Electron Transfer in Methylene-Blue-Labeled G3 Dendrimers Tethered to Gold

TY - JOUR

T1 - Electron Transfer in Methylene-Blue-Labeled G3 Dendrimers Tethered to Gold

AU - Álvarez-Martos, Isabel

AU - Kartashov, Andrey

AU - Ferapontova, Elena

PY - 2016/12/1

Y1 - 2016/12/1

N2 - Redox-modified branched 3D dendrimeric nanostructures are considered a proper tool for the wiring of redox enzymes be-cause they provide both an enzyme-friendly environment and exquisite electron transfer (ET) mediation. ET rates in G3 poly-(amido)amine (PAMAM) dendrimers, covalently attached to gold electrodes and labeled with methylene blue (MB), approached 267 s-1 and decreased as the packing density of dendrimers on the electrode surface was increased. A mechanistic analysis of the ET kinetics and fitting to the Marcus relationship showed that as the PAMAM surface coverage was increased,the ET mechanism switched from surface-confined ET (electron tunneling) in dilute monolayers to diffusional ET (electron hopping) at higher surface populations of dendrimers. Structural changes in the positively charged dendrimers electrostatically compressed at negative charges of the electrode surface, and their dependence on the dendrimer surface packing, contribute to both mechanistic pathways. Electrical wiring of horse-radish peroxidase and hexose oxidase by using MB-labeled dendrimers allowed the bioelectrocatalytic reduction of H2O2 and oxidation of glucose by these enzymes. The demonstrated electrical communication between MB groups, localized on the periphery of dendrimers and distanced 2 to 3 nm from the electrode surface, and the electrodes opens new routes to prospective biosensor and bioelectronic applications.

AB - Redox-modified branched 3D dendrimeric nanostructures are considered a proper tool for the wiring of redox enzymes be-cause they provide both an enzyme-friendly environment and exquisite electron transfer (ET) mediation. ET rates in G3 poly-(amido)amine (PAMAM) dendrimers, covalently attached to gold electrodes and labeled with methylene blue (MB), approached 267 s-1 and decreased as the packing density of dendrimers on the electrode surface was increased. A mechanistic analysis of the ET kinetics and fitting to the Marcus relationship showed that as the PAMAM surface coverage was increased,the ET mechanism switched from surface-confined ET (electron tunneling) in dilute monolayers to diffusional ET (electron hopping) at higher surface populations of dendrimers. Structural changes in the positively charged dendrimers electrostatically compressed at negative charges of the electrode surface, and their dependence on the dendrimer surface packing, contribute to both mechanistic pathways. Electrical wiring of horse-radish peroxidase and hexose oxidase by using MB-labeled dendrimers allowed the bioelectrocatalytic reduction of H2O2 and oxidation of glucose by these enzymes. The demonstrated electrical communication between MB groups, localized on the periphery of dendrimers and distanced 2 to 3 nm from the electrode surface, and the electrodes opens new routes to prospective biosensor and bioelectronic applications.

KW - dendrimers

KW - dyes/pigments

KW - electron transfer

KW - enzyme electrodes

KW - enzymes

UR - http://www.scopus.com/inward/record.url?scp=85004140778&partnerID=8YFLogxK

U2 - 10.1002/celc.201600417

DO - 10.1002/celc.201600417

M3 - Journal article

SN - 2196-0216

VL - 3

SP - 2270

EP - 2280

JO - ChemElectroChem

JF - ChemElectroChem

IS - 12

ER -