Lipid-coated CaCO-PDA nanoparticles as a versatile nanocarrier to enable pH-responsive dual modal imaging-guided combination cancer therapy.

Development of an intelligent and versatile delivery system to achieve tumor-targeted delivery and controlled release of diverse functional moieties is of great significance to realize precise cancer theranostics. In this study, we use pH-dissociable calcium carbonate-polydopamine (pCaCO) nanocomposites as a template to guide the formation of a lipid bilayer on their surface, yielding lipid-coated pCaCO nanoparticles with high loading efficacies towards gadolinium ions (Gd), doxorubicin (DOX) and 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR). The obtained liposomal nanotheranostics show excellent physiological stability and pH-dependent release of DOX and Gd; the latter could lead to pH-dependent signal enhancement under magnetic resonance (MR) imaging, as well as efficient photothermal conversion efficacy. Then, we found that tumors in mice with intravenous injection of DiR-DOX-Gd@pCaCO-PEG could be clearly visualized in a real-time manner by recording their near-infrared (NIR) fluorescence and MR signal. Furthermore, treatment with such liposomal nanotheranostics injection and NIR laser irradiation could enable collective suppression of the growth of 4T1 tumors in Balb/c mice combined chemo- and photothermal therapies. Therefore, this work highlights the concise preparation of lipid-coated pCaCO nanocomposites, which could be utilized for the construction of diverse cancer nanotheranostics by exploiting their versatile loading capacities.