2.5 Redox Mediators
37
Table 2.1 (continued)
Compound *1
E° /V versus
SHE
pH
Conditions *2 References
[Cr(CN) 6 ] 3−/4−
−1.143
1 M KCN
* [83]
*1 bpy: 2,2 -bipyridine
dpy: 2,2 -dipyridine
phen: 1,10-phenanthroline
terpy: 2,2 :6 ,2 -terpyridine
im: imidazole
py: pyridine
thmpy: 4-(tris(hydroxymethyl)methyl)pyridine
bhm:
bis(bis(hydroxymethy)methyl
dien: diethylenetriamine
ox: oxalate dianione
edta: ethylenediaminetetraacetate tetraanion
gly: glycinate anion
pdta: propylenediamineteraacetate tetraanion
trdta: trimethylenediaminetetraacetate tetraanion
cydta: 1,2-cyclohexanediaminetetraacetate tetraanion
*2 MES: 2-(N-morpholino)ethane-sulfonate buffer
Tris:
M = mol dm −3
I: ionic strength
tris(hydroxymethyl)aminomethane
*3 [5,10,15,20-tetrakis(2,6-dichloro-3-sulfonato)porphyrinato]Fe(H 2 O)(OH − )
inorganic molecules, including methylene blue, prussian blue, toluidine blue, thionine, neutral red, quinone derivatives, ferrocene and its derivate, and inorganic redox
ions such as ferri/ferrocyanide were frequently utilized as redox mediators for rapid
electron transfer between enzymes and electrodes [30]. Besides, some small electrontransfer proteins like cytrochromes [31–34], and protein nanowires [35, 36] also could
act as electron carriers for MET-type bioelectrocatalysis.
2.6 Immobilization of Enzymes and Mediators
In order to avoid the leakage of mediators used, semipermeable membranes are often
utilized in MET-type bioelectrodes. However, the use of semipermeable membranes
may causes unexpected complexity in the electrodes or resistance in the mass transfer
of enzyme substrates to the electrode surface. As a result, various methods for coimmobilization of enzymes and mediators have been developed in the past decades.
37
Table 2.1 (continued)
Compound *1
E° /V versus
SHE
pH
Conditions *2 References
[Cr(CN) 6 ] 3−/4−
−1.143
1 M KCN
* [83]
*1 bpy: 2,2 -bipyridine
dpy: 2,2 -dipyridine
phen: 1,10-phenanthroline
terpy: 2,2 :6 ,2 -terpyridine
im: imidazole
py: pyridine
thmpy: 4-(tris(hydroxymethyl)methyl)pyridine
bhm:
bis(bis(hydroxymethy)methyl
dien: diethylenetriamine
ox: oxalate dianione
edta: ethylenediaminetetraacetate tetraanion
gly: glycinate anion
pdta: propylenediamineteraacetate tetraanion
trdta: trimethylenediaminetetraacetate tetraanion
cydta: 1,2-cyclohexanediaminetetraacetate tetraanion
*2 MES: 2-(N-morpholino)ethane-sulfonate buffer
Tris:
M = mol dm −3
I: ionic strength
tris(hydroxymethyl)aminomethane
*3 [5,10,15,20-tetrakis(2,6-dichloro-3-sulfonato)porphyrinato]Fe(H 2 O)(OH − )
inorganic molecules, including methylene blue, prussian blue, toluidine blue, thionine, neutral red, quinone derivatives, ferrocene and its derivate, and inorganic redox
ions such as ferri/ferrocyanide were frequently utilized as redox mediators for rapid
electron transfer between enzymes and electrodes [30]. Besides, some small electrontransfer proteins like cytrochromes [31–34], and protein nanowires [35, 36] also could
act as electron carriers for MET-type bioelectrocatalysis.
2.6 Immobilization of Enzymes and Mediators
In order to avoid the leakage of mediators used, semipermeable membranes are often
utilized in MET-type bioelectrodes. However, the use of semipermeable membranes
may causes unexpected complexity in the electrodes or resistance in the mass transfer
of enzyme substrates to the electrode surface. As a result, various methods for coimmobilization of enzymes and mediators have been developed in the past decades.