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In this study, a CRISPR/Cas12a (LbCpf1)-mediated electrochemiluminescence (ECL) paper-based platform on the basis of a three-dimensional (3D) DNA walker was proposed for the ultrasensitive detection of miRNA-141. Initially, 3D-rGO with a tremendous loading space was modified on the paper working electrode (PWE) to construct an excellent conductive substrate and facilitate the growth of AuPd nanoparticles (NPs). Afterward, the AuPd NPs were introduced as the coreaction emitter medium of the 3D-rGO/PWE to provide convenience for the transformation between S2O82- and SO42-, amplifying the ECL emission of g-C3N4 nanosheets (NSs). Meanwhile, with the help of Nt.BsmAI nicking endonuclease, a 3D DNA walker signal amplifier was designed to convert and magnify the target miRNA-141 into a particular trigger sequence, which could act as activator DNA to motivate the trans-acting deoxyribonuclease activity of CRISPR/Cas12a to further achieve efficient annihilation of the ECL signal. Furthermore, the proposed multimechanism-driven biosensor exhibited excellent sensitivity and specificity, with a relatively low detection limit at 0.331 fM (S/N = 3) in the concentration range between 1 fM and 10 nM. Consequently, the designed strategy not only extended the application scope of CRISPR/Cas12a but also devoted a new approach for the clinical diagnosis of modern medicine.

In this work, a target-induced signal quencher release strategy was proposed to construct a sensitive photoelectrochemical (PEC) sensor. To achieve this, Cu nanoclusters (NCs) featuring outstanding chemical performance were introduced and then pickled with acid to generate Cu2+ signal quenchers to quench the photocurrent response. Moreover, the three-dimensional (3D) hierarchical seaweed-like TiO2 nanomaterial (HSTN) was prepared for the first time and served as the electron transporting material, which could provide the highly efficient pathways for the transfer of photoinduced electrons. Meanwhile, in order to extend the light response to the visible range, narrow band gap CdS quantum dots (QDs) were employed to form a HSTN/CdS heterojunction. In addition, magnetic bead (MB) modified PSA aptamer (MB-Apt) was used as the auxiliary structure which could combine with DNA-Cu NCs through specific recognition. When the target PSA was found, the MB-Apt would bond with PSA due to the relatively large interaction force, triggering the release of Cu NCs. With the aid of acid, the Cu NCs could be converted to Cu2+ and then react with CdS to form CuxS, decreasing the photocurrent signal. Consequently, the concentration of PSA could be accurately detected through monitoring the change of photocurrent. This work provides an ingenious idea for the fabrication of highly sensitive PEC sensors.

A wide-spectrum-responsive paper-based photoelectrochemical (PEC) sensor based on black phosphorus (BP) quantum dots (QDs)-sensitized titanium dioxide (TiO2-BP QDs) for prostate-specific antigen (PSA) detection was presented herein. Carbon nanotubes (CNTs) were first coated on paper to form a flexible conductive paper electrode. TiO2 nanoparticles were then in situ synthesized on the CNTs-modified paper working electrode with direct liquid-phase hydrolysis with normal temperature, shirtsleeve operation, and gentle solution. Meanwhile, BP QDs, derived from two-dimensional BP nanosheets, can harvest light from the ultraviolet to near-infrared region, broaden efficient utilization of light, add a new dimension to BP research, and impel the high expectation on the potentials of QDs. To implement an assay protocol, exciton-plasmon interactions between TiO2-BP QDs and gold nanoparticles were introduced into the PEC sensing platform for high sensitivity detection of the PSA antigen. Under the optimal conditions, this proposed method exhibited a linear response ranging from 0.005 to 50 ng/mL with a detection limit of 1 pg/mL. This sensing protocol offered a promising analytical method with favorable properties of high selectivity, stability, and reproducibility.

