Stimuli-Triggered Zein-Based Antibiotic Nanocarriers for Targeting and Eradication of Bacterial Biofilms

Abstract

Background: The resistance of antimicrobials and bacterial biofilms are significant obstacles to effective management of chronic infections. Bacteria embedded in biofilm become much more resistant to traditional antibiotics due to the markedly limited ability of drugs to penetrate the extracellular polymeric substance matrix, bacterial persistence, and treatment efficacy. Such shortcomings point to the necessity of sophisticated drug delivery mechanisms that could help to increase drug availability in the area and boost antibiofilm effect. Zein, a biodegradable and biocompatible plant-derived protein, in this case is a potential nanocarrier matrix that can be used to deliver antibiotics more effectively. Methods: The antisolvent co-precipitation process was used to prepare zein-based antibiotic nanocarriers. Tetracycline hydrochloride and ampicillin sodium-loaded zein nanoparticles prepared with and without poloxamer 407 coating. The particle size, zeta potential, morphology, and encapsulation efficiency of the formulations were checked using dynamic light scattering, electrophoretic light scattering, transmission electron microscopy, and scanning electron microscopy. Drug release was tested in non-triggered, enzyme-triggered and ultrasound-triggered conditions in vitro. Antibiofilm efficacy of Staphylococcus aureus biofilms was measured using fluorescence microscopy and colony forming unit, whereas cytotoxicity and impact on proliferation of HaCaT human keratinocyte cells was measured using Hoechst/ PI staining and MTS assay, respectively. Results: This study produced zein-based nanoparticles with an appropriate physicochemical properties to use in the delivery of drugs, the encapsulation of antibiotics was feasible in all preparations. Formulation conditions varied the particle size and surface charge, and microscopic analysis confirmed the morphology of nanoparticles. Studies of drug release revealed slower sustained-release trend within 24 hours. Enzymatic treatment and ultrasound triggering stimulate a faster release of drugs than when nothing was triggered, validating the stimuli-responsive nature of the system. Antibiotic-loaded zein nanoparticles resulted in a higher biofilm reduction compared to unloaded nanoparticles in the study of antibiofilm, and the effect was amplified with the increase in drug concentration. Ultrasound induction also boosted bacterial biofilm eradication, and anti-bacterial efficacy. The formulations developed were also found to be acceptable in in vitro biocompatible with HaCaT cells. Conclusion: The results of this study reveal that zein-based antibiotic nanocarriers that are triggered by enzymes and ultrasound cavitation are a promising platform of targeted antibiofilm therapy. The developed system, which employs a biodegradable protein-based carrier and enzyme-responsive and ultrasound-assisted drug release, provides a better approach to localized antibiotic delivery, improved performance against biofilms and may result in a so-called safer-by-design approach to treating bacterial infections associated with biofilms.