The final metabolic products of PLGA in the body are water and carbon dioxide, and therefore it is safe to use and is nontoxic (12). CD206-Fe3O4-PLGA nanoparticles were able to promote CD86 expression in TAMs, with CD86 being a specific marker of the M1 subtype. In summary, nanoparticles were characterized Hexanoyl Glycine in the present study by their mean particle size, polydispersity index, potential and morphology, as well as by their association with Fe3O4 and conjugation with the anti-CD206 Hexanoyl Glycine monoclonal antibody. Collectively, the present results suggested that this nanoparticles were able to both target M2 macrophages and reverse the M2 polarization of the macrophages to the M1 phenotype via the release of coated iron-oxide particles. (8) reported that Fe3O4 nanoparticles could promote the polarization of tumor-associated macrophages (TAMs) towards M1 type, and significantly increase the production of reactive oxygen species (ROS) in macrophages. Super paramagnetic iron-oxide nanoparticles (SPIONs) are mainly phagocytized by macrophages, and are degraded into iron ions in lysosomes (9), causing iron overload in macrophages and ultimately promoting the repolarization of M2 macrophages to M1 macrophages (10). Poly(lactic-co-glycolic) acid (PLGA) is a type of polymer synthesized by the polymerization of lactic acid and glycolic acid in a certain ratio (11). Copolymers with different degradation periods can be obtained by adjusting the ratio and molecular excess weight of the two polymers. The final metabolic products of PLGA in the body are water and carbon dioxide, and therefore it is safe to use and is non-toxic (12). PLGA, first used as a long-acting controlled-release system in the 1970s, has been qualified by the US Food and Drug Administration, and is officially included in the US Pharmacopoeia as a pharmaceutical excipient (13,14). Currently, numerous studies have focused on PLGA as a targeted nano-delivery system for delivering chemotherapeutic cancer drugs to the target tissues (15). PLGA offers a number of advantages, including decreased systemic toxicity, increased blood circulation times and enhanced accumulation at the tumor site for the delivered drug (16C19). Therapeutic nanoparticles can be rapidly removed from the internal blood circulation by phagocytic immune cells, mainly by the circulating monocytes and macrophages (20). Previous studies have revealed that the majority of the nanoparticles concentrate in the liver and spleen, and only a small portion of the nanoparticles are deposited in tumor tissues via the blood circulation (21,22). Targeted ligands, such as antibodies and aptamers, are often bound to the outer surface of nanoparticles during the process of designing active drug delivery systems, which helps to deliver payloads specifically to the sites transporting homologous receptors for targeted ligands (23). Ligands help to internalize conjugates, and the payload carried by conjugates can be transferred in cells (23C25). The present study aimed to enhance antitumor immunity by targeting the iron concentration in TAMs using Fe3O4-based PLGA nanoparticles, which were conjugated with anti-CD206 monoclonal antibody. Materials and Hexanoyl Glycine methods Materials Acid-terminated PLGA copolymer (50:50 ratio of lactic acid to glycolic acid; molecular excess weight, 12 kDa) was purchased from Sigma-Aldrich; Merck KGaA. Fe3O4 nanocrystals (diameter, 10 nm) coated with oleic acid and dispersed in chloroform (20 mg/ml) were provided by Xi’an Ruixi Biological Technology Co., Ltd. 2-Morpholinoethanesulfonic acid (MES), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and (27). The prepared nanoparticles were resuspended in 10 ml MES buffer (pH 6.0). A total of Hexanoyl Glycine 1 1 ml EDC (0.1 M) was added to the nanoparticle suspension with moderate stirring for 15 min at room temperature, then 1 ml NHS (0.7 M) was added and the mixture was continually stirred for a further 45 min. The remaining reagents in the coupling reaction were removed via centrifugation (15,000 g for 10 min at 4C). Subsequently, the nanoparticles were washed with MES (pH ETS2 8.0) for 5 min and repeat three occasions, and finally re-dispersed in 2 ml double-distilled water. Anti-CD206 antibody answer (100 l) was added to the activated Hexanoyl Glycine nanoparticle suspension for antibody conjugation, and incubated at room heat for 2 h. The combination was centrifuged again (15,000 g for 10 min at.