Catalytic Synthesis and Characterization of Biodegradable ...

Chapter 1
PANI fibers. 169 These devices have promising biomedical applications as
electrical-responsive actuators, such as micropumps and valves for labs-on-a-chip, 170
steerable catheters for minimally invasive surgery, 171 blood vessel connectors (Figure.
1.5.19), 172 and microvalves for urinary incontinence.
Figure. 1.5.18 (A) When current is applied, the left PPy film acts as anode and swells by the
entry of the hydrated counter ions. Simultaneously, the right film acts as cathode and contracts by
the expulsion of the counter ions. These volume changes and the constant length of the
non-conducting film promote the movement of the triple layer device. (B) By changing the
direction of current the movement takes place in the opposite direction. 167
Scavenging of free radicals is a protective response in biological system, which may afford
against various diseases, such as cardio-vascular diseases and cancer. The potential role of
PANi 129 as antioxidants in rubber mixes has already been considered, and the PANi was
demonstrated to be efficient in slowing down the rate of oxidation. And recently the
electroactive polymers were also used in biological applications. 173 These polymers such as
PANi and PPy in their neutral form can eliminate 2 ~ 4 free radicals per monomer unit. The
ability of these materials to scavenge free radicals is attributed to their oxidation activity and
has no relationship with electrical stimulation. These materials have potential biomedical
applications in tissues experiencing high oxidative stress.
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