The photoelectrochemical performance of rutile TiO2 mesocrystals has been demonstrated to be significantly improved by a chelating-assembly of poly-dopamine on the surface of the TiO2 mesocrystals. The formed benzoquinone groups on poly-dopamine could act as electron receivers to take over the photo-induced electrons of TiO2 mesocrystals, thereby constituting a self-reinforced functionality transducing interface to enhance the cathode photocurrent. Herein, zearalenone as a representative mycotoxin was used as a model analyte to assist the immunoassay establishment. The bioconjugates of secondary antibody integrated ordered mesoporous Co3O4 were introduced through immunoreaction. The Co3O4, as a powerful scaffold, could load more bioactive molecules due to its mesoporous structure. Owing to the inevitable steric hindrance caused by the bioconjugates, the photo-initiated electrons in the TiO2 mesocrystals/poly-dopamine composite were inaccessible to reduce the oxygen in the electrolyte, thus depressing the photocurrent density. Meanwhile, partial exciting light found it difficult to arrive at the TiO2 mesocrystals due to Co3O4 with a felicitous band gap of 2.07 eV which consumed the partial light energy. Under optimal conditions, this immunosensor had a wide linear range from 10−6 to 20 ng mL−1 for zearalenone detection. The specificity, precision, and reproducibility were satisfactory for this biosensor, which offered a valuable and versatile protocol in photoelectrochemical immunoassay development.

A versatile photoelectrochemical immunoassay protocol was designed for quantitative monitoring of tumor markers by utilizing the poly(dopamine)-sensitized titanium dioxide (TiO2) signal crystal with an ordered mesoporous carbon support. Poly(dopamine) was introduced to alter the optical properties of the TiO2 signal crystal, thereby improving the visible light absorption and photoelectrical responses. More importantly, a new enzyme-like biomimetic catalyst was exploited as the signal amplifier to catalyze the reaction of hydroquinone. The generated product was deposited on the electrode surface and served as an efficient sacrificial electron acceptor, which could receive the photo-generated electrons of the excited semiconductor to assist the cathode photocurrent enhancement. Herein, a competitive-type immunosensor was achieved through the biomimetic catalyst labeled prostate specific antigen competing with the target antigen of different concentrations to react with the specific antibody anchored on the poly(dopamine)-sensitized TiO2 signal crystal. Under optimal conditions, the photocurrent decreased with increasing target concentration in a dynamic working range from 1 × 10−6 ng mL−1 to 50 ng mL−1, which provided a new photoelectrochemical method for tumor markers analysis.

In this work, we first exposed that the application of p-type semiconductor, silver iodide-chitosan nanoparticle (SICNP), acted as peroxidase mimetic to catalyze the bioprecipitation reaction for signal-amplification photocathodic immunosensing of human interleukin-6 (IL-6). After immobilization of captured antibody onto a polyethylenimine-functionalized carbon nitride (CN) matrix, SICNPs as photoactive tags and peroxidase mimetics were labeled on secondary antibodies, which were subsequently introduced onto the sensing interface to construct sandwich immunoassay platform through antigen–antibody specific recognition. Due to the matched energy levels between CN and AgI, the photocurrent intensity and photostability of SICNP were dramatically improved with rapid separation and transportation of photogenerated carriers. Moreover, the insoluble product in effective biocatalytic precipitation reaction served as electron acceptor to scavenge the photoexcited electron, leading to great amplification of the photocurrent signal of SICNP again. With the help of multiamplification processes, this photocathodic immunosensor presented a turn-on photoelectrochemical performance for IL-6, which showed wide linear dynamic range from 10–6 to 10 pg/mL with the ultralow detection limit of 0.737 ag/mL. This work also performed the promising application of SICNP in developing an ultrasensitive, cost-effective, and enzyme-free photocathodic immunosensor for biomarkers.

