Biocompatible Temperature nanosensors based on Titanium dioxide

The measurement of temperature is of fundamental importance in a huge scale of applications, from nanomedicine, where the early detection of tumorous cells is an essential requirement, to microelectronics and microcircuits¹. Optical sensors with a micro/nano-spatial resolution can be used for temperature determination within a biological frame. Within this contest, Raman spectroscopy² is particularly interesting: the inelastic scattering of light, has the advantage of a contactless measurement and exploits the temperature-dependence of intensities in the spectrum (which originates from the vibrational population), by observing the intensity ratio of anti-Stokes and Stokes signals. Titanium Dioxide can be regarded as a potential optical material for the temperature detection in biological samples, thanks to its high biocompatibility, already demonstrated in literature³, and to its strong Raman scattering signal. It presents multiple well-defined Raman peaks at lower Raman shifts, which is appealing for a Raman based thermometry. The aim of the present work is the realization of biocompatible optical thermometers, with a sub-micrometric spatial resolution, made of Titanium dioxide. Raman measurements have been performed on Anatase powder using 488, 568 and 647.1 nm excitation lines of the CW Ar/Kr ion laser. The laser beam is focalized through a microscope on the sample, kept at defined temperature using a temperature controller. The Stokes and anti-Stokes scattered light is analysed through a triple monochromator and detected by a liquid nitrogen cooled CCD camera. Raw data are analysed and Raman spectrum parameters – like area, intensity, frequency position and width of the peak - are calculated. Preliminary results showed that good reliable temperatures can be obtained to characterize the local temperature, through Raman technique.

1. M Quintanilla and LM Liz-Marzan (2018), Nano Today, 19, 126.
2. R L McCreery, Raman spectroscopy for chemical analysis, Vol. 225. John Wiley and Sons, 2005.
3. ZF Yin, L Wu HG Yang and YH Su PCCP (2013), 15(14), 4844.