# Ultrathin Multi‐Doped Molybdenum Oxide Nanodots as a Tunable Selective Biocatalyst

## TL;DR

This paper introduces a new type of molybdenum oxide nanodots that can generate reactive oxygen species and selectively kill cancer cells without harming healthy ones.

## Contribution

The novelty lies in the tunable doping of molybdenum oxide nanodots with H+ and NH4+ for selective biocatalytic activity.

## Key findings

- Multi-doped MoOx nanodots show ultrafast dye degradation driven by hydroxyl radicals.
- The nanodots exhibit three-fold higher cytotoxicity toward HeLa cancer cells compared to healthy cells.
- The material offers a biocompatible alternative to noble metals for targeted cancer therapy.

## Abstract

The reactive oxygen species (ROS) serve a significant role in cancer therapy due to their oxidative capabilities to modulate cellular functions from homeostasis to apoptosis. While conventional noble metal nanoparticles exhibit superior biocatalytic efficacy in ROS induction, their indistinctive toxicity toward cells and organisms limit their potential for targeted cancer therapy. Here, ultrathin biocompatiable molybdenum oxides (MoOx) nanodots are explored that simultaneously incorporate hydrogen (H+) and ammonia (NH4
+) dopants, subsequently their electronic band structures can be modulated by both the relative contents of H+ and NH4
+ dopants for efficient generation of ROS. An ultrafast and repeatable dye degredation capability in the absence of light is find in MoOx doped with low H+ and high NH4
+, in which hydroxyl radicals (·OH) is identified as the agent stimulating this ROS‐driven process through scavenger analysis. More importantly, the selective biocatalytic potential of such a multi‐doped MoOx is demonstrated by the comprehensive assay analysis, revealing a three‐fold greater cytotoxicity toward HeLa cancer cells within 24 h compared with those of HEK293T healthy control. The finding shines a light on the targeted cancer therapies that spare healthy cells, showing the potential of multi‐doped metal oxide as a biocompatiable alternatives to noble metals in selective cytotoxicity against tumor cells.

This paper presents an advanced multi‐doped molybdenum oxide nanodots with tunable ammonium and proton doping, exhibiting strong ROS generation. The material demonstrates ultrafast and complete dye degradation and unique selective toxicity toward cancer cells, highlighting its promising potential for cancer therapy applications.