Nucleic Acid-Based Cell Surface Engineering Strategies and Their Applications.

The cell membrane is a biological interface regulating the communications between cells and their environment. The ability to functionalize the cell membrane with molecules or nanomaterials allows us to manipulate cellular behaviors and to expand cellular functions. Due to their unique merits of synthetic accessibility, flexible design, and precise programmability, nucleic acids provide an emerging and promising molecular toolkit for cell surface engineering. In this review, the recent progress in nucleic acid-based cell surface engineering are summarized. We first introduce approaches to nucleic acid-based cell surface engineering, including monovalent and polyvalent surface engineering strategies. Then, the biological applications of nucleic acid-based cell surface engineering in biosensing of extracellular microenvironment, programming cell-cell interactions, and mimicking cellular behaviors are reviewed. Finally, we analyze the current challenges existing in this area and discuss the prospects for the future development.

Hierarchical Morphology-Dependent Gas-Sensing Performances of Three-Dimensional SnO2 Nanostructures.

Hierarchical morphology-dependent gas-sensing performances have been demonstrated for three-dimensional SnO2 nanostructures. First, hierarchical SnO2 nanostructures assembled with ultrathin shuttle-shaped nanosheets have been synthesized via a facile and one-step hydrothermal approach. Due to thermal instability of hierarchical nanosheets, they are gradually shrunk into cone-shaped nanostructures and finally deduced into rod-shaped ones under a thermal treatment. Given the intrinsic advantages of three-dimensional hierarchical nanostructures, their gas-sensing properties have been further explored. The results indicate that their sensing behaviors are greatly related with their hierarchical morphologies. Among the achieved hierarchical morphologies, three-dimensional cone-shaped hierarchical SnO2 nanostructures display the highest relative response up to about 175 toward 100 ppm of acetone as an example. Furthermore, they also exhibit good sensing responses toward other typical volatile organic compounds (VOCs). Microstructured analyses suggest that these results are mainly ascribed to the formation of more active surface defects and mismatches for the cone-shaped hierarchical nanostructures during the process of thermal recrystallization. Promisingly, this surface-engineering strategy can be extended to prepare other three-dimensional metal oxide hierarchical nanostructures with good gas-sensing performances.