Bacterial envelope damage inflicted by bioinspired nanospikes grown in a hydrogel

Abstract

Device-associated infections are one of the deadliest complications accompanying the use of biomaterials, and despite recent advances in the development of anti-biofouling strategies, biomaterials that exhibit both functional tissue restoration and antimicrobial activity have been challenging to achieve. Here, we report the fabrication of bio-inspired bactericidal nanospikes in bacterial cellulose and investigate the mechanism underlying this phenomenon. We demonstrate these structures affects preferentially stiff membranes like those in Gram-positive bacteria, but exhibit cytocompatibility towards mammalian cells, a requisite for tissue restoration. We also reveal the bactericidal activity of the nanospikes is due to a pressure-induced mechanism, which depends on the cell's adherence time, nanospike's geometry and spacing, cell shape, and mechanical properties of the cell wall. Our findings provide a better understanding of the mechanobiology of bacterial cells at the interface with nanoscale structures, which is fundamental for the rational design bactericidal topographies.

Red Microalgal Sulfated Polysaccharide–Cu2O Complexes: Characterization and Bioactivity

“…and in Saccharomyces cerevisiae . It has also been shown that the rigidity of the microbial cells affect their susceptibility to mechanical rupture, ,, for example, Gram-negative bacteria were more sensitive than Gram-positive bacteria, probably due to the cell wall architecture. , Finally, it has been shown that the increased spike density and greater spike height promote the efficacy of the antimicrobial activity of the “nano-spiked” material. − However, the precise mechanism leading to microbial cell death is not fully understood.…”

“…Although the EDS-SEM studies indicated the existence of Cu on the surface of the complex, probably responsible for a cationic charge localized on the complex surface, the main antimicrobial effect may be attributed to the modified surface topography of the Cu 2 O–polysaccharide complex, that is, to the spikes 1000 nm in height and 10–20 nm in width, at a density of about 5000 spikes/μm 2 . It seems likely that the high density of the spikes coupled with their height can cause mechanical penetration of the microbial membrane, leading to disruption of membrane permeability and consequently to cell death, as has been shown previously. − …”

“…Recently, a different type of mechanism has been suggested for the antimicrobial activity of natural and bio-inspired materials that have a nano-spiked surface where the nano-topography spikes have been shown to physically rupture the microbial cell membrane of bacteria and fungi. − The antimicrobial activity of such natural and synthetic spikes after adhesion to the microbial cell membrane has been attributed to a number of different factors, including the density and size of the spikes (ranging from 40 to 500 nm) and the rigidity of the microbial cell-wall (envelop architecture). However, the precise mechanism that leads to microbial cell death has not yet been elucidated conclusively.…”

Ion-Induced Nanopatterning of Bacterial Cellulose Hydrogels for Biosensing and Anti-Biofouling Interfaces

“…For example, high aspect ratio nanostructures in a hydrogel increase the surface area active for molecular detection, which leads to higher sensitivity and improved signal-to-background ratio in microfluidic and sensing devices. , Similarly, higher surface areas can deliver greater drug doses in a controlled manner compared to conventional flat surfaces . Recently, we have demonstrated that HAR nanostructures can be used for the design of biofouling resistant surfaces inspired by naturally occurring bactericidal nanostructures. , …”

“…10 Recently, we have demonstrated that HAR nanostructures can be used for the design of biofouling resistant surfaces inspired by naturally occurring bactericidal nanostructures. 11,12 Photolithography and replica molding techniques have been traditionally used to fabricate nanostructures in hydrogels; however, none of those approaches achieve nanostructures with dimensions below a few microns while maintaining precise control of the size and shape distribution. 13 Indeed, creating homogeneous and reproducible nanosized features with high aspect ratios in soft materials at scale remains challenging.…”