addition to this surface chemical modification; “thiol modification” on the Au electrode

surface for the formation of a poled β-PVDF film is an additional advantage to improve

the carrier injection efficiency at the metal/organic interface of the electrode devices [36].

However, thiol modified Au electrodes presented polarization of the PVDF film-based

pressure sensors performs better.

23.4 Functions and Devices in Recent Bioelectronic Application

As an advancement towards flexible and wearable bioelectronics, they also demonstrated

that molecular doping of PTh with oligoethylene glycol side chains increases its degree of

π-stacking, strongly modulates its electrical conductivity to >52 S/cm, the toughness from

0.5 to 5.1 MJ/m³, and elastic modulus from 8 to >200 MPa [37]. A new-generation

wearable, flexible, therapeutic photoelectronic dual-responsive wound dressing has been

designed from selenoviologen-appendant polythiophene containing polyacrylamide hy­

drogels. This sandwich device ensures sustained in situ reactive oxygen species (ROS)

generation in a physiological environment via six seconds short-time light irradiation

with or without wireless-controlled electrification. The derivative harnessing the high

conductivity and strong light absorption properties of PTh along with efficient ROS

generation properties of selenoviologens was immersed in polyacrylamide hydrogels.

When put directly over the bacterially infected wound, it starts generating ROS outflow

under visible light and/or electrical stimulation thereby limiting the healing time of in­

fected full-thickness wounds up to 7 days. Interestingly, this is a BlueTooth-enabled, cell

phone–controlled, free-radical generation system. The green color, upon turning the cell

phone on, indicated a ROS generation, which turned to yellow upon switching off. This

electronic switching on and off was repeatable and had optical memory too [38].

Most of the research is limited to in vitro applications of PANi-based electrodes. It is

widely being used for in-vivo applications ranging from tumor imaging and treatment,

photothermal treatment, sensors, tissue regeneration, and drug delivery. It is used in

tumor therapy as the image-guided phototherapeutic agent. Further, limited negligible

toxicity was observed in vivo implantation. In another interesting work, researchers

tagged iron-copper co-doped PANi nanoparticle as a metal dopant platform with PANi

nanoparticles and utilized the ability of Cu to undergo redox reaction with glutathione of

tumor microenvironment. This was further verified with tumor photoacoustic imaging

and in vivo photothermal therapy [39]. The bacterial microenvironment hampers the PTT

and it leads to a decreased theranostic effect of nanoparticles. Yan et al. reported the

PANi and glycol chitosan functionalized core-shell nanostructures with persistent lu­

minescent imaging and capability of pH switchable platform for in vivo mice photo­

thermal therapy [40]. Another widely explored in vivo application is based on the utility

of PANi to sense different biomolecules. Glucose biosensors based on PANi with limited

interference was fabricated with double-sided flexible electrode for continuous mon­

itoring in a rat model after 24 hours’ post-implantation [41]. Nanoporous PANi mem­

brane along with polymerized tannic acid-coated carbon fiber electrode is being used

for DA sensing in rats at medial forebrain bundle in the brain. Here, the antifouling

capability was observed over the membrane as bovine serum albumin (BSA) protein

adsorption was found to be very low and it was then able to sense DA oxidized product

on its surface with high sensitivity [42].

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Bioelectronics