Enhancing the Photocatalytic Performance of Antibiotics Using a Z-Scheme Heterojunction of 0D ZnIn2S4 Quantum Dots and 3D Hierarchical Inverse Opal TiO2.

Limited light absorption and rapid photo-generated carriers' recombination pose significant challenges to the practical applications of photocatalysts. In this study, we employed an efficient approach by combining the slow-photon effect with Z-scheme charge transfer to enhance the photo-degradation performance of antibiotics. Specifically, we incorporated 0D ZnIn2S4 quantum dots (QDs) into a 3D hierarchical inverse opal (IO) TiO2 structure through a facile one-step process. This combination enhanced the visible light absorption and provided abundant active surfaces for efficient photo-degradation. Moreover, the ZnIn2S4 QDs formed an artificial Z-scheme system with IO-TiO2, facilitating the separation and migration of charge carriers. To achieve a better band alignment with IO-TiO2, we doped Ag into the ZnIn2S4 QDs (Ag: ZIS QDs) to adjust their energy levels. Through an investigation of the different Ag contents in the ZnIn2S4 QDs, we found that the optimal photo-degradation performance was achieved with Ag (2.0): ZIS QDs/IO-TiO2, exhibiting degradation rates 19.5 and 14.8 times higher than those of ZnIn2S4 QDs and IO-TiO2, respectively. This study provides significant insights for elevating the photocatalytic capabilities of IO-TiO2 and broadening its prospective applications.

Synergistically Enhanced Photocatalytic Degradation by Coupling Slow-Photon Effect with Z-Scheme Charge Transfer in CdS QDs/IO-TiO2 Heterojunction.

Lower light absorption and faster carrier recombination are significant challenges in photocatalysis. This study introduces a novel approach to address these challenges by anchoring cadmium sulfide quantum dots (CdS QDs) on inverse opal (IO)-TiO2, which increases light absorption and promotes carriers' separation by coupling slow-photon effect with Z-scheme charge transfer. Specifically, the IO-TiO2 was created by etching a polystyrene opal template, which resulted in a periodic structure that enhances light absorption by reflecting light in the stop band. The size of CdS quantum dots (QDs) was regulated to achieve appropriate alignment of energy bands between CdS QDs and IO-TiO2, promoting carrier transfer through alterations in charge transfer modes and resulting in synergistic-amplified photocatalysis. Theoretical simulations and electrochemical investigations demonstrated the coexistence of slow-photon effects and Z-scheme transfer. The system's photodegradation performance was tested using rhodamine B as a model. This novel hierarchical structure of the Z-scheme heterojunction exhibits degradability 7.82 and 4.34 times greater than pristine CdS QDs and IO-TiO2, respectively. This study serves as a source of inspiration for enhancing the photocatalytic capabilities of IO-TiO2 and broadening its scope of potential applications.

Rational Utilization of Photoelectrochemistry of Photosystem II for Self-Powered Photocathodic Detection of MicroRNA in Cells.

The photoanode, photosystem II (PSII)/hierarchical inverse opal (IO) TiO2, is coupled to the complementary photocathode, PbS quantum dots (QDs)/DNA probes, which is then integrated into a two-compartment photoelectrochemical (PEC) cell to achieve a self-powered system to enable photocathodic detection of microRNA-10b from HeLa cells. In such a system, all of the PSII catalytic products, i.e., electrons, protons, and O2, were rationally utilized and could overcome the general issue of varied O2 levels in photocathodic detection. The correlation between the target-triggered formation of the DNA complexes and the catalytic reduction of the dissolved O2 makes possible the steady microRNA-10b detection with good sensitivity and selectivity. This work has unveiled the ability of PSII to construct self-powered detecting devices and shed light on its application in new arenas.

An Integrated Electrochemical Nanodevice for Intracellular RNA Collection and Detection in Single Living Cell.

New tools for single-cell interrogation enable deeper understanding of cellular heterogeneity and associated cellular behaviors and functions. Information of RNA expression in single cell could contribute to our knowledge of the genetic regulatory circuits and molecular mechanism of disease development. Although significant progresses have been made for intracellular RNA analysis, existing methods have a trade-off between operational complexity and practical feasibility. We address this challenge by combining the ionic current rectification property of nanopipette reactor with duplex-specific nuclease-assisted hybridization chain reaction for signal amplification to realize a simple and practical intracellular nanosensor with minimal invasiveness, which enables single-cell collection and electrochemical detection of intracellular RNA with cell-context preservation. Systematic studies on differentiation of oncogenic miR-10b expression levels in non-malignant breast cells, metastatic breast cancer cells as well as non-metastatic breast cancer cells were then realized by this nanotool accompanied by assessment of different drugs effects. This work has unveiled the ability of electrochemistry to probe intracellular RNA and opened new opportunities to study the gene expression and heterogeneous complexity under physiological conditions down to single-cell level.

Boosting the biocatalytic precipitation with enzyme-loaded liposomes: Toward a general platform for amplified photoelectrochemical immunoassay.

