Golden Vaterite as a Thermo-Optical Agent

Abstract

Thermo-optical therapeutic approaches offer precise temperature control using light, opening new possibilities in targeted drug delivery, cancer therapy, and tissue engineering. Compared to traditional single-function plasmonic particles, mesoporous metamaterial-like nanostructures can operate in the infrared spectrum, matching the biological transparency window, while also acting as carriers for therapeutic agents. This study explores the thermo-optical characteristics of golden vaterite, a mesoporous calcium carbonate loaded with gold nanoparticles, forming a metamaterial capsule. Heating capabilities of individual particles are measured in an optical trap, where local temperature is derived from stochastic dynamics influenced by temperature-dependent viscosity. A calibration step or the use of tabulated data enables accurate mapping between irradiated power and particle temperature. Four sets of particles with varying gold content are tested, demonstrating temperature increases of up to several tens of degrees with milliwatt-scale infrared continuous-wave lasers. Heating efficiencies (𝑑𝑇/𝑑𝑃) as high as 30 °C mW⁻¹ are observed. Additionally, optomechanical tools with microfluidic features allowed efficient prototyping of thermo-optical agents without fluorescent markers. Golden vaterite, capable of both thermal and optical functions, presents a versatile platform for developing theranostic particles for heat-based optical applications and targeted therapeutic delivery.