Direct Synthesis of Photosensitizable Bacterial Cellulose as Engineered Living Material for Skin Wound Repair

Abstract

porosity to support sufficient air exchange. The current clinical approach employed for wound bacterial infection treatment is to apply antibiotics-based wound dressing, which is costly, inefficient, and may lead to antibiotic resistance. [4] Bacterial cellulose (BC), biosynthesized by microorganism fermentation with acetic acid bacteria such as Komagataeibacter sucrofermentans, possesses superior features including high safety, high permeability, high waterholding capacity, excellent flexibility adaptability, low cost, outstanding biocompatibility, and biodegradability. [5] Taking these advantages, BC has been widely applied in artificial skin and blood vessels, scaffolds for tissue engineering, bone regeneration, dental implants, and wound care products. [6] Among these applications, BC is especially suitable for wound dressing because of its 3D coherent nanofiber network structure, leading to ultrahigh porosity and water-holding ability. [6c,7] BC in its natural state does not display any intrinsic antimicrobial capacity, but it can be functionalized with antibacterial agents to realize the infection prevention feature during the wound healing process. [8] Different antibacterial agents such as silver or gold nanoparticles, antibiotics, and chitosan have been attached to BC through physical coating or chemical modification. [9] The physical coating method only requires a moderate modification condition but suffers from shedding of antibacterial moieties from time to time. [10] BC is a natural biopolymer chain composed of β-d-glucose units formed from β-1,4glycosidic bonds. [11] Due to its strong hydrogen bonding and polarizability, BC has poor solubility in conventional organic solvents or water, which often leads to low reaction efficiency for chemical modification. [12] Biosynthesis design for BC by microorganism fermentation has been a new alternative technique that may potentially overcome the limitations of physical coating and chemical modification. [13] Ideally, antibacterial agents could be firmly incorporated into BC during the fermentation process. However, incorporation of an antibacterial agent on BC via microbial biosynthesis is challenging because conventional antibacterial agents could kill the fermentation microorganism. Photosensitizers (PSs), as a class of promising candidates for antibacteria, have no toxicity under dark, but can selectively generate reactive oxygen species (ROS) to induce pathogen lethal injury under light irradiation. [14] Of particular interest are the PSs with aggregationinduced emission characteristics (AIE PSs), which have unique Living materials based on bacterial cellulose (BC) represent a natural and promising candidate for wound dressing. Both physical adsorption and chemical methods have been applied to BC for realizing antibacterial function. However, effective and long-lasting incorporation of bactericidal moieties to BC remains challenging. Herein, a Komagataeibacter sucrofermentans-based direct synthetic method to fabricate photosensitizer-grafted BC thr...

Engineered Living Materials For Sustainability

“…The bacteria took up a small amount of the glucose analogues into the synthesized BC pellicles, which exhibited detectable fluorescence in contrast to the native forms (Figure b–e) . In a recent study, Liu et al adopted a similar approach to generate antimicrobial BC materials for wound repair . They modified glucose with photosensitizers that could efficiently generate reactive oxygen species (ROS) to kill pathogens under light irradiation.…”

“…118 In a recent study, Liu et al adopted a similar approach to generate antimicrobial BC materials for wound repair. 120 They modified glucose with photosensitizers that could efficiently generate reactive oxygen species (ROS) to kill pathogens under light irradiation. After feeding the BCproducing microbes with this photosensitizer-modified glucose as a carbon source, the biologically generated BC exhibited novel light-triggered photodynamic bactericidal activity.…”

“…In addition to modification through metabolic engineering, culturing bacteria with tailored monosaccharide analogues provides another simple approach to modulating polysaccharide functions. In theory, native or reconstituted polysaccharide metabolic machinery in living cells can erroneously incorporate molecules structurally similar to monosaccharides into the final sugar product. − Gao et al cultivated Komagataeibacter sucrofermentans (a BC-producing bacterial strain) with glucose grafted with fluorescent groups (Figure a) . The bacteria took up a small amount of the glucose analogues into the synthesized BC pellicles, which exhibited detectable fluorescence in contrast to the native forms (Figure b–e) .…”

Biodegradable hydrogels with photodynamic antibacterial activity promote wound healing and mitigate scar formation

“…19 Wound dressings play an important role in the skin healing process, especially for traumatic, chronic, and thermal wounds. 20,21 Conventional wound dressings, such as gauze, bandages and cotton wool, do not prevent wound beds from drying and bacterial infection and cause repeated injury when removed, which often results in damage to the regenerating skin tissue. 22 Compared to traditional dressings, hydrogels can cool the surface of the wound to relieve pain, maintain a moist wound environment, and absorb tissue exudate.…”

Aligned electrospun fiber film loaded with multi-enzyme mimetic iridium nanozymes for wound healing

“…The skin, being the sizeable part of the human body, makes every effort to protect the body from the external stimuli. Its functions of physical insulation, immune protection, and metabolism will be severely impaired once the skin is wounded without its intact structure [ 1 , 2 ]. Production in large quantities of ROS at the wound site [ 3 , 4 ], have been demonstrated to be critical factors that suppress the wound healing.…”