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Three new low-affinity fluorescent Ca 2+ indicators excitable with visible light, namely 3-phenyl-6-(4-(3-carboxymethoxy-4-(N,N-dicarboxymethylamino)phenyl)phenyl)-2,5-dicarboxymethyl-1,4dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DPP1), 3-phenyl-6-(5-(3-carboxymethoxy-4-(N,N-dicarboxymethylamino)phenyl)thien-2-yl)-2,5-dicarboxymethyl-1,4-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DPP2) and 3-(thien-2-yl)-6-(5-(3-carboxymethoxy-4-(N,N-dicarboxymethylamino)phenyl)thien-2-yl)-2,5-dicarboxymethyl-1,4-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DPP3) have been synthesized and evaluated for their Ca 2+ binding properties via fluorimetric titrations. The in vitro dissociation constant K d measured at 21 • C in 100 mM KCl buffered solution, pH 7.05, for the Ca 2+-DPP1 complex is 10 µM; for Ca 2+-DPP2 and Ca 2+-DPP3 a K d value of 20 µM is found. All three indicators form 1 : 1 complexes with Ca 2+. The fluorescence quantum yields of the uncomplexed forms of DPP1, DPP2 and DPP3 are 1.2 × 10 −2 , 3.4 × 10 −2 and 3.6 × 10 −2 , respectively. After binding to Ca 2+ these values increase to 4.8 × 10 −2 , 5.0 × 10 −2 and 5.1 × 10 −2 , respectively.

Supermacroporous poly{2-hydroxyethyl methacrylate-co-[N,N-bis(2,6-diisopropylphenyl)-perylene-3,4,9,10-tetracarboxylic diimide]} [poly(HEMA-co-DIPPER)] monolithic cryogel column was prepared by radical cryocopolymerization of HEMA with DIPPER as functional comonomer and N,N'-methylene-bisacrylamide (MBAAm) as crosslinker directly in a plastic syringe for adsorption of albumin. The monolithic cryogel contained a continuous polymeric matrix having interconnected pores of 10-50 μm size. Poly(HEMA-co-DIPPER) cryogel was characterized by swelling studies, FTIR, scanning electron microscopy, and elemental analysis. The equilibrium swelling degree of the poly(HEMA-co-DIPPER) cryogel was 14.7 g H₂O/g dry cryogel. Poly(HEMA-co-DIPPER) cryogel was used in the adsorption/desorption of albumin from aqueous solutions. The nonspecific adsorption of albumin onto plain poly(HEMA) cryogel was very low (3.36 g/g polymer). The maximum amount of albumin adsorption from aqueous solution in acetate buffer was 40.9 mg/g polymer at pH 5.0. It was observed that albumin could be repeatedly adsorbed and desorbed with the poly(HEMA-co-DIPPER) cryogel without significant loss of adsorption capacity.

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