Hydrogels active

GRGDS, GRGES, GREDVDY, GSVVYGLR Carboxy-methyl- dextran HUVEC, human foreskin fibroblasts Noncontact printing of peptides onto activated hydrogel 2007 [161]... 

After the synthesis of the active hydrogel components these are often not immediately ready to operate and show an unsatisfying behaviour. During the design process the causes of malfunctions have to be considered to avoid inoperative devices. 

The swelling kinetics of stimuli-responsive hydrogels is described by the theory of cooperative diffusion (Sect. 3.2.2 and 3.2.3, (Tanaka and Fillmore 1979)). Besides the cooperative diffusion constant, which is specific for each solvent-polymer network combination (see Eq. (3.2.9)), the time behaviour of active hydrogel components can be as well influenced by further design-dependent aspects (Richter 2006, 2008b). 

Inside microfluidic channels the flow is laminar. Due to the absence of turbulences different media do not mix or mix only spontaneously and very slowly. Automatic elements can only operate correct in the presence of sufficient process medium. Otherwise, in the absence of stimulation, the control functionality can not be performed. Therefore, inside microfluidic channel networks the realisation of a recirculation is recommended which can provide an independency from the state (open or closed) of the active hydrogel components. 

In contrast to the area of redox protein electrochemistry, redox enzyme electrochemistry has received much greater attention, driven in many cases by the desire to construct practical, self-contained enzyme electrodes for commercial applications. Redox enzyme electrochemistry is also easier to study in many ways because the substrate or product is often detected electrochemically rather than the enzyme itself. Various types of electroactive polymers have been used with redox enzymes, including redox polymers, redox-active hydrogels, and electropolymer-ized films of conducting and nonconducting, polymers. We discuss each type of polymer in turn, starting with electropolymerized films. 

In a complete biomimetic approach, Dabiri and Parker et al. demonstrated the constmction of an artificial jellyfish (Nawroth et al. 2012). The device is formed by an elastomeric membrane coated with the active hydrogel. By applying a pulsed electric field (1 Hz, 2.5 V cm 10 ms pulse duration), a bending of the laminated stmcture is induced. This folds the discUke structure to a bowel and expels water which acts as a driving force for the movement. Overall, the mechanic behavior of this device is in excellent agreement with the natural antetype. 

AoM, X, Muramatsu, M., Nishina, A., Sanui, K., Ogata, N. Thermosensitivities of optically active hydrogels constructed with N-(L)-(l-hydroxymethyl)propylmethacrylamide. Macromol. Biosci. 4, 943-949 (2004)... 

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