Light responsive Fe-Tcpp@ICG for hydrogen peroxide detection and inhibition of tumor cell growth

Flexible and Stretchable Photoelectrochemical Sensing toward True-to-Life Monitoring of Hydrogen Peroxide Regulation in Endothelial Mechanotransduction

Hydrogen peroxide (H2O2) levels play a vital role in redox regulation and maintaining the physiological balance of living cells, especially in cell mechanotransduction. Despite the achievements on strain-induced cellular H2O2 monitoring, the applied voltage for H2O2 electrooxidation possibly gave rise to an abnormal expression and inadequate accuracy, which was still an inescapable concern. Hence, we decorated an interlaced CuO@TiO2 nanowires (NWs) semiconductor meshwork onto a polydimethylsiloxane film-supported gold nanotubes substrate (Au NTs/PDMS) to construct a flexible photoelectrochemical (PEC) sensing platform. Under white light irradiation, CuO@TiO2 NWs synergistically exhibited great stretchability and the PEC platform enabled stable photocurrent responses from the reduction of H2O2 even during mechanical deformation. Moreover, the admirable biocompatibility and an almost negligible open circuit voltage of +0.18 V for the CuO@TiO2 NWs/Au NTs/PDMS sensor guaranteed human umbilical vein endothelial cells (HUVECs) adhesion tightly thereon even under continuous illumination for 30 min. Finally, the as-proposed stretchable PEC sensor achieved sensitive and true-to-life monitoring of transient H2O2 release during HUVECs deformation, in which H2O2 release was positively correlated to mechanical strains. This investigation opens a new shade path on in situ cellular sensing and meanwhile greatly expands the application mode of the PEC approach.

Quantum Dot/TiO2 Nanocomposite-Based Photoelectrochemical Sensor for Enhanced H2O2 Detection Applied for Cell Monitoring and Visualization

This work exploits the possibility of using CdSe/ZnS quantum dot (QD)-electrodes to monitor the metabolism of living cells based on photoelectrochemical (PEC) measurements. To realize that, the PEC setup is improved with respect to an enhanced photocurrent signal, better stability, and an increased signal-to-noise ratio, but also for a better biocompatibility of the sensor surface on which cells have been grown. To achieve this, a QD-TiO2 heterojunction is introduced with the help of atomic layer deposition (ALD). The heterojunction reduces the charge carrier recombination inside the semiconductor nanoparticles and improves the drift behavior. The PEC performance is carefully analyzed by adjusting the TiO2 thickness and combining this strategy with multilayer immobilizations of QDs. The optimal thickness of this coating is ≈5 nm; here, photocurrent generation can be enhanced significantly (e.g., for a single QD layer electrode by more than one order of magnitude at 0 V vs Ag/AgCl). The resulting optimized electrode is used for hydrogen peroxide (H2O2) sensing with a good sensitivity down to µmolar concentrations, reusability, stability, response rate, and repeatability. Finally, the sensing system is applied to monitor the activity of cells directly grown on top of the electrode surface.

Immunochromatographic Assay based on Sc-TCPP 3D MOF for the rapid detection of imidacloprid in food samples

In this work, a highly sensitive immunochromatographic test strip (ITS) based on Scandium-Tetrakis (4-carboxyphenyl) porphyrin (TCPP) metal-organic framework nanocubes (ScTMNs) was developed for ultrasensitive and facile visual determination of imidacloprid (IDP). TCPP as the porphyrin-based planar ligand and Sc³⁺ as the metal center were applied to form the ScTMNs via coordination chelation. Giving the credit to its excellent optical characteristics, strong affinity with monoclonal antibodies, and favorable biocompatibility, the ScTMNs was selected as a signal tag. Under optimized conditions, the ITS exhibited a great liner relationship in the range of 0.04-3 ng/mL and the detection limit was 0.04 ng/mL for the IDP detection. Additionally, IDP was successfully detected in tomatoes, millet, corn and carrot samples with satisfied recoveries. To the best of our knowledge, this is the first time that ScTMNs have been used in immunochromatography which are expected to have potential applications in detection of other substances.