Search

A photoelectrochemical (PEC) immunosensor was designed based on MgIn2S4-decorated inorganic halide perovskite CsPbBr3 combined with the signal polarity conversion strategy for neuron-specific enolase (NSE) detection. CsPbBr3 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 MgIn2S4 with a desirable direct band gap was applied to enhance the PEC response. Also, the excellent structure of MgIn2S4 provides large surface-active sites for CsPbBr3 loaded. For enhancing the detection sensitivity of PEC immunosensor, p-type CuInS2 was used as a signal probe which fixed on detection antibody (Ab2). When the target NSE was present, the photogenerated electrons produced by CuInS2 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 CsPbBr3 in the analytical chemistry field as well as provided a reference method for other protein detections. [ABSTRACT FROM AUTHOR]

Neuron-specific enolase (NSE) has gained extensive attention as a reliable target for detecting small cell carcinoma of lungs. In this paper, an electrochemical immunoassay method based on molybdenum disulfide (MoS2) is proposed to detect NSE sensitively. By an in-situ growth method, MoS2 and Au nanoclusters (Au NCs) were composited to form a MoS2@Au nanozyme, and then the secondary antibodies were modified. Primary antibodies were immobilized on amino-reduced graphene oxides to capture NSE. The flower-like MoS2 nanozyme provided abundant sites to load Au NCs and catalyze the decomposition of H2O2, which were beneficial to amplify an amperometric response as well as build up sensitivity. Under optimum conditions, the detection range of this strategy was 0.1 pg·mL−1–10 ng·mL−1 and the limit of detection was 0.05 pg·mL−1. This sensing strategy achieved the prospect of sensitively detecting NSE. Moreover, the prepared electrochemical immunosensor provides a theoretical basis and technical support for the detection of other disease markers. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel aptasensor was constructed to detect kanamycin. • A new Gd(III) complex was designed as luminescent material. • Dy-MOF was discovered as co-reactant accelerator. • The dual sensitization strategy enhanced the ECL intensity. This research developed a signal amplification strategy to construct a highly sensitive electrochemiluminescent (ECL) aptasensor by incorporating dysprosium metal–organic framework (Dy-MOF) as a co-reaction accelerator (CRA) in gadolinium (Gd) luminescent complex based ECL system. A new Gd(III) complex GdPc(acac) (Pc = phthalocyanine, acac = acetylacetonate) with semi-sandwich structure was rationally selected as ECL emitter, exhibiting excellent luminescence performance owing to the "antenna effect" from the conjugated macrocyclic ligand. For further improving the sensitivity of the ECL biosensor, Dy-MOF was introduced into the ECL system as CRA. The purposive design and configuration of the Dy-MOF structure accelerated the separation and transport of photogenerated charges, and the nanosheets formed by the composite material provided more active sites, which could not only greatly increased the luminophore loading, but also effectively shorten the transport distance of ions and co-reactants. The constructed biosensor showed superior performance to monitor kanamycin within 0.001 pg/mL-1000 ng/mL and a detection limit down to 0.3 fg/mL (S/N = 3). The current work opened up a skillful strategy to amplify ECL singnal, extending the application field of lanthanide complexes and providing valuable information for the future biosensor design. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this work, a photoelectrochemical (PEC) aptasensor for the detection of 17β-estradiol (E2) based on an In2S3 and CdS co-sensitized cerium (Ce) doped TiO2 (Ce:TiO2) electrode was constructed successfully. In2S3 with superior properties, such as narrow band gap, attractive photoelectric conversion efficiency, hypotoxicity and low pollution, could act as a promising material in the PEC sensing detection field. Here, a PEC aptasensor based on In2S3 was fabricated for the detection of E2. Besides, Ce doped into TiO2 introduced a new intrinsic energy band into TiO2, which created an easier electron transfer path. In2S3 and CdS co-loaded on Ce:TiO2 not only improved the photocurrent response but also expanded the light absorption range. Meanwhile, an aptamer with a specific sequence, serving as a recognition unit, was used to specifically bind with E2 to enable detection. Under optimal conditions, the as-prepared aptasensor exhibited a linearity range of 10−5–100 ng mL−1 with a detection limit of 4.0 fg mL−1. The aptasensor also showed satisfactory selectivity, stability and acceptable reproducibility. [ABSTRACT FROM AUTHOR]

