Adhesion of PLGA or Eudragit/PLGA nanoparticles to Staphylococcus and Pseudomonas.

The aim of present study was to examine whether cationic Eudragit containing poly(lactide-co-glycolide) (PLGA) nanoparticles can adhere to Pseudomonas aeruginosa and Staphylococcus aureus. In order to prepare fluorescent nanoparticles, fluorescein was covalently coupled to PLGA. Fluorescent PLGA and Eudragit/PLGA nanoparticles were prepared by w/o/w emulsification solvent evaporation. Particle size and zeta potential of the nanoparticles were measured. Nanoparticles were incubated for a short time with P. aeruginosa and S. aureus followed by measurement of the size of nanoparticles and of P. aeruginosa and S. aureus with and without adherent nanoparticles. Flow cytometric measurements were performed to detect the attachment of particles to microorganisms. Eudragit containing nanoparticles possessed a positive zeta potential, while PLGA nanoparticles were negatively charged. Following adsorption of Eudragit containing nanoparticles, a size increase for P. aeruginosa was observed. Flow cytometric analyses confirmed that Eudragit containing particles showed stronger interactions with the test organisms than PLGA nanoparticles. Adhesion of particles was more pronounced for P. aeruginosa than for S. aureus. Cationic Eudragit containing nanoparticles showed better adhesion to microorganisms than anionic PLGA nanoparticles, which is probably due to enhanced electrostatic interactions.

Evaluation of ciprofloxacin-loaded Eudragit RS100 or RL100/PLGA nanoparticles.

The objective of present study was to prepare positively charged ciprofloxacin-loaded nanoparticles providing a controlled release formulation. The particles were prepared by water-in-oil-in-water (w/o/w) emulsification and solvent evaporation, followed by high-pressure homogenisation. Two non-biodegradable positively charged polymers, Eudragit RS100 and RL100, and the biodegradable polymer poly(lactic-co-glycolic acid) or PLGA were used alone or in combination, with varying ratios. The formulations were evaluated in terms of particle size and zeta potential. Differential scanning calorimetry measurements were carried out on the nanoparticles and on the pure polymers Eudragit and PLGA. Drug loading and release properties of the nanoparticles were examined. The antimicrobial activity against Pseudomonas aeruginosa and Staphylococcus aureus was determined. During solvent evaporation, the size and zeta potential of the nanoparticles did not change significantly. The mean diameter was dependent on the presence of Eudragit and on the viscosity of the organic phase. The zeta potential of all Eudragit containing nanoparticles was positive in ultrapure water (around +21/+25 mV). No burst effect but a prolonged drug release was observed from all formulations. The particles' activity against P. aeruginosa and S. aureus was comparable with an equally concentrated ciprofloxacin solution.

The influence of the use of viscosifying agents as dispersion media on the drug release properties from PLGA nanoparticles.

Poly(lactide-co-glycolide) nanoparticles incorporating ciprofloxacin HCl were prepared by means of a W/O/W emulsification solvent evaporation method. The physicochemical properties of these particles were evaluated by measuring particle size, zeta potential and drug loading efficiency. Gamma-sterilised nanoparticles were dispersed in different isoviscous polymer solutions, commonly used as vehicles in eye drops. The influence of gamma-irradiation of the viscosifying agents on the drug release properties of the dispersed nanoparticles was evaluated with respect to release in mannitol solution. The viscosity of the polymer solutions prepared was measured by flow rheometry and thereby the influence of temperature and sterilisation by autoclaving on viscosity was examined. Before and after freeze-drying and subsequent sterilisation by gamma-irradiation, the polymer solutions were also characterised by dynamic stress sweep and dynamic frequency sweep oscillation measurements to deduce possible structural changes. A possible relationship between the differences in ciprofloxacin release from the nanoparticles suspended in the various media and the network structure or rheological behaviour of the polymers was investigated.

Factorial design, physicochemical characterisation and activity of ciprofloxacin-PLGA nanoparticles.

Poly(lactide-co-glycolide) nanoparticles incorporating ciprofloxacin HCl were prepared by means of a W/O/W emulsification solvent evaporation method. The stabiliser selected was poly(vinylalcohol). A 2(4) full factorial design based on four independent variables was used to plan the experiments and the variable parameters were the number of homogenisation cycles, addition of boric acid to the inner water phase containing the drug, ciprofloxacin concentration in the inner water phase and oil:outer water phase ratio. The effects of these parameters on the particle size, zeta potential, drug loading efficiency and drug release were investigated. Also the effect of gamma irradiation on the particle size and drug release was evaluated and DSC and XRD analyses of the compounds and the nanoparticles were performed. The activity on two series of microorganisms, Pseudomonas aeruginosa and Staphylococcus aureus, was examined.