It is a great challenge to fabricate multiplex and convenient photoelectrochemical biosensors for ultrasensitive determination of biomarkers. Herein, a fascinating potentiometric addressable photoelectrochemical biosensor was reported for double biomarkers’ detection by varying the applied bias in the detection process. In this biosensor, the nanocomposite of cube anatase TiO2 mesocrystals and polyamidoamine dendrimers modified a dual disk electrode as an excellent photoelectrochemical sensing matrix. Subsequently, two important biomarkers in serum for prostate cancer, prostate-specific antigen and human interleukin-6, were immobilized onto the different disks of modified electrode via glutaraldehyde bridges. Then another two photosensitizers, graphitic-carbon-nitride-labeled and CS-AgI-labeled different antibodies, were self-assembled onto the electrode surface by a corresponding competitive immune recognition reaction. The change in photocurrent with the target antigen concentration at different critical voltages enables us to selectively and quantitatively determine targets. The results demonstrated that this potentiometric addressable photoelectrochemical biosensing strategy not only has great promise as a new point-of-care diagnostic tool for early detection of prostate cancer but also can be conveniently expanded to multiplex biosensing by simply change biomarkers. More importantly, this work provides an unambiguous operating guideline of multiplex photoelectrochemical immunoassay.

Prostaglandin E1, a cardiac biomarker, is a pivotal member of the prostaglandin family which exerts diverse and powerful effects on cell function in many organ systems. In this study, a new approach for the ultrasensitive determination of prostaglandin E1 was proposed by using the ECL of peroxydisulfate with oxygen as coreactant. Compared to most peroxydisulfate ECL sensor, this proposed ECL strategy propounded employing oxygen evolution reaction to enhance the concentration of oxygen, which was unprecedented in ECL sensing platform. Herein, ultrathin NiCo2O4 nanosheets with large surface area and mesoporous structure were prepared by a facile method, and adamantane as enhancer was decorated on the surface of amino-modified NiCo2O4 to generate a bifunctional catalyst of NiCo2O4@AD(Prostaglandin E), which possessed excellent catalytic performance toward the oxygen evolution reaction. Accordingly, the sensitivity of ECL immunosensor was enhanced with the increasing concentration of oxygen by the bifunctional catalyst of NiCo2O4@AD. And the ECL response of the peroxydisulfate would decrease owing to the interaction between antibody and antigen on the modified electrode. Consequently, on the basis of the ECL intensity change of peroxydisulfate, the proposed immunosensor has realized ultrasensitive PGE1 assay with a wide linear detection range of 0.1 fg/ml to1 ng/ml and a detection limit of 0.1 fg/ml. The proposed ECL immunosensor was performed to analyze prostaglandin E1 in human serum, and satisfactory recoveries were obtained, indicating its potential applications in clinical diagnostics.

An ultrasensitive sandwich-type electrochemiluminescent biosensor based on carbonaceous based nanomaterials was fabricated for alpha-fetoprotein detection. Herein, the composite of fullerene, graphene oxide and chitosan with specific surface area, good water dispersibility, and excellent biocompatibility was first modified onto the electrode surface and then it was in situ electrochemical reduced to improve the conductivity. After the capturing antibody was immobilized onto the modified electrode surface, the detection antibody together with poly(amidoamine) dendrimers functionalized carbon nanodots as the recognizable signal tags was self-assembled onto the electrode by typical sandwich immune reaction. By this design, the abundant functional groups, good water dispersibility and good electroconductivity of poly(amidoamine) dendrimers functionalized carbon nanodots make the composite not only an immobilizing platform to carrier numerous detection antibodies, but also an promising promoter for the electrochemiluminescent signal of luminol. With the aforementioned amplify factor, the established electrochemiluminescent biosensor under the optimal conditions demonstrated a wider dynamic response from 1 fg mL−1 to 80 ng mL−1 with a low detection limit of 0.33 fg mL−1. Additionally, the experimental results exhibited the immunosensor possessed excellent stability, reproducibility and selectively. Accordingly, this immunosensing strategy for alpha-fetoprotein with the assistance of poly(amidoamine) dendrimers functionalized carbon nanodots provided a promising approach in clinical disease scanning.

