Metal–Organic Framework Coatings as Cytoprotective Exoskeletons for Living Cells

Abstract

The biomimetic mineralization of metal-organic framework (MOF) material on living cells is reported. ZIF-8 can be crystallized on a living cell surface as an exoskeleton that offers physical protection while allowing transport of essential nutrients, thus maintaining cell viability. The MOF shell prevents cell division, leading to an artificially induced pseudo-hibernation state. Cellular functions can be fully restored upon MOF removal.

An Enzyme‐Coated Metal–Organic Framework Shell for Synthetically Adaptive Cell Survival

“…[54] Compared with the naked yeast cells,t he released cells skipped the lag phase and immediately regained full proliferation potential (growth phase);s imilar to our previous study. [30] Additionally,there is no obvious reduction of the growth rate compared to naked yeast cells at the growth-phase stage (Figure 3). These results clearly demonstrated that the large majority of yeast cells coated with the active biocomposite MOF shell remained healthy after surviving aw eek in as imulated extreme,n utrient-deficient environment.…”

“…Theimmediate death of naked cells was more apparent when lyticase was present in the media, as lyticase can lyse yeast cells in am atter of hours. [30] Theb iocomposite MOF-coated yeast cells only showed asmall drop (< 30 %) in viability even after 7days in the modified cell media with or without lyticase (Figure 2; Supporting Information, Figure S11), suggesting that the engineered exoskeletons are effective in generating essential nutrients for prolonged cell survival while also protecting the yeast from toxic enzymes.…”

“…[41,42] Confocal laser scanning microscopy (CLSM) was used to confirm the surface coverage of the enzymes on the yeast cells (Figure 1a,b;S upporting Information, Figure S1). Although ZIF-8 coatings have previously been grown on naked yeast, [30] the modification of yeast cells with ap rotein-rich surface could also favor the attraction of MOF precursors (including cations and ligands), leading to the rapid biomimetic crystallization of aM OF shell. [38,43] Herein, the biomimetic growth of aMOF shell was achieved by incubating the enzyme-coated cells in an aqueous solution containing 2-methylimidazole and zinc acetate to form ZIF-8.…”

“…SEM images revealed that the surface of individual yeast cells was covered by al ayer of nanocrystals ( Figure 1f;S upporting Information, Figure S3), while elemental mapping confirmed ah omogeneous distribution of Figure S5), which is consistent with pure ZIF-8 coatings grown directly on yeast cells. [30] Saccharomyces cerevisiae must consume specific monoand disaccharides for their metabolic needs, [44] and we hypothesized that the introduction of new non-native enzymes on as ynthetic porous shell could allow yeast cells to survive in oligotrophic environments that are otherwise inhospitable.W ef irst determined whether the new coatings could produce essential nutrients for yeast survival. b-gal is ag lycoside hydrolase enzyme that converts lactose into glucose and galactose;b oth of which can be consumed by yeast as essential nutrients.…”

“…[28,29] Among the wide choice of synthetic coatings,m etalorganic frameworks (MOFs) are ac lass of porous materials that offer several unique advantages for engineering eukaryotic cells to survive in inhospitable environments. [30] MOFs can be thermally and chemically robust, [31] and can be synthesized by modular approaches that facilitate finetuning of pore shape, [32] chemical functionality, [33,34] and size. [35] More importantly,MOFs hold promise for biomedical applications, [36] as they can be constructed from bio-friendly building blocks [37] under physiological conditions.…”