensor for detecting miRNA-21 was successfully prepared by covalently linking carbohydrazide (CON 4 H 6 ) and tris (4,4 '- dicarboxylic acid-2,2' - bipyridyl) ruthenium dichloride (Ru (dcbpy) 3 2+ ) as a self-enhanced emitter (Ru-CON 4 H 6 ). The biosensor was prepared by coating the electrode with mesoporous silica encapsulated Ru-CON 4 H 6 as luminophores (RMSNs) to covalently link a couple of DNA strands (Q1-H2). The RMSNs coated electrode exhibited strong ECL emission due to the intramolecular electron transfer between the electrochemically oxidized Ru (dcbpy) 3 2+ and co-reactant CON 4 H 6 . In the presence of target miRNA-21 and an assistant hairpin H1, H2 could be released from the surface through a strand displacement reaction (SDR), and the reserved Q1 could form G-quadruplex upon the addition of K + . The formed G-quadruplex then interacted with Q2-Fc in the presence of Mg 2+ to form a DNA complex on the biosensor surface, which quenched the nano-matrixes propped self-enhanced ECL emission through the electron exchange between Fc and electrode or oxidized ECL intermediates. Under optimal conditions, the ECL decrease showed a correlation with target concentration, leading to a biosensing method for sensitive detection of miRNA-21. The proposed ECL method demonstrated a detectable concentration range from 0.1 fM to 1 nM along with a detection limit of 0.03 fM, good accuracy, and acceptable reproducibility, showing that the self-enhanced ECL biosensing strategy supported by nano-matrix provided a new way for the ultrasensitive detection of miRNA, and promoted the development of breast cancer 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 © 2023 Elsevier B.V. All rights reserved.)

The low electrochemiluminescence (ECL) efficiency issue of zirconia (ZrO 2 ) has been a pressing problem since its discovery. In this study, a bandgap-regulated ECL enhancement strategy was developed to improve the ECL efficiency of ZrO 2 . Specifically, through the calcination of metal-organic frameworks (MOFs), the MOF-derived bimetallic oxide ZrCuO 3 was synthesized. Compared to ZrO 2 , the synthesized ZrCuO 3 exhibited a narrower bandgap and higher electron transfer efficiency, leading to enhanced ECL efficiency. Further investigation of the ECL emitter revealed that ZrCuO 3 exhibited multimodal ECL emission: annihilation ECL and co-reactant participation ECL (including anodic ECL with tripropylamine as a co-reactant and cathodic ECL with K 2 S 2 O 8 as a co-reactant). The anodic ECL with the highest efficiency was selected as the main mode for detecting the target in the aptasensor. Annihilation ECL and cathodic ECL served as alternative modes to ensure stability and continuity of the sensing system. Based on the bandgap-regulated strategy of ZrCuO 3 , a sensing chip with ITO as the working electrode was designed for the sensitive detection of florfenicol (FF). The constructed signal "off-on-off" aptasensor exhibited excellent detection performance for FF in the range of 0.0005-200 ng/mL. The proposed method provided a novel strategy for the analysis of other antibiotics or biomolecules.

Covalently modifying electrochemiluminescence (ECL) luminophores to alter their energy levels or generate energy/electron transfer processes for improved performance is hindered by the complex design and fabrication processes. In this study, non-covalent bond self-assembly was employed to enhance the ECL property of gold nanoclusters with tryptophan (Try) and mercaptopropionic acid (MPA) as ligands (Try-MPA-gold nanoclusters). Specifically, through the molecular recognition of Try by cucurbit[7]uril, some non-radiative transition channels of the charge carriers on the surface of the Try-MPA-gold nanoclusters were restricted, resulting in a significant enhancement of the ECL intensity of the nanoclusters. Furthermore, rigid macrocyclic molecules acted on the surface of the nanoclusters through self-assembly, forming a passive barrier that improved the physical stability of the nanoclusters in the water-phase and indirectly improved their luminescent stability. As an application, cucurbit[7]uril-treated Try-MPA-gold nanoclusters (cucurbit[7]uril@Try-MPA-gold nanoclusters) were used as signal probes, and Zn-doped SnO 2 nanoflowers (Zn-SnO 2 NFs) with high electron mobility were used as electrode modification material to establish an ECL sensor for kanamycin (KANA) detection, utilizing split aptamers as capture probes. The advanced split aptamer sensor demonstrated excellent sensitivity analysis for KANA in complex food substrates with a recovery rate of 96.2 to 106.0%., 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 Elsevier Ltd. All rights reserved.)

It is significantly vital to develop a convenient assay method in clinical treatment due to an atypically low abundance (∼5 μM) of bleomycin (BLM) used in clinics. Herein, an electrochemiluminescence (ECL) biosensor using a zirconium-based metal-organic frameworks (Zr-MOFs) as an intramolecular coordination-induced electrochemiluminescence (CIECL) emitter was proposed for sensitive detection of BLM. Zr-MOFs were synthesized using Zr(IV) as metal ions and 4,4',4″-nitrilotribenzoic acid (H 3 NTB) as ligands for the first time. The H 3 NTB ligand not only acts as coordination units bonding with Zr(IV) but functions as a coreactant to enhance ECL efficiency rooted in its tertiary nitrogen atoms. Specifically, a long guanine-rich (G-rich) single-stranded DNA (ssDNA) was released by the target-BLM-controlled DNA machine that could perform π-π stacking with another G-quadruplex, ssDNA-rhodamine B (S-RB), by shearing DNA's fixed sites 5'-GC-3' and the auxiliary role of exonuclease III (Exo III). Finally, due to the quenching effect of rhodamine B, a negative correlation trend was obtained between ECL intensity and BLM concentration in the range from 5.0 nM to 50 μM and the limit of detection was 0.50 nM. We believe that it is a promising approach to guide the preparation of CIECL-based functional materials and establishment of analytical methods.

