Gd Doped Hollow Nanoscale Coordination Polymers as Multimodal Imaging Agents and a Potential Drug Delivery Carriers

Gd doped hollow nanoscale coordination polymers with multimodal imaging capabilities were synthesized by solvothermal method and further coated by silica layer. The in vitro tests demonstrated uncoated and silica-coated nanoprobes exhibit longitudinal relaxivities (r_1) of 7.38 and 13.57 (mmol/L)^-1\cdots^-1, and transverse relaxivities (r_2) of 180.6 and 304.8 (mmol/L)^-1\cdots^-1, showing fairly good dual T1&T2 contrast effects, and it also emits excellent multicolor fluorescence under laser beams of various wavelengths. With the combination of magnetic resonance imaging (MRI) (both T1 and T2) and fluorescence optical imaging (FOI), the nanoprobes could correlate preoperative diagnosis with intraoperative pathology. Furthermore, it also exhibits high drug loading capacity of 1166 mg/g and encapsulation efficiency of 83.29%, which makes it a potential platform as drug carriers. The MTT assay demonstrates the moderate toxicity of the NPs, and after the silica coating process, not only the MRI contrast effects but also the biocompatibility have been enhanced. The versatility of the highly integrated systems can make up for the limitations of each imaging modality and exhibit great potentials for cancer theranostics.