Antibacterial Activity of Ciprofloxacin-Loaded Poly(lactic-co-glycolic acid)-Nanoparticles Against Staphylococcus aureus

The formation of bacterial biofilms on material surfaces is a recurrent problem in public health. Antibacterial nanoparticles (NPs) are promising because pathogens have not yet developed resistance mechanisms and encapsulation of the drug can protect it from the surrounding medium and improve pharmacokinetics. Biocompatible and biodegradable particles of various sizes (nano- and micro-scale) based on poly(lactic-co-glycolic acid) (PLGA) are elaborated using a simple and free toxic nanoprecipitation process. Particles are poly(ethylene glycol) (PEG)-ylated in order to reduce unwanted interactions with biological fluids, or loaded with the large spectrum antibiotic ciprofloxacin (CIP). NPs are studied against Staphylococcus aureus in planktonic and biofilm modes. Empty NPs with smallest size (60 nm) are able to totally eradicate planktonic culture after 24 h, even in the presence of serum proteins. CIP-loaded NPs present slightly lower antimicrobial activity against planktonic microorganisms compared with the free antibiotic, due to progressive release of CIP over time. In biofilm mode, CIP-loaded NPs show a very good antibiofilm activity, much better than free CIP, thanks to NPs penetration within the polymer matrix and a consequent release of the antibiotic close to the embedded bacteria. The present results open the way for widespread applications of PLGA-NPs in the pharmaceutical or medical fields.     

A fully consistent experimental and molecular simulation study of methane adsorption on activated carbon

The adsorption of pure methane in activated carbon Ecosorb was studied by combining grand canonical ensemble Monte Carlo molecular simulations and an experimental approach based on a gravimetric device. Experimental and calculated adsorption isotherms of methane were determined in supercritical conditions at 303.15 and 353.15 K and pressures up to 10 MPa. The comparison between both experimental and estimated data proves the consistency of the methodology used in this work, starting from the characterization of the porous media in terms of pore size distribution, the determination of the experimental adsorption isotherms, and the final estimation of computational results through estimated isotherms determination. Moreover, additional differential enthalpy of adsorption calculations were compared with experimental values obtained by means of a manometric/calorimetric technique. The good agreement shows the strength and the originality of this paper by combining experimental and computational homemade results allowing a complete characterization of the activated carbon substrate and its methane storage capacity.