What exactly is a Biosensor?
Sensing biomolecules is the main reason of the existance of biosensors, they include a biorecognition element, a transducer, and electronics circuits to generate a readable output.
 |
| Schematic of a Biosensor, a simplified one here. From top to bottom: The analytes (the biomolecule that we are interested in), are plenty and differ in shape and size, from circles to crazy star shaped things. Take a closer look and you will find only one element that fits correctly (also has the same color), to the biorecognition element. The transducer here is simplified as a the little yellow box, and a line to the read out system is coming from it. This in real life is often more complicated, and the readout system can be sometimes without the use of any electronic circuitry. |
Biomolecules are large biological constructions. These large constructions are made up of amino acids, their function range from (some examples):
- Being part of the outer layer structure of cells, some cells can have a lipid layer structure that will impede water from entering the cell, in viruses for example, their outer layer keeps their genetic information protected, and help them infect other cells or bacteria.
- They can transport other biomolecules, some proteins(others do different things), can take peptides and transport them inside the cell.
- Some can even detect viruses or bacteria, antibodies are glycoproteins made up by B-cells, capable of detecting harmful organisms, there can be an infinite number of different antibodies each one detecting a different antigen.
- They can also gather biological information, DNA keeps all the genetic information stored, and it only needs some billions aminoacids.
The biorecognition element is most of the time, a biomolecule (an antibody, a SCFV, an Aptamer or an enzyme), that will only detect the analyte, for example: The biorecognition element for detecting PSA is anti-PSA, another example is: Glucose oxidase (an enzyme), that will only recognize Glucose.
Learn more about aminoacids and the different biomolecules that they can form
What can Nanotechnology do for our biosensors?
Nanotechnology can improve most biosensors by increasing the contact area (the surface-area to volume ratio), depending of the material used, some nanostructures can also enhance their electrocatalytical effects.
Learn more about Nanostructures.
How can Nanotechnology is integrated into biosensors?
Chemically modifying the surface of the substrates can introduce the correct linkers for the nanostructures to get immobilized. This depend on the material, and crystal orientation.
Usually all biomolecules are either amino or carboxyl group terminated
What are the future trends in Biosensors?
Right now, most biosensors detect their analytes by detecting them outside the human body. This can pose many problems as the body also recognizes the sensor as foreign and the immune system attacks it, also, some of the materials used are often toxic to different organisms.
Different trends suggest the need of an implantable biosensor, with the following enhancements:
- Self sufficient (wise energy harvesting)
- Able to communicate with the outside (for monitoring purposes)
- Bio-Compatible (non toxic and immuno friendly)
- Stable, cheap, easy to produce (environmentally amicable)
In the University of South Florida, many different biosensors have been created.
A common example, integrating Nanotechnology in biosensors in the USF.
Special thanks for the fulfillment of this work goes to the Bio-MEMS group in USF. Kind acknowledgments goes to Dr. Sunil Kumar Arya for the chemical teaching, Eric Huey and Dr. Subramaniam Krishnan for growing the Silicon Oxide Nanowires.
Something to read about:
[1] Biosensor Recognition Elements, Chambers J. P, Arulanandam B. P, Matta, L. L, Weis A, Valdes J. J, Current issues in Molecular Biology, 10, 1-12(2006)
[2] Aptamer-based biosensors Song S, Wang L, Li J, Zhao J, Fan C, Trends in Analytical Chemistry, 27, 108-117(2008)
[3] Antibody phage display technology and its applications, Hoogenboom H. R, de Bruïne A. P, Hufton S. E, Hoet R. M, Arends J. W, Roovers R. C, Immunotechnology, 4, 1-20(1998)
[4] Selecting and screening recombinant antibody libraries, Hoogenboom H. R, Nature biotechnology, 23, 1105-1116(2005)
[5] Manipulating redox systems: Application to nanotechnology, Gilardi G, Fantuzzi A, Trends in Biotechnology, 19, 468-476(2001)
[6] Surface modification in microsystems and nanosystems, Prakash S, Karacor M. B, Banerjee S, Surface science reports, 64, 233-254(2009)
[7] Electrochemical Glucose Biosensors, Wang J, Chem. Rev, 108, 814-825(2008)
Note: All schematics were drawn by the author
