# N‑Doped Carbon Dot-Based Nanoconjugates with Simultaneous Generation of Nitric Oxide and Singlet Oxygen for Phototherapeutic Applications

## TL;DR

This paper introduces a new nanoconjugate that generates both nitric oxide and singlet oxygen under green light for enhanced cancer phototherapy.

## Contribution

The novel nanoconjugate combines N-doped carbon dots with a NO photodonor, enabling simultaneous generation of NO and singlet oxygen under green light.

## Key findings

- The nanoconjugate allows intramolecular photoinduced electron transfer for NO release with improved excitation wavelength.
- Green light excitation generates singlet oxygen via collisional energy transfer with molecular oxygen.
- The nanoconjugate localizes in the cytoplasm of brain cancer cells and increases cell mortality under green light.

## Abstract

Nitric oxide (NO) and singlet oxygen (1O2) represent two of the most intriguing agents for unconventional
phototherapeutic applications in cancer. In this contribution, N-doped
carbon dots (NCDs) with strong absorption in the biocompatible
green region have been synthesized and covalently decorated with an
otherwise blue-light-activatable NO photodonor (NOPD), leading to
a nanoconjugate ca. 3.5 nm in diameter. The NCD core of the nanoconstruct acts as a green light antenna,
permitting the release of NO from the NOPD by an intramolecular photoinduced
electron transfer, with an improvement of more than 100 nm in the
excitation wavelength. Simultaneously, green light excitation generates 1O2 by collisional energy transfer with molecular
oxygen. Due to its emissive properties, the nanoconjugate can be visualized
in 9L/LacZ brain cancer cells, where it localizes mainly in the cytoplasm.
Amplified mortality of cancer cells is observed upon green light irradiation
due to the mutual photodynamic action of NO and 1O2.