To ensure drinking water quality, the development of rapid and accurate analytical methods is essential. Herein, a highly sensitive electrochemiluminescence (ECL) aptasensor-based on the signal on-off-on strategy was developed to detect the water pollutant microcystin-LR (MC-LR). This strategy was based on a newly prepared ruthenium-copper metal-organic framework (RuCu MOF) as the ECL signal-transmitting probe and three types of PdPt alloy core-shell nanocrystals with different crystal structures as signal-off probes. Compounding the copper-based MOF (Cu-MOF) precursor with ruthenium bipyridyl at room temperature facilitated the retention of the intrinsic crystallinity and high porosity of the MOFs as well as afforded excellent ECL performance. Since bipyridine ruthenium in RuCu MOFs could transfer energies to the organic ligand (H 3 BTC), the ultra-efficient ligand luminescent ECL signal probe was finally obtained, which greatly improved the sensitivity of the aptasensor. To further improve the sensitivity of the aptasensor, the quenching effects of noble metal nanoalloy particles with different crystal states were investigated, which contained PdPt octahedral (PdPt Oct ), PdPt rhombic dodecahedral (PdPt RD ), and PdPt nanocube (PdPt NC ). Among them, the PdPt RD nanocrystal exhibited higher activity and excellent durability, stemming from the charge redistribution caused by the hybridization of Pt and Pd atoms. Moreover, PdPt RD could also load more -NH 2 -DNA strands because it exposed more active sites with a large specific surface area. The fabricated aptasensor exhibited outstanding sensitivity and stability in MC-LR detection, with a linear detection range of 0.0001-50 ng mL -1 . This study provides valuable directions for the application of alloy nanoparticles of noble metals and bimetallic MOFs in the field of ECL immunoassay.

The successful application of electrochemiluminescence (ECL) in immunoassay for clinical diagnosis requires improving sensitivity and accuracy. Herein was reported an ECL analytical model based zinc-based metal-organic frameworks of ruthenium hybrid (RuZn MOFs) as the signal emitter. To enlarge the output difference, the quenching effect of three different noble metal nanoparticles included palladium seeds (Pd seeds ), palladium octahedrons (Pd oct ), and Pt-based palladium (Pd@Pt oct ) core-shell were researched. Among them, Pd@Pt oct core-shell possessed higher activity and improved durability than Pd-only (NPs), they could load more protein macromolecules amicably and stabilized in the analysis system. Furthermore, since the charge redistribution owing to the hybridization of the Pt and Pd atoms in Pd@Pt oct , it could generate the electron flow maximumly from the emitter RuZn MOFs to Pd@Pt oct and result in the enhancement of quenching ECL. And the UV absorption of noble metal nanoparticles overlapped with the ECL emission of RuZn MOFs to varying degrees, which caused the behavior of resonance energy transfer (RET) reaction at the same time. This would greatly promote the sensitivity of this ECL system compared with the traditional single quenching mechanism. Based on this, a signal-off immunsensor was constructed to sensitive detection of D-dimer with linearity range from 0.001 to 200 ng mL -1 , limit of detection (LOD) was 0.20 pg mL -1 and provide a further theoretical basis for the clinical application of ECL technology., 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 Elsevier B.V. All rights reserved.)

The establishment of new mechanisms for target identification and signal amplification continues to drive innovation in electrochemiluminescence (ECL) sensing platforms. In this paper, a novel ECL insulin sensing platform was constructed by utilizing the molecular recognition properties of cucurbit[7]uril. Specifically, the macrocyclic host molecule cucurbit[7]uril was immobilized on the surface of the sensing platform as an identification probe, which could selectively capture insulin according to the inherent properties of the protein N-terminal. Introducing the rigid molecule cucurbit[7]uril into the sensing interface could reduce the influence of the environmental parameters on the sensing system, which provides a reliable guarantee for the accurate detection of insulin. Furthermore, gold nanoclusters were modified by utilizing the molecular recognition properties of cucurbit[7]uril, and used as anode signal probes for ECL sensing platform. The macrocyclic molecules cucurbit[7]uril passivated the surface of the nanoclusters, inhibited the non-radiative relaxation and improved the physical stability of the luminophore, leading to a significant increase in the sensitivity and stability of the ECL probe. The ECL sensing platforms exhibited a linear range from 50.00 fg/mL to 100.0 ng/mL, with a detection limit of 5.44 fg/mL. This study revealed the critical role of cucurbit[7]uril in target recognition and signal amplification, extending the scope of supramolecular applications in ECL., 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 Elsevier B.V. All rights reserved.)

As an inflammatory marker, procalcitonin (PCT) is more representative than other traditional inflammatory markers. In this work, a highly efficient photoelectrochemical (PEC) immunosensor was constructed based on the photoactive material Bi 2 S 3 /Ag 2 S to realize the sensitive detection of PCT. Bi 2 S 3 was prepared by a hydrothermal method, and Ag 2 S quantum dots were deposited on the ITO/Bi 2 S 3 surface via in situ reduction. Bi 2 S 3 is a kind of admirable photoelectric semiconductor nanomaterial on account of its moderate bandgap width and low binding rate of photogenerated electron holes, which can effectively convert light energy into electrical energy. Therefore, based on the energy level matching principle of Bi 2 S 3 and Ag 2 S, a labeled Bi 2 S 3 /Ag 2 S PEC immunosensor was constructed, and the sensitive detection of PCT was successfully established. The linear detection range of the PEC immunosensor was 0.50 pg∙mL -1 to 50 ng∙mL -1 , and the minimum detection limit was 0.18 pg∙mL -1 . Compared with the traditional PEC strategy, the proposed PEC immunosensor is simple, convenient, and has good anti-interference, sensitivity, and specificity, which could provide a meaningful theoretical basis and reference value for the clinical detection of PCT.

