A biosensor is based on the combination of biological element with a detector (transducer) to produce a measurable signal that is relative to the concentration of target.
By thermal, electrochemical, piezoelectric or optical means transducer change the signal into a quantifiable reaction for example: potential, current, temperature change, mass increase or absorption of light.
DNA biosensor
DNA biosensors is the promising technique that permits persistent, quick, delicate and particular recognition of DNA hybridization and they likewise can be reused. DNA sensors are generally found as chips, crystals and electrodes. These biosensors translate the Watson and Crick event of base pair recognition into a decipherable signal. The principle of a DNA biosensor is the hybridization between complementary strands of DNA attached on target and on transducer.
Peptide nucleic acids
Another technique is the utilization of peptide nucleic acids (PNAs) rather than DNA segments. PNA imitate DNA as the pseudo peptide chain is present in place of sugar phosphate backbone. PNA is highly stable, unaffected by cleavage enzymes therefore protected from degradation in cells. PPy (polypyrrole) is the most frequently used polymer for making DNA sensors.
Surface plasmon resonance
Surface plasmon resonance (SPR), fluorescence , interferometry or colorimetry are the techniques used in optical biosensor for detecting DNA hybridization. These techniques are also used for the identification of mutations.
Electrochemical DNA biosensor
This DNA biosensor have regularly been utilized for identifying DNA hybridization because of their increased reactivity, cheap and small size. In Quartz crystal microbalance (QCM) sensor, piezoelectric materials are used for detecting minor differences.
β-thalassemia is diagnosed by designing a DNA sensor utilizing the QCM method. Microcantilever sensors as of late have risen as an advantageous instrument to distinguish interactions between biological molecules.
Electrochemical DNA biosensor are used for the differentiation and identification of herpes simplex Type I and Type II viruses. They are also used to detect damage in the DNA. For detecting DNA hybridization nanotubes made from carbon are used.
With the fast advancement in the electrochemical biosensing technology, it very well may be visualized that DNA biosensors lacking PCR amplification will before long be available. In this way electrochemical DNA biosensors with lots of advantages can be anticipated to become progressively prevalent in the future.