Fundamentals of Biosensing: Aspects of Graphene For Biosensing

Biosensors: Biosensors are analytical devices that combine a biological component with a physicochemical detector to detect the presence of specific biological molecules or compounds. The biological component, often referred to as a bioreceptor, interacts with the target analyte, and the resulting signals are transduced into a measurable output by the detector.

Classification of Biosensors:

Types of Biosensors:

1. Enzyme-Based Biosensors: Use enzymes as bioreceptors, and the reaction between the enzyme and the substrate generates a measurable signal.
2. Immunosensors: Rely on the specific binding between antibodies and antigens for detection.
3. DNA Biosensors: Utilize the specific binding of DNA strands for the detection of complementary DNA sequences or other targets.
4. Microbial Biosensors: Employ whole microbial cells as bioreceptors, which respond to changes in their environment.
5. Optical Biosensors: Measure changes in light properties, such as fluorescence or absorbance, during a biochemical reaction.

How Biosensors Work:

1. Recognition: The bioreceptor selectively binds to the target analyte.
2. Transduction: The binding event generates a measurable signal, which is transduced into a readable form by the detector.
3. Signal Processing: The output signal is processed to obtain quantitative information about the analyte concentration.

Graphene-Based Biosensors: Graphene, a single layer of carbon atoms arranged in a hexagonal lattice, has unique properties that make it an excellent material for biosensors. The basic framework of a graphene-based biosensor includes:

1. Graphene Sheets: The sensing element, where the interaction between the target analyte and the graphene surface occurs.
2. Bioreceptor: This could be enzymes, antibodies, or other biomolecules, immobilized on the graphene surface, facilitating selective binding with the target analyte.
3. Transducer: The transduction mechanism converts the binding event into a measurable signal. In graphene-based biosensors, this could involve changes in electrical conductivity, impedance, or other electronic properties of graphene.
4. Substrate and Support: The graphene layer is often supported on a substrate, and the entire biosensor may be incorporated into a larger device.

Applications: Graphene-based biosensors find applications in various fields, including:

1. Medical Diagnostics: Detection of biomarkers for diseases such as cancer, diabetes, and infectious diseases.
2. Environmental Monitoring: Detection of pollutants, toxins, and pathogens in air, water, and soil.
3. Food Safety: Identification of contaminants and pathogens in food.
4. Biotechnology: Monitoring of biomolecular interactions and processes in research and development.
5. Wearable Health Devices: Integration into wearable devices for continuous health monitoring.

Graphene's unique properties, such as high surface area, excellent electrical conductivity, and biocompatibility, make it a promising material for enhancing the sensitivity and performance of biosensors.

Reference Papers:
1] Fundamental aspects of graphene and its biosensing applications