A pH-modulated polymeric drug-release system simultaneously combats biofilms and planktonic bacteria to eliminate bacterial biofilm

Abstract

Bacterial infection, leading to biofilm formation, raises grave concerns. With the aim of eliminating both integrity of biofilms and individual bacterial cells, it is desirable to develop bacterial biofilm-eliminating material to be combined with dispersal and anti-microbial agents. Herein, a biofilm-eliminating enzyme (α amylase) was incorporated in novel pH-sensitive polymer hydrogel, Poly (methacrylic acid-co-2-(dimethylamino)ethyl methacrylate), which encapsulates drug-loaded porous Zeolitic Imidazolate Framework-8 (ZIF-8). At body temperature (37 °C) the maximum swelling of the hydrogel was observed at pH 8.5, which assisted in rupturing biofilm by releasing α amylase. Amylase, encapsulated in polymer matrix reached 90% release after 6 days at 8.5, while CIP was released 96% on day 23 at pH 8.5. The antibiofilm activity of drug-releasing system was assessed against E. coli and S. aureus. The overall bacterial viability of biofilms showed significant time-dependent declines, when exposed to drug-loaded hydrogel. Importantly, cytotoxicity experiments showed excellent biocompatibility of hydrogel. In the in vivo deep wound infection model, drug-loaded hydrogel treatment showed complete wound closure with proper tissue regeneration. No inflammatory, or systemic toxicity of hydrogel was observed. The drug release from hydrogel is initiated only upon receiving physiological cue arising due to biofilm formation. Therefore, this hydrogel serves as reservoir for antibacterial drug, which release it only in presence of biofilm and thus work for sustained release for long period, compared to conventional drug loaded films or coatings. A powerful modality for management of biofilm-associated infections can be provided by the proposed synergistic strategy for complete elimination of biofilms.