pH-responsive gelatin nanoparticles for targeted delivery of ciprofloxacin against bacterial infections.

Abstract

Background: Given the rise in antimicrobial resistance and challenges associated with traditional antibiotic dosage forms, there is an urgency to develop drug delivery systems that improve, safeguard, and augment the present antibiotics on the market. Further research is required to maximize extended and targeted drug release, which can be accomplished via stimuli-responsive approaches such as pH-responsive nano-drug delivery systems. Furthermore, these pH-responsive nanosystems may be employed as carriers for antimicrobial drugs, which could be beneficial against antimicrobial resistance. Aim: The aim of this study was to prepare novel pH-responsive gelatin nanoparticles to function as delivery agents of Ciprofloxacin (CIP) to enhance their antibacterial effectiveness against methicillin-resistant Staphylococcus aureus (MRSA). Methods: CIP-GNPs were prepared using a two-step desolvation method. The particle size, polydispersity index (PDI) and zeta potential (ZP) of CIP-GNPs were determined using the dynamic light scattering technique. Transmission electron microscopy analysis was conducted to confirm particle size and visualize the morphology of CIP-GNPs. The entrapment efficiency (EE %) of CIP-GNPs was determined using the ultrafiltration method and was quantified using High-Performance Liquid Chromatography (HPLC). In vitro drug release of CIP-GNPs was conducted using the dialysis bag technique and CIP released was quantified using HPLC. Drug release dissolution factors were analysed using the DDSolver program. Hemocompatibility of CIP-GNPs was performed using sheep blood. In vitro antibacterial activity of CIP-GNPs was determined using micro broth assay against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), MRSA, and P. aeruginosa. Bacterial killing kinetics were performed against MRSA and P. aeruginosa using the plate colony counting method. MRSA and P. aeruginosa biofilm inhibition of CIP-GNPs was evaluated using the microtiter method. Results: CIP-GNPs had a particle size, polydispersity index, zeta potential, and entrapment efficiency of 212.3 ± 1.739, 0.259 ± 0.023, +4.58 ± 0.148 mV and 38.1 ± 3.85%, respectively. In vitro, biosafety testing identified CIP-GNPs as non-hemolytic. The CIP-GNPs demonstrated pH responsiveness with an increase in particle size from 204.1 ± 0.100 to 226.4 ± 0.451 nm and a charge switch on the zeta potential from -3.59 ± 0.428 to 1.06 ± 0.271 mV, followed by a significantly faster release of CIP at pH 6.0 compared to 7.4. The in vitro antibacterial activity of CIP-GNPs showed 2-fold lower minimum inhibitory concentration values compared to bare ciprofloxacin against Methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa). Moreover, the bacterial-killing kinetic test showed 100% elimination of MRSA and P. aeruginosa within eight and one hour(s) of treatment with CIP-GNPs, respectively. In contrast, 100% elimination of MRSA and P. aeruginosa was observed within 24 and 12 hours of treatment with bare ciprofloxacin, respectively. CIP-GNPs eliminated 3,75-fold MRSA biofilm compared to bare ciprofloxacin, whereas 1.4-fold Pseudomonas aeruginosa biofilms were eliminated. Conclusion: CIP-GNPs could effectively treat MRSA infections at a faster rate as compared to bare CIP. Therefore, this novel pH-responsive CIP-GNPs may serve as a promising nanocarrier for enhancing antibiotic delivery and antibacterial activity