Photoelectrochemical (PEC) biosensing is a newly developed and promising analytical technique. The complete separation of excitation source (light) and detection signal (current) greatly reduces the ...undesired background signal, which is advantageous over both optical and electrochemical determination. Using a photocurrent from the PEC process as a detection signal, PEC biosensor can be operated at a low applied potential and exhibits high sensitivity with repeating cycles. In this account, we summary recent results in the study on PEC biosensing. To construct PEC sensors, exciting light sources of chemiluminescence (CL) and electrochemiluminescence, and PEC active materials including the selected semiconductors, dyes, composites of semiconductors-semiconductors and hybrids of dyes-semiconductors are employed. The principle of PEC biosensing is described and the mechanism in anodic and cathodic photocurrent generation processes is well investigated. On the other hand, in typical PEC biosensors, biomolecules such as antibodies and nucleic acids, are immobilized on the biosensing interface and bind with their corresponding targets via chemical reaction or biological recognition, enabling quantitative detection of the targets possible according to the variation of the photocurrents. Finally, several examples with the PEC biosensing application including immunosensors, DNA sensors, RNA sensors, aptasensors, enzymatic analysis, cytosensors, and detection of small molecules and metal ions are briefly introduced.
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•Selective photoelectrochemical architectures for biosensing have been outlined.•The principle and the mechanism of PEC biosensing are presented and summarized.•Exciting light sources for constructing PEC biosensors are well discussed.•The performance of PEC biosensors towards biomolecules is briefly introduced.
A novel photoelectrochemical biosensing platform for the detection of biomolecules at relatively low applied potentials was constructed using porphyrin-functionalized TiO2 nanoparticles. The ...functional TiO2 nanoparticles were prepared by dentate binding of TiO2 with sulfonic groups of water-soluble meso-tetrakis(4-sulfonatophenyl)porphyrin iron(III) monochloride (FeTPPS) and characterized by transmission electron microscopy; contact angle measurement; and Raman, X-ray photoelectron, and ultraviolet−visible absorption spectroscopies. The functional nanoparticles showed good dispersion in water and on indium tin oxide (ITO) surface. The resulting FeTPPS-TiO2-modified ITO electrode showed a photocurrent response at +0.2 V to a light excitation at 380 nm, which could be further sensitized through an oxidation process of biomolecules by the hole-injected FeTPPS. Using glutathione as a model, a methodology for sensitive photoelectrochemical biosensing at low potential was thus developed. Under optimal conditions, the proposed photoelectrochemical method could detect glutathione ranging from 0.05 to 2.4 mmol L−1 with a detection limit of 0.03 mmol L−1 at a signal-to-noise ratio of 3. The photoelectrochemical biosensor had an excellent specificity against anticancer drugs and could be successfully applied to the detection of reduced glutathione in gluthion injection, showing a promising application in photoelectrochemical biosensing.
On the basis of the absorption and emission spectra overlap, an enhanced resonance energy transfer caused by excition-plasmon resonance between reduced graphene oxide (RGO)-Au nanoparticles (AuNPs) ...and CdTe quantum dots (QDs) was obtained. With the synergy of AuNPs and RGO as a planelike energy acceptor, it resulted in the enhancement of energy transfer between excited CdTe QDs and RGO-AuNPs nanocomposites. Upon the novel sandwichlike structure formed via DNA hybridization, the exciton produced in CdTe QDs was annihilated. A damped photocurrent was obtained, which was acted as the background signal for the development of a universal photoelectrochemical (PEC) platform. With the use of carcinoembryonic antigen (CEA) as a model which bonded to its specific aptamer and destroyed the sandwichlike structure, the energy transfer efficiency was lowered, leading to PEC response augment. Thus a signal-on PEC aptasensor was constructed. Under 470 nm irradiation at −0.05 V, the PEC aptasensor for CEA determination exhibited a linear range from 0.001 to 2.0 ng mL–1 with a detection limit of 0.47 pg mL–1 at a signal-to-noise ratio of 3 and was satisfactory for clinical sample detection. Since different aptamers can specifically bind to different target molecules, the designed strategy has an expansive application for the construction of versatile PEC platforms.
Walnut shell, a renewable and easy-accessible agricultural biowaste, was utilized as a precursor for the preparation of activated carbon materials with KOH activation in this study. After a series of ...activation processes, therefore, the activated carbon derived from walnut shells achieved a specific surface area of 1016.4 m
2
/g. With the advantage of low cost and environmental friendly, the prepared carbon materials have superior electrochemical performance and excellent prospects in the application of supercapacitor electrodes. The morphology and textural properties of the AC samples were examined by N
2
adsorption–desorption, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and FTIR spectra. All the electrode samples exhibited excellent electrochemical performance. The AC-650 electrode achieved a maximum specific capacitance of 169.2 F/g at current density of 0.5 A/g in 6 M KOH electrolyte. This work provided an effective approach for the treatment and utilization of agricultural biowastes, which was worthwhile for economic, environmental, and societal viewpoints.
