Hysteresis peaks absence

Figure 2(A) shows the SAXS profiles of water-adsorbed PlT-5 (u) = 0.8iim) iis a fuiict ion of (p. The SAXS profiles for all relative pressures had no peak and the scattering intensities deciease wit h the incre iso of s over the whole. s region. The soli. The s< atler-ings on desorption are overlapped to those of adsor )-tion process, corresponding to absence of adsorption hysteresis.

The products of the reaction they catalyze may inhibit many enzymes through Michaelis-Menten kinetic retroaction. Protons, which are involved as products or reactants in a number of cases, may also influence the enzymatic kinetics. The course of the reaction may therefore be altered by the attending production or depletion of protons. It is thus interesting to examine whether these phenomena may be revealed by the effect they might have on the electrochemical responses of immobilized enzyme films under appropriate conditions [92]. A first clue of the existence of such inhibition effects is the observation of hysteresis behaviors of the type shown in Fig. 18(a) where data obtained with 10 glucose oxidase monolayers with ferrocene methanol as cosubstrate have been taken as example. In the absence of inhibition, the forward and reverse traces should be exactly superimposed. Hysteresis increases to the point of making a peak appear on the forward trace as the scan rate decreases and as the concentration of the buffer decreases, as illustrated in Fig. 18c, c , c , c by comparison with Fig. 18(a). 

Increasing the length of the alkyl chain beyond 7-9 carbon atoms produces an increase in both the mean conjugation length of the polymer chain and the electrochemical reversibility as illustrated by the symmetry of the cyclic voltammograms [64,128]. The absence of hysteresis, i.e. of a high separation between forward and backward peak potentials, may be due to a better solvation, with electrolyte permeation, of the polymers. 

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