3 Surface-enhanced Raman Scattering ...
41
section rules [8, 115]. Figure 3.6 shows SERRS spectrum of Cc electrostatically
immobilized on silver electrode, which has been covered with a monolayer of thioglicolic acid (tgA) and resonance Raman spectrum of Cc solution. As may be seen,
both spectra exhibit different frequencies and intensity pattern of the bands, which
excludes risk that the bands detected in the SERRS spectrum originate from the
protein in the solution. the band positions in the SERRS spectra are characteristic
of the native 6cLS configuration of heme iron. Namely, the band at 1362 cm
−1
indicates Fe
2+
oxidation state, together with the 1493, 1542 and 1618 cm
−1
bands which
are markers of the native low spin (LS) configuration. on the contrary, in some cases bands assigned to oxidized form of Cc (at 1568 and 1638 cm
−1
) are clearly visible
as for Ag support modified with mercaptoethanesulphonate (mES) (see spectrum
in Fig. 3.6). the band at 1568 cm
−1
indicates lots of met-80 axial ligand leading to
a non-native B2 5chS state of heme and 1638 cm
−1
feature is ascribed to the native
B1 6cLS state [110].
Potential-dependent SERRS studies for Cc immobilized on functionalized
SAms on Ag allow monitoring conformational changes in interfacial redox processes [111]. SERRS experiments may be performed in the stationary conditions
with continuously changing electrode potential [111, 116], as well as in time-resolved mode by applying a potential jump [117]. these spectroelectrochemical exFig. 3.6 SERRS spectra of cytochrome c adsorbed from 10
−4
m aqueous solution of Cc on Ag
electrode, coated with monolayer of thioglicolic acid (tgA) ( upper spectrum—left panel) (A.
Królikowska, unpublished results) and mercaptoethanesulphonate (mES) monolayer ( right panel),
as compared with the resonance Raman spectrum of 0.5 × 10
−4
m Cc solution. (Reproduced from
Ref. [110] with kind permission of John Wiley and Sons)
41
section rules [8, 115]. Figure 3.6 shows SERRS spectrum of Cc electrostatically
immobilized on silver electrode, which has been covered with a monolayer of thioglicolic acid (tgA) and resonance Raman spectrum of Cc solution. As may be seen,
both spectra exhibit different frequencies and intensity pattern of the bands, which
excludes risk that the bands detected in the SERRS spectrum originate from the
protein in the solution. the band positions in the SERRS spectra are characteristic
of the native 6cLS configuration of heme iron. Namely, the band at 1362 cm
−1
indicates Fe
2+
oxidation state, together with the 1493, 1542 and 1618 cm
−1
bands which
are markers of the native low spin (LS) configuration. on the contrary, in some cases bands assigned to oxidized form of Cc (at 1568 and 1638 cm
−1
) are clearly visible
as for Ag support modified with mercaptoethanesulphonate (mES) (see spectrum
in Fig. 3.6). the band at 1568 cm
−1
indicates lots of met-80 axial ligand leading to
a non-native B2 5chS state of heme and 1638 cm
−1
feature is ascribed to the native
B1 6cLS state [110].
Potential-dependent SERRS studies for Cc immobilized on functionalized
SAms on Ag allow monitoring conformational changes in interfacial redox processes [111]. SERRS experiments may be performed in the stationary conditions
with continuously changing electrode potential [111, 116], as well as in time-resolved mode by applying a potential jump [117]. these spectroelectrochemical exFig. 3.6 SERRS spectra of cytochrome c adsorbed from 10
−4
m aqueous solution of Cc on Ag
electrode, coated with monolayer of thioglicolic acid (tgA) ( upper spectrum—left panel) (A.
Królikowska, unpublished results) and mercaptoethanesulphonate (mES) monolayer ( right panel),
as compared with the resonance Raman spectrum of 0.5 × 10
−4
m Cc solution. (Reproduced from
Ref. [110] with kind permission of John Wiley and Sons)