Colloidal Multiscale Assembly via Photothermally Driven Convective Flow for Sensitive In-Solution Plasmonic...

Area of Science:

• Nanotechnology
• Spectroscopy
• Materials Science

Background:

• Sensitive detection in solution using surface-enhanced Raman spectroscopy (SERS) requires assembling nanoparticles and targets within a small volume.
• Current methods often rely on chemical linkers or templates, or sample drying, to overcome random colloid diffusion.

Purpose of the Study:

• To develop a facile method for creating 3D multiscale assemblies for sensitive in-solution SERS detection.
• To achieve assembly without chemical linkers or templates by utilizing photothermally driven convective flow.

Main Methods:

• Simulations were performed to understand the assembly of colloids of various sizes (sub-100 nm to micrometers) by photothermally driven convective flow.
• Experimental validation confirmed the role of photothermally driven convective flow in coassembling plasmonic gold nanorods with molecules or microparticles.

Main Results:

• Photothermally driven convective flow effectively assembles colloids <100 nm regardless of density.
• Assembly of larger colloids is significant if their density is close to water.
• Coassembly with plasmonic nanoantennae enhanced Raman signals of molecules, microplastics, and microbes by up to five orders of magnitude.

Conclusions:

• Photothermally driven convective flow is a viable strategy for creating 3D multiscale assemblies for in-solution SERS.
• This method enables sensitive detection of various targets without chemical linkers or templates.
• The technique significantly boosts Raman signal enhancement, improving detection capabilities.