Direct Virus Gene Detection: A CRISPR/dCas9-Mediated Surface-Enhanced Raman Scattering Strategy with Enzyme-Catalyzed Signal Amplification

The aberrant growth of cervical cells caused by the infection of human papillomavirus (HPV) may cause cervical cancer. In order to effectively prevent the occurrence of cervical cancer and for better follow-up treatment after surgery, a rapid and reliable detection method of HPV DNA is essential. Here, a surface-enhanced Raman scattering (SERS) detection method was developed based on the clustered regularly interspaced short palindromic repeats (CRISPR)/dCas9 technique and the enzyme catalysis amplification reaction, which achieved a simple and rapid detection of low-content HPV genes. The CRISPR/dCas9/sgRNA complex was anchored above a magnetic bead, which can precisely capture target DNA sequences, exhibiting high selectivity for HPV genes. When the biotinylated target DNAs exist, they can bridge a streptavidin-modified horse radish peroxidase (HRP) to the magnetic bead, producing an HRP-decorated conjugate. This conjugate allows an HRP-catalyzed reaction for its substrate (3,3′,5,5′-tetramethylbenzidine, TMB). Gold nanostars with a silica shell exhibiting the lightning rod effect of SERS were employed to measure the SERS spectra of the oxidative product of TMB. Enzyme catalysis and SERS co-contribute to the SERS signal output, ensuring a high detection sensitivity. This method is a proof of concept for detecting HPV DNAs in a complex system. The current method can be applied to other target DNAs simply by changing the sgRNA sequence. Many superiors portend that the CRISPR/dCas9-based SERS method is promising for further clinical application.