Polydopamine assisted transformation of ZnO from nanospheres to nanosheets grown in nanoporous BiVO4 films for the improved photocatalytic performance

This work demonstrates the fabrication of nanoporous BiVO4/ZnO nanosheets heterostructures grown on stainless steel mesh. The ZnO nanospheres were used as precursors for ZnO nanosheets, and the number of ZnO...

Biocompatibility and Electrical Stimulation of Skeletal and Smooth Muscle Cells Cultured on Piezoelectric Nanogenerators

Nanogenerators are interesting for biomedical applications, with a great potential for electrical stimulation of excitable cells. Piezoelectric ZnO nanosheets present unique properties for tissue engineering. In this study, nanogenerator arrays based on ZnO nanosheets are fabricated on transparent coverslips to analyse the biocompatibility and the electromechanical interaction with two types of muscle cells, smooth and skeletal. Both cell types adhere, proliferate and differentiate on the ZnO nanogenerators. Interestingly, the amount of Zn ions released over time from the nanogenerators does not interfere with cell viability and does not trigger the associated inflammatory response, which is not triggered by the nanogenerators themselves either. The local electric field generated by the electromechanical nanogenerator–cell interaction stimulates smooth muscle cells by increasing cytosolic calcium ions, whereas no stimulation effect is observed on skeletal muscle cells. The random orientation of the ZnO nanogenerators, avoiding an overall action potential aligned along the muscle fibre, is hypothesised to be the cause of the cell-type dependent response. This demonstrates the need of optimizing the nanogenerator morphology, orientation and distribution according to the potential biomedical use. Thus, this study demonstrates the cell-scale stimulation triggered by biocompatible piezoelectric nanogenerators without using an external source on smooth muscle cells, although it remarks the cell type-dependent response.

Significant effect of SDS on the optimum operating temperature of ZnO nanosheets gas-sensitive materials

Many methods have been used to reduce the operational energy consumption of ZnO gas-sensitive material effectively. In this paper, different morphologies of ZnO nanomaterials are respectively prepared in the anionic hydrophilic surfactant sodium lauryl sulfate (SDS) with different concentrations as soft templates by hydrothermal method. The influence of SDS concentrations is investigated on the morphology of materials under the conditions of a weak alkali environment with the same pH, and their gas sensitivity after annealing with the same temperature and time. The morphologies and phase structures of all samples are characterized by FESEM and XRD, and their gas-sensitive properties are analyzed by CGS-1TP. Interestingly, the experimental results show that the optimal working temperature of ZnO gas-sensitive materials containing low concentration SDS is reduced by nearly 55% than that of containing 10 times this concentration, and its sensitivity is also slightly improved. The possible mechanism by which the SDS concentration affects the gas sensitivity of the material is also proposed.