# Matrix Metalloproteinase‑9 (MMP-9) Activatable Gold Nanoparticles for In Situ Zymography and Diagnostics of Neurofibromatosis Type 2 (NF2) Tumors

## TL;DR

Researchers developed gold nanoparticles that detect early signs of a rare tumor syndrome by measuring enzyme activity, enabling earlier treatment.

## Contribution

MMP-9 activatable gold nanoparticles with high accuracy for detecting NF2-associated tumors and monitoring treatment response.

## Key findings

- AuNPs distinguish schwannoma tumors from healthy nerve tissue with >95% accuracy.
- Nanoparticles detect 2 mm tumors up to 23 months earlier than conventional MRI.
- Longitudinal measurements track changes in MMP-9 activity during therapy.

## Abstract

Neurofibromatosis
type 2-related schwannomatosis (NF2-SWN) is a
devastating genetic tumor-disposition syndrome characterized by multiple
nervous system neoplasms. A hallmark of NF2-SWN is bilateral vestibular
schwannomas (VSs) that cause hearing loss, vertigo, and life-threatening
brainstem compression. Current imaging methods detect NF2-associated
VS often late in their development and could lead to delayed therapeutic
interventions. Matrix metalloproteinase-9 (MMP-9) is a key protease
involved in extracellular matrix remodeling and tumor progression
in NF2-associated VS, making it an attractive molecular target for
activity-based sensing. Here, we develop MMP-9 activatable gold nanoparticles
(AuNPs) incorporating a protease-cleavable peptide to enable sensitive
reporting of protease activity in VS tissue. Through systematic tuning
of polyethylene glycol (PEG) linker length and peptide valency, we
establish an AuNP configuration that exhibits both efficient enzymatic
cleavage and selectivity for MMP-9 over other VS-associated proteases.
In schwannoma tissue, nanoparticles distinguish tumor from healthy
nerve with >95% accuracy and detect 2 mm tumorscorresponding,
based on published VS growth rates, to detection approximately 23
months earlier than conventional MRIenabling substantially
earlier intervention. Longitudinal measurement of nanoparticle activation
further resolves changes in MMP-9 activity within the tumor in response
to therapeutic intervention, illustrating the platform’s capacity
in monitoring treatment response. Together, these findings establish
MMP-9 activatable AuNP as a sensitive, spatially resolved diagnostic
tool for NF2-SWN that complements imaging by directly quantifying
protease activity in tumors that are inaccessible to biopsy.