Figure 5TG and DTG curves of resveratrol.Figure 6TG curves of resveratrol, PHBV/PCL and physical mixtures (a) and (b), PHBV microparticles (c), and PCL microparticles (d).PHBV microparticles demonstrated onset temperatures of degradation selleck bio at 585, 581, 577, and 582K for M1R0, M1R5, M1R10, and M1R20, respectively. Otherwise PCL microparticles started their degradation at 671K (M2R0), 689K (M2R5), 686K (M2R10), and 683K (M2R20). These results indicate that PCL microparticles are thermally more stable than those composed by PHBV. Similar data were previously described for carvedilol-loaded microparticles, in which formulations containing PCL revealed increased thermal stability than formulations prepared with PHBV [23].3.6.2.

Differential Scanning Calorimetry DSC curves of pure resveratrol, PHBV, PCL, physical mixtures, and PHBV/PCL microparticles are indicated in Figure 7. Resveratrol showed a sharp endothermic event at 539K in accordance with the literature values [44, 45]. The melting temperatures (Tm) obtained for polymers were 438K for PHBV and 333K for PCL, confirming previously reported data [41]. The typical melting event of resveratrol was not observed in DSC curves of PHBV/PCL microparticles. This thermal behavior suggests that a drug amorphization occurred. This result is reinforced by the XRPD patterns of PHBV/PCL microparticles in which only the characteristic crystalline peaks of the polymers were observed.Figure 7DSC curves of resveratrol, PHBV/PCL, physical mixtures, and PHBV/PCL microparticles.3.7.

In Vitro Drug Release and Analysis of Release BehaviorThe dissolution rates of resveratrol and PHBV/PCL microparticles are shown in Figure 8. By the performed dissolution test, the mean time for 80% release of pure resveratrol was 45min. However, PHBV microparticles demonstrated mean dissolution times of 300min (M1R5), 240min (M1R10), and 90min (M1R20) for 80% drug release. For PCL microparticles, a value of 80% drug release was achieved in mean dissolution times of 720, 300, and 180min for M2R5, M2R10, and M2R20, respectively. Therefore resveratrol from PHBV/PCL microparticles showed a slower dissolution rate than pure drug.Figure 8In vitro release profiles of pure drug and resveratrol-loaded PHBV/PCL microparticles.These results demonstrate that PHBV/PCL played an important role on the delay of drug dissolution.

This behavior can be related to polymer:drug ratio and morphological aspects. For both PHBV/PCL microparticles, formulations obtained at a polymer:drug ratio of 19:1 (5% resveratrol) showed slower release of resveratrol. Probably the greater amount of polyester in these formulations had a remarkable effect in controlling the drug release Anacetrapib rate. This faster release of resveratrol from PHBV microparticles can also be related to their porous surface previously observed by SEM. In general, microparticle studies have showed that the drug release rate is faster for higher-porosity materials [41].