Development of Antimicrobial Nanoplatforms: Synthesis, Functionalization, and Characterization of Polymeric and Bioactive Glass Nanoparticles for Bacterial Biofilm Eradication

Healthcare-associated infections (HAIs) refer to a set of infectious diseases acquired in a health facility. Among the pathogens involved in HAIs, it has been observed that bacteria can adhere to surfaces and aggregate, forming a complex structure, called biofilm, which makes them much less sensitive to external agents. From this scenario, the urgent need to explore innovative strategies for treating biofilm infections arises. The goal of this Ph.D. project was to develop a multitarget nano-platform capable of degrading bacterial biofilm and killing dispersed cells to reduce diverse types of infections, allowing more effective treatment paths. Initial work involved the synthesis of modified polycaprolactone (PCL-COOH) nanoparticles functionalized with the enzyme α-amylase and quercetin, a natural bioflavonoid with notable antioxidant and antimicrobial activity, to specifically target Staphylococcus aureus strains. Subsequently, expand the project fabricating mesoporous bioactive glass nanoparticles (MBGNs) functionalized with copper, manganese, and quercetin targeting multiple bacterial strains. The PCL-COOH nanoparticles were engineered to facilitate conjugation with α-amylase, leveraging the polymer’s biocompatibility and degradability. The structural and functional attributes of these enzyme-bound nanoparticles were characterized through techniques such as dynamic light scattering (DLS) and Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), while antibiofilm efficacy was assessed on S. aureus strains collected from clinical settings, by using atomic force microscopy (AFM). For the second phase, MBGNs were synthesized via a sol-gel process and subsequently functionalized with copper (Cu), manganese (Mn), and quercetin (Q). These MBGNs were analyzed in terms of morphology (SEM), composition (EDX, FTIR, XRD), in vitro bioactivity, cytotoxicity, and antibacterial activity on S. aureus and E. coli. The PCL-COOH nanoparticles conjugated with α-amylase and quercetin demonstrated strong biofilm degradation on S. aureus strains without compromising structural stability, indicating their potential for hospital surface disinfection. For MBGNs, quercetin encapsulation significantly enhanced the antibacterial efficacy without affecting cell viability, suggesting a synergistic effect between quercetin and the Cu/Mn ions. Both Cu-Q-MBGNs and Mn-Q-MBGNs formulations displayed elevated antibacterial properties against both S. aureus and E. coli strains, thus verifying the multifunctional potential of these formulations. This work highlights the potential of enzyme-functionalized nanoparticles and metal-ion-enhanced MBGNs as versatile, effective solutions for bacterial biofilm eradication in healthcare environments. These nanoformulations present promising applications not only in environmental disinfection but also in biomedical fields such as wound healing and infection control. The successful incorporation of natural antimicrobials like quercetin with metal-functionalized MBGNs paves the way for the development of future theragnostic platforms, which could be applied in both diagnostic and therapeutic contexts to combat multidrug-resistant infections.