Long tethers binding redox centers to polymer backbones enhance electron transport in enzyme "Wiring" hydrogels.
A redox hydrogel with an apparent electron diffusion coefficient (D(app)) of (5.8 +/- 0.5) x 10(-)(6) cm(2) s(-)(1) is described. The order of magnitude increase in D(app) relative to previously studied redox hydrogels results from the tethering of redox centers to the backbone of the cross-linked redox polymer backbone through 13 atom spacer arms. The long and flexible tethers allow the redox centers to sweep electrons from large-volume elements and to collect electrons of glucose oxidase efficiently. The spacer arms make the collection of electrons from glucose oxidase so efficient that glucose is electrooxidized already at -0.36 V versus Ag/AgCl, the reversible potential of the redox potential of the FAD/FADH(2) centers of the enzyme at pH 7.2. The limiting current density of 1.15 mA cm(-)(2) is reached at a potential as low as -0.1 V versus Ag/AgCl. The novel redox center of the polymer is a tris-dialkylated N,N'-biimidazole Os(2+/3+) complex. Its redox potential, -0.195 V versus Ag/AgCl, is 0.8 V reducing relative to that of Os(bpy)(2+/3+), its 2,2'-bipyridine analogue.
Mao
Fei
F
TheraSense Inc., 1360 South Loop Road, Alameda, California 94502, USA.
Mano
Nicolas
N
Heller
Adam
A
D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry; D004563:Electrochemistry; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry; D005949:Glucose Oxidase / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry; D010084:Oxidation-Reduction; D011145:Polyvinyls / Q000737:chemistry*
D020100:Hydrogels; D007093:Imidazoles; D009942:Organometallic Compounds; D011145:Polyvinyls; D005182:Flavin-Adenine Dinucleotide; C019535:poly(4-vinylpyridine); D015082:2,2'-Dipyridyl; C085573:osmium bis(2,2'-bipyridine)chloride; D005949:Glucose Oxidase