CARBON QUANTUM DOTS AS THERANOSTIC AGENTS FOR PHOTOTHERMAL THERAPY AND SIMULTANEOUS FLUORESCENT IMAGING

Abstract

Theranostic agents are multifunctional biomaterials designed to simultaneously diagnose, monitor, and treat diseases. One of their most notable applications is fluorescent imaging, both in vitro and in vivo, while they are also focused on the treatment of diseases such as cancer. Currently, research is focused on optimizing the efficacy of these agents through chemical modifications and specific bioconjugations, with the goal of selectively targeting the tumor site and thus minimizing the side effects of conventional therapies. In this context, carbon quantum dots (CQDs) were synthesized using a microwave-assisted method, using citric acid and BSA as precursors. The materials were characterized using various techniques such as dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), infrared spectroscopy (FT-IR), UV-Vis spectroscopy, and photoluminescence to evaluate their potential for theranostic applications in biological systems. Thermal, photoluminescent, and turbidimetric stability studies were conducted, as well as studies in media with different pH values (physiological and cancerous) to determine how environmental conditions affect the material´s properties. The CQDs obtained had an average size of 4 nm, a spherical morphology, and an amorphous graphitic nature. FT-IR analysis results showed the formation of amide bonds and carbonization processes, while optical properties (excitation at 320 nm and emission between 360 and 400 nm) revealed fluorescent stability that lasts for a month. Additionally, CQDs demonstrated high efficiency in photothermal conversion, reaching temperatures above 41°C in just a few minutes under NIR irradiation, with a weight loss of less than 1% at clinical temperatures. Although their stability under pH variations needs to be improved, their heating capacity and remarkable thermal performance compared to triple-distilled water position them as promising candidates for theranostic approaches to cancer diagnosis and treatment. The synthesized CQDs show great potential for theranostic applications, thanks to their efficient combination of optical and photothermal properties, making them ideal for cancer diagnosis and treatment. Although they face some limitations in terms of stability under pH variations, their remarkable photothermal conversion capacity and effectiveness in triple-distilled water make them a promising option for the development of more precise and less invasive therapies.