The data that support the findings of this study are available from the corresponding author upon reasonable request.

No abstract

Supramolecular self-assembly of Fe 3+ and tannic acid (TA) has received great attention in the fields of materials science and interface engineering because of its exceptional surface coating properties. Although advances in coating strategies often suggest that kinetics in the generation of interface-active Fe 3+ -TA species is deeply involved in the film formation, there is no acceptable elucidation for the coating process. In this work, we developed the enzyme-mediated kinetic control of Fe 2+ oxidation to Fe 3+ in a Fe 2+ -TA complex in the iron-gall-ink-revisited coating method. Specifically, hydrogen peroxide, produced in the glucose oxidase (GOx)catalyzed reaction of D-glucose, accelerated Fe 2+ oxidation, and the optimized kinetics profoundly facilitated the film formation to be about 9 times thicker. We also proposed a perspective considering the coating process as nucleation and growth. From this viewpoint, the kinetics in the generation of interface-active Fe 3+ -TA species should be optimized because it determines whether the interface-active species forms a film on the substrate (i.e., heterogeneous nucleation and film growth) or flocculates in solution (i.e., homogeneous nucleation and particle growth). Moreover, GOx was concomitantly embedded into the Fe 3+ -TA films with sustained catalytic activities, and the GOx-mediated coating system was delightfully adapted to catalytic single-cell nanoencapsulation.

Single‐cell nanoencapsulation (SCNE) demands cytocompatible materials and processes to ensure the maintenance of cell viability and prefers the degradation‐on‐demand and postfunctionalization of the cytoprotective shells. Although the layer‐by‐layer (LbL) method has intensively been used for SCNE, there have been few reports on the cytocompatible LbL shells that are postfunctionalizable under mild conditions. Herein, the use of nature‐derived eggshell membrane hydrolysate (ESMH) as a counter component to tannic acid (TA) for hydrogen bonding‐based LbL shell formation on Saccharomyces cerevisiae is proposed. In addition to the great cytocompatibility of the LbL process and protective capability of the ESMH/TA shell (e.g., 18‐fold increase in survival against Cu2+), the shell is postfunctionalizable, benefitting from the presence of various functional groups in the ESMH, as demonstrated by reactions with N‐hydroxysuccinimide‐ or maleimide‐conjugated fluorescent probes and bioinspired silicification. This work suggests that ESMH would be an advanced biomaterial for chemically interfacing with living cells in a controlled fashion.

Living cells have the irreplaceable capability to achieve a wide range of complex biochemical reactions precisely and efficiently, which makes them attractive materials for therapeutic applications. In lieu of the traditional biochemical and biological approaches primarily focused on the augmentation of the innate functions of cells, there has been appreciable progress in the development of engineered therapeutic cells, mainly based on the chemical modifications of cell surfaces, at the single‐cell level, which empowers individual living cells with designed therapeutic functions in a cytocompatible manner. This review highlights the latest advances in the development of therapeutic living cells using single‐cell surface engineering, for potential applications in blood transfusion, drug delivery, cancer therapy, probiotic therapy, and tissue engineering and regenerative medicine. The methodological strategies for functionalizing cell surfaces with biomolecules, and inorganic and organic materials, to endow living cells with extrinsic physicochemical and biological properties as well as to increase the durability and efficacy of engineered therapeutic cells, are also briefly overviewed. The review ends with a perspective that discusses the construction of active cell‐in‐shell nanobiohybrid systems, in which exogenous materials formed on cell surfaces mutually and intimately communicate with the cells inside, as a future research direction for single‐cell surface engineering.

Layer‐by‐layer (LbL) assembly of food waste‐derived materials, eggshell membrane hydrolysates and coffee melanoidins, is applied to the single‐cell nanoencapsulation (SCNE) of Saccharomyces cerevisiae. The hydrogen bonding‐based LbL process is extremely cytocompatible (viability > 99%), and the cell is protected from external assaults, such as heavy metals and UV‐B, after the SCNE. The shell's durability is further augmented by ferric ion‐mediated cross‐linking. More information can be found in the Research Article by Insung S. Choi et al. Photo credit: E. K. Kang.

Coordination-driven self-assembly of metal-ligand complex is a powerful nanoarchitectonic tool for particle engineering, but its usability is limited when using two immiscible coating components. This paper reports that simple vortexing...

One-step fabrication method for thin films and shells is developed with nature-derived eggshell membrane hydrolysates (ESMHs) and coffee melanoidins (CMs) that have been discarded as food waste. The nature-derived polymeric materials, ESMHs and CMs, prove highly biocompatible with living cells, and the one-step method enables cytocompatible construction of cell-in-shell nanobiohybrid structures. Nanometric ESMH-CM shells are formed on individual probiotic Lactobacillus acidophilus, without any noticeable decrease in viability, and the ESMH-CM shells effectively protected L. acidophilus in the simulated gastric fluid (SGF). The cytoprotection power is further enhanced by Fe3+-mediated shell augmentation. For example, after 2 h of incubation in SGF, the viability of native L. acidophilus is 30%, whereas nanoencapsulated L. acidophilus, armed with the Fe3+-fortified ESMH-CM shells, show 79% in viability. The simple, time-efficient, and easy-to-process method developed in this work would contribute to many technological developments, including microbial biotherapeutics, as well as waste upcycling.