title: Polyphosphonate induced coacervation of chitosan: encapsulation of proteins/enzymes and their biosensing.
abstract: Based on the polyphosphonate-assisted coacervation of chitosan, a simple and versatile procedure for the encapsulation of proteins/enzymes in chitosan-carbon nanotubes (CNTs) composites matrix was developed. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectrum (EDS) mapping demonstrated the hemoglobin (Hb) uniformly distributed into chitosan-CNTs composites matrix. Raman measurements indicated the CNTs in composites matrix retained the electronic and structural integrities of the pristine CNTs. Fourier transform infrared (FT-IR), ultraviolet-visible (UV-vis) and circular dichroism (CD) spectroscopy displayed the encapsulated Hb preserved their near-native structure, indicating the polyphosphonate-chitosan-CNTs composites possessed excellent biocompatibility for the encapsulation of proteins/enzymes. Electrochemical measurements indicated the encapsulated Hb could directly exchange electron with the substrate electrode. Moreover, the modified electrode showed excellent bioelectrocatalytic activity for the reduction of hydrogen peroxide. Under optimum experimental conditions, the fabricated electrochemical sensor displayed the fast response (less than 3s), wide linear range (7.0×10(-7) to 2.0×10(-3)M) and low detection limit (4.0×10(-7)M) for the determination of hydrogen peroxide. This newly developed protocol was simple and mild and would certainly find extensive applications in biocatalysis, biosensors, bioelectronics and biofuel cells.
authors.affiliation: Jiangsu Key Laboratory of Power Batteries, Laboratory of Electrochemistry, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Hailing
authors.initials: H
authors.lastname: Liu
authors.forename: Yanyun
authors.initials: Y
authors.lastname: Cui
authors.forename: Pan
authors.initials: P
authors.lastname: Li
authors.forename: Yiming
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Yawen
authors.initials: Y
authors.lastname: Tang
authors.forename: Tianhong
authors.initials: T
authors.lastname: Lu
mesh_terms: D015374:Biosensing Techniques; D048271:Chitosan / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D006454:Hemoglobins / Q000737:chemistry / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000737:chemistry; D055767:Immobilized Proteins / Q000737:chemistry / Q000378:metabolism; D037742:Nanotubes, Carbon / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000737:chemistry*
chemical_list: D006454:Hemoglobins; D055767:Immobilized Proteins; D037742:Nanotubes, Carbon; D009943:Organophosphorus Compounds; C020477:polyphosphonate; D048271:Chitosan; D006861:Hydrogen Peroxide