In this work, a ratiometric electrochemiluminescent immunosensor on octahedral anatase mesocrystals (OAM) support for the ultrasensitive determination of alpha-fetal protein (AFP) by exploiting chitosan functionalized silver iodide (CS-AgI) as biomimetic catalyst was developed. The proposed system was achieved by choosing luminol and potassium persulfate (K2S2O8) as promising ECL emitter units, due to the potential-resolved property and maximum emission wavelength-resolved property of them. And OAM with high porosity, oriented subunit alignment and large surface area was adopted to adsorb luminol to form solid state ECL and as affinity support to immobilize abounding antibodies of AFP (Ab) firstly. Furthermore, CS-AgI was found to possess biomimetic catalyst activity, which could catalyze the decomposition of hydrogen peroxide that as the common coreactant both of luminol and K2S2O8 and thus the dual ECL responses was amplified. When the biosensor incubated in the mixture solution of CS-AgI labeled AFP (CS-AgI@AFP) and the target AFP, owing to the competitive recognition of the CS-AgI@AFP and the target AFP with Ab, the amount of the CS-AgI@AFP captured by the immobilized Ab reduced with the increasing concentration of AFP, accordingly, the dual ECL responses decreased. Upon the basis of the ratio of ECL intensities at two excitation potentials, this proposed ratiometric ECL strategy achieved ultrasensitive determination for the alpha-fetal protein via competitive immunoreaction with a wide linear detection range of 1 fg/ml to 20 ng/ml and a detection limit was 1 fg/ml.

•Multifunctional all-carbon nanohybrids were applied as the photoelectrochemical matrix for providing the basal photocurrent response.Herein, a new photoelectrochemical sensor for aflatoxin B1 (AFB1) detection was established based on the all-carbon nanohybrids as transducer scaffold accompanied with quasi-octahedral TiO2 mesocrystal (QOTM) absorbed dentritic Si phthalocyanines (SiPcs) as the efficient bioprobe. Specifically, the all-carbon nanocomposites exhibited fine photoelectric properties due to the photo-generated electrons of carbon quantum dots could be rapidly accepted by conductive carbon nanohorns, which evidently expedited the electron transport, and the nanohybrids were first employed as affinity support to anchor AFB1 antibody. The dentritic SiPcs sensitized QOTM presented better photocurrent response and stability in comparison with QOTM alone due to impressive light-harvesting capability of the dentritic SiPcs. Under light irradiation, the photo-induced electrons of SiPcs migrated to the QOTM, and successively transferred to carbon quantum dots as electron relay mediator then via carbon nanohorns to the electrode surface based on suitable band alignment. This hierarchical charge transport cascade paradigm efficiently impeded the charge recombination, resulting in noticeably increased photocurrent. In this competitive immunosensor, the AFB1 standards compete with the labeled AFB1, leading to photocurrent decreased with the increasing target concentration in a wide linear range of 10− 6–102 ng/mL. The newly developed methodology provided a versatile approach for ultrasensitive detection of small molecules.

•We developed a photoelectrochemical biosensor for highly sensitive detection of glyphosate.•The prepared photoelectrochemical biosensor was successfully utilized to detect practical samples.•The proposed platform exhibited fine photoelectric conversion performance under light illumination.The exploitation and design of sensitive photoelectrochemical sensor with high performance materials is of great significance to expanding approaches for practical evaluation. Herein, a signal-on photoelectrochemical strategy with graphitic carbon nitride decorated Ag+ based on the binding-induced internal-displacement for glyphosate monitoring was established. The mechanism of this platform has been elaborately explored and the high sensitivity should be ascribed to two aspects. Firstly, graphite-like carbon nitride as visible light-active material possesses fine photocatalytic activity. The pyridine nitrogen units on g-C3N4 backbone could absorb Ag+ through chemical absorption and then photo-generated electrons would be reacted by Ag+, leading to the inhibition of electrons transfer and decrement of photocurrent. However, binding-induced internal-displacement of chelate effect between Ag+ and glyphosate, which promoted the constitution of current circuit and signal improvement owing to that Ag+ was deprived from the carbon nitride nanosheets and photo-induced electrons could transfer to the electrode. Under the optimal conditions, the photocurrent change was proportional to the glyphosate concentration logarithmically with the wide liner range from 1.0 × 10−10 to 1.0 × 10−3 M and a low detection limit of 30 pM. This economical and sensitive sensor system showed fine practicability which could be applied for broader applications.

