Design and evaluation of D-α tocopheryl polyethylene glycol 1000 succinate emulsified poly-ε-caprolactone nanoparticles for protein/peptide drug delivery

Background: Incorporation of proteins/peptide drugs into nanoparticulate drug delivery system is one of the effective approaches to increase the stability of protein/peptide drugs against enzymatic degradation, to release them in a controlled fashion and to achieve site-specific drug delivery. Objective: Our goal was to design and evaluate poly-epsilon-caprolactone (PCL) nanoparticles using bovine serum albumin (BSA) as a model protein. D-alpha-tocopheryl polyethylene glycol 1000 (vitamin E TPGS) was used as an emulsifier in the fabrication of these nanoparticles. Methods: Double emulsion solvent evaporation method was employed to formulate BSA-loaded PCL nanoparticles and the nanoparticles thus prepared were further characterized. Results: The size of BSA-loaded PCL nanoparticles were in the range of 400-500 nm with a polydispersity index (PDI) of 0.195 and zeta potential was about -28.6 mV. Scanning electron microscopy (SEM) confirmed the presence of smooth and spherical surface of nanoparticles. Encapsulation efficiency was about 85% and a yield of 70-75% was attained. BSA was released in a biphasic pattern with an initial 20% release within 2 h followed by a slower release patter over 5 days. Flow cytometry and fluorescence microscopy was used to study the uptake of these nanoparticles. Circular dichroism (CD) results showed that there was no significant effect of formulation conditions on the secondary structure of BSA. Conclusion: Based on the results obtained, these TPGS-emulsified PCL nanoparticles proved to be potential carriers for the delivery of protein/peptide drugs.