Design of advanced multifunctional biomaterial-based biomimetic and pH-responsive hybrid nanocarriers for antibiotic delivery against bacterial infections and sepsis.

Abstract

Despite the notable improvements in the management of bacterial infections and sepsis, the mounting threat of antibiotic resistance on a global scale is leading towards a post-antibiotic era. Nano-drug delivery systems have improved the delivery and efficacy of various antibiotics. Biomimicry and stimuli-responsiveness have recently been used to improve the targetability of these nanocarriers, and enhance their localization at infected sites, thus improving overall therapeutic outcomes and reducing toxicity. Strategies such as targeting bacterial biofilms and efflux pumps can further enhance the delivery and effectiveness of antibiotics. Developing smart biomaterials with multifunctional properties to confer biomimetic, stimuli-responsive and antivirulence properties to antibiotic nanocarriers is the focus of ongoing research. Therefore, the general aim of this study was to investigate the potential of various novel multifunctional biomaterial-based hybrid nanocarriers (HNs), including biomimetic and/or pH-responsive HNs in enhancing the targeted delivery of antibiotics and modulating the proinflammatory response against bacterial infections and sepsis. In this study, two biomaterials with multifunctional activities, hyaluronic acid-lysine conjugate (HA-Lys) and tannic acid (TA), were employed to design, formulate, and extensively characterize innovative biomimetic and pH-responsive HNs for efficient and targeted delivery of antibiotics. The novel HA-Lys was synthesized and fully characterized using proton nuclear magnetic resonance (1H NMR) spectroscopy and Fourier-transform infrared spectroscopy (FT-IR). Then it was successfully employed with tocopherol succinate (TS) and Oleylamine (OLA) to fabricate biomimetic pH-responsive vancomycin-loaded hybrid nanostructured lipid carriers (VCM-HNLCs). The prepared VCM-HNLCs were spherical and had average diameters, zeta potential, polydispersity index, drug encapsulation efficiency and loading capacity of 110.77  1.69 nm, 0.11  0.02, -2.92  0.21 mV, 76.27  1.20 % and 8.36  0.25 %, respectively. Both HA-Lys conjugate and its respective nanoformulations had excellent biosafety profiles (>70 % cell viability and ˂ 1 % hemolytic effect). Possible VCM-HNLCs competitive inhibition activity to toll-like receptors 2 and 4 (TLR2 and TLR4) was demonstrated via microscale thermophoresis (MST) analysis, which showed a 5-times and 16-times lower Kd values than their natural substrates peptidoglycan (PGN) and lipopolysaccharide (LPS), respectively. VCM-HNLCs exhibited a pH-responsive drug release profile under acidic conditions, higher bacterial killing kinetics, enhanced antibacterial, anti-biofilm, and efflux pump inhibition activities over bare VCM. Also, they showed an improved activity in neutralizing reactive oxygen species (ROS) and modulating the inflammatory response induced by LPS. On the other hand, tannic acid (TA) and Oleylamine (OLA) were successfully employed to formulate biomimetic ciprofloxacin-loaded tannic acid hybrid nanoparticles (CIP-loaded TAH-NPs) to enhance the efficacy of CIP against bacterial infections and sepsis. The prepared HNs had onion-shaped morphology, with average diameters, zeta potential, polydispersity index, drug encapsulation efficiency and loading capacity of 85.65 ± 0.89 nm, 0.126 ± 0.01, +16.3 ± 0.23 mV, 68.73 ± 0.54 % and 6.86 ± 0.09 %, respectively. The hemolysis and MTT assays confirmed the biosafety and non-hemolytic activity of CIP-loaded TAH-NPs formulations (>70 % cell viability and ˂ 1 % hemolytic effect). The results of MST investigations and in-silico simulations demonstrated that TA and its nanoformulation (CIP-loaded TAH-NPs) competitively inhibited TLR4 compared to its natural substrate LPS. CIP-loaded TAH-NPs showed a diffusion-based sustained release profile at physiological pH 7.4. Also, in comparison to bare CIP, the hybrid nanovesicles demonstrated improved antibacterial, anti-biofilm and efflux pump inhibition properties, as well as faster bacterial killing kinetics. Moreover, they showed a significant neutralization of ROS and the ability to control the inflammatory responses brought on by LPS. In summary, VCM-HNLCs and CIP-loaded TAH-NPs were successfully formulated and showed significant improvement in antibiotics efficacy and overall therapeutic outcomes. This study confirmed the potential of biomimetic stimuli-responsive antibiotic hybrid nanocarriers for enhancing antibiotic efficacy against bacterial sepsis and addressing the antimicrobial resistance crisis. The data from this study has resulted in one first-authored review article, two first-authored research publications and one co-authored review article.