•Magnetic functionalized nanofibers were synthesized by electrospun technology.•Magnetically controlled technology was used to immobilize the magnetic electrospun nanofibers.•We developed a label-free ECL immunosensor for highly sensitive detection of aflatoxin B1.•The prepared immunosensor was successfully utilized to detect practical samples.A label-free electrochemiluminescent (ECL) immunoassay protocol was fabricated based on magnetic nanoarchitecture for sensitive detection of aflatoxin B1 (AFB1). It was constructed by using magnetic control technology to immobilize the magnetic nanofibers on carbon nanohorns (CNHs) matrix. First, CNHs possessed superstructure with excellent electrical conductivity, biocompatibility, large specific surface areas, and variable porosity, which could effectively amplified the ECL signal of luminol. In addition, magnetic nanofibers with magnetism could be immobilized tightly on magnetic electrode and accommodated large number of antibody on the interface. Finally, owing to the specific recognition of antibody with AFB1 antigens and the effective ECL amplification of the nanoarchitecture, the as-proposed immunosensor afforded a remarkably sensitive analysis of the AFB1 with a wide detection linear range from 0.05 ng/mL to 200 ng/mL and a detection limit of 0.02 ng/mL. More importantly, the immunosensor was successfully utilized to detect practical samples. Therefore, the prepared immunosensor exhibited its reliability and feasibility. Furthermore, with the good stability, acceptable precision and reproducibility, the proposed immunosensor possessed promising practicability for other analytical fields.

•A feasible photoelectrochemical sensor based on graphene supported TiO2 mesocrystal for highly sensitive and selective monitoring Con A was designed.•The introduction of graphene heavily strengthened photocurrent response of TiO2 mesocrystal and enhanced the detectable sensitivity due to the prominent conductivity of graphene.•The NiCo2O4 labeled glucose probe could capture the photo-induced electrons from TiO2 mesocrystal.This work designed a delicate signal-on photoelectrochemical sensing methodology for concanavalin A monitoring by coupling graphene-supported quasi-octahedral TiO2 mesocrystal with an efficient enzyme-free labeling strategy. Herein, graphene with prominent conductivity could accelerate photo-generated electrons transfer, thus enhancing the photocurrent response. Currently, labeling of various enzymes was the mainly strategy for signal amplification, unfavorably, this method usually suffered inferior stability. Hence, the exploration and development of NiCo2O4 labeling was proposed here, which could effectively accept the photo-induced electrons from conduction band of TiO2 mesocrystal, leading to the decrease of the photocurrent intensity. Accordingly, a signal-on non-enzymatic photoelectrochemical sensor was constructed based on immobilized concanavalin A competing with isolated concanavalin A of various concentrations for reaction with the NiCo2O4 labeled glucose conjugates. Under the optimized conditions, the photocurrent increased with the increasing concanavalin A concentration in a dynamic linear range from 0.05 ng/mL to 0.5 μg/mL, thereby proposing a general format for practical use in quantitative determination of concanavalin A. Promisingly, the successful consideration of graphene sensitized TiO2 mesocrystal further broadened the application of excellent photoactive materials for photoelectrochemical sensing platform.

