Adriamycin loading and release characteristics of albumin-heparin conjugate microspheres

CD44/Folate Dual Targeting Receptor Reductive Response PLGA-Based Micelles for Cancer Therapy

In this study, a novel poly (lactic-co-glycolic acid) (PLGA)-based micelle was synthesized, which could improve the therapeutic effect of the antitumor drug doxorubicin hydrochloride (DOX) and reduce its toxic and side effects. The efficient delivery of DOX was achieved by active targeting mediated by double receptors and stimulating the reduction potential in tumor cells. FA-HA-SS-PLGA polymer was synthesized by amidation reaction, and then DOX-loaded micelles were prepared by dialysis method. The corresponding surface method was used to optimize the experimental design. DOX/FA-HA-SS-PLGA micelles with high drug loading rate and encapsulation efficiency were prepared. The results of hydrophilic experiment, critical micelle concentration determination, and hemolysis test all showed that DOX/FA-HA-SS-PLGA micelles had good physicochemical properties and biocompatibility. In addition, both in vitro reduction stimulus response experiment and in vitro release experiment showed that DOX/FA-HA-SS-PLGA micelles had reduction sensitivity. Molecular docking experiments showed that it can bind to the target protein. More importantly, in vitro cytology studies, human breast cancer cells (MCF-7), human non-small cell lung cancer cells (A549), and mouse colon cancer cells (CT26) were used to demonstrate that the dual receptor-mediated endocytosis pathway resulted in stronger cytotoxicity to tumor cells and more significant apoptosis. In and in vivo antitumor experiment, tumor-bearing nude mice were used to further confirm that the micelles with double targeting ligands had better antitumor effect and lower toxicity. These experimental results showed that DOX/FA-HA-SS-PLGA micelles have the potential to be used as chemotherapeutic drugs for precise tumor treatment.

Controlled Release of Vascular Endothelial Growth Factor from Heparin-Functionalized Gelatin Type A and Albumin Hydrogels

Bio-based release systems for pro-angiogenic growth factors are of interest, to overcome insufficient vascularization and bio-integration of implants. In this study, we investigated heparin-functionalized hydrogels based on gelatin type A or albumin as storage and release systems for vascular endothelial growth factor (VEGF). The hydrogels were crosslinked using carbodiimide chemistry in presence of heparin. Heparin-functionalization of the hydrogels was monitored by critical electrolyte concentration (CEC) staining. The hydrogels were characterized in terms of swelling in buffer solution and VEGF-containing solutions, and their loading with and release of VEGF was monitored. The equilibrium degree of swelling (EDS) was lower for albumin-based gels compared to gelatin-based gels. EDS was adjustable with the used carbodiimide concentration for both biopolymers. Furthermore, VEGF-loading and release were dependent on the carbodiimide concentration and loading conditions for both biopolymers. Loading of albumin-based gels was higher compared to gelatin-based gels, and its burst release was lower. Finally, elevated cumulative VEGF release after 21 days was determined for albumin-based hydrogels compared to gelatin A-based hydrogels. We consider the characteristic net charges of the proteins and degradation of albumin during release time as reasons for the observed effects. Both heparin-functionalized biomaterial systems, chemically crosslinked gelatin type A or albumin, had tunable physicochemical properties, and can be considered for controlled delivery of the pro-angiogenic growth factor VEGF.

Amoxicillin-bearing microparticles: potential in the treatment of Listeria monocytogenes infection in Swiss albino mice

The present study was aimed at evaluating the effectiveness of amoxicillin-bearing HSA (human serum albumin) and PLGA [poly(lactic-co-glycolic acid)] microparticles in combating Listeria monocytogenes infection in Swiss albino mice. Amoxicillin-bearing HSA microspheres were prepared by chemical cross-linking of a drug/albumin mixture with glutaraldehyde, and PLGA microspheres were prepared by the W/O/W (water-in-oil-in-water) emulsion technique. The microspheres were characterized for their size, ζ potential and entrapment efficiency using SEM (scanning electron microscopy) and a Zetasizer. Release kinetics was performed in a phosphate buffer (pH 7.4) at 37°C simulating physiological conditions. Bacterial burden in various vital organs and survival data established enhanced efficacy of PLGA and HSA microspheres as compared with free drug. Among the two delivery systems, PLGA microspheres, when compared with HSA microspheres, imparted better efficacy in terms of reduction in bacterial load as well as increase in survival. The results of the present study clearly demonstrate that microparticles successfully target the infected macrophages and the approach could be well exploited for targeting the intracellular pathogens as well.

Effects of preparation conditions on the monodispersity of albumin microspheres

Monodisperse albumin microspheres were successfully prepared by both chemical or thermal hardening methods via membrane emulsification using microporous glass membranes with uniform pore sizes. The monodispersity of the microspheres was found to depend strongly on parameters such as albumin concentration, emulsifier concentration, and volume ratio of the internal aqueous phase (albumin solution) to the dispersion medium (organic solvent). The optimum conditions for obtaining monodisperse albumin microspheres are described.

Degradation and intrahepatic compatibility of albumin-heparin conjugate microspheres

The in vitro degradation properties of glutaraldehyde cross-linked albumin and albumin-heparin conjugate microspheres (AMS and AHCMS respectively) were evaluated using light microscopy, turbidity measurements and heparin release determinations, showing that the microspheres are degraded by proteolytic enzymes such as trypsin, proteinase K and lysosomal enzymes. The degradation rate was inversely related to the cross-link density of the microspheres. After intrahepatic administration of AHCMS, cross-linked with 0.5% glutaraldehyde, to male Wag/Rij rats by injection into a mesenteric vein (intravenoportal: i.v.p.), the microspheres were entrapped in the hepatic vascular system. The AHCMS were entrapped within terminal portal veins predominantly at the periphery of the liver. The AHCMS were degraded by cellular enzymatic processes within 2 wk after injection, with a half life of approximately 1 d. Biocompatibility of AHCMS and adriamycin-loaded AHCMS was evaluated by histological assessment of the mitotic activity of liver parenchyma and inflammatory response, and by determination of liver damage marker enzymes during 4 wk after administration. Liver damage marker enzymes were not increased compared with controls, nor were adverse effects observed upon histological examination. There was no difference in response between empty and adriamycin-loaded AHCMS.