Opportunities for hybrid diamond nanosensors targeting photothermal applications in biological systems

Abstract

Functionalized diamond nanocrystals persistently expand their use for sensing and labeling in a biological context. The surface of such crystals modified chemically adds additional modality to such applications. In this Perspective, we discuss mainly applications in nanothermometry but begin with a brief general introduction of fluorescent nanodiamonds. Then we consider temperature at the sub-cellular environment, explain the working principle of fluorescent nanodiamonds as temperature probes, and demonstrate their biological applications from the literature. The application of nanohybrids (such as heater-thermometer hybrids built within a single nanoparticle) in biological cells will be covered with more details. We summarize recent results of intracellular measurements to estimate that 0.1 nJ of heat released in a cellular hot spot of 1-μm radius can produce a 1-K temperature rise lasting for about 50 μs and repeatable approximately every 2 ms. Our view on the reason for limitations in biological applications of nanodiamonds concludes the review.