Antibody-Conjugated Silica-Modified Gold Nanorods for the Diagnosis and Photo-Thermal Therapy of Cryptococcus Neoformans: an Experiment in Vitro

Background: Cryptococcus neoformans is an encapsulated yeast. There is still little quick and effective solution for the diagnosis or treatment of C. neoformans infection at an early stage in clinical. Antibody-conjugated silica-modified gold nanorods (GNR-SiO2-Ab) can conjugate C. neoformans selectively. It may provide a possibility for treatment of cryptococcosis safely and effectively. Methods: Gold nanorods (GNRs) were synthesized according to the seed-mediated template-assisted protocol. Anti-C. neoformans antibody was covalently anchored on the surface of GNRs with silane coupling agent. In vitro computer tomography imaging was performed to explore the diagnostic effect of the GNR-SiO2-Ab. The viability of cells was evaluated to confirm the photo-thermal therapy effect of GNR-SiO2-Ab combined with near-infrared (NIR) laser light. Results: GNR-SiO2-Ab has a potential application as a positive X-ray/CT imaging contrast agent. An antibody can induce a much greater aggregation of GNRs by binding to the surface of C. neoformans cells resulting in a much higher attenuation values than ever. After irradiation, C. neoformans cells suffered photo-thermal damages and the normal structure of cells were destroyed. The viability of cells reduced significantly compared to the untreated cells. Conclusions: Our work confirmed that antibody-conjugated silica-modified gold nanorods could enhance X-ray attenuation of C. neoformans cells in CT images. And immune GNRs, which were mediated by antibodies, could increase the effects of NIR-induced photo-thermal therapy in C. neoformans cells.