TiO2-B nanorods, with excellent properties including large specific surface area, open structures with significant voids, and continuous channels, were explored for the first time in the photoelectrochemical biosensing field. To reduce the destructive effect of UV light on biomolecules, dopamine was introduced onto the TiO2-B nanorod surface through the coordination of dopamine to the undercoordinated titanium atoms of the TiO2-B nanorods, which makes the complex a promising matrix for subsequent biosensing. Furthermore, concanavalin A as a recognition element was attached onto the TiO2-B nanorod/dopamine modified electrode surface by virtue of covalent interaction between concanavalin A and dopamine. Accordingly, a new competitive-like non-enzymatic photoelectrochemical biosensor was established by using glucose labeled SiO2 nanospheres of fixed concentration as photoelectrochemical signal inhibitors competing with target glucose of various concentrations for reaction with concanavalin A. Moreover, this ultrasensitive biosensor with excellent analytical performance was successful applied to noninvasive glucose determination in human saliva. Promisingly, the successful application of TiO2-B nanorods in this research provides a new consideration in the selection of excellent photoactive materials for photoelectrochemical sensing.

An ultrasensitive dual-signal electro-chemiluminescent intelligent biosensor constructed from superstructure TiO2 mesocrystals is proposed for the detection of metallothionein.

A visible light responsive photocatalytic hybrid with excellent photoelectrochemical activity was first fabricated via the self-assembly of Au nanorods onto poly(L-cysteine) modified graphitic carbon nitride nanosheets. Herein, layered structural graphitic carbon nitride nanosheets with a proper band gap, high stability, and nontoxicity, as a photoactive material, demonstrate a high photocatalytic activity. Furthermore, the incorporation of multifunctional Au nanorods gave the hybrid a Schottky barrier and localized surface plasmonic resonance, which considerably enhanced the separation of the photo-excited electrons and holes, resulting in increased photoelectrochemical performance. As a proof of concept, mercapto-beta-cyclodextrin as a bionic recognition device was introduced into the hybrid to selectively detect naringin on the basis of the dramatic decreasing of photocurrent. The visible-light driven photoelectrochemical sensor exhibited excellent analytical performance, including high sensitivity, good selectivity and wide linear range from 1 × 10−4 to 1 × 10−10 M.

We have developed a sensor for 4-aminophenylarsonic acid (4-APhAA) by coating a glassy carbon electrode (GCE) with a composite prepared from an ionic liquid and dahlia-like carbon nanohorns (CNHs). The good electric conductivity, large surface area and high pore volume of the CNHs, and the synergistic action of the ionic liquid (which is a good dispersant with excellent ion conductivity) result in efficient electrocatalysis towards oxidation of 4-APhAA. The effect was investigated by various electrochemical methods, and the electron transfer coefficient, diffusion coefficient, standard heterogeneous rate constant and thermodynamic activation energy were determined. The response range of 4-APhAA was evaluated using an i-t plot. If operated at a working voltage of 900 mV (vs Ag/AgCl), the sensor responds to 4-APhAA over the 0.5 μM to 3.5 M concentration range.

•The photoelectrochemical performances of TiO2 mesocrystals and TiO2 single crystals were firstly compared by a series of photoelectrochmeical tests for exploring the influence of structure differences between mesocrystals and single crystals on photoelectrochemical activity.•An elegant photoelectrochemical immune sensing platform was firstly developed by using the multifunctional TiO2 mesocrystals as excellent photoactivity materials and strong absorbers.•In this sensing platform, carbon nanohorns with outstanding electrical conductivity was employed to support TiO2 mesocrystals and accelerate the transfer of photogenerated electrons, and horseradish peroxidase was introduced by the immune recognition reaction to enzyme-assisted in situ generation of CdS QDs.•The multiplex amplification strategy successfully realized the ultrasensitive detection of α-fetoprotein antigen and achieved excellent analytical performances, which will offer a rational and practical consideration for fabricating new and high-performance photoelectrochemical sensing devices.Mesocrystals, as the assemblies of crystallographically oriented nanocrystals, have single-crystal-like atom structures and scattering features but with much higher porosity than single-crystalline materials, making them promising substitutes for conventional single crystals in photoelectrochemical application. As a proof-of-concept, a series of photoelectrochemical tests were investigated to understand the influence of the differences between them on photoelectrochemical activity. Expectedly, comparing with TiO2 single crystals, TiO2 mesocrystals demonstrated higher photoelectrochemical capability, which provides unique new opportunities for materials design in the fields of solar-energy conversion and catalysis. Therefore, an elegant photoelectrochemical biosensing platform was firstly developed by virtue of carbon nanohorns with outstanding electrical conductivity support multifunctional TiO2 mesocrystals to accelerate the transfer of photogenerated electrons, and then horseradish peroxidase was introduced through the immune recognition reaction for enzyme-assisted in situ generating CdS QDs. The multiplex amplification strategy successfully achieved the ultrasensitive detection of α-fetoprotein antigen. Promisingly, the successful application of multiplex amplification strategy affords a rational and practical consideration for the fabrication of new and high-performance photoelectrochemical sensing devices.

