3D-printed dual drug delivery nanoparticle- loaded hydrogels to combat antibiotic-resistant bacteria.

Implant-associated infections are not easy to diagnose and very difficult to treat, due to the ability of major pathogens, such as Staphylococcus aureus, to develop biofilms and escape the immune response and antibiotic treatment. We, therefore, aimed to develop a 3D-printed dual rifampicin (Rif)- and vancomycin (Van)-loaded polylactic- co-glycolic acid (PLGA) nanoparticles (NPs) delivery system based on hydrogels made of gelatin methacrylate (GelMA). The release of Rif and Van from NPs manufactured from different PLGA molecular weights was studied in phosphate-buffered saline for 21 days. Low molecular weight PLGA NPs exhibited the fastest release of Rif and Van within the first 7 days and were selected for antimicrobial evaluation. Four different GelMA-based 3D-printed samples were successfully produced, carrying non-loaded NPs, Rif-NPs, Van-NPs, or alternating layers of Rif-NPs and Van-NP. The exposition of S. aureus against increased concentrations of Rif or Van produced new resistant strains to Rif (RifR) or Van (VanR). The GelMA hydrogel co-delivering Rif and Van eradicated S. aureus RN4220 RifR and RN4220 VanR strains. S. aureus RN4220 and S. aureus AMC 201 colonies developed resistance to Rif after contact with the GelMA hydrogel containing only Rif-NPs which appeared to be due to known mutations in the rpoB gene. In conclusion, 3D-printed GelMA hydrogel loaded with PLGA Rif-Van-NPs drug delivery system show promising in vitro results to prevent implant-associated infections caused by antimicrobial-resistant bacteria.