FRET-Amplified Singlet Oxygen Generation by Nanocomposites Comprising Ternary AgInS$_2$/ZnS Quantum Dots and Molecular Photosensitizers

TL;DR

This paper introduces a novel water-soluble nanocomposite combining AgInS$_2$/ZnS quantum dots and TPP molecules in a chitosan matrix, enhancing singlet oxygen generation for antibacterial photodynamic therapy through FRET mechanisms.

Contribution

It presents a new biocompatible nanocomposite that improves photosensitizer efficiency by leveraging FRET between quantum dots and TPP molecules.

Findings

Successful transfer of TPP into chitosan maintaining monomeric form

Enhanced singlet oxygen generation via FRET mechanism

Potential application in improved antibacterial photodynamic therapy

Abstract

Antibacterial photodynamic therapy (a-PDT) has emerged as a promising non-invasive therapeutic modality that utilizes the combination of a photosensitive agent, molecular oxygen, and excitation light to generate reactive oxygen species (ROS), demonstrating remarkable activity against multidrug-resistant bacterial infections. However, the effective use of conventional photosensitizers is significantly limited by a number of their shortcomings, namely, poor water solubility and low selectivity. Herein, we present a novel biocompatible water-soluble nanocomposite based on hydrophobic tetraphenylporphyrin (TPP) molecules and hydrophilic ternary AgInS$_2$/ZnS quantum dots incorporated into a chitosan matrix as an improved photosensitizer for a-PDT. We demonstrated that TPP molecules could be successfully transferred into chitosan solution while remaining primarily in the form of monomers, which are capable of singlet oxygen generation. We performed a detailed analysis of the F\"orster resonance energy transfer (FRET) between quantum dots and TPP molecules within the nanocomposite and proposed the mechanism of the singlet oxygen efficiency enhancement via FRET.