A ternary hybrid was developed through interaction between a hierarchical-ordered TiO2 and a thiol group that was obtained by in situ chemical polymerization of l-cysteine on the carbon nanohorn (CNH) superstructure modified electrode. Herein, unique-ordered TiO2 superstructures with quasi-octahedral shape that possess high crystallinity, high porosity, oriented subunit alignment, very large specific surface area, and superior photocatalytic activity were first introduced as a photosensitizer element in the photoelectrochemical determination. Additionally, the assembly of hierarchical-structured CNHs was used to provide an excellent electron-transport matrix to capture and transport an electron from excited anatase to the electrode rapidly, hampering the electron–hole recombination effectively, resulting in improved photoelectrochemical response and higher photocatalytic activity in the visible light region. Owing to the dependence of the photocurrent signal on the concentration of electron donor, 4-methylimidozal, which can act as a photogenerated hole scavenger, an exquisite photoelectrochemical sensor was successfully fabricated with a wide linear range from 1 × 10–4 to 1 × 10–10 M, and the detection limit was down to 30 pM. The low applied potential of 0.2 V was beneficial to the elimination of interference from other reductive species that coexisted in the real samples. More importantly, the mesocrystal was first introduced in the fabricating of a biosensor, which not only opens up a new avenue for biosensors manufactured based on mesocrystal materials but also provides beneficial lessons in the research fields ranging from solar cells to photocatalysis.

•Peroxydisulfate was used as a new cheap, strong ECL reagent for immunoassay.•Using electrospun composite nanofibers to form 3D electrode for ECL immunoassay.•An ECL image of peroxydisulfate on the sensing platform was firstly recorded.•Offering a method to calculate the interaction of biological recognition system.A new biosensing platform based on electrospun carbon nanotubes nanofibers (CNTs@PNFs) composite, which enabled strong electrochemiluminescent emission of peroxydisulfate, was firstly developed for immunoassay with favorable analytical performances, and then was utilized to evaluate the interaction between antibody and antigen in vitro. Moreover, the obvious ECL image of peroxydisulfate on the prepared sensing platform was firstly recorded in this report. In order to expand the application of peroxydisulfate ECL, the specific recognization biomolecules, α-fetoprotein (AFP) antibody was bound to the functionalized film via electrostatic interaction for fabricating label-free ECL immunosensor to detect α-AFP. Based on the ECL change resulting from the specific immunoreaction between antigen and antibody, the quantitative analysis for AFP with wide dynamic response in the range from 0.1 pg mL−1 to 160 ng mL−1 was realized. And the limit of detection was estimated to be 0.09 pg mL−1. Therefore, the flexible sensing platform not only acted as the sensitized sensing element, but also offered a suitable carrier for immobilization of biological recognition elements with low-toxicity and eco-friendliness, which opened a promising approach to developing further electrospun nanofiber based amplified ECL biosensor with favorable analytical performances.