A novel photoelectrochemical (PEC) aptasensor was fabricated for DNA detection based on the coupling of cosensitization and peroxidase-like catalytic activity. Specifically, the surfaces of branched-TiO2 nanorods (B-TiO2 NRs) were modified with Cd2+ and S2+ to obtain B-TiO2 NRs/CdS hybrid structures, which were subsequently used as matrices to immobilize hairpin DNA (hDNA) probes. CdTe/TCPP (TCPP = meso-tetra(4-carboxyphenyl)-porphine) used for signal amplification was labeled on the terminal of the hDNA probe. Without the target DNA (tDNA) presence, the immobilized hDNA probe with CdTe/TCPP possessed a hairpin form and was located near the B-TiO2 NRs/CdS electrode surface, forming a cosensitized structure formation and then generating strong photocurrent with H2O2 as the electron donor. During detection, the specific recognition of tDNA by the sensing hDNA probe triggered the formation of the G-quadruplex/hemin DNAzyme, which effectively catalyzed the decomposition of H2O2. Meanwhile, cosensitization disappeared when the hDNA probe hybridized with tDNA, further reducing the photocurrent. With a double-signal amplification strategy, the sensing platform designed in this work demonstrated a linear detection ability in the 0.5 fM-5 nM range with a detection limit equal to 0.14 fM. Notably, through encoding in the base sequences of the hDNA and marking it, a versatile PEC platform could be structured for the detection of various DNA targets, which could promise applications in point-of-care diagnostic fields.

Exploring efficient luminophores in the electrochemiluminescence (ECL) system is highly desired to pursue a sensitive ECL sensing platform. Herein, the black phosphorus nanosheets (BP NSs) with excellent ECL properties are investigated and serve as the luminophore with the coreactant of peroxydisulfate (S2O82-) solution. Moreover, owing to the overlapping of emission and absorbance spectra, effective resonance energy transfer (RET) is realized between the BP NSs and the introduced Au nanoparticles. In order to achieve the portable and miniaturized developing trends for the paper-based ECL sensing platform, a paper-based perovskite solar cell (PSC) device is designed to act as the power source to replace the commonly utilized expensive and cumbersome electrochemical workstation. Benefiting from that, a PSC driven paper-based constant potential ECL-RET sensing platform is constructed, thereby realizing sensitive microRNAs (miRNAs) detection. What's more, to attain the preferable analytical performance, the duplex-specific nuclease (DSN) is also introduced to assist the target recycling signal amplification strategy. Based on this, highly sensitive detection of miRNA-107 with a range from 0.1 pM to 15 nM is achieved by this designed sensing platform. Most importantly, this work not only pioneers a precedent for developing a high-sensitivity PSC triggered ECL sensing platform but also explores the application prospect of BP nanomaterial in the field of bioanalysis.

A photoelectrochemical (PEC) sensor based on hierarchical branched titanium dioxide nanorods (B-TiO2 NRs) modified with molecularly imprinted polymer (MIP) was constructed for sensitive and efficient detection of chlorpyris (CPF). B-TiO2 NRs were grown directly on fluorine doped tin oxide substrate by the hydrothermal method and employed as matrix for immobilization of MIP. P-aminothiophenol (ATP) and CPF were assembled on the surface of B-TiO2 NRs by formation of hydrogen-bonding interactions through electropolymerization in the MIP preparation process. The MIP was characterized by scanning electron microscopy, and further confirmed by cyclic voltammetry to prove the successful synthesis. In the proposed sensing platform, the photocurrent response is inversely proportional to the CPF concentration because the insulating layer hinders the harvesting of light and electron transfer with increasing of CPF concentration. Moreover, the MIP based B-TiO2 NRs (MIP-B-TiO2 NRs) had an excellent recognition capacity for specific detection CPF over other pesticides. The PEC sensing platform is developed for the detection of CPF in the linear range from 0.01 ng mL−1 to 100 ng mL−1 with a low detection limit of 7.4 pg mL−1. The proposed sensor offered a promising platform for application in detecting pesticide residuals and other environment deleterious chemicals with excellent sensitivity and selectivity, low interference and high stability.

