To establish a satisfactory delivery system for the delivery of salinomycin (Sal), a novel, selective cancer stem cell inhibitor with prominent toxicity, gelatinase-responsive core-shell nanoparticles (NPs), were prepared by nanoprecipitation method (NR-NPs) and single emulsion method (SE-NPs). The gelatinase-responsive copolymer was prepared by carboxylation and double amination method. We studied the stability of NPs prepared by nanoprecipitation method with different proportions of F68 in aqueous phase to determine the best proportion used in our study. Then, the NPs were prepared by nanoprecipitation method with the best proportion of F68 and single emulsion method, and their physiochemical traits including morphology, particle size, zeta potential, drug loading content, stability, and in vitro release profiles were studied. The SE-NPs showed significant differences in particle size, drug loading content, stability, and in vitro release profiles compared to NR-NPs. The SE-NPs presented higher drug entrapment efficiency and superior stability than the NR-NPs. The drug release rate of SE-NPs was more sustainable than that of the NR-NPs, and in vivo experiment indicated that NPs could prominently reduce the toxicity of Sal. Our study demonstrates that the SE-NPs could be a satisfactory method for the preparation of gelatinase-responsive NPs for intelligent delivery of Sal.

Gambogic acid(GA)is a natural compound that exhibits strong antitumor activity against a variety of tumors. However, its poor water solubility, low specificity, and high toxicity lead to inevitable systemic adverse effects. To minimize side effects, combining gambogic acid (GA) with delivery systems such as nanohydrogels to develop an in situ vaccine system (ISV) shows great promise. In this study, we loaded GA into a novel in situ nanocomposite hydrogel vaccine system (Gel-NPs@GA) along with a near-infrared (NIR) fluorescent dye, IR-1061. The Gel-NPs@GA system allowed for temperature-triggered gelation, simplifying injection and the in vivo formation of a drug-releasing gel, with near-infrared monitoring for drug metabolism. Slow, continuous release of gelatinase-targeted GA nanoparticles from the hydrogel occurs, followed by cleavage of mPEG-peptide-PCL conjugates by gelatinase, causing particle aggregation for endocytosis by tumor cells. This approach tackled solubility issues and curbs excessive GA release, boosting therapeutic drug levels. The sustained GA release induces tumor cell apoptosis, releasing tumor antigens and reprogramming the immune-suppressive tumor microenvironment. In the CT26 colorectal cancer mice model, this in situ vaccine system significantly inhibited tumor growth. By integrating information about immune cell clusters within the tumor microenvironment with RNA sequencing results, we hypothesized that Gel-NPs@GA could synergistically stimulate the immune response through various pathways, promote the maturation of dendritic cells (DCs), increase the infiltration of T cells, and thereby remodel the tumor's immune microenvironment.