Competitive near-infrared PEC immunosorbent assay for monitoring okadaic acid based on a disposable flower-like WO3-Modified screen-printed electrode

Signal amplification strategies in photoelectrochemical sensing of carcinoembryonic antigen

Early detection of cancer markers is critical for cancer diagnosis and cancer therapy since these markers may indicate cancer risk, incidence, and disease prognosis. Carcinoembryonic antigen (CEA) is a type of non-specific and broad-spectrum cancer biomarker commonly utilized for early cancer diagnosis. Moreover, it serves as an essential tool to assess the efficacy of cancer treatment and monitor tumor recurrence as well as metastasis, thus garnering significant attention for precise and sensitive CEA detection. In recent years, photoelectrochemical (PEC) techniques have emerged as prominent methods in CEA detection due to the advantages of PEC, such as simple equipment requirements, cost-effectiveness, high sensitivity, low interference from background signals, and easy of instrument miniaturization. Different signal amplification methods have been reported in PEC sensors for CEA analysis. Based on these, this article reviews PEC sensors based on various signal amplification strategies for detection of CEA during the last five years. The advantages and drawbacks of these sensors were discussed, as well as future challenges.

Dual-modal biosensor for mercuric ion detection based on Cu2O@Cu2S/D-TA COF heterojunction with excellent catalase-like, electrochemical and photoelectrochemical properties

In this study, a dual-mode biosensor based on the heterojunction of Cu2O@Cu2S/D-TA COF was constructed for ultra-sensitive detection of Hg2+ using both photoelectrochemical and electrochemical approaches. Briefly, a 2D ultra-thin covalent organic framework film (D-TA COF film) with excellent photoelectrochemical signals was prepared on ITO surfaces through an in situ growth method. Subsequently, the probe H1 was immobilized onto the biosensor via Au-S bonds. In the presence of Hg2+, the formation of T-Hg2+-T complexes triggered hybridization chain reactions (HCR), leading to the attachment of abundant Cu2O@Cu2S probes onto the biosensor. As a p-type semiconductor, Cu2O@Cu2S could form a heterojunction with the underlying D-TA COF films. Meanwhile, it exhibited catalase-like activity, and the O2 produced by its catalytic decomposition of H2O2 can interact with the D-TA COF films, thus achieving double amplification of the photocurrent signal. Benefiting from the excellent and inherent Cu2+/Cu+ redox pairs of Cu2O@Cu2S, satisfactory differential pulse voltammetry (DPV) signals were obtained. As expected, the dual-mode biosensor was realized with wider linear ranges and low detection limits. Additionally, the analytical performance for Hg2+ in real water samples was excellent. Briefly, this suggested approach offers a facile and highly efficient modality for monitoring heavy metal ions in aquatic environments.

An electrochemiluminescent dual-signal immunosensor based on a Ru(bpy)32+-doped silica nanoparticle/copper nanocluster composite for okadaic acid detection

In this study, a sensitive dual-signal electrochemiluminescence (ECL) immunosensor was developed for okadaic acid (OA) detection utilizing copper nanoclusters (CuNCs) and Ru(bpy)32+-doped silica nanoparticles (RuSiNPs). Interestingly, the CuNCs could simultaneously enhance both cathodic (-0.95 V) and anodic (+1.15 V) ECL signals of RuSiNPs, forming a dual-signal ECL sensing platform. Further, RuSiNPs@CuNCs were used as immunomarkers by covalently conjugating them with an anti-OA monoclonal antibody (mAb) to form probes. Finally, dual ECL signals of the immunosensor were fabricated and showed good linear relationships with OA concentrations in the range of 0.05-70 ng mL-1, having a median inhibitory concentration (IC50) of 1.972 ng mL-1 and a limit of detection of 0.039 ng mL-1. Moreover, the constant ratio of the cathodic and anodic ECL peaks achieved self-calibration of the detection signal and improved the reliability of the results. Finally, we successfully applied the ECL sensor to detect OA in spiked oyster samples.

