Early detection and improved cancer sensing tools are crucial for increasing cancer patient survival rates. High-pressure high-temperature (HPHT) fluorescent nanodiamonds (FNDs) are an emerging probe for biolabeling and cancer detection due to the unique photophysics of the nitrogen vacancy center (NVCs). FNDs are ideal biolabelling probes because they are non-cytotoxic, contain no heavy metals, are an IR emitter (575-800 nm) and have long term photostability. Current surface chemistry protocols of HPHT FNDs are not mature and robust modification of FNDs poses a challenge due to their chemical inertness. Here we accomplish the synthetic growth of SiO2 shells (3-25 nm) onto FNDs using wet chemistry. Silica growth is controlled by fixed reaction times and particle size is measured using DLS, SEM and TEM. Silica priming of the diamond surface is thought to proceed by nucleophilic attack of tetrahydroxysilane forming a silyl ether bond (C-O-Si-OH3) to the diamond surface. Future directions include bioconjugation to small molecules and biolabeling of HeLa cells with functionalized FNDs.

Growth of SiO2 Shells on Fluorescent Nanodiamond Cores for Biodetection

Advisor: Dr. Abraham Wolcott

Author: Perla J. Sandoval