The wide and even whole pH range electrochemiluminescence (ECL) is attractive for steroid estrogens detection under harsh conditions (such as strong acid and alkali). Herein, we presented an efficient europium-based metal-organic framework (Eu-MOF) as ECL luminophore, which has been synthesized via the specific 2, 4-bis(3, 5-dicarboxyphenylamino)-6-oltriazine (H 4 BDPO) ligand with acid-base buffering effect. The functional groups with weak acid and base endowed the H 4 BDPO with eight ionogenic group states, thereout different total charges of H 4 BDPO were derived, thus high and steady ECL signals of Eu-MOF were acquired under different environments with pH = 1.0-14.0. Most notably, combined with the means of UV-vis, fluorescence spectra, cyclic voltammetry (CV) and density functional theory (DFT) calculations, the Eu-MOF has been explored different luminescence mechanisms with variational total charges. The constructed ECL biosensor based on the Eu-MOF realized sensitive detection of trenbolone under wide pH range (In order to maintain the biological activity of antigen and antibody, the studied pH value is 5-8.5), in which the limits of detection were 3.95 fg/mL (pH = 5.0), 2.36 fg/mL (pH = 7.4) and 5.48 fg/mL (pH = 8.5) respectively. This work provides a considerable method to realize efficient trace detection of steroid estrogens under the wide or even whole pH conditions., 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 © 2022 Elsevier B.V. All rights reserved.)

Gold nanoclusters (AuNCs) are promising electrochemiluminescence (ECL) signal probes for their outstanding biocompatibility, unusual molecule-like structures, and versatile optical and electrochemical properties. Nevertheless, their relatively low ECL efficiency and poor stability in aqueous solutions hindered their application in the ECL sensing field. Herein, a facile host-guest recognition strategy was proposed to enhance the ECL efficiency and stability of Au NCs by rigidifying the surface of ligand-stabilized AuNCs via supramolecular self-assembly between cucurbiturils[7] (CB[7]) and l-phenylalanine (l-Phe). Meanwhile, mercaptopropionic acid (MPA) was introduced as a ligand in order to cooperatively enhance the performance of the AuNCs and facilitate the link between AuNCs and bioactive substances. The prepared CB[7]/l-Phe/MPA-AuNCs had a higher ECL emission efficiency, achieving about 2-fold stronger ECL intensity than that of l-Phe/MPA-AuNCs. In addition, after non-covalent modification with CB[7], the finite stability of the papered AuNCs was significantly improved. The prepared CB[7]/l-Phe/MPA-AuNCs showed excellent D-dimer sensing results, exhibiting a linear range from 50.00 fg/mL to 100.0 ng/mL and a detection limit of 29.20 fg/mL (S/N = 3). Our work demonstrated that the host-guest self-assembly strategy provided a universal approach for strengthening the ECL efficiency and stability of nanostructures on an ultra-small scale.

Herein, a high-efficiency biosensor based on ternary electrochemiluminescence (ECL) system was constructed for procalcitonin (PCT) detection. Specifically, silver nanoclusters (Ag NCs) with stable luminescence properties were prepared with small-molecule lipoic acid (LA) as the ligand, and its ECL emission in persulfate (S 2 O 8 2- ) was first reported. Meanwhile, the prepared Ag NCs possessed ligand-to-metal charge-transfer characteristics, thus transferring energy from LA to Ag + for luminescence. Based on the small particle size, good biocompatibility, and molecular binding ability, Ag NCs-LA was used as an ideal luminescent probe. In addition, α-Fe 2 O 3 -Pt was introduced to facilitate the activation of S 2 O 8 2- , thereby generating more sulfate radicals to react with the free radicals of Ag NCs to enhance ECL emission. The synergistic effect of the variable valence state of transition metals and high catalytic activity of noble metals endows α-Fe 2 O 3 -Pt with excellent catalytic ability for S 2 O 8 2- . Importantly, the sensing mechanism was systematically demonstrated by UV-vis, fluorescence, and ECL analysis, as well as density functional theory calculations. At last, NKFRGKYKC was designed for specific immobilization of antibodies, thus releasing the antigen binding sites to improve the antigen recognition efficiency. Based on this, the developed biosensor showed high sensitivity for PCT detection, with a wide linear range (10 fg/mL-100 ng/mL) and a low detection limit (3.56 fg/mL), which could be extended to clinical detection of multiple biomarkers.

Herein, a novel dual mode detection system of split-type photoelectrochemical (PEC) and visual immunoassay was developed to detect neuron specific enolase (NSE), which achieved simultaneous and reliable NSE detection due to the completely different signal readouts and transduction mechanism. Specifically, specific reactions of antigens and antibodies were performed in 96-microwell plates. Gold nanoparticle (Au NP)-loaded Fe 3 O 4 (Au@Fe 3 O 4 ) NPs were used as secondary antibody markers and signal regulators, which could produce a blue-colored solution in the presence of 3,3',5,5'-tetramethylbenzidine (TMB) and H 2 O 2 because of its peroxidase-like activity. Therefore, the visual detection of NSE was realized, making the results more intuitive. Meanwhile, the above biological process could also be used as part of the split-type PEC sensing platform. Oxidized TMB and Fe 3+ were consumptive agents of the electron donor, which both realized the double quenching of PEC signal generated by the SnO 2 /MgIn 2 S 4 /Zn 0.1 Cd 0.9 S composites. Owing to the waterfall band structure, SnO 2 /MgIn 2 S 4 /Zn 0.1 Cd 0.9 S composites partially absorb visible light and effectively inhibit the electron-hole recombination, thereby providing significantly enhanced and stable initial signal. On the basis of the multiple signal amplification strategy and the split-type mode, NSE could be sensitively detected with a low detection limit of 14.0 fg·mL -1 (S/N = 3) and a wide linear range from 50.0 fg·mL -1 to 50.0 ng·mL -1 .

