CC BY
0Laser synthesis of hybrid nanoparticles for optical nanosensing
and light-to-heat conversion
E. Mitsai1*, A. Kuchmizhak1,2
1-Institute of Automation and Control Processes of the FEB RAS, 5 Radio St., 690041 Vladivostok, Russia 2- Saint Petersburg State University, 26 Universitetskii Prospect, 198504 Saint-Petersburg, Russia
We demonstrate the possibility of a one-step synthesis of silicon-germanium (Sii-xGex) alloyed nanoparticles (NPs) of controlled composition by nanosecond laser ablation of SiGe targets in isopropanol (Fig. 1.a). The synthesized product retains the stoichiometry of the targets, and the method of suspension centrifugation enables isolation of a product fraction with an average diameter of about 200 nm (Fig. 1.b). Nano-thermometry using registration and analysis of the Raman signal from these NPs demonstrated 3 times greater heating efficiency than similar-sized pure Si NPs under the influence of continuous laser radiation with a wavelength of 785 nm, located in the center of the "transparency window" of biological tissues (Fig. 1.c).
Fig. 1. (a) Schematic representation of the process of obtaining SiGe NPs by ablation of alloyed films on a sapphire substrate. (b) SEM image of NPs obtained after centrifugation of the resulting suspension. (c) Thermal-induced Raman peak shift (AQSi-Si) of single Si and Sio.45Geo.55 NPs with diameter ~200 nm from the pumping intensity of laser radiation (>,=785 nm). The inset shows a schematic representation of the process of measuring the efficiency of laser-induced heating of isolated NPs.
An important feature of the synthesized NPs is their phase and structural transformation under the influence of continuous IR radiation-induced heating. The diffusion of Si atoms to the surface (when heated above 650 K) and their oxidation leads to the gradual transformation of alloyed SiGe NPs into Ge clusters encapsulated in a silicon oxide shell, which is important for the creation of tunable photonic elements. Also, since it is known that both the SiGe alloy and its decomposition products in biological fluids and tissues do not have a significant toxicological effect [1], the encapsulation of NPs' material into an oxide shell during heating potentially increases their biocompatibility and demonstrates high potential for the development of tumor photohyperthermia methods.
This work was supported by the Russian Science Foundation (Grant No. 23-49-10044).
[1] S.K. Kang, G. Park, K. Kim, S.W. Hwang, H.Y. Cheng, J.H. Shin, S.J. Chung, M. Kim, L. Yin, J.C. Lee, K.M. Lee, J.A. Rogers, ACS Applied Materials & Interfaces, 7(17), pp. 9297-9305, (2015).
* mitsai@dvo.ru
