Boosting the Brightness of Raman Tags Using Cyanostar Macrocycles

Ramanprobes have received growing attention for their potentialuse in super-multiplex biological imaging and flow cytometry applicationsthat cannot be achieved using fluorescent probes. However, obtainingstrong Raman scattering signals from small Raman probes has poseda challenge that holds back their practical implementation. Here,we present new types of Raman-active nanoparticles (Rdots) that incorporateionophore macrocycles, known as cyanostars, to act as ion-driven andstructure-directing spacers to address this problem. These macrocycle-enhancedRdots (MERdots) exhibit sharper and higher electronic absorption peaksthan Rdots. When combined with resonant broadband time-domain Ramanspectroscopy, these MERdots show a & SIM;3-fold increase in Ramanintensity compared to conventional Rdots under the same particle concentration.Additionally, the detection limit on the concentration of MERdotsis improved by a factor of 2.5 compared to that of Rdots and a factorof 430 compared to that of Raman dye molecules in solution. The compactsize of MERdots (26 nm in diameter) and their increased Raman signalintensity, along with the broadband capabilities of time-domain resonantRaman spectroscopy, make them promising candidates for a wide rangeof biological applications.

Automated summary

This article introduces a new type of Raman-active nanoparticles called MERdots, which enhance Raman signals by using ionophore macrocycles. These MERdots, combined with resonant broadband time-domain Raman spectroscopy, showed a 3-fold increase in Raman intensity compared to conventional Rdots, and improved the detection limit on their concentration. With their small size and strong Raman signal, along with the broadband capabilities of time-domain resonant Raman spectroscopy, MERdots are promising candidates for a wide range of biological applications.