In this work, we utilized polycyclic aromatic hydrocarbon (PAH) derivatives as ligands to develop a zinc-based metal-organic framework (Zn-MOF) as an effective detection probe to construct an electrochemiluminescence (ECL) sensor for trenbolone detection. As traditional ECL emitters, PAHs and their derivatives have limited luminescence efficiency because of the aggregation-induced quenching (ACQ) effect. Therefore, Zn-PTC was designed by the coordination of 3,4,9,10-perylenetetracarboxylic (PTC) in the MOF to eliminate the ACQ effect. Meanwhile, Zn-PTC formed based on an aromatic ligand possessed the metal-to-ligand charge-transfer (MLCT) effect, which could transfer the energy of Zn 2+ to the aromatic ligand for strong luminescence. The ECL efficiency of Zn-PTC was calculated to be approximately 2.2 times that of the ligand (K 4 PTC). Second, the Ag@Fe core-shell bimetallic nanocrystal was prepared for efficient activation of persulfate (S 2 O 8 2- ), thereby generating more sulfate radicals (SO 4 •- ) to further promote ECL emission. According to ECL characterizations, UV-vis and fluorescence spectra, and density functional theory calculations, the luminescence and signal amplification mechanisms were investigated. In addition, NKFRGKYKC (NKF) was introduced as an affinity ligand to directionally immobilize the target antibodies, thus releasing specific sites in their Fab fragment to enhance binding activity. Based on the above strategies, the constructed biosensor exhibited high sensitivity, realizing trace detection of TBE with a wide detection range (10 fg/mL-100 ng/mL) and a low detection limit (3.28 fg/mL). This study provided an important reference for sensitive monitoring of steroid pollutants in the environment.

Nanoarrays (NAs) with stable signal output have become the most promising photoelectrochemical (PEC) biosensing substrate. However, a general issue is that interfacial charge-carrier recombination in a single-component semiconductor cannot be easily prevented, resulting in a low photocurrent density. Herein, a biosensor utilizing a Ag-embedded TiO 2 -Ag 2 S nanojunction (TiO 2 -Ag-Ag 2 S) as a signal converter was developed for the detection of CD44 protein─a transmembrane glycoprotein highly expressed in breast cancer cells. The ternary Z-scheme heterojunction was prepared by a distinctive scheme in which the Ag layer is introduced onto the surface of rutile TiO 2 NAs by magnetron sputtering, whereas the Ag 2 S is rooted in the local sulfuration of Ag. With a sufficient density of oriented nanorods, TiO 2 -Ag-Ag 2 S exhibits a smooth photocurrent output and minimal variation among different batches; it is undoubtedly a satisfactory PEC sensing carrier, which enables highly specific identification of target CD44 on the surface of MDA-MB-231 cells due to DNA strand displacement reactions (SDRs) and host-guest recognition between hyaluronic acid (HA) and CD44. The biosensor shows a sensitive PEC response to CD44 over a wide range of 37 to 5.0 × 10 5 cells/mL. We can conclude that this approach will provide an alternative solution to breast cancer diagnosis.

Relying on the electrochemiluminescence (ECL) and microfluidic technology, an immunosensor chip with high bioactivity was designed for sensitive determination of cytokeratin 19 fragment 21-1 (CYFRA 21-1). The mesoporous nanomaterial Fe 3 O 4 @Cu@Cu 2 O as the co-reaction accelerator was used to catalyze the S 2 O 8 2- to produce more SO 4 •- to achieve the amplification of the ECL signal. In fact, the generating of SO 4 •- could not only be done with the aid of the reversible cycles of Fe 2+ and Fe 3+ and Cu + and Cu 2+ , but could be achieved also through the catalase-like function of Fe 3 O 4 . What is more, it has also been proved that Fe 3 O 4 @Cu@Cu 2 O exhibited better catalytic performance than single Fe 3 O 4 , Cu 2 O, and Cu@Cu 2 O, which supported its application in this system. In addition, a portable microfluidic immunosensor chip for CYFRA 21-1-sensitive determination was assembled, which showed high selectivity, sensitivity, and strong universality in clinical cancer screening and diagnosis. It should be noted that HWRGWVC (HWR) was introduced as the antibody fixator to improve the incubation and binding efficiency of the antibody, which increased the ECL intensity and improved the sensitivity of the immunosensor. This strategy provided a new idea for cancer identification and diagnosis in clinical medicine., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The exploitation of accurate and robust photoelectrochemical (PEC) approaches in whole biosensing community counts on the smooth electrons transport and delicate biological design. An aptasensor using depositional rutile titanium dioxide/bismuth vanadate nanoarrays (TiO 2 /BiVO 4 NAs) as photoanode generator and strand-displacement model as nucleic acid frame was developed for microRNA-155 (miRNA-155) detection root in original idea. Photoanode was fabricated via a three-step overlayer deposition procedure including hydrothermal method, electrodeposition and ion beam sputtering. With a sufficient dense of oriented arrays, it provided a solid substrate and fast electronic kinetics reaction during host-guest recognition. In situ yielding electron donors were integrated into the PEC system to provide the most accurate quantitative analysis. The nanoarrays-triggered PEC platform opens another potential perspective in biosensing., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The successful application of electrochemiluminescence (ECL) in various fields required continuous exploration of novel ECL signal emitters. In this work, we have proposed a pristine ECL luminophor named NiRu MOFs, which owned extremely high and stable ECL transmission efficiency and was synthesized via a straightforward two-step hydrothermal pathway. The foundation framework of pure Ni-MOFs with the initial structure was layered-pillared constructed by the coordinated octahedrally divalent between nickel and terephthalic acid (BDC). The terephthalates were coordinated and pillared directly to the nickel hydroxide layers and the three-dimensional framework was formed, which had a weak ECL response strength. Then, the ruthenium pyridine complex was recombined with pure Ni-MOFs to produce NiRu MOFs and part of the introduced ruthenium was atomically dispersed in the layered-pillared structure through an ion-exchange method, which led to the ECL luminous efficiency being significantly boosted more than pure Ni-MOFs. In order to verify the superiority of this newly synthesized illuminant, an ECL immunoassay model has been designed, and the results demonstrated that it had extremely strong and steady signal output in practical application. This study realized an efficient platform in ECL immunoassay application with the limit of detection of 0.32 pg mL -1 for neuron-specific enolase (NSE). Therefore, the approach which combined the pristine pure Ni-MOFs and the star-illuminant ruthenium pyridine complex would provide a convenient and meaningful solution for exploring the next-generation ECL emitters.

