The interactions between colloidal plasmonic nanostructures (such as Au nanoparticles, AuNPs) and proximal fluorescent dyes result in efficient quenching of the dye photoluminescence (PL). This has provided researchers with a popular strategy (using this quenching as a signal transduction mechanism) for developing a variety of analytical biosensors.<br/><br/>Here, we report on the use of stable lipoic acid-PEG-functionalized gold nanoparticles, covalently coupled with several dye-labeled peptides (containing specific enzyme recognition sequences), as sensitive, fluorescence-based sensors to evaluate the activities of the matrix metalloproteinases-14 (MMP-14), a biomarker of breast cancer. We use the configuration of varying enzyme format (while keeping the substrate concentration fixed) to measure real-time PL recovery triggered by MMP-14 hydrolysis of AuNP-peptide-dye conjugates, which we use to develop quantitative analysis of the digestion kinetics. These AuNP-peptide-dye platforms exhibited great sensitivity to the presence of even small concentration of MMP-14; detection limits of ~0.05−2 nM have been achieved using this design. In addition, we apply theoretical rationales that consider the effects of larger size and reduced diffusion of the NP-peptide conjugates, compared to peptide only system, to gain additional insights into the kinetic of the PL recovery and to evaluate the specificity constant (Kcat/KM) for these plasmonic-peptide-dye platforms.

Evaluating the enzymatic activity of the breast cancer marker MMP-14 using AuNP−peptide-dye conjugates

ACS Spring 2022

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