Myoglobin electrodes

PSS-SG composite film was tested for sorption of heme proteins hemoglobin (Hb) and myoglobin (Mb). The peroxidaze activity of adsorbed proteins were studied and evaluated by optical and voltammetric methods. Mb-PSS-SG film on PG electrode was shown to be perspective for detection of dissolved oxygen and hydrogen peroxide by voltammetry with linear calibration in the range 2-30 p.M, and detection limit -1.5 p.M. Obtained composite films can be modified by different types of biological active compounds which is important for the development of sensitive elements of biosensors. 

S. Kroning, F.W. Scheller, U. Wollenberger, and F. Lisdat, Myoglobin-clay electrode for nitric oxide (NO) detection in solution. Electroanalysis 16, 253—259 (2004). 

G.C. Zhao, L. Zhang, X.W. Wei, Z.S. Yang, Myoglobin on multi-walled carbon nanotubes modified electrode direct electrochemistry and electrocatalysis. Electrochem. Commun. 5, 825—829 (2003). 

J.F. Stargardt, F.M. Fiawkridge, and H.L. Landrum, Reversible heterogeneous reduction and oxidation of sperm whale myoglobin at a surface modified gold minigrid electrode. Anal. Chem. 50, 930-932 (1978). 

I. Taniguchi, K. Watanabe, M. Tominaga, and F.M. Hawkridge, Direct electron transfer of horse heart myoglobin at an indium oxide electrode. J. Electroanal. Chem. 333, 331-338 (1992). 

M. Tominaga, T. Kumagai, S. Takita, and I. Taniguchi, Effect of surface hydrophilicity of an indium oxide electrode on direct electron transfer of myoglobins. Chem. Lett. 10, 1771-1774 (1993). 

A.E.F. Nassar, W.S. Willis, and J.F. Rusling, Electron transfer from electrodes to myoglobin facilitated in surfactant films and blocked by adsorbed biomacromolecules. Anal. Chem. 67, 2386-2392 (1995). 

A.E.F. Nassar, Z. Zhang, N.F. Hu, J.F. Rusling, and T. Kumosinski, Protein-coupled electron transfer from electrodes to myoglobin in ordered biomembrane-like films. J. Phys. Chem. B 101, 2224-2231 (1997). 

J. Ye and R.P. Baldwin, Catalytic reduction of myoglobin and haemoglobin at chemically modified electrodes containing methylene blue. Anal. Chem. 60, 2263—2268 (1988). 

Direct electron transfer has also been achieved with many metalloproteins such as cytochrome C, horseradish peroxidase, microperoxidase (MP-11), myoglobin, hemoglobin, catalase, azurin, and so on, immobilized on different CNT-modified electrodes [45, 61, 144—153]. 

Figure 3.22 (a) Cyclic voltammogram of myoglobin covalently attached to a CNT forest in PBS solution under nitrogen atmosphere. The reversible redox behavior of the iron redox center is observed, (b) and (c) electrocatalytic response of Myoglobin/CNT forest electrode to oxygen and peroxide... 

The first electrochemical studies of Mb were reported for the horse heart protein in 1942 (94) and subsequently for sperm whale Mb (e.g., 95) through use of potentiometric titrations employing a mediator to achieve efficient equilibriation of the protein with the electrode (96). More recently, spectroelectrochemical measurements have also been employed (97, 98). The alternative methods of direct electrochemistry (99-102) that are used widely for other heme proteins (e.g., cytochrome c, cytochrome bs) have not been as readily applied to the study of myoglobin because coupling the oxidation-reduction eqiulibrium of this protein to a modified working electrode surface has been more difficult to achieve. As a result, most published electrochemical studies of wild-type and variant myoglobins have involved measurements at eqiulibrium rather than dynamic techniques. 

Recent work has resolved some of the issues that complicate direct electrochemistry of myoglobin, and, in fact, it has been demonstrated that Mb can interact effectively with a suitable electrode surface (103-113). This achievement has permitted the investigation of more complex aspects of Mb oxidation-reduction behavior (e.g., 106). In general, it appears that the primary difficulty in performing direct electrochemistry of myoglobin results from the change in coordination number that accompanies conversion of metMb (six-coordinate) to reduced (deoxy) Mb (five-coordinate) and the concomitant dissociation of the water molecule (or hydroxide at alkaline pH) that provides the distal ligand to the heme iron of metMb. 

Figure 11.19 (a) Schematic representation of silver NPs and myoglobin modified electrode,... 

The applicability of the theoretical expressions discussed above has been tested with different systems such as the oxidation of protein myoglobin in the presence of sodium ascorbate [96] or the oxidation of ferrocene in the presence of potassium ferrocyanide [95]. The case corresponding to ferrocene-containing monolayers on a gold electrode in the presence of potassium ferrocyanide will be addressed here. 

One of the requirements in MALDI-MS analysis is the use of a liquid matrix. The electrowetting-on-dielectric (EWOD) method has been used to move and mix droplets containing proteins and peptides with the liquid matrix, all of which were situated at specific locations on an array of electrodes. With this method, insulin (1.75 pM), insulin chain B (2 pM), cytochrome c (1.85 pM), and myoglobin (1.45 pM) have been analyzed [518]. 

Gold nanoparticles have been used to immobilize micro-peroxidase 11,46 tyrosinase,47 and hemoglobin48 to construct amperometric sensors, while silver nanoparticles have been used to enhance electron transfer of cytochrome c and myoglobin onto pyrolitic graphite electrodes.49 The use of semiconductor and oxide nanoparticles has also been reported, such as horseradish peroxidase (HRP) on TiC>2 nanoparticles,50 as well as Fe304 and MnC>4 nanoparticles to immobilize and facilitate direct electron transfer.51... 

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