Based-on novel semi-sandwich phthalocyanine(Pc) gadolinium complex as luminophore and three-dimensional flower-like nanorods In 2 O 3 /ZnIn 2 S 4 as co-reactant accelerator (CRA), an electrochemiluminescent (ECL) aptasensor with a highly sensitive signal amplification strategy was constructed. The Pc-Gd complex exhibited excellent luminescent property enhanced by "antenna effect" of 18-electron conjugated macrocycle ligand. In addition, the proper design and configuration of In 2 O 3 /ZnIn 2 S 4 tubular heterogeneous structure accelerated the transfer of photo-generated charges and the flower-like nanosheets formed provided more active sites, which could not only greatly increase luminophore loading but also effectively shorten transmission distance between ions and co-reactants. The constructed biosensor showed superior kanamycin (KAN) detection performance within 0.01 pg/mL-1000 ng/mL and a detection limit down to 0.003 pg/mL(S/N = 3). The current work developed a new strategy to amplify ECL using lanthanide complex as luminophore and In 2 O 3 /ZnIn 2 S 4 as CRA, providing valuable information for the future ECL sensor design and extending the application field of lanthanide luminescent complex. • Semi-sandwich Pc-lanthanum complex was rationally designed as ECL luminophore. • In 2 O 3 /ZnIn 2 S 4 was discovered as an excellent co-reactant accelerator. • Novel aptasensor was assembled for kanamycin detection with LOD of 0.003 pg/mL. [ABSTRACT FROM AUTHOR]

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, SnO2 porous nanoflowers with good photocatalytic performance were prepared by combining hydrothermal synthesis and calcining. BiOI nanoflowers were synthesized by facile ultrasonic mixed reaction. Ag2S quantum dots were deposited on SnO2/BiOI composites by in situ growth method. The SnO2/BiOI/Ag2S 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 SnO2, BiOI and Ag2S and the good light absorption performance. Accordingly, a PEC immunosensor based on SnO2/BiOI/Ag2S 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. [ABSTRACT FROM AUTHOR]

A photoelectrochemical (PEC) immunosensor was designed based on MgIn2S4-decorated inorganic halide perovskite CsPbBr3 combined with the signal polarity conversion strategy for neuron-specific enolase (NSE) detection. CsPbBr3 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 MgIn2S4 with a desirable direct band gap was applied to enhance the PEC response. Also, the excellent structure of MgIn2S4 provides large surface-active sites for CsPbBr3 loaded. For enhancing the detection sensitivity of PEC immunosensor, p-type CuInS2 was used as a signal probe which fixed on detection antibody (Ab2). When the target NSE was present, the photogenerated electrons produced by CuInS2 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 CsPbBr3 in the analytical chemistry field as well as provided a reference method for other protein detections. [ABSTRACT FROM AUTHOR]

This work for the first time proposed a photoelectrochemical (PEC) sensor based on the in situ generation of BiOBr/Bi 2 S 3 by Cs 3 Bi 2 Br 9 to detect trenbolone (TB). To be specific, Cs 3 Bi 2 Br 9 /BiOBr/Bi 2 S 3 heterojunction, the chosen photoelectric material, that could produce stable and large photocurrent was obtained through two steps in situ growth method on the basic of Cs 3 Bi 2 Br 9 perovskite. CdS and Au nanoparticles with outstanding light absorption characteristics were selected as TB antigen (Ag) marker. Under the aid of Au/CdS, the association between TB concentration and output current will be revealed by the competitive combining of TB antibodies (Ab) with TB or Ag-Au/CdS. If the concentration of TB was lower, the more Ag-Au/CdS was connected to the Ab, and the higher photocurrent signal was obtained. Hence, the competitive PEC sensor could realize reliable detection of TB with a lower detection limit of 29.7 fg mL-1. • We for the first time constructed a PEC sensor to detect trenbolone. • Cs 3 Bi 2 Br 9 /BiOBr/Bi 2 S 3 was prepared by two steps in situ growth method. • Au/CdS was selected as a signal enhancer to improve the sensitivity of sensor. • The detection limit was 29.7 fg mL−1. [ABSTRACT FROM AUTHOR]

