Poly(I:C) Fluorescein was chemically labeled by covalent coupling of a fluorescein probe containing a reactive alkylating group. This confers fluorescent properties to poly(I:C) (HMW) whilst retaining TLR3 recognition properties.

Polyinosinic-polycytidylic acid (poly(I:C)) is a synthetic analog of double stranded RNA (dsRNA), a molecular pattern associated with viral infection.

Both natural and synthetic dsRNAs are known to induce type I interferons (IFN) and other cytokines production. Poly(I:C) is recognized by Toll-like receptor 3 (TLR3).