Facile one-pot preparation of chitosan/calcium pyrophosphate hybrid microflowers.

Flower-like chitosan/calcium pyrophosphate hybrid microparticles (microflowers) are prepared using a facile one-pot approach by combining ionotropic gelation with biomimetic mineralization. Chitosan-tripolyphosphate (CS-TPP) nanocomplexes are first synthesized through ionotropic gelation; meanwhile, excess TPP is partly hydrolyzed into pyrophosphate ions (P2O7(4-)). Upon addition of CaCl2, CS-TPP nanocomplexes serve as a versatile template, inducing in situ mineralization of Ca2P2O7 and directing its growth and assembly into microflowers. The whole preparation process can be completed within half an hour. The as-prepared microflowers are composed of 23.0% CS-TPP nanocomplexes and 77.0% Ca2P2O7 crystals. Mesopores (3.7 and 11.2 nm) and macropores coexist in the microflowers, indicating porous and hierarchical structures. The microflowers exhibit high efficiency in dye adsorption and enzymatic catalysis. Specifically, a high adsorption capacity of 520 mg g(-1) for Congo red is achieved. And the immobilized enzyme retains about 85% catalytic activity compared with that of the free enzyme. The facile one-pot preparation process ensures the broad applications of the porous hybrid microflowers.