Synthesis of isocyanate containing cryogels for fast (bio)molecular immobilization

Cryogels containing isocyanate reactive groups were synthesized via photopolymerization of 2-isocyanoethyl methacrylate (ICEMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA). By changing the PEGMEMA and ICEMA ratios, cryogel series with varying ratios of reactive isocyanate groups were successfully prepared. The cryogels were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, scanning electron microscope, and rheometry. To demonstrate that molecules containing amine groups can be immobilized onto synthesized cryogels through isocyanate-amine reactions, the cryogels were conjugated with 4-(trifluoromethyl)benzylamine (TFBA) and fluorescein amine (FLA) molecules, and the conjugations were confirmed through FTIR and fluorescence microscopy, respectively, for TFBA and FLA. Additionally, immobilization of fluorescein isothiocyanate conjugated albumin from bovine serum (FITC-BSA) as fluorescein-labeled model proteins was studied to illustrate that biomolecules can also be bound to the cryogels without any linker. It was shown that the amount of immobilized FITC-labeled model proteins can be controlled by adjusting the concentration of isocyanate reactive groups within the cryogel matrix, and this functionalization was confirmed by fluorescence microscope.