Zhongpeng Zhu

Foolproof Method for Fast and Reversible Switching of Water-Droplet Adhesion by Magnetic Gradients

Reversible switching of water-droplet adhesion on solid surfaces is of great significance for smart devices, such as microfluidics. In this work, we designed a foolproof method for fast and reversible magnet-controlled switching of water-droplet adhesion surfaces by doping iron powders in soft poly(dimethylsiloxane). The water adhesion is adjusted by magnetic field-induced structure changes, avoiding complex chemical or physical surface design. The regulation process is so convenient that only tens of milliseconds are needed. The on-site responsive mechanism extends its use to unusual curved surfaces. Moreover, the excellent reversibility and stability make the film an ideal candidate for real-time applications.

Engineering subcellular-patterned biointerfaces to regulate the surface wetting of multicellular spheroids

Studying the wetting behaviors of multicellular spheroids is crucial in the fields of embryo implantation, cancer propagation, and tissue repair. Existing strategies for controlling the wetting of multicellular spheroids mainly focus on surface chemistry and substrate rigidity. Although topography is another important feature in the biological micro-environment, its effect on multicellular spheroid wetting has seldom been explored. In this study, the influence of topography on the surface wetting of multicellular spheroids was investigated using subcellularpatterned opal films with controllable colloidal particle diameters (from 200 to 1,500 nm). The wetting of hepatoma carcinoma cellular (Hep G2) spheroids was impaired on opal films compared with that on flat substrates, and the wetting rate decreased as colloidal particle diameter increased. The decrement reached 48.5% when the colloidal particle diameter was 1,500 nm. The subcellular-patterned topography in opal films drastically reduced the cellular mobility in precursor films, especially the frontier cells in the leading edge. The frontier cells failed to form mature focal adhesions and stress fibers on micro-patterned opal films. This was due to gaps between colloidal particles leaving adhesion vacancies, causing weak cell–substrate adhesion and consequent retarded migration of Hep G2 spheroids. Our study manifests the inhibiting effects of subcellular-patterned topography on the wetting behaviors of multicellular spheroids, providing new insight into tissue wetting-associated treatments and biomaterial design.

Bio-Inspired Underwater Super Oil-Repellent Coatings for Anti-Oil Pollution

Underwater superoleophobic surfaces have attracted great attention due to their broad applications such as anti-oil adhesion, oil capture and transportation, and oil/water separation. However, it is often fairly complex and time-consuming, involved in the construction of micro/nanostructures and the regulation of chemical compositions; there is an urgent need to develop new strategies to conquer these problems. Inspired by the strong anchoring capability and easy accessibility of plant polyphenols, we can readily and rapidly fabricate tannic acid (TA) coated copper surfaces with the excellent underwater super oil-repellent property. To achieve the optimal condition for TA modification, the influence of immersion time, TA concentration, and pH value on underwater-oil wettability and adhesion has been systematically explored. Furthermore, the underwater super oil-repellent feature can be widely achieved for different oils and on various metal sheets, suggesting the potential applications for plenty of fields such as anti-oil pollution.