Nanoparticle Tracking Analysis-Based In Vitro Detection of Critical Biomarkers

Nanoparticles emerge to be powerful probes for the sensing of critical biomarkers because of their characteristic optical/electrochemical/magnetic properties. However, the versatility and prevalence of nanoparticle-based assays remain hampered because each kind of nanoprobe has designated properties, which requires different instruments for the readout of the signals. Herein, a versatile nanoparticle tracking analysis (NTA)-based strategy is innovatively proposed for the in vitro detection of critical biomarkers without demanding specific properties of the nanoparticles. Based on the sandwich-type immunoreaction and the duplex-specific nuclease-assisted cycling nucleic acid cleavage, the quantitative relationships are rationally built up between the level of both protein and microRNA biomarkers and the nanoparticles’ number variation. Under proper conditions, NTA will provide the absolute number count and accurate size distribution of the nanoparticles in the solution phase in a real-time manner to facilely determine the level of the protein and microRNA targets. Benefiting from the intrinsic ability of NTA for grouping the nanoparticles by size and composition, the multiplexed assay of biomolecules is also achieved. Compared with the conventional nanoparticle-based biosensing systems, NTA can directly count the nanoparticles in aqueous solution, without depending on the nanoparticles’ specific properties. This work remarkably improves the versatility and convenience of nanoparticle counting-based bioanalysis, inspiring the future application of NTA in biosensing.