Liposome-assisted photoelectrochemical (PEC) bioanalysis represents one of the latest frontiers in the arena of PEC bioanalysis. This work reports a general enzyme-amplified liposomal PEC bioanalysis protocol via the use of enzyme-loaded liposomes to boost the biocatalytic precipitation (BCP) effect. In the representative system, the horseradish peroxidase (HRP)-loaded liposome (HRPLL) and the Au nanoclusters (NCs)/Au nanoparticles (NPs)/TiO2 nanotubes (NTs) framework (AATF) were used as liposomal label and photoelectrode, respectively. In the detection, the sandwich immunocomplex reaction was accomplished in a 96-well plate to confine the HRPLL label, which was then lysed to release the HRP molecules to initiate the BCP process. Due to the amplified formation of HRP-induced BCP on the AATF scaffold, the photo-current response correlated closely with the immunorecognition process and the analyte could be detected very sensitively. This work features the first integration of enzyme-loaded liposomes and the BCP for sensitive PEC bioanalysis, which to our knowledge has not been reported. With the use of various other enzymes, this work could serve as a general basis for the PEC bioanalysis of numerous other target of interest.

In situ chemical redox and functionalization of graphene oxide: toward new cathodic photoelectrochemical bioanalysis.

This report outlines the first exploration of graphene oxide (GO) itself as a light harvesting material with an innovative in situ chemical redox and functionalization (CRF) strategy for versatile and high-throughput cathodic photoelectrochemical (PEC) bioanalysis.

Dual Functional Molecular Imprinted Polymer-Modified Organometal Lead Halide Perovskite: Synthesis and Application for Photoelectrochemical Sensing of Salicylic Acid.

This work reports the synthesis of dual functional molecularly imprinted polymer (MIP)-modified organometal lead halide perovskite (CH3NH3PbI3) and its application for photoelectrochemical (PEC) bioanalysis of salicylic acid (SA). Specifically, the CH3NH3PbI3 was encapsulated into the MIPs via a simple thermal polymerization process on the indium tin oxide (ITO) glass, and the as-obtained MIPs/CH3NH3PbI3/ITO electrode was characterized by various techniques, which revealed that the MIPs could not only stabilize CH3NH3PbI3 but also improve the electron-hole separation efficiency of CH3NH3PbI3 under light illumination. In the detection of model analyte SA, the PEC sensor, with numerous amounts of recognition sites to SA, exhibited desirable performance in terms of good sensitivity, selectivity, stability, and feasibility for real sample analysis. This work not only featured the use of MIPs/CH3NH3PbI3 for PEC detection of SA but also provided a new horizon for the design and implementation of functional polymers/perovskite materials in the field of PEC sensors and biosensors.

Enhanced organic-inorganic heterojunction of polypyrrole@Bi2WO6: Fabrication and application for sensitive photoelectrochemical immunoassay of creatine kinase-MB.

In this report, enhanced organic-inorganic heterojunction of polypyrrole@Bi2WO6 was fabricated and applied for sensitive photoelectrochemical (PEC) immunoassay of creatine kinase-MB (CK-MB). Specifically, heterostructured polypyrrole@Bi2WO6 photoelectrode was prepared and sandwich immunorecognition were integrated for the CK-MB immunoassay. In the detection, with the aid of alkaline phosphate (ALP)-induced biocatalytic precipitation (BCP), the precipitation-dependent suppression of the photocurrent can be recorded due to the impediment of the interfacial mass and electron transfer. On the basis of target-controlled BCP formation, a novel PEC immunoassay could be developed for the sensitive and specific CK-MB detection. This work manifested the great potential of polypyrrole@Bi2WO6 heterojunction as a novel platform for PEC bioanalysis development and also a PEC method for CK-MB detection. This work is expected to stimulate more interest in the design and implementation of numerous other organic-inorganic heterojunction for advanced PEC bioanalysis development.

Tyrosinase-encapsulated liposomes: Toward enzyme-induced in situ sensitization of semiconductor for sensitive photoelectrochemical immunoassay.

Liposomal photoelectrochemical (PEC) bioanalysis holds enormous potential for future sensitive PEC bioanalysis. With tyrosinase (Tyr) and TiO2 as representative enzyme and electrode, respectively, this communication reports the elegant use of Tyr-loaded liposomes (TLL) toward in situ sensitization of the electrode and thereby the realization of ultrasensitive PEC immunoassay. Specifically, Tyr-encapsulated and detection antibody-functionalized liposomes were first prepared and used as the signal probe. The subsequent sandwich immunobinding could confine the functional liposomes, which were then lysed with surfactant to release the encapsulated Tyr. The free Tyr could then initiate the transformation of tyrosine to dopa, the latter could bind with the undercoordinated Ti sites, forming the stable dopa-Ti charge transfer complex and thus generating enhanced anodic photocurrent under visible light for signaling. Since different semiconductors and enzymes may be adapted into this format, this work is expected to stimulate more interest in the enzyme-induced activation of semiconductors for advanced liposomal PEC bioanalysis.