# Engineering Biocompatible Glutathione-Capped Cu2ZnSnS4 Quantum Dots Toward Integrated Photothermal and Photodynamic Effects

## TL;DR

Researchers developed tiny quantum dots that can both heat up and produce reactive oxygen under infrared light, offering a new way to treat cancer.

## Contribution

The study introduces glutathione-capped Cu2ZnSnS4 quantum dots with dual photothermal and photodynamic capabilities for cancer therapy.

## Key findings

- CZTS@GSH QDs showed effective photothermal conversion under 808 nm laser irradiation.
- The QDs generated singlet oxygen, confirming their photodynamic therapy capability.
- The QDs have a band gap of 1.47 eV and an average hydrodynamic diameter of ~6.2 nm.

## Abstract

Ultrasmall near-infrared (NIR)-responsive quantum dots (QDs) are highly promising for deep-tissue phototherapy but often face challenges with biocompatibility and clearance. In this study, Cu2ZnSnS4 quantum dots (CZTS QDs) were synthesized via a non-injection method and surface-functionalized with glutathione (GSH) to create water-dispersible and biocompatible CZTS@GSH QDs. Comprehensive characterization using XRD, TEM, DLS, XPS, and UV-Vis spectroscopy confirmed a sphalerite-type ZnS crystal structure, an average hydrodynamic diameter of ~6.2 nm, and a band gap of 1.47 eV (843.5 nm). The CZTS@GSH QDs demonstrated effective photothermal conversion under 808 nm laser irradiation, achieving a temperature increase sufficient for photothermal therapy (PTT). Furthermore, using a DPBF assay, the QDs were shown to generate singlet oxygen, confirming their photodynamic therapy (PDT) capability. Owing to their ultrasmall size, strong NIR absorption, and demonstrated dual PTT/PDT functions, the CZTS@GSH QDs are established as a nanoplatform with potential for combined cancer treatment.