**4. Applications of biosensors**

Biosensors find various applications, limited only by the creator´s imagination. Since they can be constructed on unlimited configurations, based on the most diverse detection and recognition methods, employing a whole world of polymeric materials, biological elements, luminescent organic and inorganic molecules, in film form or solution, their application can be as numerous as the elements combinations on their construction.Some of them can be numbered:


**•** Good fabrication practices: nanobiosensors in the strategic steps of a product fabrication are able to detect minimum defects that could lead to the final product mischaracterization.

**4. Applications of biosensors**

130 State of the Art in Biosensors - General Aspects

numbered:

processes.

Biosensors find various applications, limited only by the creator´s imagination. Since they can be constructed on unlimited configurations, based on the most diverse detection and recognition methods, employing a whole world of polymeric materials, biological elements, luminescent organic and inorganic molecules, in film form or solution, their application can be as numerous as the elements combinations on their construction.Some of them can be

**•** Medicine development: for example, cellular biosensors are engineered to optically report specific biological activity. Since they employ living cells in their construction, they can be used to form a "data basis"of cell behaviour when in the presence of several actives,

**•** Drug Abuse or addiction: detection (and quantification) at nanoscale are possible due to the recent biosensors development. This feature is essential in the determination of the limits at which a person can be susceptible to addiction reactions. In this way, biosensor can limit whether a drug can be used in therapeutics, avoiding the addiction. Further‐ more, DNA biosensors act as potential detection devices for investigation of DNA–drug

**•** Clinical diagnostics: this must be the most moving topic for the biosensors development. They are capable of detecting single-nucleotide polymorphisms, which are caused by gene mutations. Faster detection methods are developed every day, aiming the early de‐ tection of breast cancer, prostate cancer, AIDS, genetic diseases, bacterial and viral infec‐ tions. Although clinically relevant point mutations are detected by piezoelectrical biosensors, optical biosensors also had a large contribution, especially the FRET-based bi‐ osensors, which are able to identify minor changes related to these mutations and permit the construction of nanodevices, a feature that has been attractive due to the possibilities

**•** Genome analysis: biosensors are able to inform about the interaction nature between pro‐ teins, peptides and DNA sequences present in the gene and identify it.They can also be

**•** Food Quality control: Toxins, microbes, bacteria, fungal contamination are all detectable by optical biosensors, as presented in former sections. In this way, they provide a mecha‐ nism of controlling the quality of food and industrial processes involved, contributing with the industrial development of preventing processes. Biosensors are also useful in monitoring fermentation processes, being applied on the food and beverage fabrication

**•** Industrial microbiology monitoring: these analyses are indispensible in cosmetic and pharmaceutical industries, among others. By using biosensors, they can be accomplished

used in genetic-engineered products proposaland in newdrugs development.

in real time, avoiding product contamination and possible destruction.

interactions, which can be used to elucidate the addiction mechanisms.

which can be used for design new drugs and medicines.

offered by the nanoscaled biosensors perspective.


showed by Guiseppi-Elie, [70] when polymers such as polypyrrole and polyaniline are combined to hydrogels, they generate bioactive polymers that act as bioreceptor hosting membranes of enzyme-based implantable biosensors.

**•** Aging research: optical biosensors based in fluorescence and bioluminescence emissions are proposed as devices for monitoring certain hormones dosage in the living body, as well as the release and the action of drugs administrated via dietary paths in these hormone levels. [71] The proposal is that an implantable biosensor could, in periods of days or even in the lifespan of an individual, inform about hormone fluctuations and valuable insights into the mode of action of the intervention could result from this monitoring. It is well known that in dietary restriction and other interventions, hormones such as insulin show profound changes. To be able to continuously monitor blood levels of these hormones, drugs or other factors by less invasive methods, could allow, for example, the adjustment of the hormone levels, retarding aging processes and preventing aging diseases.
