Low-Coordination Configuration Single-Atom Manganese Nanozymes for NIR-Imaging-Oriented Efficient Catalytic...

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Catalysis

Background:

• Single-atom nanozymes (SAzymes) are crucial for improving tumor catalytic therapy due to their high atomic-level active sites.
• Low coordination structures in SAzymes enhance their efficiency.

Purpose of the Study:

• To develop a simple method for preparing single-atom manganese-doped carbon dots (SA Mn-CDs) with a low coordination (Mn-N2) configuration.
• To evaluate the potential of SA Mn-CDs for near-infrared fluorescence-guided tumor catalytic therapy.

Main Methods:

• SA Mn-CDs were synthesized by chelating manganese atoms with ethylenediamine tetraacetic acid (EDTA).
• Characterization included assessment of dispersibility, biological safety, stability, two-photon fluorescence imaging, lysosome targeting, and peroxidase-like activity.
• In vitro and in vivo experiments were conducted to evaluate tumor cell killing and tumor shrinkage.

Main Results:

• SA Mn-CDs exhibited good dispersibility, safety, and stability, with deep-level two-photon fluorescence imaging (34 µm) and specific lysosome targeting (Pearson's correlation coefficient: 0.752).
• The nanozyme demonstrated high peroxidase-like activity (0.64 U mg⁻¹) via Fenton-like reactions.
• Significant tumor cell killing and tumor tissue shrinkage were observed in vitro and in vivo.

Conclusions:

• SA Mn-CDs show great potential as nanozymes for near-infrared fluorescence-guided tumor catalytic therapy.
• The low coordination (Mn-N2) configuration contributes to the enhanced catalytic activity and therapeutic efficacy.