A simple and sensitive electrochemical sensor which was constructed with alkoxy silane and carbon nanohorns was first utilized to detect some food borne contaminants, including malachite green, sudans, triclosan, bisphenol A. Due to the large surface area, good conductivity, admirable electrochemical activity of carbon nanohorns and excellent immobility of alkoxy silane, the synergistic effect root from the easily controlled composition of organic–inorganic hybrid film was achieved. The present work demonstrated this functional film brings advantageous features such as stable and strong adherence to electrode matrix and excellent electrochemical catalysis, to electrochemical sensor to achieve advanced application. By choosing triclosan and malachite green as object, their kinetic parameters on this modified electrode were calculated and the relative quantitive protocols were established. Compared with previous reports, the designed sensor presented lower detection limit, higher sensitivity and more broad linear range. This electrochemical platform offered a useful tool for the on-site determination of food born contamination.The electrochemical sensor based on carbon nanohorns formed hybrid for food born contamination was proposed.

We have constructed a novel electrochemiluminescence (ECL) platform by functionalizing a poly(amidoamine) dendrimer (PAAD) with titanate nanotubes (TiNTs). The PAAD has an open spherical structure that possesses a high density of active groups and thus favors mass transport, while the TiNTs possess excellent electronic conductivity and thus can promote electron transfer on the surface of a glassy carbon electrode (GCE). A study on the intensity and stability of the ECL of luminol on the modified GCE revealed a substantial improvement compared to that of a bare GCE. The effects of the concentration of TiNTs, the pH value of the solution, and of electrochemical parameters on the intensity of the ECL of luminol were studied and resulted in a sensitive ECL sensor for hydrogen peroxide (H2O2) that works in the concentration range of 1 nM to 0.9 μM. The scavenging effect of superoxide dismutase (SOD) on the H2O2 electrode ECL was then exploited to design a biosensor for the determination of SOD in concentrations between 50 and 500 nM.

A simple and highly sensitive electrochemiluminescent immunosensor based on nanocomposite architecture of the one-pot synthesized carbon nanodots and Nafion composite film was proposed for the detection of α-fetoprotein.

In this paper, we propose a facile approach for palladium nanoparticles load using silicon carbide nanoparticles as the new supported matrix and a familiar NaBH4 as reducer. Detailed X-ray photoelectron spectrum (XPS) and transmission electron microscopy (TEM) analysis of the resultant products indicated that palladium nanoparticles are successfully immobilized onto the surface of the silicon carbide nanoparticles with uniform size distribution between 5 and 7 nm. The relative electrochemical characterization clearly demonstrated excellent electrocatalytic activity of this material toward alcohol in alkaline electrolytes. Investigation on the characteristics of the electrocatalytic activity of this material further indicated that the palladium nanoparticles supporting on SiC are very promising for direct alcohol fuel cells (DMFCs), biosensor and electronic devices. Moreover, it was proved that silicon carbide nanoparticles with outstanding properties as support for catalysis are of strong practical interest. And the silicon carbide could perform attractive role in adsorbents, electrodes, biomedical applications, etc.

A highly porous three-dimensional sensing interface was achieved on glassy carbon (GCE) by employing ordered mesoporous carbon (OMC) and polyaniline (PANI). Compared with the cathodic electrochemiluminescence (ECL) of luminol at bare glassy carbon electrode, a stable and intense cathodic ECL emission of luminol over −0.5 V which related to the reduction of dissolved oxygen in solution was triggered at OMC and PANI constructed ECL sensing platform. The influence factors affecting the electrode configuration such as the concentration of OMC, the dripping amount of OMC, the polymerization cycles of PANI and the pH value of buffer solution on cathodic ECL intensity of luminol were investigated in detail. The PANI/CMK composite modified electrode exhibited an effective ECL platform for cathodic ECL of luminol due to its attractive features, such as excellent electrical conductivity, extremely well-ordered pore structure and high specific pore volume. The possible ECL mechanism was discussed according to the presented experimental results.

