Introduction: Exists various release models of active ingredients such as liposomes, nanoparticles and microparticles. In the microspheres, the active ingredient is released by diffusion and also by the microsphere degradation[1]. So many variables can be found during the construction of microspheres such as type of active tense, relation between the dispersed phase and the continuous phase in the working solution, solvent condition and the percentage of the active ingredient encapsulated[2]. As a result, it is important to standardize the conditions of the microsphere production in order to manufacture and characterize chitosan microspheres.
Method: Furthermore, in order to verify the proper concentration of SPAN 80, different concentrations were used. 0.25, 0.5 and 1% of SPAN 80 were mix in 25ml of mineral oil and stir at 12.2 rpm in an IKA Ultraturrax. In one hand, a 2% chitosan solution in 5% acetic acid were prepared and placed in a 5ml syringe; which was added to SPAN 80 solution drop by drop and stirred for 5, 10 and 15 minutes. Later, SPAN/ chitosan solutions were first stirring for 30 minutes and fixed with glutaraldehyde and finally stirred for 6 hours. Chitosan/SPAN solution was centrifuged and washed with hexane and distilled water. Finally, the microspheres of chitosan were incubated with BMP 2 and VEFG-1 in order to evaluate bone marrow stem cell diffentiation to osteoblats .
Results and Discussion: It was observed that stirring at 12.2 rpm for 10 minutes was the optimum speed for the production of homogeneous microspheres in form and size. The increase of stirring speed has induced the microspheres breakage, while the decreased stirring speed has induced the development of bigger microspheres. Regarding the SPAN concentration, the 1% SPAN solution was the one which has induced the formation of microspheres from 5 to 10 microns, according to the analysis made by Scanning Electron Microscopy, Flow cytometry and the Zetasizer. Bone marrow cells incubated with microspheres were positive to alkaline phosphatase and osteopontin.
This investigation was supported by DGAPA PAPIIT IN218315; The first author is a student of Posgrado en Ciencias Médicas y de la Salud.; Francisco Pasos Nájera and Raquel Guerrero Alquicira for their technical assistance in this investigation
References:
[1] L. D. F. Santos, J. A. P. Coutinho, and S. P. M. Ventura, "From Water-in-Oil to Oil-in-Water emulsions to optimize the production of fatty acid using ionic liquids in micellar system"" American Institute of Chemical Engineers. 2015
[2] R. Pareta and M.J. Edirisinghe, " A novel method for the preparation of biodegradable microspheres for protein drug delivery". Journal of the Royal Society Interface. Published online 21. March 2006