the optical input to produce thermal or electrical responsiveness able to stimulate target

cells selective and systematically.

Significant examples of materials that use electromagnetic radiation of UV and in­

frared to bioelectronics application are a light-responsive glass (regio-regular poly(3-

hexylthiophene)) supported on indium tin oxide, abbreviated as ITO, which is a mix­

ture of indium oxide (In2O3) and tin oxide (SnO2), to manufacture of the mesoporous

electrodes that work in aqueous solution [37]; a bio-syncretic phototransistor con­

formed of living HEK293 cells endowed with photosensitive ion channels supported on

graphene to complete the phototransistor [38]; a composite with two types of semi­

conductors, polymer silicon nanowire (n-type) on the support of SU-8 (p-type), to

optical stimulation of cardiac cells [39]; and a metal-organic “optrode” with a Pt black

layer on a base of organic copolymer PEDOT/PSS to improve the neural monitoring

[40]. Works presented are a sample of the future of bioelectronics materials.

2.3.1.3 Materials for Drug Administration

In drug administration, the vehicle takes a relevant role in oral medication such as pills,

tablets, powders, as well as via epidermises such as gels and unguents. Even if the dosage

is the most important factor, bioavailability depends on the success of treatments and a

great percentage of bioavailability depends, subsequently, on vehicle or excipient. In fact,

among different routes of administration, topical and oral medication bring the most

diversity among new materials for excipients, such as microcapsules, hydrogels,

temperature- and pH-responsive polymers, and even nanoporous surfaces. Materials for

drug administration must reduce dosing frequency, improve therapeutic effects, and

minimize side effects. For this reason, both traditional and new materials have been

adopted by bioelectronics to create sophisticated devices worth mentioning are multipart

systems, in the sense of a large number of components. Some representative examples of

biocompatible materials for drug delivery are anti-inflammatory oral administration of

antisense oligonucleotide using a microfluidics system Konjac glucomannan and gelatin

methacryloyl [41]; a composite of microbeads with chitosan and magnetic nanoparticles

loaded with antibiotic Vancomycin [42]; a glucose monitoring device for transdermal

metformin (or chlorpropamide) delivery, the multi-component device comprises poly­

dimethylsiloxane, and sensor contains poly(3,4-ethylene dioxythiophene), among other

materials [43]; and programmable microspheres as a dexamethasone delivery system [44].

2.3.2 Biological Systems Used in Electronics Applications

Living systems have acquired the ability to synthesize materials with unique properties to

selectively and efficiently carry out biological functions. This is the case of some derived from

polyconjugates natural pigments and dyes, which show remarkable electronic properties

and are essential for processes such as photosynthesis, charge transport, and control of free

radicals. These materials are difficult to synthesize, so on some occasions, they are extracted

from their natural environment to take advantage of them in the components manufacture of

electronic devices. Furthermore, their structures may be employed as a model for the design

of synthetic materials with mimetic properties to make electronic devices that can adapt to

biological environments. Most of the essential electronic components, such as semi­

conductors and insulators, can be found in materials of natural origin [45].

Pigments, such as eumelanins, carotenoids, and indigo, are the better well-known natural

semiconductors. Eumelanins are an ununiform group of conjugated macromolecules that

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Bioelectronics