Thin Polymeric Film Functionalized by AuNPs for High Sensitive Protein Biosensing

Polymer films are playing a pivotal role in a wide range of sensor applications thanks their cost-effectiveness and feasibility. Herein, an antibody-gold nanoparticles (AuNPs)-polymer conjugate thin-film biosensor is fabricated to selectively capture an aggregated neurodegeneration biomarker with high sensitivity. Biomarkers of neurodegenerative diseases are usually based on the formation of prion-like aggregates and in vitro fluorescent aggregation reporter systems are usually performed to detect amyloid aggregates. These techniques are usually based on high analyte concentrations and so they don't mimic the cellular processes in low picogram range. In this context, we developed a fine sensitive-based sensor able to detect biomarkers in low picogram levels thanks to the use of AuNP as sensing elements. In detail, AuNPs were deposited on a thin PLGA film before or previously absorbed with a monoclonal antibody with high affinity for the selected biomarker and afterwards, different concentrations of protein were added to the polymeric film generating a color change due to the colloidal status of AuNPs from dispersed to aggregated. All steps about AuNP adsorption on the top of membranes or inside the membrane matrix were evaluated to finally quantify the intensity of AuNP color thin films respect to the protein target concentration.