Desenvolvimento e caracterização de nanopartículas contendo meropenem e avaliação da atividade frente à Klebsiella pneumoniae resistente aos carbapenêmicos

Abstract

The World Health Organization (WHO) has declared antimicrobial resistance as one of the greatest threats to global public health in the 21st century. Consequently, it highlights the urgent need for research into innovative alternatives, particularly against critical Gramnegative bacteria such as carbapenem-resistant Klebsiella pneumoniae (CRKp). In this context, nanotechnology emerges as a promising strategy for developing new therapeutic approaches. Thus, the present study aimed to develop and characterize nanoparticles for the delivery of meropenem (MRP), with the goal of providing a new therapeutic alternative against CRKp. Three different formulations containing chitosan (QT), a polymer with promising antimicrobial activity, were developed: nanoparticles primarily composed of QT (NPQT), liposomes made of dipalmitoylphosphatidylcholine and cholesterol coated with QT (LQT), and nanoparticles combining silver, which also has antimicrobial activity, with QT (AgNPQT). Although NPQT showed results consistent with the literature in terms of average hydrodynamic diameter (DHm) (100.73 ± 2.71 nm), polydispersity index (PdI) (0.300 ± 0.02), and zeta potential (ZP) (+26.97 ± 0.21 mV), they exhibited low encapsulation efficiency (EE) (~3%), precluding further studies. For the liposomes, after QT coating, we observed an increase in DHm (from 120.79 ± 9.89 nm to 205.46 ± 18.41 nm), maintenance of PdI, and inversion of ZP to a positive value (+27.17 ± 1.36 mV). Furthermore, EE was higher than that observed for NPQT (~26%). However, in vitro antibacterial activity results against reference strains of carbapenemase-producing K. pneumoniae indicated that nanoencapsulation was not effective in reducing the minimum inhibitory concentration (MIC) compared to free MRP (MIC > 500 µg/mL for both samples). Finally, the AgNPQT-ME-MRP exhibited DHm = 75.21 ± 6.06 nm, PdI = 0.542 ± 0.02, and ZP = 41.60 ± 1.13 mV. Additionally, Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) analyses corroborated the adsorption of MRP onto the AgNPQT surface. Morphological characterization of this formulation using Atomic Force Microscopy revealed spherical particles with sizes consistent with the DHm measurements. Regarding activity against CRKp, the MIC of AgNPQT-MRP was lower than that of free MRP for all tested strains (reference and clinical), with a bacteriostatic effect. These results may be associated with a potential synergistic action between MRP and the nanoparticle constituents, indicating promising potential for combating carbapenem-resistant bacteria.