OPTIMIZATION OF CHITOSAN NANOCAPSULES USING A TWO-STEP NANOPRECIPITATION PROCESS FOR THE DELIVERY OF Α-CASEIN TO CANCER CELLS OVEREXPRESSING FOLIC ACID RECEPTORS

Vanessa C. Barceló-Bovea,¹ Ellianne N. Saladini-Alvarado,¹ Louis J. Delinois,1 Freisa M. Joaquín-Ovalle,¹  Yancy Ferrer-Acosta² and Kai Griebenow¹.

1. University of Puerto Rico, Rio Piedras Campus.
2. Central University of the Caribbean.

Chitosan has big potential in the development of drug delivery systems because of its biocompatibility and pH dependent solubility. The protein α-casein activates the interferon/STAT1 pathway and induces cell death. We designed a drug delivery system composed of α-casein nanoparticles coated with chitosan. The decoration of its surface with folic acid (FA), the acid response release and the enhanced permeation and retention (EPR) effect are expected to confer selectivity to this system. α-Casein was nano-precipitated using a solvent displacement method and we tested different protein concentrations and solvents. The coating was achieved by adding the nanoparticle suspension to a chitosan solution. We tested two methods for the FA modification: EDC/Sulfo-NHS based covalent chemistry and electrostatic coupling. Morphology, diameter, surface charge, and encapsulation efficiency were determined. Viability in MDA-MB-231 and NIH-3T3 cells was assessed using the MTS assay. The effect of the addition of the excipients PEG 200 and trehalose is being studied. Optimal conditions for nanoprecipitation were found using acetonitrile and a protein concentration of 60 mg/ml. This resulted is spherical nanoparticles with a diameter of 129 nm. Maximum encapsulation efficiency (92.7%) was achieved using a 0.4 mg/ml chitosan solution during the coating step. The yield of FA modification was 67.4% and 81.7 % using the EDC/sulfo-NHS reaction and electrostatic coupling respectively. Cell viability was reduced to a 53.6% for MDA-MB-231 and 79.4% for NIH-3T3 after 40 hours of treatment with 19 μg/ml of encapsulated α-casein (non-modified with FA). Non-encapsulated α-casein was less cytotoxic in both cell lines. Preliminary experiments showed that PEG 200 enhances nanocapsules suspension. Drug release will be studied under different pH. The effect of FA modification will be tested in MDA-MB-231, NIH-3T3 and LL/2 (LLC1) cells and it is expected to produce higher cytotoxicity. Our results support the suitability of this drug delivery system for cancer therapy.