A novel in situ-generated nanogold plasmon-enhanced photoelectrochemical aptasensor for Hg2+ ions was fabricated using a perylene-3,4,9,10-tetracarboxylic acid/graphene (PTCA-GR) heterojunction. The ...fabricated photoelectrochemical aptasensor was based on thymine–Hg2+–thymine coordination chemistry and the plasmonic near-field absorption enhancement effect of the subsequent specific catalytic formation of nanogold. The energetic electrons from the surface plasmons of the nanogold were injected into the LUMO orbit of the organic PTCA semiconductor and then rapidly transferred to the electrode through GR due to the possible Hg2+-DNA molecular wires following irradiation with the visible light (λ > 450 nm) and at a bias voltage of 0.2 V. The fabricated aptasensor was linear in its response to the concentration of Hg2+ ions in the range of 5–500 pmol L–1, with a detection limit of 2 pmol L–1. The presence of up to 200-fold greater concentrations of other common metal ions did not interfere with the detection of Hg2+ ions in an aqueous system, and the results corresponded well with those obtained by ICP-MS. This novel plasmon-enhanced photoelectrochemical aptasensor exhibited good performance with its high sensitivity, good selectivity, low cost, and portable features. The strategy of the localized surface plasmon resonance through the in situ generation of noble metal nanoparticles paves the way for improvements in PEC aptasensor performance.
A versatile photoelectrochemical biosensing platform was developed based on DNA-CdS quantum dots (QDs) sensitized single-walled carbon nanotubes (SWCNTs)-COOH. Combining with cyclic enzymatic ...amplification, a convenient, sensitive and specific biosensor for the direct detection of microRNAs (miRNAs) was designed, which provided a novel approach for analysis of miRNAs.
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► The near-infrared QDs are synthesized in an aqueous solution. ► QDs-based biosensor exhibits visible-light induced cathodic photocurrent. ► The oxygen dependency of the photocurrent ...is verified. ► A photoelectrochemical strategy is established by coupling with enzymatic reaction. ► Photoelectrochemical sensor shows high upper detection limit, acceptable stability and accuracy.
A visible light induced photoelectrochemical biosensing platform based on oxygen-sensitive near-infrared quantum dots (NIR QDs) was developed for detection of glucose. The NIR QDs were synthesized in an aqueous solution, and characterized with scanning electron microscopy and X-ray photoelectron spectroscopy. The as-prepared NIR QDs were employed to construct oxygen-sensitive photoelectrochemical biosensor on a fluorine-doped tin oxide (FTO) electrode. The oxygen dependency of the photocurrent was investigated at as-prepared electrode, which demonstrated the signal of photocurrent is suppressed with the decreasing of oxygen. Coupling with the consumption of oxygen during enzymatic reaction, a photoelectrochemical strategy was proposed for the detection of substrate. Using glucose oxidase (GOx) as a model enzyme, that is, GOx was covalently attached to the surface of CdTe QDs, the resulting biosensor showed the sensitive response to glucose. Under the irradiation of visible light of a wavelength at 505nm, the proposed photoelectrochemical method could detect glucose ranging from 0.1mM to 11mM with a detection limit of 0.04mM. The photoelectrochemical biosensor showed a good performance with high upper detection limit, acceptable stability and accuracy, providing an alternative method for monitoring biomolecules and extending the application of near-infrared QDs.
A robust aptasensor for Ag(+) was proposed for the first time using an enhanced ZnO nanorod-based photoelectrochemistry by in situ generated AgBr via layer-by-layer assembly. This work opens up new ...avenues for application of one-dimensional ZnO nanorod arrays in photoelectrochemical sensing. Additionally, the strategy of employing in situ generated narrow-bandgap semiconductors paves a new way for photoelectrochemical sensing.
A low potential and competitive photoelectrochemical biosensing platform was developed using quantum dots sensitized titanium dioxide decorated reduced graphene oxide (TiO2–RGO) nanocomposites. The ...nanocomposites were prepared through electrostatic interaction between mercaptoacetic acid wrapped CdSe quantum dots with negative charge and TiO2–RGO hybrids with positive charge obtained via ultrasonic and acid treatments. Electron microscopes and spectroscopes were used to characterize the functionalized nanocomposites films of CdSe/TiO2–RGO, and the fabrication process of the photoelectrochemical biosensor. Based on the high photovoltaic conversion efficiency of CdSe/TiO2–RGO nanocomposites films, after introducing biological recognition and competitive immunoreaction, a low potential and competitive photoelectrochemical biosensor for carcinoembryonic antigen (CEA) detection was fabricated. The synergic effect of horseradish peroxide and benzo-4-chlorohexadienone decreased the background signal, leading to signal amplification. Under the light irradiation of 430nm and the applied potential of 0V, the biosensor detected CEA with a linear range from 0.003 to 100ngmL−1 and the detection limit was estimated to be 1.38pgmL−1 at a S/N of 3. It was satisfactory for clinical sample detection. The proposed competitive and low potential photoelectrochemical biosensor under irradiation of visible light exhibited good performance, which has a promising prospect in clinical diagnose.
•A low-potential and competitive photoelectrochemical biosensor was constructed under visible light irradiation.•The nanocomposites of CdSe quantum dots and TiO2 decorated reduced graphene oxide exhibited high photovoltaic conversion efficiency.•Enzymatic biocatalytic precipitation and competitive non-productive absorption of HRP were used for signal amplification.
Montmorillonite is successfully attached to the surface of porous graphitic carbon nitride by electrostatic self-assembly method, so that the composite photocatalyst has larger specific surface area ...and rich pore structure. Through a series of characterization methods such as surface area measurement (BET), photoluminescence spectra, and UV–vis diffuse reflection spectroscopy, it is confirmed that the introduction of montmorillonite is conducive to the separation of photogenerated carriers and holes in graphitic carbon nitride. The photocatalytic degradation of 20 ppm rhodamine B by composite materials only takes 90 min, and it shows the ability to degrade high concentration rhodamine B. After four cycles of regeneration, the degradation rate of rhodamine B by composite materials is still 95.4%. After the combination of porous graphitic carbon nitride and montmorillonite with electrostatic self-assembly, it has the ability to degradation of high concentration dyes, which provides a development idea for the practical application of photocatalytic technology in the field of dye degradation.
