A colorimetric sensing platform based on site-specific endonuclease IV-aided signal amplification for the detection of DNA related to the human immunodeficiency virus†
Nicking endonucleases, widely applied for signal amplification, have an intrinsic limitation on sequences, as they require specific nucleotide sequences to recognize. Endonuclease IV (Endo IV) recognizes a specific site rather than specific sequences and is used for the first time to amplify colorimetric signals for DNA detection in this work. Our proposed colorimetric sensing platform with Endo IV-aided signal amplification and G-quadruplex-hemin DNAzyme is demonstrated using the human immunodeficiency virus type 1 (HIV-1) DNA as a target model. We designed a visual signal probe containing an apurinic/apyrimidinic (AP) site. In the presence of the targeted DNA, the signal probe turns from “Off” to “On”, and thus the AP site can be recognized and cleaved by Endo IV to circularly release the G-quadruplex DNAzyme sequences for signal amplification. Consequently, color changes related to G-quadruplex DNAzyme can be acquired, which is discernable even with the naked eye. Our proposed sensing platform shows a good ability for detection of the targeted DNA ranging from 2.50 nM to 120 nM, with a limit of detection (LOD) as low as 1.22 nM. This sensing platform also shows a high selectivity towards the targeted DNA. Moreover, the sensing platform has been demonstrated to be potentially useful for the targeted DNA detection in human serum. Considering the good sensitivity and specificity, as well as the intuitive and simple-to-operate features, this sensing platform has a great potential of becoming a routine tool for DNA detection and provides valuable information for biological studies and early clinical diagnosis.