Harnessing DNA for nanothermometry

Temperature measurement at the nanoscale has brought insight to a wide array of research interests in modern chemistry, physics, and biology. These measurements have been enabled by the advent of nanothermometers, which relay nanoscale temperature information through the analysis of their intrinsic photophysical behavior. In the past decade, several nanothermometers have been developed including dyes, nanodiamonds, fluorescent proteins, nucleotides, and nanoparticles. However, temperature measurement using intact DNA has not yet been achieved. Here, we present a method to study the temperature sensitivity of the DNA molecule within a physiologic temperature range when complexed with fluorescent dye. We theoretically and experimentally report the temperature sensitivity of the DNA‐Hoechst 33342 complex in different sizes of double‐stranded oligonucleotides and plasmids, showing its potential use as a nanothermometer. These findings allow for extending the thermal study of DNA to several research fields including DNA nanotechnology, optical tweezers, and DNA nanoparticles. Temperature measurement at the nanoscale, achievable by the recent development of nanothermometers, has many potential applications in cells and living organisms. Here we characterize theoretically and experimentally the thermal sensitivity of DNA bound to Hoechst dye. These findings are attractive since HOECHST is cell‐permeable, non‐cytotoxic, and binds to any DNA sequence. We anticipate this work to provide a basis for the extension of nanoscale temperature measurement to all DNA‐based research.