Advanced bioelectronic detection based on the integration of modern optical electronics and biological systems has a broad prospect. The strategy of cathode signal amplification in self-powered photoelectrochemical (PEC) immunosensors with excellent performance is rarely reported in the field of immune analysis. Herein, the work demonstrates a self-powered PEC biosensor formed with BiOI photocathode and WO 3 /SnS 2 /ZnS photoanode, and CsPbBr 3 @COF–V was used as the photocathode signal quenching source for the quantitative monitoring of heart fatty acid binding protein (H-FABP). The high efficiency and stable self-powered biosensor formed not only provides continuous and powerful photocurrent response for bioanalysis through reasonable stepped band structure, but also effectively eliminates the interference of reducing substances. The quenching source CsPbBr 3 @COF–V greatly affects the photocurrent response due to steric hindrance, weak conductivity, competition with the substrate for dissolved oxygen and excitation light source. And the intervention of this key factor achieves multiple signal amplification effect and opens up an innovative vision for self-powered PEC immunosensor. Taking H-FABP as a representative analyte, the proposed signal amplification self-powered photoelectrochemical presents a broad linear range from 0.0005 to 150 ng/mL with the detection limit of 0.19 pg/mL. [ABSTRACT FROM AUTHOR]

In this work, a photoelectrochemical (PEC) aptasensor for the detection of 17β-estradiol (E2) based on an In2S3 and CdS co-sensitized cerium (Ce) doped TiO2 (Ce:TiO2) electrode was constructed successfully. In2S3 with superior properties, such as narrow band gap, attractive photoelectric conversion efficiency, hypotoxicity and low pollution, could act as a promising material in the PEC sensing detection field. Here, a PEC aptasensor based on In2S3 was fabricated for the detection of E2. Besides, Ce doped into TiO2 introduced a new intrinsic energy band into TiO2, which created an easier electron transfer path. In2S3 and CdS co-loaded on Ce:TiO2 not only improved the photocurrent response but also expanded the light absorption range. Meanwhile, an aptamer with a specific sequence, serving as a recognition unit, was used to specifically bind with E2 to enable detection. Under optimal conditions, the as-prepared aptasensor exhibited a linearity range of 10−5–100 ng mL−1 with a detection limit of 4.0 fg mL−1. The aptasensor also showed satisfactory selectivity, stability and acceptable reproducibility. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ultrasensitive electrochemical aptasensor was developed for detecting Pb2+. • Au@p-rGO was applied as support for immobilizing the aptamer. • Au NPs@GO as signal probe exhibited high electrocatalytic activity towards H 2 O 2. • The aptasensor displayed low detection limit of 1.67 pmol/L for Pb2+. Abstract A sensitive electrochemical aptasensor was designed based on gold modified graphene nanocomposite with different morphologies for the detection of lead ion (Pb2+). Specifically, a sulfydryl-labeled substrate strand (Apt1) and a sulfydryl-labeled catalytic strand (Apt2) were devised in fabricating the electrochemical aptasensor. Gold modified porous reduced graphene oxide (Au@p-rGO) was synthesized and applied as support for immobilizing the Apt1. And gold modified graphene oxide (Au NPs@GO) was employed as signal probe and connected with Apt2 to realize the immobilization of it on the electrode by means of the principle of complementary base pairing. The current signal can be obtained by recording the electrocatalytic conditions toward H 2 O 2. The Pb2+-dependent DNAzyme could play a role when Pb2+ existed. With the increase of the concentration of Pb2+, the current response revealed a diminishing signal, thus realizing the sensitive detection of Pb2+. Under the optimal conditions, the fabricated electrochemical aptasensor exhibited a linear response toward Pb2+ ranging from 5 pmol/L to 1 μmol/L, together with a low limit of detection of 1.67 pmol/L. Moreover, the prepared aptasensor displayed outstanding selectivity, acceptable stability and superior reproducibility for detecting Pb2+. This proposed tactics may provide reference and potential applications for detecting some other heavy metal ions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Biocompatible nitrogen-doped hydrazide-conjugated carbon dots (NHCDs) as an anodic luminophores with low excitation potential were equipped with an efficient multiple signal-amplification strategy for electrochemiluminescence (ECL) trace bioanalysis. To promote the ECL emission of NHCDs-H 2 O 2 system, gold nanoparticles (Au NPs) functionalized tin oxide nanocrystals (Au@SnO 2 NCs) were adopted to anchor large amount of NHCDs, the formed NHCDs-Au@SnO 2 NCs could conjugate with detection antibody as the signal label. Moreover, 3,4,9,10-perylenetetracarboxylic acid (PTCA) molecules were immobilized on the flower-like microsphere (PTCA@ZnCo 2 O 4 /ZnO) nanocomposites to fabricate as an electro-active sensing substrate to incubate the capture antibody, which could efficiently accelerate the generation of reactive oxygen species (OH · /O 2 ·- ) through electrocatalytic excitation and co-reaction acceleration. Integrating with the sandwich-type sensing model, an ECL immunosensor was established to detect biomarkers of squamous cell carcinomas named cytokeratin 19 fragments (cyfra21–1). Combining with the synergistic signal-amplification induced by the Au@SnO 2 NCs, PTCA, and ZnCo 2 O 4 /ZnO nanocomposites, the developed immunosensor performed detection range from 0.09 pg/mL to 100 ng/mL with a detection limit of 34.38 fg/mL. The results showcased the great potential of this sensing strategy for real sample analysis of biomarker with reliable stability, selectivity and repeatability. • Flower-like PTCA-modified ZnCo 2 O 4 /ZnO was synthesized by hydrothermal method. • PTCA-modified ZnCo 2 O 4 /ZnO was demonstrated that can efficiently achieve electrocatalytic excitation and catalyze the ROSs production to amplify the ECL signal. • Au@SnO 2 NCs was utilized to construct highly efficient catalytic nanocarriers. • Signal multiple-amplification strategy was built to improve sensitivity. • The established immunosensor exhibited low detection limit of 34.38 fg·mL-1 for CYFRA21-1. [ABSTRACT FROM AUTHOR]

