Lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) is a water soluble, cytocompatible, Type I photoinitiator for use in the polymerization of hydrogels or other polymeric materials. This photoinitator is preferred over Irgacure 2959 for biological applications due to its increased water solubility, increased polymerization rates with 365 nm light, and absorbance at 400 nm allowing for polymerization with visible light. The improved polymerization kinetics enable cell encapsualation at reduced initiator concentration and longer wavelength light, which has been shown to reduce initiator toxicity and increase cell viability.