Nowadays, continuous efforts have been devoted to searching highly efficient electrochemiluminescence (ECL) emitters for applications in clinical diagnosis and food safety. In this work, triazinyl-based hydrogen bond organic frameworks (Tr-HOFs) were synthesized by N···H hydrogen bond self-assembly aggregation, where 6,6'-(1,4-phenylene)bis(1,3,5-triazine-2,4-diamine) (phenyDAT) was prepared via the cyclization reaction and behaved as a novel ligand. Impressively, the resulting Tr-HOFs showed strong ECL responses with highly enhanced ECL efficiency (21.3%) relative to the Ru(bpy) 3 2+ standard, while phenyDAT hardly showed any ECL emission in aqueous phase. The Tr-HOFs innovatively worked as a new ECL luminophore to construct a label-free biosensor for assay of kanamycin (Kana). Specifically, the ECL response greatly weakened upon assembly of captured DNA with ferrocene (cDNA-Fc) onto the Tr-HOFs-modified electrode, while the ECL signals were adversely recovered by releasing linked DNA (L-DNA) from double-stranded DNA (dsDNA, hybridization of aptamer DNA (aptDNA) with L-DNA) due to the specific recognition of Kana with the aptDNA combined by the linkage of L-DNA and cDNA-Fc on the electrode. The as-built sensor showed a broadened linear range (1 nM-10 μM) and a limit of detection (LOD) down to 0.28 nM, which also displayed satisfactory results in the analysis of Kana in the milk and diluted human serum samples. This work offers a novel pathway to design an ECL emitter with organic molecules, holding great promise in biomedical analysis and food detection.

Dynamic self-assembly of iridium complexes in water-soluble nanocontainers is an important bottom-up process for fabricating electrochemiluminescence (ECL) bioprobes. PEGylated apoferritin (PEG-apoHSF) as the host offers a confined space to alter and modify the self-assembly of trans -bis(2-phenylpyridine)(acetylacetonate)iridium(III) [Ir(ppy) 2 (acac)] based on a pH-dependent depolymerization/reassembly pathway, allowing the formation of ECL-active iridium cores in PEG-apoHSF cavities (Ir@PEG-apoHSF). With an improved encapsulation ratio in PEG-apoHSF, the coreactant ECL behavior of the fabricated Ir@PEG-apoHSF nanodots with tri- n -propylamine (TPrA) was further demonstrated, exhibiting maximum ECL emission at 530 nm that was theoretically dominated by the band gap transition. The application of Ir@PEG-apoHSF as a bioprobe in a "signal-on" ECL immunosensing system was developed based on electroactive Ti 3 C 2 T x MXenes/TiO 2 nanosheet (Ti 3 C 2 T x /TiO 2 ) hybrids. Combining with the efficiently catalyzed electro-oxidation of TPrA and Ir(ppy) 2 (acac) by Ti 3 C 2 T x /TiO 2 hybrids, the developed immunosensor showed dramatically amplified ECL responses toward the target analyte of neuron-specific enolase (NSE). Under experimental conditions, linear quantification of NSE from 100 fg/mL to 50 ng/mL was well established by this assay, achieving a limit of detection (LOD) of 35 fg/mL. The results showcased the capability of PEGylated apoHSF to host and stabilize water-insoluble iridium complexes as ECL emitters for aqueous biosensing and immunoassays.

Based on the necessity and urgency of detecting infectious disease marker procalcitonin (PCT), a novel unlabeled photoelectrochemical (PEC) immunosensor was prepared for the rapid and sensitive detection of PCT. Firstly, SnO 2 porous nanoflowers with good photocatalytic performance were prepared by combining hydrothermal synthesis and calcining. BiOI nanoflowers were synthesized by facile ultrasonic mixed reaction. Ag 2 S quantum dots were deposited on SnO 2 /BiOI composites by in situ growth method. The SnO 2 /BiOI/Ag 2 S composites with excellent photoelectric properties were employed as substrate material, which could provide significantly enhanced and stable signal because of the energy level matching of SnO 2 , BiOI and Ag 2 S and the good light absorption performance. Accordingly, a PEC immunosensor based on SnO 2 /BiOI/Ag 2 S was constructed by using the layered modification method to achieve high sensitivity analysis of PCT. The linear dynamic range of the detection method was 0.50 pg·mL -1 ~100 ng·mL -1 , and the detection limit was 0.14 pg·mL -1 . In addition, the designed PEC immunosensor exhibited satisfactory sensitivity, selectivity, stability and repeatability, which opened up a new avenue for the analyzation of PCT and further provided guidance for antibiotic therapy.