•An efficient photoelectrochemical strategy was designed for trypsin detection.•Polyethylenimine decorated TiO2 mesocrystal were used as photoactive matrix.•Boron-doped carbon dots further elevated sensitivity by labeling on the peptide.Herein, a delicate photoelectrochemical biosensor for quantitative detection of trypsin was successfully established by virtue of polyethylenimine-sensitized TiO2 mesocrystal as the photoactive matrix integrated with Boron-doped carbon quantum dots labeled peptide as the signal amplification tags. Specifically, polyethylenimine with fine photo-stability was introduced here as the electron transporting layer to reduce the energy barrier of TiO2 mesocrystal, thereby facilitating the carriers transfer and improving the photocurrent response. Moreover, the Boron-doped carbon dots-peptide bioconjugates could noticeably decrease the photocurrent due to the competitively light harvesting by Boron-doped carbon dots and the steric hindrance of peptide chains, leading to less light energy arriving at the TiO2 mesocrystal and hindering the electrons transfer between the electrolyte and electrode. The anchored conjugates synergistically promoted the decline of photocurrent signal, evidently enhancing the sensitivity of this detection protocol. When trypsin was incubated, the photoelectric signal was obviously re-promoting because arginine-containing peptide chains could be specifically cleaved by trypsin and the Boron-doped carbon quantum dots was affranchised from the electrode, making the most of the previous suppression effects released. Therefore, the intensity of photocurrent signal was proportional to the trypsin concentration in a wide linger range from 1×10−7 mg/mL to 1.0 mg/mL. This practical and elegant “on-off-on” biosensor with high sensitivity offered a promising scheme to monitor various proteases and the inhibitors screening for early diagnoses of different diseases.

TiO2-B nanorods, with excellent properties including large specific surface area, open structures with significant voids, and continuous channels, were explored for the first time in the photoelectrochemical biosensing field. To reduce the destructive effect of UV light on biomolecules, dopamine was introduced onto the TiO2-B nanorod surface through the coordination of dopamine to the undercoordinated titanium atoms of the TiO2-B nanorods, which makes the complex a promising matrix for subsequent biosensing. Furthermore, concanavalin A as a recognition element was attached onto the TiO2-B nanorod/dopamine modified electrode surface by virtue of covalent interaction between concanavalin A and dopamine. Accordingly, a new competitive-like non-enzymatic photoelectrochemical biosensor was established by using glucose labeled SiO2 nanospheres of fixed concentration as photoelectrochemical signal inhibitors competing with target glucose of various concentrations for reaction with concanavalin A. Moreover, this ultrasensitive biosensor with excellent analytical performance was successful applied to noninvasive glucose determination in human saliva. Promisingly, the successful application of TiO2-B nanorods in this research provides a new consideration in the selection of excellent photoactive materials for photoelectrochemical sensing.

A versatile photoelectrochemical immunoassay protocol was designed for quantitative monitoring of tumor markers by utilizing the poly(dopamine)-sensitized titanium dioxide (TiO2) signal crystal with an ordered mesoporous carbon support. Poly(dopamine) was introduced to alter the optical properties of the TiO2 signal crystal, thereby improving the visible light absorption and photoelectrical responses. More importantly, a new enzyme-like biomimetic catalyst was exploited as the signal amplifier to catalyze the reaction of hydroquinone. The generated product was deposited on the electrode surface and served as an efficient sacrificial electron acceptor, which could receive the photo-generated electrons of the excited semiconductor to assist the cathode photocurrent enhancement. Herein, a competitive-type immunosensor was achieved through the biomimetic catalyst labeled prostate specific antigen competing with the target antigen of different concentrations to react with the specific antibody anchored on the poly(dopamine)-sensitized TiO2 signal crystal. Under optimal conditions, the photocurrent decreased with increasing target concentration in a dynamic working range from 1 × 10−6 ng mL−1 to 50 ng mL−1, which provided a new photoelectrochemical method for tumor markers analysis.

An ultrasensitive dual-signal electro-chemiluminescent intelligent biosensor constructed from superstructure TiO2 mesocrystals is proposed for the detection of metallothionein.

A simple and highly sensitive electrochemiluminescent immunosensor based on nanocomposite architecture of the one-pot synthesized carbon nanodots and Nafion composite film was proposed for the detection of α-fetoprotein.