A Removable Artificial Cell Wall for Withstanding Ciprofloxacin

Protective Mechanism of a Layer-by-Layer-Assembled Artificial Cell Wall on Probiotics

Constructing an artificial cell wall (AFCW) based on the layer-by-layer assembly of polymer films to protect probiotics in harsh conditions is highly desirable. Early findings showed that encapsulating yeast cells by an AFCW improved the cell viability by 50% in antibiotic solution. However, the detailed molecular interaction mechanism remains unclear by experiments. Herein, two ciprofloxacin (CPFX) permeation models, including models 1 and 2 that were, respectively, composed of just the yeast cell membrane and the AFCW coating cell membrane, were investigated by molecular dynamics simulations. The free energy profiles delineating the permeation process of CPFX reveal that the permeation of CPFX through the cell membrane of model 2 is more difficult than through that of model 1. The analysis results show that the AFCW leads to two sharp increases in free energy barriers, amounting to 8.9 and 6.2 kcal/mol, thereby reducing the penetrating rate of CPFX into the cell membrane. Moreover, decomposition of the potentials of mean force into free energy components suggested that the electrostatic interactions of CPFX with the AFCW predominantly contributed to the high free energy barriers. The current results provide a good understanding of the protective mechanism of the self-assembled cell walls against CPFX and help to design other AFCWs.

Nanoarchitectonics on living cells

In this review article, the recent examples of nanoarchitectonics on living cells are briefly explained. Not limited to conventional polymers, functional polymers, biomaterials, nanotubes, nanoparticles (conventional and magnetic ones), various inorganic substances, metal-organic frameworks (MOFs), and other advanced materials have been used as components for nanoarchitectonic decorations for living cells. Despite these artificial processes, the cells can remain active or remain in hibernation without being killed. In most cases, basic functions of the cells are preserved and their resistances against external assaults are much enhanced. The possibilities of nanoarchitectonics on living cells would be high, equal to functional modifications with conventional materials. Living cells can be regarded as highly functionalized objects and have indispensable contributions to future materials nanoarchitectonics.