Introduction
A biosensor is an electronic device mostly used in surgical hospitals and laboratory by analytical chemist to detect, using a specific transducer, a biomolecule –related species or elements such as enzymes, antibodies, DNA, RNA and cells. The transducer produces a signal from the sample under investigation (Alwarappan, 2018, p. 248). These biological signals that can be detected by the bio receptors are usually physically, chemically, optically, thermally or electrochemically transduced into observable data that are then analyzed quantitatively. There has been a great need for the development of an efficient system to try and replace the older biosensor systems in data collection and data analysis (Gürel & Salmankurt, 2016, p. 3). Science as Human Endeavour (SHE) is the use of biological development and technology to help improve the society by providing solutions to their problems which is well illustrated in this report .These SHE concepts in the use of graphene as biosensor include improvement on drug delivery for patients, detection and diagnosis of biomolecules, food safety, better data collection and data analysis. The biosensor that has been in the use for decades now has however not been very effective and efficient to achieve all these improvements needed. The biosensor first needed labelling process in the preparation, it had low selectivity and specificity power to the biomolecule elements which are the key features for a better biosensor system (Knopf, 2017, p. 199).For all these weaknesses realized, the use of graphene label-free method was incorporated. This technique uses molecular, physical, mechanical, electrical and optical properties in monitoring the binding activities. Additionally, it provides real time trace in the bimolecular events giving instant information on the target species under study (Lawal, 2018, p. 150). The use of graphene as biosensor has improved a lot in the electronic and sensor communities due to its outstanding physical and electronic properties discussed below.
Main Body
Graphene is a carbon compound, made up of carbon atoms which are arranged and bonded together forming a hexagonal pattern. It is very thin and can exist as double layer or just a single layer – a property that makes it be considered as a two dimensional material. It is one of the strongest, lightest and transparent materials (Ohno, Maehashi, & Matsumoto, 2015, p. 95). Graphene cannot be used in its natural form in the bio sensing system but in other forms such as GQDs – Graphene –based Quantum Dots, RGO – Reduced Graphene Oxide and GO -Graphene Oxide which is considered cheaper and easier to fabricate (Sengupta & Hussain, 2019, p. 328).
Moreover its admirable properties in the fabrication process, surface chemistry as well as in photo luminescent makes graphene an essential player in the integration of biosensors for both medical and biological applications. Graphene oxide for example is a derivative of graphene, formed by oxidation of natural graphite using strong oxidants such as KMn04, and strong acids such as concentrated sulfuric acid and nitric acid. It is therefore used as a biosensor due to its outstanding physical and chemical properties (Zan, 2018, p. 10).
These graphene based –biosensors are prepared and synthesized chemically to be used as bio sensor. Graphene, as mentioned earlier, is chemically synthesized by the oxidation of pure graphite using strong oxidant such nitric acid and sulfuric acid to produce graphene oxide. Reduced graphene oxide on the other hand is produced by exfoliation of the graphene solution through mechanical or ultrasonic stirring giving (RGO) as the end product. Finally for the graphene –based quantum dots, the carbon dots of different pigment are selected and irradiated to give rise to graphene –based quantum dots (Zhou et al., 2019, p. 11).The whole process of chemical synthesis of the graphene –based sensor materials is systematically shown in figure 2 below.
The application of the graphene – based materials in the bio sensing system takes place in two broad ways .One involves the charge –biomolecule interacting at the π-π bonds between the charge exchange and the electrostatic forces causing variations that are electrical in nature at the surface of the graphene based sensors .The other way involves chemical functionalization, use of disorder and defects to immobilize on the surfaces of the sensors (Zan, 2018, p. 10).
Graphene, because of its charges which are highly mobile, possess admirable electronic properties. Engineers use it as receptor for targeting biomolecule elements due to its wide surface area hence ability to functionalize on its surface (Ohno, Maehashi, & Matsumoto, 2015, p. 98). It offers a large surface area at the molecular level in the bio-sensing process. This increases the number of active sites which it provides for the interactions between the charges and the biomolecules. This overally leads to sensing enhancement thus improving the selectivity of the biosensor as shown in the figure 3 below.
In practice, graphene- based nanostructures have been on trial and literature review which tends to illustrate the benefit of its high selectivity in bio sensing process. Non-porous graphene, for example, is a simplest form of graphene based membrane. It’s a flexible, mechanically and chemically stable single layer membrane that is suitable for separation process. Graphene has got high selectivity power too (Knopf, 2017, p. 199).The outstanding improvements made on the current biosensors such, improved drug delivery, safer food, improvement in detection systems, diagnosis of diseases at very early stage which has positively improve the life of the society by providing solutions to their cancer related problems through early detection and diagnosis of cancer at a very early stage .Graphene therefore is the key SHE concept for the next generation.
When graphene – based biosensors are fully implemented, a greater improvement in the health sector will be realized. Solutions will be provided to the deadly incurable diseases affecting the society such as cancer. It will be very economical, in terms of the raw material for making the biosensors and cost of the graphene materials. Moreover, incorporation of the graphene based membrane will reduce the energy consumption rate to a greater percentage as it uses little amount electrical energy (Gürel & Salmankurt, 2016, p. 6). A lot of drugs will be produced and supplied. Graphene has a zero intrinsic defect translating to almost zero leakages a cross the membrane. Its less toxicity makes it environmentally friendly.
Limitations
Although graphene is an excellent choice as SHE concept as biosensor material its platform should be improved to avoid adsorption of unwanted materials rather than thee target.
Conclusion
In conclusion, with the invention of graphene as a potential sieve to help solve the problems such as low selectivity and specificity realized in the previous systems, drug supply will be improved and most importantly the solution to cancer menace will be found through early cancer detection system. These problems will be fully addressed at a low cost and with great conservations to the environment and the entire ecosystem since the use of graphene based membrane has no effect to the environment.
Graphene -being durable, chemically and mechanically stable, resistant to chemicals, highly selective and with its 2D structure- finds several applications in the medical field as the best sensor. In addition to this, it opens room for further developments to improve biosensors. Therefore, graphene is the best SHE application for the next generation.
References
Alwarappan, S. (2018). Graphene-Based Biosensors and Gas Sensors. Graphene, 248-277.
Gürel, H. H., & Salmankurt, B. (2016). Graphene based biosensors.
Knopf, G. K. (2017). Biosensor Design and Fabrication. Smart Biosensor Technology, 199-199.
Lawal, A. T. (2018). Progress in utilisation of graphene for electrochemical biosensors. Biosensors and Bioelectronics, 106, 149-178.
Ohno, Y., Maehashi, K., & Matsumoto, K. (2015). Graphene Biosensor. Frontiers of Graphene and Carbon Nanotubes, 91-103.
Sengupta, J., & Hussain, C. M. (2019). Graphene and its derivatives for Analytical Lab on Chip platforms. TrAC Trends in Analytical Chemistry, 114, 326-337.
Zan, X. (2018). Flexible electrochemical biosensors based on interfacially assembled metal nanocrystals and graphene paper.
Zhou, L., Wang, K., Sun, H., Zhao, S., Chen, X., Qian, D., … Zhao, J. (2019). Novel Graphene Biosensor Based on the Functionalization of Multifunctional Nano-bovine Serum Albumin for the Highly Sensitive Detection of Cancer Biomarkers. Nano-Micro Letters, 11(1), 1-13.
