MultiDots consist of several quantum dots within a patented PEG polymer coating. The pegylated fluorescent nanoparticles have very tight size distribution and the amine functional groups on the surface allows conjugation of proteins to label cells of interest. MultiDots with a tighter emission spectrum than current fluorescent reagents, reduces spectral overlap, increases assay sensitivity and eliminates complex spectral compensation. The SK7 anitbody conjugated to this MultiDot recognizes the T-cell surface glycoprotein CD3 epsilon chain (CD3ɛ), also known as T-cell surface antigen T3/Leu-4 epsilon. CD3ɛ is a subunit of the TCR-CD3 cell surface receptor complex, which is expressed at the surface of mature T cells, NKT cells and thymocytes.