Síntese e caracterização de nanopartículas termossensíveis de galactomanana de Delonix regia enxertada com n-isopropilacrilamida

Abstract

The pharmaceutical science has sought in recent decades ideal release drug delivery systems where the required therapeutic concentration is reached quickly and efficiently, thereby reducing the dosage number and side effects. Given the importance of developing new drug delivery systems, thermoresponsive copolymers grafted with N-isopropylacrylamide (NIPAm) are promising candidates as they are able to change their structure quickly and reversibly in response to a small variation of external stimulus, in our case the temperature. thermoresponsive copolymers were synthesized by radical polymerization of N-isopropylacrylamide with Delonix regia galactomannan, natural polysaccharide. The copolymers with the best yields were those synthesized with galactomannan concentration of 1%, an acid concentration of 0.1 mol / L , molar ratio GM: NIPA 1: 1.5. The copolymers were characterized by infrared spectroscopy and proton nuclear magnetic resonance. The presence of bands and characteristic peaks of galactomannan structure (3600, 2934, 1016-1076 cm-1) (5.03 and 4.74 ppm) and isoproprilacrilamida (1550, 2972 cm-1) (2.17, 1 66, 1.15 ppm) confirmed the grafting reaction. The copolymers exhibited phase transition with increasing temperature. All the copolymers showed transition temperature (LCST) greater than homopolymer (32 ° C) due to the presence of a hydrophilic polymer. The transition temperature was higher for CP1-0.1 polymers (39 ° C) and CP2-0.3 (41 ° C) due to the lower content of NIPA (TN). The transition temperature for CP2-0,1, CP-3, CP-4 copolymer were smaller (35 ° C). The CP1-0,1copolymer presented CAC higher (0.63 mg / ml) than the other copolymers at 50 ° C. The morphology of the formed nanoparticles of the CP-3 copolymer presents spherical aggregates in the manometric scale. The copolymer CP-4 showed the highest encapsulation efficiency while CP-3 copolymer showed the lowest one due to the low solubility in DMSO.