Functionalized Nanodiamonds for Sensing Biochemical Processes

Summary

Chemotherapy is limited by the failure to clinically monitor the efficacy of the treatment in real-time, which results in suboptimal chemotherapy being given for a prolonged period. Predicting the outcome of chemotherapy immediately after drug administration can increase diagnostic accuracy, efficacy outcomes, and successful treatment. Quantum nanodiamond sensors can be used as optical sensors and drug delivery probes for chemotherapy. In particular, nanodiamonds containing nitrogen-vacancy (NV) centers can serve as attractive probes for optically sensing chemical reactions and biological processes, thanks to their small size, bio-compatibility, and fluorescent properties of the NV centers. This work focuses on variations in the relaxation time in the nanodiamond NV centers, which change when the nanodiamonds are brought into proximity to Gadolinium (Gd) ions – for example, by using a peptide sequence as a connector between the nanodiamond and a Gd compound – and can be optically monitored. The experiment will investigate one type of action of chemotherapeutic drugs, which is to induce cell death (apoptosis) of the cancer cells. Specific enzymes released during apoptosis can cut the connection between the nanodiamonds and Gd, separating NVs from the Gd and decreasing the relaxation rate. Thus, observing the differences in relaxation rate upon chemotherapy allows the drug’s efficacy to be immediately monitored.

Figure 1. A specific enzyme (Caspase 3) is released in the presence of an effective chemotherapeutic drug, resulting in the separation of nanodiamonds and Gd and decreasing the relaxation rate.