Investigating The Performance of Floating Particles in The Simulation Process of Plasmonic Enhanced Nanosensors Based On Multi- to Monolayer Nanoparticles

Note:  Plasmonic-based nanosensors have attracted considerable attention due to their extraordinary sensitivity even at the single-molecule level.  However, at present, plasmonic-enhanced nanosensors have not achieved excellent performances in practical applications and their detection at femtomolar or attomolar concentrations is very challenging.

Large size floating particles combined with a slippery surface may prevent the coffee ring effect and enhance the spatial enrichment of analyte at plasmonic sensitive sites through aggregation and lifting effect.  The current floating particle strategy can be used in a wide range of plasmonic enhanced sensing applications for cost-effective, simple, rapid, flexible and portable detection. For nanosensors,  a plasmonic nanosensing process involves a complex three-element interaction among photons, molecules and nanostructures .  , nanosheets, nanotubes and nanoparticles, to enhance the surface Raman spectroscopy and fluorescence sensitivity in  plasmonic enhanced nanosensors based on nanoparticle-to-nanolayer nanosensors and , detection is difficult for many small cross-sections or weakly adsorbed molecules in plasmonic nanosensors. The performance of floating particles for plasmonic enhanced nanosensors based on nanoparticle-to-nanolayer nanosensors depends on the interaction between molecules and nanostructure surfaces.  Based on the colloidal aggregation pathway  , poorly adsorbed molecules cannot be adsorbed onto a metal surface during rapid aggregation.  Therefore, this inherent defect prevents these nanosensors from exhibiting significant sensitivity.  On a solid surface with finely divided nanoparticles,  immersing the nanosensor substrate in a solution containing the analyte may result in homogeneous molecule adsorption.  However, the adsorption time (e.g., several hours) is far beyond practical timescales.  Instead, by drying the analyte-containing droplet on a substrate, the distribution of molecules on nanosensors based on few- to monolayer plasmonic enhanced nanosensors may face the problem of uniformity.

Localization of analytes to high-efficiency plasmonic hot spots is of great importance in enhancing the sensitivity of plasmonic nanosensors. The coffee ring effect is a very common phenomenon and its nature is that the capillary flow outward from the center of the droplet transports dispersed droplets to the edge, where   they continue  to evaporate .  In many detections based on plasmonic nanosensors, the formation of a ring may result in a completely uncontrolled distribution of colloidal nanoparticles and target molecules, resulting in a decreasing signal uniformity and lower sensitivity in  the performance of floating particles for plasmonic enhanced nanosensors based on few to monolayer nanoparticles.

Conclusion:

Plasmonic-based nanosensors have attracted considerable attention due to their extraordinary sensitivity even at the single-molecule level.  However, at present, plasmonic-enhanced nanosensors have not achieved excellent performances in practical applications and their detection at femtomolar or attomolar concentrations is very challenging.