Near-infrared light-induced homogeneous photoelectrochemical biosensor based on 3D walking nanomotor-assisted CRISPR/Cas12a for ultrasensitive microRNA-155 detection

The dysregulation of microRNA (miRNA) expression levels is intricately linked to a myriad of human diseases, and the precise and delicate detection thereof holds paramount significance in the realm of clinical diagnosis and therapy. Herein, a near-infrared (NIR) light-mediated homogeneous photoelectrochemical (PEC) biosensor was constructed for miRNA-155 detection based on NaYF4: Yb, Tm@ZnIn2S4 (NYF@ ZIS) coupled with a three-dimensional (3D) walking nanomotor-assisted CRISPR/Cas12a strategy. The upconverted light emitted by the NYF in the visible and UV region upon NIR light excitation could be utilized to excite ZIS to produce a photocurrent response. The presence of target miRNA-155 initiated an amplification reaction within the 3D walking nanomotor, resulting in the production of multiple nucleic acid fragments. These fragments could activate the collateral cleavage capability of CRISPR/Cas12a, leading to the indiscriminate cleavage of single-stranded DNA (ssDNA) on ALP-ssDNA-modified magnetic beads and the subsequent liberation of alkaline phosphatase (ALP). The released ALP facilitated the catalysis of ascorbic acid 2-phosphate to generate ascorbic acid as the electron donor to capture the photogenerated holes on the NYF@ZIS surface, resulting in a positively correlated alteration in the photocurrent response. Under optimal conditions, the NIR light-initiated homogeneous PEC biosensor had the merits of good linear range (0.1 fM to 100 pM), an acceptable limit of detection (65.77 aM) for miRNA-155 detection. Considering the pronounced sensitivity, light stability, and low photodamage, this strategy presents a promising platform for detecting various other miRNA biomarkers in molecular diagnostic practice.

Near-Infrared Responsive Ag@Au Nanoplates with Exceptional Stability for Highly Sensitive Colorimetric and Photothermal Dual-Mode Lateral Flow Immunoassay

Lateral flow immunoassay (LFIA) has played a vital role in point-of-care (POC) testing on account of its simplicity, rapidity, and low cost. However, the low sensitivity and difficulty of quantitation limit its further development. Sensitive markers with new detection modes are being developed to dramatically improve LFIA's performance. Herein, a ligand-complex approach was proposed to uniformly coat a thin layer of Au onto Ag triangular nanoplates (Ag TNPs) without etching the Ag cores, which not only retain the unique optical properties from Ag TNPs but also acquire the surface stability and biocompatibility of gold. The localized surface plasmon resonance absorption of these Ag@Au TNPs could be finely adjusted from visible (550 nm) to the second near-infrared region (NIR-II) (1100 nm), and even longer, by simply adjusting the ratio between edge length and thickness. Utilizing the Ag@Au TNPs as new markers for LFIA, a highly sensitive colorimetric and photothermal dual-mode detection of the SARS-CoV-2 nucleocapsid protein was achieved with a very low background. The Ag@Au TNPs showed an exceedingly high photothermal conversion efficiency of 61.4% (ca. 2 times higher than that of Au nanorods), endowing the LFIA method with a low photothermal detection limit (40 pg/mL), which was 25-fold lower than that of the colorimetric results. The generality of the method was further verified by the sensitive and accurate analysis of cardiac troponin I (cTnI). This method is robust, reproducible, and highly specific and has been successfully applied to SARS-COV-2 detection in 35 clinical samples with satisfactory results, demonstrating its potential for POC applications.

Magnetic-encoded fluorescent nanospheres-based competitive immunoassay for near-simultaneous detection of four mycotoxins in wheat

Simultaneous detection of mycotoxins is important for food safety. In this study, a magnetic-encoded fluorescent nanosphere-based competitive immunosensor (cFMEIS) with 2×2 array was first developed for simultaneous detection of aflatoxin B1 (AFB1), ochratoxin (OTA), deoxynivalenol (DON), and zearalenone (ZEN) in wheat. Specifically, magnetic nanoparticles with strong and weak responses were conjugated with mycotoxin antigens as capture probes. Fluorescent nanoparticles doped with europium ion (Eu3+) and terbium ion (Tb3+) with red and green emission were coupled with mycotoxin antibodies as signal probes. Using a magnetic field, immune complexes were sequentially separated in a complex system and fluorescently detected. The detection limits of AFB1, DON, OTA, and ZEN were 0.032, 0.141, 0.097, and 0.376 μg/kg, respectively. The recoveries in the certified reference material of wheat flour ranged from 81.6 to 120.0 %. Owing to its high accuracy, selectivity, and sensitivity, the cFMEIS shows great promise as an efficient and sensitive multitarget sensor for mycotoxins.

