Combating Pseudomonas aeruginosa Biofilms by a Chitosan-PEG-Peptide Conjugate via Changes in Assembled Structure

Abstract

Pseudomonas aeruginosa (P. aeruginosa) biofilms are associated with a wide range of infections, from chronic tissue diseases to implanted medical devices. In a biofilm, the extracellular polymeric substance (EPS) causes an inhibited penetration of antibacterial agents, leading to a 100− 1000 times tolerance of the bacteria. In view of the water-filled channels in biofilms and the highly negative charge of EPS, we design a chitosan-polyethylene glycol-peptide conjugate (CS-PEG-LK 13 ) in this study. The CS-PEG-LK 13 prefers a neutrally charged assembly at a size of ∼100 nm in aqueous environment, while undergoes disassembly to expose the α-helical peptide at the bacterial cell membrane. This behavior provides CS-PEG-LK 13 superiorities in both penetrating the biofilms and inactivating the bacteria. At a concentration of 8 times the minimum inhibitory concentration, CS-PEG-LK 13 has a much higher antibacterial efficiency (72.70%) than LK 13 peptide (15.24%) and tobramycin (33.57%) in an in vitro P. aeruginosa biofilm. Moreover, CS-PEG-LK 13 behaves comparable capability of combating an implanted P. aeruginosa biofilm to highly excess tobramycin. This work has implications for the design of new antibacterial agents in biofilm combating.

Water in bacterial biofilms: pores and channels, storage and transport functions

“…Experiments with stealth, poly(ethylene glycol) coated liposomes and polystyrene nanoparticles (see Figure 3), unable to adsorb to biofilm components, demonstrated that liposomes with diameters above 100-130 nm were unable to diffuse through channels in Burkholderia multivorans and P. aeruginosa biofilms (see Figure 3) (Forier et al 2014). A similar minimal width of 100 nm was reported in order to avoid adsorption of antimicrobials to channel walls upon diffusion-controlled penetration of an antimicrobial in an infectious biofilm (Ju et al 2020). However, intra-colony channels with much larger diameters of around 10 mm have also been described in E. coli, using giant objective lens microscopy with a high numerical aperture at low magnification ("mesoscopy") (Rooney et al 2020) and even wider channels (18-99 mm) have been described in P. aeruginosa (Lei et al 2020).…”

Bioinspired Intrinsic Versatile Hydrogel Fabricated by Amyloidal Toxin Simulant‐Based Nanofibrous Assemblies for Accelerated Diabetic Wound Healing

“…ANS fluorescence and PI fluorescence measurements of the hydrogel-treated groups show obvious enhancements compared with the control group (Figure S24, Supporting Information), indicating that bacteria died and their membranes turned over after treatment. [58] On the basis of these observations, we inferred that the antibacterial activity of the FLN-based hydrogel, like that of other amyloid fibrils, is based on a membrane-disrupting mechanism (Figure 7h). Interestingly, the FLN nanofibrils could capture the planktonic microorganisms and achieved bead-like bacterial agglomeration (MRSA and P. aeruginosa), as recorded by AFM (Figure 7g), which is likely a consequence of the organized β-sheet structure of the nanofibrils and the positive charge of the Lys exposed on the surface of the nanofibrils (Figure 3).…”

“…Notably, bacteria do not easily develop resistance to such a physical-damage-based antibacterial mechanism. [58] A diabetic ulcer, as a typical chronic wound, is prone to wound nonclosure and persistent microbial infection, eventually resulting in a 41% possibility of amputation. Diabetic ulcers thus pose a large challenge to medicine and represent a financial burden to society.…”

Antimicrobial Contribution of Chitosan Surface-Modified Nanoliposomes Combined with Colistin against Sensitive and Colistin-Resistant Clinical Pseudomonas aeruginosa

“…However, recent evidence revealed that chitosan penetrates the cell membrane of P. aeruginosa, releasing the cell contents and aggregating the residue cytoplasmic material into a mass. It was presumed that the cytoplasmic material was agglomerated by flocculation of chitosan after entering the cell [50], an effect that would overcome the resistance mechanisms mentioned above. Finally, so far, this finding could mean highly deacetylated chitosan is a potential antimicrobial agent to use against CST-resistant MDR strains.…”