title: Enhanced enzymatic reactivity for electrochemically driven drug metabolism by confining cytochrome P450 enzyme in TiO₂ nanotube arrays.
abstract: Understanding the enzymatic reaction kinetics that occur within a confined space or interface is a significant challenge. Herein, a nanotube array enzymatic reactor (CYP2C9/Au/TNA) was constructed by electrostatically adsorbing enzyme on the inner wall of TiO2 nanotube arrays (TNAs). TNAs with different dimensions could be fabricated by the anodization of titanium foil through varying the anodization potential or time. The electrical conductivity of TNAs was improved by electrodepositing Au nanoparticles on the inner wall of TNAs. The cytochrome P450 2C9 enzyme (CYP2C9) was confined inside TNAs as a model. The enzymatic activity of CYP2C9 and tolbutamide metabolic yield could be effectively regulated by changing the nanotube diameter and length of TNAs. The enzymatic rate constant k(cat) and apparent Michaelis constant K(m)(app) were determined to be 9.89 s(-1) and 4.8 μM at the tube inner diameter of about 64 nm and length of 1.08 μm. The highest metabolic yield of tolbutamide reached 14.6%. Furthermore, the designed nanotube array enzymatic reactor could be also used in situ to monitor the tolbutamide concentration with sensitivity of 28.8 μA mM(-1) and detection limit of 0.52 μM. Therefore, the proposed nanotube array enzymatic reactor was a good vessel for studying enzyme biocatalysis and drug metabolism, and has potential applications including efficient biosensors and bioreactors for chemical synthesis.
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University , Nanjing 211189, People's Republic of China.
authors.forename: Jusheng
authors.initials: J
authors.lastname: Lu
authors.forename: Henan
authors.initials: H
authors.lastname: Li
authors.forename: Dongmei
authors.initials: D
authors.lastname: Cui
authors.forename: Yuanjian
authors.initials: Y
authors.lastname: Zhang
authors.forename: Songqin
authors.initials: S
authors.lastname: Liu
mesh_terms: D065729:Cytochrome P-450 CYP2C9 / Q000378:metabolism*; D055664:Electrochemical Techniques; D007004:Hypoglycemic Agents / Q000493:pharmacokinetics*; D008855:Microscopy, Electron, Scanning; D043942:Nanotubes; D014025:Titanium / Q000737:chemistry*; D014044:Tolbutamide / Q000493:pharmacokinetics*
chemical_list: D007004:Hypoglycemic Agents; C009495:titanium dioxide; D014044:Tolbutamide; D014025:Titanium; D065729:Cytochrome P-450 CYP2C9