Simultaneous quantification of polymeric and surface active stabilizers of nanosuspensions by using near-infrared spectroscopy

Nanosuspensions as delivery system for gambogenic acid: characterization and in vitro/in vivo evaluation

Nanosuspensions (NS) can enhance the saturation solubility and dissolution velocity of poorly soluble drugs. PEG as a non-ionic surfactant plays an important role in surface modification of nanoparticles for prolonging in vivo circulation. In this study, anti-solvent precipitation method was introduced to prepare gambogenic acid nanosuspensions (GNA-NS) with PVPK30 and PEG2000 as stabilizers to settle the disadvantages of GNA. The obtained nanoparticles were spherical with a mean particle size of 183.7 nm and a zeta potential of -22.8 mV. The entrapment efficiency and drug loading of the resultant formulation were 97.3 and 29.73%. X-ray diffraction analysis confirmed the amorphous phase of GNA in NS. Fourier transform infrared indicated there may be hydrogen bond interaction between the drug and excipients. After lyophilization of GNA-NS, the freeze-dried powder displayed sufficient long-term physical stability at 4 and 25 °C. In comparison to GNA solution, in vitro studies of GNA-NS showed much slower release and higher cytotoxicity in HepG2 cells. What's more, the pharmacokinetic study in rats revealed that the AUC_0-∞ and t_1/2 of GNA-NS were increased 2.63- and 1.77-fold than that of the reference formulation. Taken together, in vitro/in vivo evaluations showed NS would be an effectively strategy to change the poor aqueous solubility and prolong the half-life for GNA. The GNA-NS with enhanced bioavailability and drug efficacy provided a promising delivery system for the application of GNA.

Immune system targeting by biodegradable nanoparticles for cancer vaccines

The concept of therapeutic cancer vaccines is based on the activation of the immune system against tumor cells after the presentation of tumor antigens. Nanoparticles (NPs) have shown great potential as delivery systems for cancer vaccines as they potentiate the co-delivery of tumor-associated antigens and adjuvants to dendritic cells (DCs), insuring effective activation of the immune system against tumor cells. In this review, the immunological mechanisms behind cancer vaccines, including the role of DCs in the stimulation of T lymphocytes and the use of Toll-like receptor (TLR) ligands as adjuvants will be discussed. An overview of each of the three essential components of a therapeutic cancer vaccine - antigen, adjuvant and delivery system - will be provided with special emphasis on the potential of particulate delivery systems for cancer vaccines, in particular those made of biodegradable aliphatic polyesters, such as poly(lactic-co-glycolic acid) (PLGA) and poly-ε-caprolactone (PCL). Some of the factors that can influence NP uptake by DCs, including size, surface charge, surface functionalization and route of administration, will also be considered.