Amplification of the Fluorescence Signal with Clustered Regularly Interspaced Short Palindromic Repeats-Cas12a Based on Au Nanoparticle-DNAzyme Probe and On-Site Detection of Pb2+Via the Photonic Crystal Chip

Although great headway has been made in DNAzyme-based detection of Pb2+,its adaptability, sensitivity, and accessibility in complex media still need to be improved. Forthis, we introduce new ways to surmount these hurdles. First, a spherical nucleic acid (SNA)fluorescence probe (Au nanoparticles-DNAzyme probe) is utilized to specifically identifyPb2+and its suitability for precise detection of Pb2+in complex samples due to its excellentnuclease resistance. Second, the sensitivity of Pb2+detection is greatly enhanced via the useof a clustered regularly interspaced short palindromic repeats-Cas12a with target recognitionaccuracy to amplify thefluorescent signal upon the trans cleavage of the SNA (signal probe),and the limit of detection reaches as low as 86 fM. Third, we boost thefluorescence onphotonic crystal chips with a bionic periodic arrangement by employing a straightforwarddetection device (smartphone and portable UV lamp) to achieve on-site detection of Pb2+with the limit of detection as low as 24 pM. Based on the abovementioned efforts, themodified Pb2+fluorescence sensor has the advantages of higher sensitivity, better specificity,accessibility, less sample consumption, and so forth. Moreover, it can be applied to accuratelydetect Pb2+in complex biological or environmental samples, which is of great promise for widespread applications.

Automated summary

A new DNAzyme chip for detecting Pb2+ in complex media includes the use of SNA fluorescence probe, Cas12a for sensitivity enhancement, and photonic crystal chip for accessibility, ultimately achieving low limit detection. These methods make Pb2+ detection more sensitive, specific, and promising for widespread applications.