Nowadays, brain natriuretic peptide (BNP-32) is fundamental to early cardiovascular clinical diagnosis, whose accurate assay is of significance by photoelectrochemistry (PEC) for the low background and high precision. Herein, a novel enhanced PEC platform was built by successive deposition of N-doped ZnO nanopolyhedra (N-ZnO NP) and protoporphyrin IX (PPIX). Specifically, the N-ZnO NP with a narrow bandgap of 2.60 eV was synthesized by direct calcination of zeolitic imidazole framework-8 (ZIF-8), and performed as the substrate to enhance the photocurrents of PPIX (as photosensitizer) whose photoelectron transfer pathway and enhanced PEC mechanism were studied in detail. Under such foundation, a label-free PEC aptasensor was developed by deposition of DNA aptamer onto the PEC platform and then ultrasensitive assay of BNP-32 based on a "signal off" model. The biosensor showed a wide linear range (1 pg mL -1 - 0.1 μg mL -1 ) with a limit of detection (LOD) as low as 0.14 pg mL -1 . This doping technique of ZnO nanomaterials provides some valuable guidelines for synthesis of advanced PEC probes in bioanalysis., 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 © 2021 Elsevier B.V. All rights reserved.)

Integrating a microfluidic sensor with a ratiometric photoelectrochemical (PEC) strategy to build a bioanalysis device for actual sample testing is often limited to large-volume space-resolution equipment and wavelength-dependent or potential-dependent paired photoactive materials. This work reports a microfluidic ratiometric magnetic-photoelectrochemical (M-PEC) biosensor on the photochromic composite platform to solve the above problems. In particular, as a proof-of-concept study, the platform Bi 2 WO 6- x /amorphous BiOCl nanosheets/Bi 2 S 3 (p-BWO-s) mediated by photochromic color centers and the magnetic photoactive secondary antibody marker ZnFe 2 O 4 @Ag 2 O are integrated on the microfluidic biosensor. By enhancement of the photochromic color centers, p-BWO-s outputs a considerable photocurrent signal. Meanwhile, the photoactivity of the secondary antibody marker can be changed with a magnetic field; thus, different photocurrent signals can be obtained to realize ratiometric detection. The quenching photocurrent signal without the magnetic field and the difference photocurrent signal under the magnetic field are quantitatively related to the target concentration, which unfolds a novel general strategy for bioanalysis. Different from traditional ratiometric PEC biosensors, this work characterizes the first ratiometric PEC biosensor based on an external magnetic field. Generally speaking, combined with different biorecognition cases, this scheme with good expansibility brings a unique new perspective.

A method for the detection of procalcitonin (PCT) with improved accuracy is urgently needed. A dual-mode electrochemical immunosensor with CuCo 2 S 4 -Au bimetallic sulfides as enhancer for accurate detection of PCT was fabricated in this work. The immunosensor not only displays a heavy square wave voltammetry (SWV) signal due to the electron transfer of Cu 2+ and Cu + but not the addition of electron mediators. But also presents high electrocatalytic activity towards H 2 O 2 redox reactions and enhances the detection sensitivity of the amperometric i-t curve (i-t). The introduction of Au nanoparticles, not only improves the conductivity but also has synergistic effects between Au NPs and CuCo 2 S 4 , which promote the detection sensitivity by SWV and i-t. To firmly immobilize antibodies, electrolytic gold was used as the matrix for the immunosensor. Based on a CuCo 2 S 4 -Au dual-signal indicator and electrolytic gold as the matrix, the developed immunosensor for PCT detection in this study demonstrates a wide linear response (0.0001-50 ng/mL) and a low detection limit (SWV: 82.6 fg/mL and i-t: 95.4 fg/mL). Additionally, the fabricated immunosensor exhibited an outstanding analytical approach for PCT and broad application for other biomarkers in clinical diagnosis and treatment., 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 © 2020 Elsevier B.V. All rights reserved.)

In this study, a sensitive label-free electrochemical immunosensor was designed based on nanoporous Fe3O4 and a biotin-streptavidin system to specifically detect zearalenone (ZEN). Herein, nanoporous Fe3O4 was employed to carry streptavidin to prepare the highly sensitive immunosensor. The application of nanoporous Fe3O4 and the biotin-streptavidin reaction provided large amounts of antibodies on each conjugate, thus amplifying the detected signal. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted to characterize the modification with ZEN. Factors which might influence the properties of the immunosensor, including concentration of nanoporous Fe3O4, pH of the buffer, incubation time and temperature were studied. Under the best conditions, the immunosensor displayed a highly sensitive response toward ZEN, ranging in concentration from 10.0 pg mL-1 to 3.00 ng mL-1 and 3.00 ng mL-1 to 12.0 ng mL-1, with a low detection limit of 3.7 pg mL-1. The results for analysis of human urine samples were satisfactory. Furthermore, this proposed method may find promising applications in the detection of other mycotoxins.

An ultrasensitive label-free photoelectrochemical (PEC) immunosensor was developed to detect amyloid β-protein (Aβ) based on CdS/CdTe-cosensitized SnO2 nanoflowers. Specifically, SnO2 with a flower-like porous nanostructure was utilized as a perfect substrate for the construction of PEC immunosensors, and the SnO2-modified electrode was first coated with CdTe quantum dots (QDs) and then further deposited with CdS by successive ionic layer adsorption and reaction techniques. The formed SnO2/CdS/CdTe-cosensitized structure exhibited excellent photocurrent intensity and was employed as an excellent photoactive matrix to immobilize Aβ antibody to further construct the immunosensor. Under optimal conditions, the as-constructed PEC immunosensor was used to detect Aβ and exhibited a wide linear concentration range from 0.5 pg mL-1 to 10 ng mL-1, with a low limit of detection (LOD, 0.18 pg mL-1, S/N = 3). Meanwhile, it also presented good reproducibility, specificity, and stability and may open a new promising platform for the clinical detection of Aβ or other biomarkers.

