Enzyme-linked lectin assay for amplified electrochemical detection of HPV DNA

Human papillomaviruses (HPV) are non-enveloped double-stranded DNA (dsDNA) viruses that are closely associated with various warts and precancerous lesions, and the assay of the strain-specific DNA sequences has become an integral part of the clinical screening of high-risk HPV infections. Herein, we illustrate the development of an enzyme-linked lectin assay (ELLA)-based electrochemical method for the amplified detection of HPV DNA. Specifically, the ELLA-based method involves the capture of the target sequences by the complementary peptide nucleic acid (PNA) probes, the decoration of the phosphate sites of the targets with the disaccharide linkers via the phosphate-Zr(IV)-carboxylate (PZrC) crosslinking, the recruitment of alkaline phosphatase (ALP) labels via the disaccharide-lectin affinity, and the enzymatic deposition of silver nanoparticles (AgNPs). As the PZrC crosslinking can enable the decoration of each phosphate site with a disaccharide linker, each target can be decorated with multiple ALP labels. As a result, the ELLA can enable the dual signal amplification, leading to the highly sensitive detection of HPV DNA. Under optimal conditions, this method exhibits a detection limit of 0.24 fM for an HPV16-specific DNA sequence. In addition, the capture by a PNA probe confers this method with high selectivity even against discriminating the single base mismatch, and the method is applicable to the detection of HPV DNA in serum samples. Overall, the ELLA-based electrochemical method is robust, user-friendly, and timesaving, holding great promise in the highly sensitive and selective detection of DNA targets associated with the screening of high-risk HPV infections especially in the point-of-care settings.