This work described that one–step synthesis three dimensional anatase hierarchically cactus–like TiO 2 arrays (AHCT) and their application in constructing a novel photoelectrochemical (PEC) and visualized sensing platform based on molecular imprinting technique, which reports its result with the prussian blue (PB) electrode served as the electrochromic indicator for the detection of glycoprotein (RNase B). The AHCT arrays were perpendicularly grown on FTO substrate with tunable sizes, offering many advantages, such as large contact area, rapid charge electron separation and transport. A possible formation process of the interesting AHCT arrays has been investigated based on time–dependent experiment. In addition, the PEC and visualized sensing platform was constructed based on the molecularly imprinted polymer modified AHCT arrays. Specifically, in the proposed system, the more RNase B being, the more insulating layer was formed on the surface of AHCT arrays that impeded the harvesting of light and electron transfer, resulting in the reduction of photocurrent. When upon light illumination, the photogenerated electrons flow through an external circuit to PB, leading to the reduction of PB to prussian white (PW), which is transparent. The rate of decolourization of PB is proportional to the concentration of RNase B. In this way, a visualized PEC sensing platform that gives its quantitative information could be performed by monitoring the change of color intensity. Under optimal conditions, the protocol possessed a detection range of 0.5 pM to 2 μM (r=0.997) and the limit of detection was 0.12 pM toward RNase B. Our method eliminates the need for sophisticated instruments and high detection expenses, making it possible to be a reliable alternative in resource–constrained regions.

By incorporating the Prussian Blue (PB) electrochromic display as cathode, a solar-driven photoelectrochemical (PEC) cell was constructed through combining sandwich-structured graphite-like carbon nitride (g-C3N4)-Au-branched-titanium dioxide (B-TiO2) nanorods as photoanode for self-powered hydrogen peroxide (H2O2) sensing, which exhibits both direct photoelectrochemical and electrochromic response. The gold nanoparticles (Au NPs) sandwiched between the B-TiO2 nanorods and the g-C3N4 layer served as electron relay as well as plasmonic photosensitizer to enhance the solar-to-chemical energy conversion efficiency. Owing to the effective disproportionation of H2O2 and specific recognition of mannose on cell surface, concanavalin-A conjugated porous AuPd alloy nanoparticles were introduced as the catalytically active nanolabels promoting generation of hydroxyl radicals (·OH). Based on the cleavage of DNA with the participation of ·OH radicals generated by the decomposition of H2O2 under the catalysis of AuPd alloy result in the disassembly of cancer cells to achieve further signal enhancement. The multiple-signal-output sensing response not only provides a promising strategy for different analytical purposes based on novel stimuli-responsive materials, but also enhances the reliability in the analyte detection.

In this work, a novel sensing platform based on visible light driven biofuel cell (BFC) has been facilely designed for sensitive detection of prostate-specific antigen (PSA) with the photo-response bioanode, realizing the dual route energy conversion of light energy and chemical energy to electricity. The hierarchical branched TiO2 nanorods (B-TiO2 NRs) decorated with CdS quantum dots (QDs) act as the substrate to confine glucose dehydrogenase (GDH) for the visible light driven glucose oxidation at the bioanode. Three dimensional flowers like hierarchical carbon/gold nanoparticles/bilirubin oxidase (3D FCM/AuNPs/BOD) bioconjugate served as biocatalyst for O2 reduction at the biocathode. With an increase in the concentration of PSA, the amount of BOD labels on biocathode increases, thus leading to the higher current output of the as-proposed visible light driven BFC. Based on this, this sensing platform provide great performance in sensitivity and specificity, increasing linear detection range from 0.3pgmL(-1) to 7μgmL(-1) with a detection limit of 0.1pgmL(-1). Most importantly, our new sensing strategy provided a simple and inexpensive sensing platform for tumor markers detection, suggesting its wide potential applications for clinical diagnostics.

In this work, an electrochemiluminescence (ECL) cytosensor for ultrasensitive and selective cytosensing of K562 cancer cells was developed. Pt nanoparticles (PtNPs) dotted carbon nanotubes (CNTs) was immobilized on the working electrode which can not only improve the electronic transmission rate but also increase the surface area. And aptamers modified electrode was employed for specific and efficient cancer cell capture. A new class of nanoprobes were also prepared by integrating the functions of specific recognition of concanavalin A (Con A) and signal amplification of Au cage/Ru(bpy) 3 2+ nanostructures. With a sandwich-type cytosensor format, the amount of Au cage/Ru(bpy) 3 2+ -labeled Con A increased with the increment of K562 cancer cells in the samples, resulting in the increase of ECL signals. The as-proposed cytosensor exhibited excellent analytical performance toward the cytosensing of K562 cells in a wide detection linear range from 500 to 5.0 × 10 6 cells mL −1 with a detection limit of 500 cells mL −1 . Moreover, the proposed method showed good precision, acceptable stability and reproducibility.