The point of fabricating ultrasensitive electrochemiluminescence (ECL)-based biosensors should be focused on how to maintain high immune recognition of antigens by antibodies in whole process. That is not effortless due to the structure of the protein can be destroyed root in toxic nanocarriers, excessive cyclic potential and superoxide radicals in coreactant, all of which can lead to reduce the bioactivity of antigen and antibody. In this work, the effect of negative voltage and divers coreactant on protein bioactivity were verified. Based on that, a motivated ECL biosensor with good biocompatibility was fabricated for procalcitonin (PCT) detection using Au nanoclusters (Au NCs) as low-potential cathodic luminophor and K 2 S 2 O 8 as non-toxic coreactant, respectively. Besides, highly-branched Cu 2 O was utilized to catalyze K 2 S 2 O 8 and produce more radical anion SO 4 •- , which can oxidize Au NCs •- to generate more high-energy-state Au NCs*, thus doubling the ECL intensity to meet the requirements of trace analysis. In addition, protein A (PA) as specific antibody capturer was employed to bind the Fc region of anti-PCT in an orientated way, further maintaining the physiological activity of antibody. As expected, all strategies undoubtedly practically improved the immune recognition of the biosensor and reduced the detection limit to 2.90 fg/mL., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Nowadays, the electrochemiluminescence (ECL) immunosensor with the unique superiority of tunable luminescence and ultrahigh sensitivity has become one of the most promising immunoassay techniques, especially for low-abundance biomarkers analysis. However, the use of signal probes with high excited potential and applied emitters which owned good intensity but biotoxicity limited its application. Herein, an ECL resonance energy transfer strategy was developed based on protein bioactivity protection utilizing europium-doped phosphoric acid gadolinium (GdPO 4 :Eu) as novel low-potential luminophor (donor) and Pd@Cu 2 O as the quenching probe (acceptor). Specifically, GdPO 4 :Eu was first prepared by using the hydrothermal synthesis method to apply in ECL, and when it coexisted with K 2 S 2 O 8 , cathode, a strong ECL signal would be generated at a low potential of -1.15 V (vs Ag/AgCl), where the immunocompetence of antigens and antibodies can be maintained well. Electrical pair Eu 3+ /Eu 2+ , as the coreactant promoter, produced by potential excitation could produce more SO 4 •- to accelerate the oxidation process of GdPO 4 :Eu. Meanwhile, Cu 2 O coated onto Pd (Pd@Cu 2 O), as a dual-quencher, enhanced the quenching effect of Pd alone and controlled the ECL intensity of the "signal on" state within a reasonable range. As a result, the proposed biosensor for detection of trace procalcitonin, a biomarker of systemic inflammatory response syndrome, exhibited a far low detection limit, 0.402 fg/mL (S/N = 3). Importantly, this work not only utilized a promising ECL emitter for biosensing platform construction but also had momentous potential in biomarker detection of disease diagnosis and clinical analysis.

The rapid and reliable measurement of procalcitonin (PCT) level exerts a prominent impact on controlling infections and preventing septicemia. This work presents a "signal on-off" electrochemiluminescence (ECL) immunosensor for ultrasensitive PCT detection based on the double quenching effects of Fe 3 O 4 @PDA-Cu x O towards a self-enhanced Ru (bpy) 3 2+ -functionalized metal organic framework (MOF). Specifically, mesoporous and hollow MIL-101(Al)-NH 2 is first applied in ECL system to load Ru (bpy) 3 2+ abundantly and stably. Poly (ethylenimine), as the coreactant, is covalently linked with MIL-101(Al)-NH 2 to prevent the leakage of Ru (bpy) 3 2+ and form a self-enhanced Ru complex, thus strong and stable ECL signals are obtained initially. To achieve high-efficiency quenching of "signal on" state, Fe 3 O 4 @PDA-Cu x O-Ab 2 is synthesized tactfully as the quenching probe by which catechol or benzoquinone units in PDA and Cu 2+ adsorbed by PDA quench the excited states of Ru (bpy) 3 2+ via electron transfer and resonance energy transfer. In this way, a rapid and robust signal-quenched type ECL immunosensor is developed for PCT measurement with a detection limit of 0.18 pg mL -1 and a dynamic range from 0.0005 ng mL -1 to 100 ng mL -1 . Given desirable selectivity, stability and reproducibility, the elaborated ECL immunoassay based on luminescence-functionalized MOF prefigures its great promise in bioanalysis of PCT and other biomarkers., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The expansion of electrochemiluminescence (ECL) technology to immunoassay at the core of care emphasizes all immune molecules will not be inactivated in the analysis process. That poses a major challenge to ECL-based biosensors due to the deoxynucleotide sequences of an antigen or antibody could be oxidized through a route of excessive cyclic potential. Herein, an ultrasensitive ECL biosensor was developed based on a novel bioactivity-protected sensing strategy utilizing Au nanoclusters (Au NCs) as low-potential luminophor for detection of procalcitonin (PCT). Bovine serum albumin (BSA)-templated Au NCs exhibited a low-potential anodic ECL signal in triethylamine (TEA) solution at 0.87 V, where it is suitable for the survival of immune molecules. Taking advantage of good conductivity and high surface area, a Cu 2 S snowflake not only functions as a satisfying substrate for connecting immune molecules but also acts as co-reaction accelerator to produce more cationic radicals TEA •+ , which could improve the ECL intensity needed to meet the requirements of trace analysis. Otherwise, HWRGWVC (HC-7) heptapeptide as specific antibody immobilizer for site-oriented fixation was introduced to further maintain the bioactivity of an antibody. In view of the preceding discussion, the obtained biosensor exhibited ultrahigh immune recognition to targets so that the detection limit was as low as an unprecedented value of 2.36 fg/mL, which will be of great significance to the application and development of a biosensor in the future.