Construction of Multi-Mode Photoelectrochemical Immunoassays for Accurate Detection of Cancer Markers: Assisted with MOF-Confined Plasmonic Nanozyme

In clinical diagnostics, sensitive and accurate biomarker monitoring is greatly challenged by the limitations of false positive/negative errors in single-modal photoelectrochemical analysis. Herein, we propose a multimode immunoassay by integrating photoelectrochemical, colorimetric, and photothermal imaging analysis into one electrode. The immunosensors could simultaneously achieve three detection modes at one electrode, which provided a new pathway for the accurate detection of the target prostate-specific antigen (PSA) and circumvented false-positive or negative errors during the detection process. To this end, an integrated multifunctional chip (TiO2/ZIF-8/Cu(II)) was first constructed via in situ embedding of Cu(II) in the Metal-organic framework growth process. Then, an alkaline phosphatase-labeled magnetic probe was designed to achieve split-type detection for PSA. In a sodium thiophosphate solution, the in situ generated H2S could react with Cu(II) to form small-size CuS due to the nanoconfinement of ZIF-8 and thus result in the formation of p-n heterojunctions (TiO2/ZIF-8/CuS). The TiO2/ZIF-8/CuS could efficiently improve the light-harvesting ability and facilitate the charge separation efficiency, thus finally resulting in an increased photocurrent in the PEC mode. Furthermore, by constructing the portable colorimetric and photothermal sensors based on the Arduino microcontroller and photothermal imager, the TiO2/ZIF-8/CuS also provided point-of-care and visual detection modes, as the in situ-formed CuS exhibited peroxidase-mimicking activity and outstanding photothermal properties. The work had important prospects for establishing multimode immunoassays for the accurate detection of cancer markers in early disease diagnosis.

A paper-based photoelectrochemical aptsensor using near-infrared light-responsive AgBiS2 nanoflowers as probes for the detection of Staphylococcus aureus in pork

Staphylococcus aureus is a gram-positive bacterium that can easily cause outbreaks of food-borne diseases. In this work, a signal-enhanced three-dimensional paper-based photoelectrochemical (PEC) aptsensor for the rapid and sensitive determination of S. aureus was developed. Specifically, gold nanoparticles (AuNPs) were electrodeposited on a paper-based working electrode to provide binding sites for a sulfhydryl-functionalized aptamer. Subsequently, S. aureus was captured with high specificity by a carboxyl-functionalized aptamer modified with amino-functionalized AgBiS2 nanoflowers (NH2-AgBiS2 NFs), which functionalized as PEC probes that generated strong photocurrent under irradiation with 980-nm light. By exploiting the "aptamer-target-aptamer" PEC sensing platform, the rapid and ultrasensitive detection of S. aureus was achieved. The sensor had a wide linear range of 20 to 2 × 107 CFU/mL and low limit of detection of 4 CFU/mL. Further, the applicability of the as-prepared aptsensor was successfully certified for the analysis of pork samples artificially contaminated with S. aureus.

NIR-responsive photoelectrochemical sensing platform for the simultaneous determination of tetrodotoxin and okadaic acid in Nassariidae

Simultaneous detection of tetrodotoxin (TTX) and okadaic acid (OA) is important for seafood safety. In this work, a novel paper electrode-based near-infrared (NIR) light-responsive photoelectrochemical (PEC) immunosensor was constructed using Ag2S quantum dots (QDs) and NaYF4: Yb, Er upconversion nanoparticles (UCNPs) matched with BiOI for the simultaneous detection of TTX and OA in aquatic products. A low-cost, easily prepared gold nanoparticle-functionalized paper-based screen-printed electrode with six channels was designed to immobilize OA and Ab1 of TTX. Correspondingly, PEC signal immunoprobes (BiOI@UCNPs-Ab and Ab2-Ag2S QDs) with NIR-light response were introduced to construct competitive-type and sandwich-type PEC immunosensors for OA and TTX, respectively. Under optimal conditions, the linear ranges for TTX and OA were 0.001-100 and 0.001-80 ng mL-1, respectively, and the detection limits were 5 and 7 pg mL-1, respectively. The proposed sensor was successfully used for the simultaneous analysis of TTX and OA in Nassariidae samples.

