The unique photophysical features of Au and Ag nanoparticles, including their size- and shape-dependent surface plasmon absorption along with a large molar absorption coefficient, have generated much interest to use these materials for designing analytical biosensors. Signal transduction in the sensing platforms are based on color changes, or quenching of proximal fluorophores. A variety of sensing modalities using colloidal gold nanostructures have been described in the literature. Several of those were designed to detect early-stage biomarkers of malignant diseases such as enzymes.<br/>Here, we report the design of a colorimetric sensing platform, based on AuNP-peptide conjugates. In this approach, the strong dependence of the localized surface plasmon resonance (LSPR) peak(s) on the inter-particle separation distance yields a visual color change of the dispersion when mixed with the target enzyme. We exploit this strategy to track the activity of Matrix Metalloproteinase-14 (MMP-14). This proteinase is overly expressed in cancer tissues at all stages, rendering it a good target for early diagnosis of cancer. Our sensor function relies on a charge-mediated assembly of AuNPs upon interactions with MMP-14 and cleavage of a specifically designed charge switchable peptide substrate. This manifests in a bathochromic shift and broadening of the SPR peak which tracks the MMP-14 activity.<br/>We describe the nanoparticle and peptide substrate design and the use of AuNP-peptide-substrate conjugates to screen the activity of MMP-14 under a few key conditions. The collected data are then used to evaluate the kinetic parameters associated with the enzyme proteolysis reaction.

Screening of a cancer enzyme activity using a plasmon-based colorimetric assay

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.