Chitosan‐Cross‐linked Osmium Polymer Composites as an Efficient Platform for Electrochemical Biosensors

Abstract

A new family of chitosan-cross-linked osmium polymer composites was prepared and its electrochemical properties were examined. The composites were prepared by quaternization of the poly(4-vinylpyridine) osmium bipyridyl polymer (PVP-Os) which was then cross-linked with chitosan, yielding PVP-Os/chitosan. Films made of the composites showed improved mass and electron transport owing to the porous and hydrophilic structure which is derived from the cross-links between the Os polymer and chitosan. The rate for glucose oxidation was enhanced four times when glucose oxidase (GOx) was immobilized on PVP-Os/chitosan compared immobilization on PVP-Os.

Bioelectrochemical Behavior of the Composite PVP-Os/chitosan as a Mediator with Different Types of Enzymes at Graphite Electrode

“…The redox polymer poly (4-vinylpyridine) osmium bipyridyl, PVP-Os-(bpy) 2 -Cl was synthesized according to a reported procedure and obtained as a powder [19]. Glutaraldehyde (25% in water solution), chitosan (low molecular weight, degree of deacetylation 85-90%) were obtained from Sigma Aldrich Co., St. Louis, Mo, USA and glucose oxidase (from Aspergilus niger, AnGOx, 50.000 units, 10 mg/ml) were obtained from the Sigma-Aldrich, where one unit will oxidize 1.0 µmole of β-Dglucose to D-gluconic acid and H 2 O 2 per min at pH 5.1.…”

“…The PVP-Os/chitosan composite was prepared by mixing 10 µL of an aqueous solution of PVP-Os (5 mg ml -1 in water) with 50 µL of a 1% chitosan solution (in 1% acetic acid solution, pH 4.5) followed by either the addition of 5 µL of a 0.5% GA (in water solution) or the addition of 2.5 μl of freshly prepared 10 mg ml -1 PEGDGE-water solution. The PVP-Os polymer solution or the PVP-Os/chitosan composite were well mixed with 5 μL of enzyme solution to prepare a mixture composite of (enzyme/PVP-Os) as well as (enzyme/PVP-Os/chitosan) as reported in [19]. The solution matrix was mixed well and kept overnight at 4°C before use.…”

“…More recently, Shin and his co-workers succeeded in using the polymer PVP-Os-(bpy) 2 -Cl to form a composite that was covalently connected to chitosan producing a reactive matrix well adapted for enzyme immobilization. Such composite showed a porous form that positively reflected on the electron transfer rate, and revealed a significant enhancement in the current density for glucose oxidation based on immobilization of glucose oxidase (GOx) in such a composite [19]. Here, we introduce the use of the same Os-polymer, PVP-Os-(bpy) 2 -Cl, after being covalently attached to chitosan through either glutaraldehyde or poly(ethylene glycol) diglycidyl ether as cross-linker, to form a three dimensional structure with mediating properties, which is mixed with six different sugar oxidizing enzymes.…”

Ferrocene Tethered Polyvinyl Alcohol/Silica Film Electrode for Electrocatalytic Sulfite Sensing

“…Polymers modified with redox active moieties like ferrocene, osmium complexes, quinone and viologen derivatives are widely used as a mediators and the immoblization platform for biosensoring and bio-fuel cell applications [7][8][9][10][11][12][13]. Functional polymeric backbones like polyacrylic acid, polyallylamine, polyvinyl alcohol and chitosan are useful for being tethered by redox active centers [14][15][16] and, among them, polyvinyl alcohol is a highly hydrophilic and biocompatible macromolecule.…”

Chitosan-Cu-salen/Carbon Nano-Composite Based Electrode for the Enzyme-less Electrochemical Sensing of Hydrogen Peroxide

“…Salen based electro-active complexes and their polymers have potential applications in the field of electro-catalysts, chemical sensors and optical devices [6,7]. The metal complexes are often coated on the electrode surfaces either by electro-deposition or immobilizing them with polymer matrix for the catalytic purposes [8][9][10]. Copper complexes of salentype ligands are important in some biochemical pro-cesses, and DNA cleavage and antimicrobial activity [11][12][13][14].…”