In this work, by using amorphous bimetallic sulfides of CoSnS x Pd as signal amplifier and magnetic material of Fe 3 O 4 @PPyAu as the substrate, we fabricated an electrochemical immunoassay for Nterminal prohormone of brain natriuretic peptide (NTpro BNP). CoSnS x was used as the signal amplifier of the immunosensor for the first time, which was synthesized by fast stoichiometric co-precipitation method. The binary sulfide was identified as an amorphous structure and performed apparent electrochemical behavior. The excellent performance of signal marker was induced by the synergistic effect between SnS 2 and cobalt, as well as the loaded Pd nanoparticles (NPs). Both CoSnS x and Pd NPs presented excellent electrocatalytic activity toward H 2 O 2 oxidation. Moreover, the magnetic nanocomposite of Fe 3 O 4 @PPyAu was firmly immobilized on the magnetic glassy carbon electrode (MGCE) by the magnetic force. The magnetic substrate not only performed good electron conductivity, but also improved the stability of the fabricated electrochemical immunosensor. The developed immunosensor for the NTpro BNP detection exhibited a wide linear response (0.1 pg/mL to 50 ng/mL), and low detection limit of 31.5 fg/mL. In addition, the immunosensor held an excellent analysis capability and broad fascinating application for the detection of other biomarkers in medical diagnosis and treatment., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This work reported curcumin quenched electrochemiluminescence (ECL) behavior of luminol with H 2 O 2 as coreactant. To achieve excellent ECL signal, luminol was anchored on Au functionalized MoS 2 /Bi 2 S 3 nanorods (Luminol-Au@MoS 2 /Bi 2 S 3 ), which not only exhibited super catalysis for H 2 O 2 decomposition to enhance the ECL intensity of luminol/H 2 O 2 system, but also offered a satisfying substrate material for grafting more Au nanoparticles via Au-S binding which was used to adsorb luminol and primary antibodies. As an antioxidant, the hydrophobicity of curcumin limited its bioavailability. Herein, curcumin was conjugated with ZnO nanomaterials (ZnO-CR) to increase its dispersity in water which can make it more bioavailable. Moreover, the possible quenching mechanism between luminol/H 2 O 2 system and ZnO-CR was ascribed to the consumption of superoxide radical (O 2 •- ) and energy transfer. The consumption amount of O 2 •- was calculated to be 1.2092 μM/mL through superoxide anion free radical detection kit. Besides, polydopamine was self-polymerized on the surface of ZnO-CR (PDA@ZnO-CR) to anchor secondary antibodies. In optimum parameter, the ECL immunosensor exhibited excellent performance for amyloid-β(Aβ) proteins detection with a wide detection range from 0.05 pg mL -1 to 10 ng mL -1 and a low detection limit of 21 fg mL -1 (S/N = 3)., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this work, the heterostructures of Au nanoparticles loaded on 3D flower-like α-Fe 2 O 3 (Au NPs/α-Fe 2 O 3 ) as a platform and core-shell CdSe@CdS quantum dots sensitized graphene oxide (GO/CdSe@CdS QDs) as a signal amplification label were established in an ultrasensitive sandwich-type photoelectrochemical (PEC) immunosensor based on the "signal-on" type amplification method for detection of amyloid β-protein (Aβ). Specifically, the ultrahigh sensitivity of the proposed immunosensor came from two main properties. First, Au NPs/α-Fe 2 O 3 could partially absorb visible-light, which dramatically promotes electron transfer because of the excellent conductivity of Au NPs, and effectively inhibits the electron-hole recombination, thanks to the effect of heterostructures. Second, the signal-on type is based on the signal amplification label of GO/CdSe@CdS QDs which on adequate absorption of visible-light can improve generation of photogenerated electron-hole pairs effectively. Under optimal conditions, the well-prepared PEC immunosensor exhibited a low detection limit of 0.02 pg mL -1 and a wide linear range from 0.06 pg mL -1 to 350 ng mL -1 for Aβ detection. Meanwhile, it also presented good reproducibility, specificity, and stability and might open a new promising pathway for detection of other important biomarkers.

An ultrasensitive label-free photoelectrochemical (PEC) immunosensor with high visible-light activity was developed for quantitative detection of amyloid β-protein (Aβ) by cross-linking anti-Aβ antibody onto the Ag 2 S sensitized SnO 2 /SnS 2 nanocomposites. Specifically, SnO 2 with flower-like porous nanostructure was innovatively applied in PEC immunosensor as a basal material. It could form a heterostructure with SnS 2 , which brought about the sensitization of SnO 2 and enhanced the separation of photogenerated electrons and holes. Moreover, Ag 2 S was in-situ growth on the surface of SnO 2 /SnS 2 , which further enhanced the photocurrent response significantly. Therefore, SnO 2 /SnS 2 /Ag 2 S could form stepwise band-edge structure, which benefited the light harvesting and provided a good foundation for sensor construction and detection. Under optimal conditions, the PEC immunosensor was used to detect the content of Aβ and exhibited a wide linear concentration range from 0.5 pg mL -1 to 100 ng mL -1 , with low limit of detection (0.17 pg mL -1 ) and limit of quantification (0.56 pg mL -1 ). Additionally, the designed PEC immunosensor exhibited good reproducibility, specificity, and stability which may find potential applications in the biosensor, biomedicine, clinical diagnosis, photocatalysis and other related fields., (Copyright © 2018 Elsevier B.V. All rights reserved.)