A label-free silicon-based spherical nucleic acid enzyme (SNAzyme) for ultrasensitive chemiluminescence detection of acute myocardial infarction-related nucleic acids

As a nano-form of G-quadruplex (G4) based DNAzymes, spherical nucleic acid enzymes (SNAzymes) with gold nanoparticles (AuNPs) as cores have shown great promise for applications in nucleic acid detection. SNAzymes can be constructed by modifying thiolated G4 DNAs onto AuNPs through various methods. However, those constructed with label-free G4 DNAs were found to have a weak enzyme activity due to the G4 destruction on the surface of AuNPs. To address this, here we constructed label-free silicon-based SNAzymes using silica nanoparticles (SiO2) as the core for the first time. We took advantage of the versatility of SiO2 and loaded N-(4-aminobutyl)-N-ethylisoluminol (ABEI) on the surface of silicon spheres (SiO2@ABEI). Then, we found that SiO2@ABEI can achieve high-efficiency adsorption of arbitrary G4 sequences within a few minutes without high requirements for modification methods. In this way, a highly sensitive CL nanoprobe integrated with a catalyst and a chemiluminescence (CL) reagent was successfully constructed. Finally, we use the nanoprobe for the ultrasensitive chemiluminescence detection of acute myocardial infarction (AMI)-related nucleic acids, achieving a detection range of 10 fM-100 pM and an excellent detection limit of 0.8 fM. Compared with Au@SNAzyme, SiO2-SNAzyme@ABEI higher catalytic activity, which can be applied chemiluminescence detection of miDNA-499.