Detection of 5-hydroxymethylfurfural based on split-DNAzyme assisted signal amplification via quartz crystal microbalance

5-hydroxymethylfurfural (HMF) is one of the food contaminants mainly formed by Maillard and caramelization reaction. Here, we developed a simple method to detect HMF based on split-DNAzyme assisted signal amplification via Quartz crystal microbalance . Firstly, two fragments of the split-DNAzyme (ESΙ and ESII) and AuNPs-ssDNA were prepared. In the absence of HMF, the amino group of ESΙ reacted with the aldehyde group of ESΙΙ by Schiff base condensation，which linked ESΙ and ESII as DNAzyme. With the help of Mg 2+ , this DNAzyme cleaved AuNPs-ssDNA, freeing the complementary sequence of capture DNA from the ssDNA. In the presence of the target HMF, the aldehyde group in its molecular structure preferred to react with ESΙ, which prevented the link of ESΙ and ESII. In this case, DNAzyme cannot be formed effectively and the ssDNA modified on AuNPs cannot be cleaved. Secondly, the capture DNA was immobilized on Au chip in the QCM chamber. Then, the intact AuNPs-ssDNA was introduced to hybridize with the capture DNA, resulted in a large frequency change (ΔF) of the QCM biosensor because of the huge increased mass of AuNPs. So, HMF can be detected based on the frequency change (ΔF) of the QCM biosensor. This QCM biosensor is more sensitive than previously reported methods, which provide a new direction for the analytical detection of HMF and other food contaminants.