Controllable Synthesis of Hemoglobin–Metal Phosphate Organic–Inorganic Hybrid Nanoflowers and Their Applications in Biocatalysis

Abstract

In recent years, organic–inorganic hybrid nanoflower technology has become an effective method for enzyme immobilization. Here, seven hierarchical flower-like hemoglobin-phosphate organic-inorganic hybrid nanomaterials (Hb-M3(PO4)2 ·nH2O HNFs) were synthesized through an improved universal one-pot wet-chemical method, with Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ as inorganic components. In this synthesis process, the metal cations are successively involved in the coordination reaction with Hb and the metathesis reaction to generate phosphate precipitation. The coordination ability of metal cations and the generation rate of phosphate precipitations were evaluated, then the progress of the two chemical reactions was controlled synchronously by adjusting the phosphate buffer (PB) concentration, and finally a flower-like structure conducive to substrate diffusion and transport was obtained. Due to the conformational transformation of hemoglobin and the abundant Cu2+/Fe3+ active sites, the hemoglobin-Cu3(PO4)2·3H2O nanoflowers have extremely high catalytic activity, which is ∼14 times that of Hb. Importantly, this method is suitable for the monometallic-ionic, polymetallic-ionic and polyvalent metal-ion nanoflowers, which broadens the chemical composition and structural diversity of nanoflowers.

Enhancing the Catalytic Activity of Laccase@Copper–Metal–Organic Framework Nanofractal Microspheres: Synergistic Contribution of the Mass Transfer and Electron Transfer Pathway

“…(iii) Formation of Laccase@Cu 3 (BTC) 2 Nanofractal Microspheres . Cu 3 (BTC) 2 primary crystals grew continuously in multiple directions on the laccase, and laccase@Cu 3 (BTC) 2 nanofractal microspheres were obtained after 8 h. The following equations describe the formation of laccase@Cu 3 (BTC) 2 nanofractal microspheres Cu 2 + + polypeptide chain → [ Cu false( polypeptide chain false) n ] 2 + H 2 BTC − ↔ HBTC 2 − + H + HBTC 2 − ↔ BTC 3 − + H + 3 [ Cu false( polypeptide chain false) n ] 2 + + 2 BTC 3 − → [ Cu false( polypeptide chain false) n ] 3 ( BTC ) 2 …”

“…(iii) Formation of Laccase@Cu 3 (BTC) 2 Nanofractal Microspheres . Cu 3 (BTC) 2 primary crystals grew continuously in multiple directions on the laccase, and laccase@Cu 3 (BTC) 2 nanofractal microspheres were obtained after 8 h. The following equations describe the formation of laccase@Cu 3 (BTC) 2 nanofractal microspheres …”

Engineered Metal‐Loaded Biohybrids to Promote the Attachment and Electron‐Shuttling between Enzymes and Carbon Electrodes

“…[ 8–10 ] This process is regulated by metal‐binding sites—specific regions on the protein surface rich in chelating amino acids, notably glutamic acid, aspartic acid, and histidine. [ 11,12 ] Formed nanostructures can exhibit outstanding catalytic performance, [ 13 ] surpassing the activity of the corresponding soluble enzyme, such as a remarkable 450% increase for laccase or up to 7260% for papain. [ 8,14 ] Further, enzyme nanoflowers demonstrate prolonged shelf‐life and exceptional reusability maintained for more than five reaction cycles with minimal loss of catalytic performance.…”