ICG Labeling Kit - NH2 is used primarily for the preparation of ICG (Iindocyanin green)-labeled antibody for near-infrared fluorescence imaging.This kit contains all required compornents required for labeling, including storage buffer for conjugates. The labeling process is simple:. Add NH2-reactive ICG to protein solution on a filter membrane, and incubate at 37ºC, for 10 minutes. A filtration tube can remove excess ICG molecules.