G-Quadruplex/Hemin-Mediated Polarity-Switchable and Photocurrent-Amplified System for Escherichia coli O157:H7 Detection

The contamination of food by pathogens is a serious problem in global food safety, and current methods of detection are costly, time-consuming, and cumbersome. Therefore, it is necessary to develop rapid, portable, and sensitive assays for foodborne pathogens. In addition, assays for foodborne pathogens must be resistant to interference resulting from the complex food matrix to prevent false positives and negatives. In this study, hemin and reduced graphene oxide-MoS2 sheets (GMS) were used to design a near-infrared (NIR)-responsive photoelectrochemical (PEC) aptasensor with target-induced photocurrent polarity switching based on a hairpin aptamer (Hp) with a G-quadruplex motif. A ready-to-use analytical device was developed by immobilizing GMS on the surface of a commercial screen-printed electrode, followed by the attachment of the aptamer. In the presence of Escherichia coli O157:H7, the binding sites of Hp with the G-quadruplex motif were opened and exposed to hemin, leading to the formation of a G-quadruplex/hemin DNAzyme. Crucially, after binding to hemin, the charge transfer pathway of GMS changes, resulting in a switch of the photocurrent polarity. Further, G-quadruplex/hemin DNAzyme enhanced the cathodic photocurrent, and the proposed sensor exhibited a wide linear range ((25.0-1.0) × 107 CFU/mL), a low limit of detection (2.0 CFU/mL), and good anti-interference performance. These findings expand the applications of NIR-responsive PEC materials and provide versatile PEC methods for detecting biological analytes, especially for food safety testing.

Single-stranded DNA binding protein coupled aptasensor with carbon-gold nanoparticle amplification for marine toxins detection assisted by a miniaturized absorbance reader

Okadaic acid (OA), one of the most widely distributed marine toxins worldwide poses a severe threat to human health. Previous sensing methods for OA detection are usually based on antigen-antibody binding mechanism. However, the drawbacks of antibodies especially the enzyme-labeled antibodies, such as the harsh storage condition and high cost, lead to significant challenges to OA detection in biological samples. To overcome these limitations, a single-stranded DNA binding protein (SSB) coupled aptasensor was developed for OA detection. SSB was incubated on the microplate as a substitute for conventional OA-protein conjugations. Carbon-gold nanoparticles were synthesized and labeled with horseradish peroxidase and thiol-modified aptamers to obtain a capture probe (CGNs@HRP-Apt) instead of the enzyme-labeled antibody for signal amplification. OA and SSB competed to bind with limited aptamers on CGNs@HRP-Apt probes followed by colorimetric assay to obtain the optical signals correlated to OA concentration. To achieve on-site detection, a miniaturized and multichannel absorbance reader (Smart-plate reader) was self-designed with full automation for OA detection. Utilizing the SSB coupled aptasensor and the Smart-plate reader, our approach enables cost-effective and on-site OA sensing with a detection range of 2.5-80 ppb and an ultra-low limit of detection of 0.68 ppb. Moreover, novel OA detection kits based on the SSB coupled aptasensor were prepared which can effectively reduce the cost by 15 times lower than that of commercial ELISA kits. Therefore, the developed platform provides a favorable and promising avenue for marine toxin detection in aquaculture and food safety.

An NIR light-responsive "on-off-on" photoelectrochemical aptasensor for carcinoembryonic antigen assay based on Y-shaped DNA

This work develops a novel photoelectrochemical sensor for the detection of carcinoembryonic antigen (CEA) based on the composite of UCNPs with semiconductors and conformational changes in the DNA structure. Firstly, SnS₂, ZnIn₂S₄ and UCNPs were assembled on the surface of the ITO electrode. Then Au NPs were dropped, which could facilitate the coupling of CdSe NPs modified DNA1 via Au-S bond, giving an ITO/SnS₂/ZnIn₂S₄/UCNPs/CdSe heterojunction structure. When irradiated with 980 nm near-infrared (NIR) light, the UV-visible light emitted by the UCNPs could excite the nanocomposite, producing an enhanced photoelectric reaction. Subsequently, CEA aptamer and DNA2-modified SiO₂ were added to form a Y-shaped DNA structure. At this time, the photocurrent was significantly reduced by the combination of the light-blocking effect of SiO₂ and the departure of CdSe NPs from the electrode surface. When the target CEA was added, the recognition between CEA and the aptamer led to the collapse of the Y-shaped DNA structure, the restoration of hairpin DNA and the proximity of CdSe to the electrode. Accordingly, the photocurrent signals enhanced again. Under optimal experimental conditions, the detection limit as low as 0.3 pg mL^-1 was obtained with good selectivity, achieving a sensitive "on-off-on" photoelectrochemical sensor for CEA detection.

