Chaomin Gao

A disposable paper-based electrochemiluminescence device for ultrasensitive monitoring of CEA based on Ru(bpy)32+@Au nanocages

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.

Visible-light driven biofuel cell based on hierarchically branched titanium dioxide nanorods photoanode for tumor marker 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.

Platelike WO3 sensitized with CdS quantum dots heterostructures for photoelectrochemical dynamic sensing of H2O2 based on enzymatic etching.

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.

Engineering anatase hierarchically cactus-like TiO2 arrays for photoelectrochemical and visualized sensing platform

This work described that one-step synthesis three dimensional anatase hierarchically cactus-like TiO2 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 0.5pM to 2μM (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.

High-Quality Perovskite Films Grown with a Fast Solvent-Assisted Molecule Inserting Strategy for Highly Efficient and Stable Solar Cells

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.

Self-powered sensing platform equipped with Prussian blue electrochromic display driven by photoelectrochemical cell.

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.

Growth temperature-dependent performance of planar CH3NH3PbI3 solar cells fabricated by a two-step subliming vapor method below 120 °C

Using an extremely simple but promising two-step sequential subliming vapor deposition method, we grow high-quality perovskite CH3NH3PbI3 films with a uniform and continuous surface coverage. The perovskite film morphology and growth orientation can be well controlled by the growth temperature. The temperature influence on the power conversion efficiency (PCE) and the current–voltage hysteresis of the Spiro/CH3NH3PbI3/TiO2 P-i-N planar film solar cells is also investigated. Furthermore, a novel solvent annealed PCBM film was introduced between the TiO2 compact layer and perovskite active layer, which not only reduces the J–V hysteresis obviously but also enhances device performance. After optimization of the fabrication temperature and device structure, it was found that the PCEs of the solar cells fabricated at 120 °C on glass and flexible PET substrates can reach 15.59% and 7.62%, respectively. This promising approach provides a way to construct low-cost and large-area perovskite cell devices.

A single-interface photoelectrochemical sensor based on branched TiO2 nanorods@strontium titanate for the detection of two biomarkers

In this study, a single-interface photoelectrochemical (PEC) sensor for detecting two antigens, alpha fetoprotein (AFP) and cancer antigen 153 (CA 153), was achieved based on the heterostructure of branched titanium dioxide nanorods (B-TiO2 NRs)@strontium titanate (SrTiO3) heterostructures. The B-TiO2 NRs@SrTiO3 heterostructure, prepared by a facile hydrothermal method with the feature of enhanced photogenerated charge carrier separation properties, was first employed as a photoactive substrate for anchored analyst. In order to achieve the goal of successfully detecting two biomarkers at a single interface, the two specific enzyme tags β-galactosidase and acetylcholine esterase linked with a secondary detection antibody were utilized to catalytically hydrolyze p-aminophenyl galactopyranoside and acetylthiocholine to p-aminophenol and thiocholine, respectively. Based on the above enzyme-catalyzed reactions to produce sacrificial electron donors, the photocurrent signals generated from different analytes could be distinguished at a single interface. The results demonstrate that this single-interface PEC sensor not only provides a method for the early detection of AFP and CA 153 but also provides new insight into designing a novel PEC sensor for the detection of two biomarkers with high efficiency and a simple method of operation.