In vitro characterization and cellular uptake profiles of TAMs-targeted lipid calcium carbonate nanoparticles for cancer immunotherapy

Tumor-associated macrophages (TAMs) are key contributors to tumor development, accelerated tumor invasion and metastasis, and induction of immunosuppression. Targeted delivery of immunomodulatory agents to promote polarization of TAMs may alleviate the immunosuppressive tumor microenvironment. Calcium carbonate nanoparticles (CCN), which exhibit excellent biocompatibility, pH sensitivity, and easy surface modification, have attracted substantial attention in targeted nano delivery. In this study, CCN were used as a matrix material to develop UNO-peptide-modified lipid CCN for targeted immunomodulation of TAMs by using the mannose receptor overexpressed on the surfaces of TAMs as targets. The preparation of CCN was optimized through single-factor testing with the gas diffusion method with the particle size as the index. The surface modification of CCN with UNO-peptide-modified phospholipids was performed, and its targeting effect on TAMs was investigated. The average particle size of the CCN and UNO-peptide-modified CCN was 144.5 ± 3.8 nm and 167.0 ± 1.3 nm, respectively. UNO-peptide-modified CCN entered TAMs via actively targeted uptake mediated by mannose receptors. Our results demonstrated that the developed UNO-peptide-modified CCN with controlled nano-size and excellent TAMs-targeting properties is a highly promising nanocarrier for targeted delivery of TAM immunomodulatory agents.