Insight into a Target-Induced Photocurrent-Polarity-Switching Photoelectrochemical Immunoassay for Ultrasensitive Detection of Escherichia coli O157:H7

Sensitive, portable methods of detection for foodborne pathogens hold great significance for the early warning and prevention of foodborne diseases and environmental pollution. Restricted by a complicated matrix and limited signaling strategies, developing a ready-to-use sensing platform with ultrahigh sensitivity remains challenging. In this work, near-infrared (NIR) light-responsive AgBiS₂ nanoflowers (NFs) and Cu₂O nanocubes (NCs) were introduced to construct a novel target-induced photocurrent-polarity-switchable system and verified for the development of an all-in-one, ready-to-use photoelectrochemical (PEC) immunosensor. NIR-responsive n-type AgBiS₂ NFs and p-type Cu₂O NCs producing anodic and cathodic photocurrents were conjugated with monoclonal (MAb₁) and polyclonal antibodies (PAb₂), respectively. Using a sandwich-type immunocomplex bridged by Escherichia coli O157:H7, an efficient photocurrent-polarity-switching PEC system was formed on a paper-based working electrode (PWE). Owing to the spatial separation of the photogenerated carriers and the elimination of false-positive/negative signals by the polarity-switchable photocurrent, the proposed NIR PEC immunoassay for E. coli O157:H7 exhibits a considerably low detection limit of 8 colony-forming units/milliliter (CFU/mL) with a linear range from 25 to 5 × 10⁷ CFU/mL. The platform includes a PWE with an automatic cleaning function and a portable PEC analyzer with smartphone-compatible Bluetooth capability, thus achieving point-of-care testing of E. coli O157:H7. The sensor was applied to the analysis of pork samples artificially contaminated with E. coli O157:H7, and the detection results were in good agreement with the plate counting method, a gold standard in the field. This work aimed to investigate the photoelectric activity of the NIR-responsive p/n-type composites and to provide a new signal-reversal route for the construction of an all-in-one ready-to-use PEC immunosensor for the detection of low-concentration biomolecules.

Signal-On Near-Infrared Photoelectrochemical Aptasensors for Sensing VEGF165 Based on Ionic Liquid-Functionalized Nd-MOF Nanorods and In-Site Formation of Gold Nanoparticles

The low photon energy and deep penetrating ability of near-infrared (NIR) light make it an ideal light source for a photoelectrochemical (PEC) immunosensing system. Absorption wavelengths of the metal-organic frameworks (MOFs) can be regulated by adjusting the metal ions and the conjugation degree of the ligands. Herein, an ionic liquid with a large conjugated structure was synthesized and was used as a ligand to coordinate with Nd ions to prepare Nd-MOF nanorods with a band gap of 1.26 eV. The Nd-MOF rods show a good photoabsorption property from 200 to 980 nm. A PEC platform was constructed by using Nd-MOF nanorods as the photoelectroactive element. A detachable double-stranded DNA labeled with alkaline phosphatase (ALP), which is specific to VEGF165, was immobilized onto the PEC sensing interface. After blocking unspecific active sites with bovine albumin, an NIR PEC aptasensing system was developed for VEGF165 detection. After being incubated in a mixture of VEGF165, l-ascorbic acid 2-phosphate (magnesium salt hydrate) (AAP), and chloroauric acid, the aptamers for VEGF165 were detached from the PEC aptasensing interface, thus resulting in the decrease of the charge-transfer resistance and the increase of the photocurrent response. The shedding of the aptamers also makes the ALP approach the electrode surface, thus catalyzing the reduction of AAP to produce ascorbic acid (AA). Subsequently, AA reduces in situ chloroauric acid to produce AuNPs on the Nd-MOF-based sensing interface. With the excellent conductivity and localized surface plasmon resonance effect, the AuNPs can accelerate the separation of electron-hole pairs generated from Nd-MOF nanorods, thus promoting the photoelectric conversion efficiency and achieving signal amplification. Under optimized conditions, the PEC responses were linearly related to the VEGF165 concentrations in the range of 0.01-100 ng mL^-1 and exhibit a low detection limit of 3.51 pg mL^-1 (S/N = 3). VEGF165 in human serum samples was detected by the NIR PEC aptasensor. Their concentrations were found to be well consistent with that obtained from ELISA. Furthermore, the PEC aptasensor demonstrated recoveries from 96.07 to 103.8%. The relative standard deviations were within 5%, indicating good accuracy and precision. The results further verify its practicability for clinical diagnosis.

