Analysis of antifreeze protein activity using colorimetric gold nanosensors

Abstract

ABSTRACT High activity and long stability of antifreeze proteins (AFPs), also known as ice-binding pr oteins (IBPs), are necessary for exerting their physiological functions in biotechnology and cryomedicine. Here we report a simple analysis of antifreeze protein activity and stability ba sed on self-assembly of gold nanopar ticles (AuNPs) via freezing and thawing cycles. While the mercaptosuccinic acid- capped AuNP (MSA-AuNP) was easily se lf-assembled after a freezing/thawing cycle, due to the mechanical attack of ice crystal on the MSA-AuNP surface, the presence of AFP impeded the self-assembly of MSA-AuNP via the interac tion of AFP with ice crystals via freezing and thawing cycles, which led to a strong color in the MSA-AuNP solution. As a result, the aggregation parameter ( E 520 /E 650 ) of MSA-AuNP showed the rapid detection of both activity and stability of AFPs. We suggest that our newly developed method is very suitable for measuring antifreeze activity and stab ility in a simple and rapid manne r with reliable quantification. Keywords: protein activity, antifreeze protein, ice-binding protei n, gold nanoparticle, colorimetric analysis