Fabrication of carbon nanotube-laden microdevices for Raman labeling of macrophages

Capability to detect or track macrophages in vivo is important for developing macrophage-based therapies. Dispersed carbon nanotubes (CNTs) have been used for Raman labeling of cells and a topdown approach has been developed to fabricate disk-shaped microparticles for the same application. This study presents the first fabrication of disk-shaped microparticles termed microdevices containing densely packed CNTs and Raman labeling of macrophages with the microdevices. The fabrication is featured by the use of spray coating of CNTs to produce the microdevices. Raman detection of a single microdevice at a centimeter-scale working distance and the feasibility of using chemically modified CNTs for multiplexed Raman labeling were demonstrated. Macrophages were stably labeled with the microdevices by simply adding the microdevices to cultivated macrophages. The labeling slightly reduced viability of the macrophages and the labeled macrophages retained their ability to capture foreign particles. Moreover, Raman detection of a single macrophage was demonstrated. The microdevices promise to be useful for detection or tracking of macrophages in vivo as well as for other biomedical applications.