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.