Visual detection of tropomyosin,a major shrimp allergenic protein using gold nanoparticles(AuNPs)-assisted colorimetric aptasensor

摘要

A gold nanoparticle-based label-free colorimetric assay was developed to detect the shrimp allergenic protein tropomyosin(TM),an important biomarker responsible for severe clinical reactivity to shellfish.In a gold nanoparticles(AuNPs)-tropomyosin-binding aptamer(TMBA)complex,the aptamer adsorbs onto the surface of AuNPs and dissociates in the presence of TM.In addition,AuNPs tend to aggregate in the presence of ionic salt,revealing a color change(i.e.,wine-red to purple/blue)with a shift in the maximum absorption peak from 520 nm.In the presence of specific binding TM,the aptamer folds into a tertiary structure where it more efficiently stabilizes AuNPs toward the salt-induced aggregation with a hypsochromic shift in the absorption spectra compared to the stabilized AuNPs by aptamer alone.Based on the aggregation and sensitive spectral transformation principle,the AuNPs-based colorimetric aptasensor was successfully applied to detect TM with a range of 10-200 nmol/L and a low detection limit of 40 nmol/L in water samples.The reliability,selectivity,and sensitivity of the aptasensor was then tested with food samples spiked with TM.The observed detection limit was as low as 70 nmol/L in shrimp,90 nmol/L in tofu,and 80 nmol/L in eggs,respectively.We anticipate the proposed AuNPs-based colorimetric aptasensor assay possesses a high potential for the easy and efficient visual colorimetric detection of TM.