Imidazole-Grafted Nanogels for the Fabrication of Organic-Inorganic Protein Hybrids

Here, a platform for the development of highly responsive organic-inorganic enzyme hybrids is provided. The approach entails a first step of protein engineering, in which individual enzymes are armored with a porous nanogel decorated with imidazole motifs. In a second step, by mimicking the biomineralization mechanism, the assembly of the imidazole nanogels with CuSO4 and phosphate salts is triggered. A full characterization of the new composites reveals the first reported example in which the assembly mechanism is triggered by the sum of Cu(II)-imidazole interaction and Cu-3(PO4)(2) inorganic salt formation. It is demonstrated that the organic component of the hybrids, namely the imidazole-modified polyacrylamide hydrogel, provides a favorable spatial distribution for the enzyme. This results in enhanced conversion rates, robustness of the composite at low pH values, and a remarkable thermal stability at 65 degrees C, exhibiting 400% of the activity of the mineralized enzyme lacking the organic constituent. Importantly, unlike in previous works, the protocol applies to the use of a broad range of transition metal cations (including mono-, di-, and trivalent cations) to trigger the mineralization mechanism, which eventually broadens the chemical and structural diversity of organic-inorganic protein hybrids.