A rapid, easy, and sensitive method for detecting His-tag-containing chitinase based on ssDNA aptamers and gold...

Chitooligosaccharides are oligosaccharides with many biological activities that can be used in food production for sweeteners, preservatives and humectants, among other products. Chitin, a long-chain polymer of N-acetylglucosamine and a derivative of glucose, can be hydrolyzed by applying chitinase to break down glycosidic bonds to form chitooligosaccharides. Chitinases arising from heterologous gene expression are usually linked to a 6 × His-tag to facilitate easy purification. Heterologously expressed chitinase linked to a 6 × His-tag is a transgenic element, but enzyme activity tests cannot be used to distinguish transgenic elements from natural elements. In this study, we established a rapid and easy method to detect His-tag-containing chitinase using gold nanoparticles (AuNPs) and ssDNA aptamers. Using this method, His-tag-containing chitinase could be detected at concentrations as low as 0.136 nM within 5 min. Color changes of AuNPs showed a positive correlation with His-tag-containing chitinase concentrations.