We present here a cSeNP (Figure , panel D) as a contrast agent in electron, Xray, and visible light-based imaging modalities. The cSeNP is comprised of a dimeric selenodiglutatione (GS-Se-SG) reducing enzyme (Glutathione Reductase Like Metalloid Reductase, GRLMR) modified to be a single-chain construct with 2 SeNP binding peptides attached (Figure , panel D). Expression of GRLMR in cells grown on SeO3 2- supplemented media results in a striking-red color, attributable to the red allotrope of intracellular SeNPs (Figure , panel B).