In this work, an electrochemiluminescence (ECL) immunoassay integrated with the proposed 3D microfluidic origami device for the sensitive detection of carcinoembryonic antigen (CEA) was developed based on Ag nanospheres modified paper working electrode (Ag-PWE) as the sensor platform and Au nanocages functionalized tris-(bipyridine)-ruthenium(II) (Ru(bpy)32+) as the ECL signal amplification label. The novel Ag-PWE with excellent conductivity was constructed through the growth of an Ag nanosphere layer on the surfaces of cellulose fibers and served to provide a good pathway for electron transfer and enhance the amount of captured antibody (Ab1). Au nanocages, which possessed a hollow structure, were first used to construct the ECL immunosensor as a signal amplification carrier. Both the inner and outer surfaces of the Au nanocages can adsorb Ru(bpy)32+, therefore the signal can be amplified as much as possible. In addition, this as-prepared 3D microfluidic origami ECL immunodevice had the advantages of high sensitivity, acceptable precision and reasonable accuracy. On the basis of the considerably amplified ECL signal and sandwich-type format, the as-proposed immunodevice successfully fulfilled the highly sensitive detection of CEA with a linear range of 0.001–50 ng mL−1 and a detection limit of 0.0007 ng mL−1. The resulting 3D microfluidic origami ECL immunodevice exhibited great promise in the point-of-care diagnostics application of clinical screening of tumor markers.

The performance of organolead halide perovskites based solar cells has been enhanced dramatically due to the morphology control of the perovskite films. In this paper, we present a fast solvent-assisted molecule inserting (S-AMI) strategy to grow high-quality perovskite film, in which the methylammonium iodide/2-propanol (MAI/IPA) solution is spin-coated onto a dimethylformamide (DMF) wetted mixed lead halide (PbX2) precursor film. The DMF can help the inserting of MAI molecules into the PbX2 precursor film and provide a solvent environment to help the grain growth of the perovskite film. The perovskite film grown by the S-AMI approach shows large and well-oriented grains and long carrier lifetime due to the reduced grain boundary. Solar cells constructed with these perovskite films yield an average efficiency over 17% along with a high average fill factor of 80%. Moreover, these unsealed solar cell devices exhibit good stability in an ambient atmosphere.

Rutile titanium dioxide (TiO2 ) is a promising photocatalyst due to its high thermodynamic stability and few intragrain defects. However, it has not yet achieved photocatalytic activity comparable to that of anatase TiO2 owing to its higher recombination rate of electron-hole pairs. To effectively separate the electron-hole pairs in rutile TiO2 , a facet heterojunction (FH) structure to prolong the lifetime of the photogenerated electrons is proposed. Ultrathin TiO2 nanosheets with different facets are coated in situ onto TiO2 nanorod (NR) substrates, where FHs are built among the nanosheets as well as between the nanosheets and NR substrates. The as-prepared rutile TiO2 , with an FH structure (FH-TiO2 ), serves as an effective photocatalyst for water splitting. More than 45 and 18 times higher photogenerated current density and H2 production rate, respectively, are obtained compared to those of pure rutile TiO2 NRs. Moreover, FH-TiO2 delivers a 0.566 mmol g-1 h-1 H2 production rate even in pure water. This study offers important insights into the rational design of rutile TiO2 structures for highly efficient photocatalytic reactions. Accepted version

A platelike tungsten trioxide (WO3) sensitized with CdS quantum dots (QDs) heterojunction is developed for solar-driven, real-time, and selective photoelectrochemical (PEC) sensing of H2O2 in the living cells. The structure is synthesized by hydrothermally growing platelike WO3 on fluorine doped tin oxide (FTO) and subsequently sensitized with CdS QDs. The as-prepared WO3-CdS QDs heterojunction achieve significant photocurrent enhancement, which is remarkably beneficial for light absorption and charge carrier separation. Based on the enzymatic etching of CdS QDs enables the activation of quenching the charge transfer efficiency, thus leading to sensitive PEC recording of H2O2 level in buffer and cellular environments. The results indicated that the proposed method will pave the way for the development of excellent PEC sensing platform with the quantum dot sensitization. This study could also provide a new train of thought on designing of self-operating photoanode in PEC sensing, promoting the application of semiconductor nanomaterials in photoelectrochemistry.