Naturally modified nonionic alginate functionalized upconversion nanoparticles for the highly efficient targeted pH-responsive drug delivery and enhancement of NIR-imaging

[Display omitted] •Novel biocompatible amphiphilic alginates for functionalizing UCNPs are developed.•The functionalized-UCNPs possess high stability and less cytotoxicity.•Functionalized-UCNPs enhanced bioimaging and specific in targeting KB cancer cells.•Novel UCNP is potentially capable of pH responsive targeted DOX to cancer cell. Naturally modified nonionic alginate-based polymers were synthesized to act as functionalizing agents for upconversion nanoparticles (UCNPs). The synthesized polymer-UCNPs hybrid nanoparticles show high stability, excellent biocompatibility and enhanced luminescence intensity for NIR imaging. Additionally, our results show that due to the large cavities of the materials and amphiphilic polymer shell, these nonionic alginate-functionalized UCNPs were able to load the anticancer drug doxorubicin (DOX) with the exceptional efficiency as well as release it in a highly controlled and selective pH-responsive manner via folate receptor-mediated endocytosis. Targeting using this multifunction polymer significantly improved the capability of DOX-loaded UCNPs to inhibit the growth of KB cancer cells than free DOX. These biocompatible nonionic alginate-functionalized UCNPs hold substantial potential as effective anticancer drug-delivery carriers and NIR imaging agents.