posted on 2023-11-28, 21:04authored byJiwon Yoon, Dong-Ho Kim, Sung-Gyu Park, Shin-Hyun Kim
Surface-enhanced Raman scattering
(SERS) is an effective
technique
for amplifying the Raman signal of molecules by using metal nanostructures.
However, these metal surfaces are susceptible to contamination by
undesirable adhesives in complex mixtures, typically necessitating
a time-consuming and costly sample pretreatment. In order to circumvent
this, metal nanoparticles have been uniformly embedded within microgels
by using microfluidics. In this work, we introduce a simple, scalable
micromolding method for creating SERS-active cylindrical microgels
designed to eliminate the need for pretreatment. These microcylinders
are created through the simultaneous photoreduction and photo-cross-linking
of precursor solutions. These solutions are optimized for consistent,
high-intensity Raman signals as well as molecular size and charge
selectivity. A sequential micromolding method is employed to design
dual-compartment microcylinders, offering additional functionalities
such as optical encoding, magnetoresponsiveness, and dual-charge selectivity.
These SERS-active microcylinders provide robust Raman signals of small
molecules, even in the presence of adhesive proteins, without compromising
sensitivity. To demonstrate this capability, we directly detect pyocyanin
in saliva and tartrazine in whole milk without any need for sample
pretreatment.