Magnetic-assisted sequential templated self-assembly of hybrid colloid nanoparticle systems.

The assembly of hybrid nanoparticles is a pioneering route for developing nanoscale functional devices, enabling breakthroughs in various fields, including electronics, photonics, energy, sensing, and biomedical applications. Here, we focus on the templated assembly of nano-sized colloidal systems using a combination of silica-coated superparamagnetic beads (MBs) and polymer-coated gold nanoparticles (AuNPs) or silver nanoparticles (AgNPs). These hybrid nanoparticles introduce new functionalities that allow them to be used as nanomachines with numerous possible applications. Using sequential capillarity-assisted particle assembly (sCAPA), we deposit MBs with activating nano-transducers made of PNIPAm@AuNPs, which respond to specific external stimuli such as temperature variations. We deposit MBs with surface-enhanced Raman scattering (SERS) AgNPs, which have the ability to detect molecules at low concentrations. A key achievement of our study is demonstrating the successful CAPA assembly of nanoparticles with ingenious surface chemistry and retrieving these assembled structures from nanotraps in a liquid medium. This ability highlights the potential of hybrid colloids in precisely targeted drug delivery systems and highly effective mobile sensors. It represents a significant leap forward in using nanotechnology to create more complex and responsive nanoscale assemblies.