• CoOOH was used as the ECL quencher probe for the first time. • A new ECL-RET donor-receptor was proposed and fabricated for ultrasensitive detection of PCT. • Dual-quenching system was built to improve sensitivity. • NH 2 -MIL-101 conjugated with g-C 3 N 4 to increase its biocompatibility and emission performance. • The established immunosensor exhibited low detection limit of 3.4 fg mL−1 for PCT. Herein, an ultrasensitive electrochemiluminescence (ECL) biosensing platform for early diagnosis of procalcitonin (PCT) was developed based on enhancing the stability of ECL signal and dual-quenching strategies. In this proposal, in order to improve the deficient of luminescence signal stability of semiconductor luminescent materials, the chromophore graphitic carbon nitride (g-C 3 N 4) was loaded onto the MOF material (amine-functionalized MIL-101: NH 2 -MIL-101). Due to the excellent catalytic performance of NH 2 -MIL-101, more ECL reaction intermediate SO 4 - are restored from the co-reactant S 2 O 8 2-, thus the ECL signal of g-C 3 N 4 becomes stronger and more stable. With the aim of achieving detection of trace markers and improving sensor sensitivity, the dual-quenching strategy is carried out, which was achieved as follows: (i) the strong energy transfer between the donor of g-C 3 N 4 @NH 2 -MIL-101 and the acceptor of cobalt oxyhydroxide nanoflakes@gold nanoparticle (CoOOH@Au NPs) rational diminishes the ECL signal of g-C 3 N 4 ; (ii) the perfect spectral overlap with the luminescent matrix achieves efficiency quenching through resonance energy transfer (RET). Benefiting from the ultrastability of luminophore and the reasonable dual quenching effect, the fabricated ECL biosensor presented dominant stability, selectivity and reproducibility accompanied by detection ranges from 0.014 pg/mL to 40 ng/mL and extremely low detection limit of 3.4 fg/mL. Consequently, it is worth believing that this method can provide a potential analytical strategy for trace immunoassay in clinical analysis. [ABSTRACT FROM AUTHOR]

A sensitive electrochemical aptasensor was prepared on the basis of gold modified thiol reduced graphene (Au@HS-rGO) and thymine-Hg2+-thymine (T-Hg2+-T) constitution for the checkout of Hg2+. Firstly, Au@HS-rGO was fabricated as the substrate onto the glassy carbon electrode (GCE) surface, which facilitated the subsequent introduction of single-stranded DNA onto the electrode. Following that, thionine (Th) was immobilized on the electrode surface depend on the physical size effect of T and Hg2+. Finally, the amount of Hg2+ was determined by differential pulse voltammetry (DPV) of Th. Under the best conditions, the linear range of the aptasensor to Hg2+ was in the range of 1–200 nmol/L and the detection limit was as low as 0.38 nmol/L. Simultaneously, good selectivity and acceptable reproducibility were revealed in the designed aptasensor. Moreover, the design thought may provide an idea for the detection of other substances in the water sample. [ABSTRACT FROM AUTHOR]