title: Halloysite Clay Nanotubes for Enzyme Immobilization.
abstract: Halloysite clay is an aluminosilicate nanotube formed by rolling flat sheets of kaolinite clay. They have a 15 nm lumen, 50-70 nm external diameter, length of 0.5-1 μm, and different inside/outside chemistry. Due to these nanoscale properties, they are used for loading, storage, and controlled release of active chemical agents, including anticorrosions, biocides, and drugs. We studied the immobilization in halloysite of laccase, glucose oxidase, and lipase. Overall, negatively charged proteins taken above their isoelectric points were mostly loaded into the positively charged tube's lumen. Typical tube loading with proteins was 6-7 wt % from which one-third was released in 5-10 h and the other two-thirds remained, providing enhanced biocatalysis in nanoconfined conditions. Immobilized lipase showed enhanced stability at acidic pH, and the optimum pH shifted to more alkaline pH. Immobilized laccase was more stable with respect to time, and immobilized glucose oxidase showed retention of enzymatic activity up to 70 °C, whereas the native sample was inactive.
authors.affiliation: Institute for Micromanufacturing and Biomedical Engineering Program, Louisiana Tech University , Ruston, Louisiana, United States.
authors.forename: Joshua
authors.initials: J
authors.lastname: Tully
authors.affiliation: Institute for Micromanufacturing and Biomedical Engineering Program, Louisiana Tech University , Ruston, Louisiana, United States.
authors.forename: Raghuvara
authors.initials: R
authors.lastname: Yendluri
authors.affiliation: Institute for Micromanufacturing and Biomedical Engineering Program, Louisiana Tech University , Ruston, Louisiana, United States.|Ural Federal University, Ekaterinburg, Russia.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Lvov
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D000077215:Clay; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005949:Glucose Oxidase / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D042845:Laccase / Q000737:chemistry; D008049:Lipase / Q000737:chemistry; D043942:Nanotubes; D011485:Protein Binding; D013696:Temperature
chemical_list: D000538:Aluminum Silicates; D004800:Enzymes, Immobilized; C049037:aluminosilicate; D005949:Glucose Oxidase; D042845:Laccase; D008049:Lipase; D000077215:Clay