This study presents the influence of the primary formulation parameters on the formation of poly-DL-lactic-co-glycolic nanoparticles by the emulsification-solvent evaporation, and the nanoprecipitation techniques. In the emulsification-solvent evaporation technique, the polymer and tensoactive concentrations, the organic solvent fraction, and the sonication amplitude effects were analyzed. Similarly, in the nanoprecipitation technique the polymer and tensoactive concentrations, the organic solvent fraction and the injection speed were varied. Additionally, the agitation speed during solvent evaporation, the centrifugation speeds and the use of cryoprotectants in the freeze-drying process were analyzed. Nanoparticles were characterized by dynamic light scattering, laser Doppler electrophoresis, and scanning electron microscopy, and the results were evaluated by statistical analysis. Nanoparticle physicochemical characteristics can be adjusted by varying the formulation parameters to obtain specific sizes and stable nanoparticles. Also, by adjusting these parameters, the nanoparticle preparation processes have the potential to be tuned to yield nanoparticles with specific characteristics while maintaining reproducible results.

Vaccination is the most effective and least expensive technique used for human diseases prevention and eradication. The need for more vaccine doses and the rapid establishment of facilities for the development of new vaccines are stimulating significate changes in the vaccine industry, which is gradually moving towards cell culture production. One approach is the third generation of vaccines, which are based on the use of plasmid DNA (pDNA) containing transgenes that encode an antigen capable of mimicking intracellular pathogenic infection and triggering both humoral and cellular immune responses. Plasmid DNA vaccination has distinct advantages over other vaccine technologies in terms of safety, ease of fabrication and stability. The effectiveness of pDNA vaccines against viruses, bacteria, parasites and cancer cells has been demonstrated in preclinical and clinical assays. Furthermore, currently there are a few veterinary pDNA vaccines in the market. The application of a simple formulation of naked pDNA as a vaccine is attractive, but a low transfection efficiency is often obtained. The use of nanoparticles to increase transfection efficiency is an approach that has been tested clinically. This review provides a summary of vaccine production, advances and major challenges associated with pDNA lipid and polymeric nanovaccines applications.

The delivery of photosensitizer compounds using biodegradable nanoparticles could improve dosage, controlled release and its bioavailability. In this study, methylene blue (MB) loaded PLGA nanoparticles (MB-PNP) are prepared by a new approach combining single and double emulsification techniques. Comparisons of MB-PNP obtained with the combined and the individual techniques are presented. Nanoparticles are characterized by dynamic light scattering, laser Doppler electrophoresis and scanning electron microscopy. Particles prepared by the combined technique presented hydrodynamic diameters of 186 nm. The sizes of MB-PNP obtained from the single emulsion technique are similar to the combined technique, while the diameter of particles prepared by double emulsion increased from 201 nm to 287 nm as the TDL increased. MB-PNP displayed an average zeta potential between −21 mV and −28 mV for all formulations. MB loading ranges between 0.3–1.4%, while the encapsulation efficiency ranges from 8–14%, both depending on the TDL and the preparation technique. In vitro release studies show a monophasic release profile that was analyzed by considering the mechanisms of initial burst, drug diffusion and a combination of them. Experimental results could be better described using a mathematical model of release that simultaneously combines the mechanisms of initial burst and drug diffusion. The approach presented to encapsulate MB and also to analyze the drug release could be extended to other drugs with partial solubility.