A near-infrared light-driven photoelectrochemical aptasensing platform for adenosine triphosphate detection based on Yb-doped Bi2S3 nanorods

Due to its capability of low spectral interference, high light stability, and minimal photodamage to biological species, near-infrared (NIR) light is advantageous in biosensing and biochemical analysis. This work developed a photoelectrochemical (PEC) aptasensor for adenosine triphosphate (ATP) detection using NIR light as the irradiation source. In order to utilize NIR light, we prepared Yb-doped Bi₂S₃ (Yb-Bi₂S₃) nanorods to act as photoelectric transducing materials. Due to the unfilled 4f orbitals of Yb which introduced the impurity level between the valence band and conduction band of Bi₂S₃, Yb-Bi₂S₃ exhibited admirable photo-to-current conversion efficiency under NIR light irradiation. The Yb-Bi₂S₃ modified electrode was employed to construct a NIR light-driven PEC sensor using an ATP-binding aptamer as the recognition element. When ATP was present, the photocurrent signal of the proposed aptasensor declined, owing to the formation of an ATP-aptamer complex which enhanced the steric hindrance of electron transfer on the electrode. Under optimal conditions, the sensor showed a sensitive response to ATP in the concentration range from 0.5 to 300 nmol L^-1 with a detection limit of 0.1 nmol L^-1. The proposed aptasensor exhibited high selectivity, good repeatability and desirable stability. Moreover, it was successfully applied to ATP detection in human serum samples.

Combining printing and nanoparticle assembly: Methodology and application of nanoparticle patterning

Functional nanoparticles (NPs) with unique photoelectric, mechanical, magnetic, and chemical properties have attracted considerable attention. Aggregated NPs rather than individual NPs are generally required for sensing, electronics, and catalysis. However, the transformation of functional NP aggregates into scalable, controllable, and affordable functional devices remains challenging. Printing is a promising additive manufacturing technology for fabricating devices from NP building blocks because of its capabilities for rapid prototyping and versatile multifunctional manufacturing. This paper reviews recent advances in NP patterning based on the combination of self-assembly and printing technologies (including two-, three-, and four-dimensional printing), introduces the basic characteristics of these methods, and discusses various fields of NP patterning applications.

•

Nanoparticles (NPs) printing assembly is a good solution for patterned devices

•

NPs assembly can be combined with 2D, 3D, and 4D printing technologies

•

A variety of ink-dispersed NPs are available for printing assembly

•

NPs printing assembly technology is applied for nanosensing, energy storage, photodetector

A microfluidic cloth-based photoelectrochemical analytical device for the detection of glucose in saliva

Photoelectrochemical (PEC) detection is a widely used detection method that uses light to stimulate and photocurrent signals to detect the target. Due to the disengagement of the excitation unit and the detection unit, the PEC background signal is reduced, and the detection sensitivity is improved. In this work, we report the first demonstration of PEC detection for microfluidic cloth-based analytical devices (μCADs). Using PEC μCADs integrated with cadmium sulfide quantum dots (CdS QDs) and multiwalled carbon nanotubes (MWCNTs), the nonenzymatic, sensitive and rapid measurement of glucose in saliva has been achieved. For the cloth-based device, the PEC reaction zone and cloth-based electrodes can be fabricated by inexpensive wax-based and carbon ink-based screen-printing, respectively. By the layer-by-layer method, the as-prepared poly (dimethyl diadly ammonium chloride-functionalized) MWCNTs (PDDA-MWCNTs) and CdS QDs are successively adsorbed onto the working electrode surface of the cloth-based device. In the presence of an excitation source and glucose, the CdS QDs generate a strong oxidizing electron hole that can then continuously oxidize glucose to produce an electrical signal for glucose detection. Under optimized conditions, a linear dependence is obtained between the PEC signal and glucose concentrations in the range of 0.05-1000 μM with a detection limit of 15.99 nM. In the detection range, the cloth-based device also shows acceptable selectivity, reproducibility, and long-term stability. Moreover, the method has been implemented for the detection of glucose in real saliva samples, suggesting good potential for biochemical applications.

A Novel Photoelectrochemical Sensor Based on SiNWs@PDA for Efficient Detection of Myocardial Infarction

Based on the necessity and urgency of Cardiac Troponin I (cTnI) detection for the diagnosis of myocardial infarction, a novel unlabeled photoelectrochemical (PEC) immunosensor was developed to detect cTnI rapidly...