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Polypeptoid-coated surfaces and many surface-grafted hydrophilic polymer brushes have been proven efficient in antifouling-the prevention of nonspecific biomolecular adsorption and cell attachment. Protein adsorption, in particular, is known to mediate subsequent cell-surface interactions. However, the detailed antifouling mechanism of polypeptoid and other polymer brush coatings at the molecular level is not well understood. Moreover, most adsorption studies focus only on measuring a single adsorbed mass value, and few techniques are capable of characterizing the hydrated in situ layer structure of either the antifouling coating or adsorbed proteins. In this study, interfacial assembly of polypeptoid brushes with different chain lengths has been investigated in situ using neutron reflection (NR). Consistent with past simulation results, NR revealed a common two-step structure for grafted polypeptoids consisting of a dense inner region that included a mussel adhesive-inspired oligopeptide for grafting polypeptoid chains and a highly hydrated upper region with very low polymer density (molecular brush). Protein adsorption was studied with human serum albumin (HSA) and fibrinogen (FIB), two common serum proteins of different sizes but similar isoelectric points (IEPs). In contrast to controls, we observed higher resistance by grafted polypeptoid against adsorption of the larger FIB, especially for longer chain lengths. Changing the pH to close to the IEPs of the proteins, which generally promotes adsorption, also did not significantly affect the antifouling effect against FIB, which was corroborated by atomic force microscopy imaging. Moreover, NR enabled characterization of the in situ hydrated layer structures of the polypeptoids together with proteins adsorbed under selected conditions. While adsorption on bare SiO2 controls resulted in surface-induced protein denaturation, this was not observed on polypeptoids. Our current results therefore highlight the detailed in situ view that NR may provide for characterizing protein adsorption on polymer brushes as well as the excellent antifouling behavior of polypeptoids.

With the progress of modern biotechnology and people's strong attention to the quality of life and health, intellectualization and individuation have become a new trend of biomedicine development. Nanogenerators which can collect energy from the surrounding environment and convert mechanical energy into electricity become an ideal choice for self‐powered medical systems. In this review article, two types of nanogenerators, friction triboelectric nanogenerators (TENG), and piezoelectric nanogenerators (PENG), which are commonly used in self‐powered medical systems, are mainly introduced. The working mechanism and operation mode of PENG and TENG are introduced, and the mechanism and research progress of human‐centered intelligent self‐powered medical technologies based on PENG and TENG are focused on in the fields of drug delivery, wound healing, treatment for cardiovascular diseases and tumor, neuromodulation, and so on. In addition, also the opportunities and challenges facing the future development of wearable or implanted nanogenerators are introduced. In this review, it is hoped that a comprehensive overview and clarity will be provided for readers committed to self‐powered medical devices. [ABSTRACT FROM AUTHOR]

Contact electrification (CE) is a very common phenomenon in the daily life and occurs in almost all contact processes of dissimilar materials, including insulators, metals, and semiconductors. However, CE has been considered a phenomenon with negative effects for a long time until Wang et al. exploited this phenomenon to invent triboelectric nanogenerators (TENG). Atomic force microscopy (AFM) has unparalleled advantages in studying some basic scientific problems of CE phenomena, especially for study of CE mechanism at the nanoscale, thus greatly promoting the development of TENGs. Here, the research work of AFM in exploring CE mechanisms, including CE between solid and solid and CE between liquid and solid is systematically introduced. And the working mechanism of metal‐semiconductor DC triboelectric nanogenerators based on C‐AFM studies is also introduced. In addition, the potential utility and limitations of AFM in the future development of TENG technology, and discuss the direction of its improvement is analyzed. This review summarizes the important role of AFM technology in the development of TENG‐based energy and sensor technology, and it is hoped it can provide an updated overview on the understanding of the existing challenges and opportunities, which would be useful to promote the development of TENG technologies. [ABSTRACT FROM AUTHOR]