Biosensing is an innovative approach for real-time health monitoring and point-of-care diagnostics through direct human-machine interaction. To explore the potential of this field, an article published in Materials Letters demonstrated the application of nano-biodetection systems based on 2D graphene.
To study: Emergence of an ultra-efficient and ultra-fast 2D graphene nano-biodetection system. Image Credit: Marco de Benedictis / Shutterstock.com
2D layered nanomaterials have become attractive targets for the field of wearable technology. These layered materials have a strong covalent bond within the individual layers. The weak interactions between the layers favor the exfoliation of the material. 2D layered nanomaterials have been identified as key materials for areas such as bioimaging, biodetection, nanomedicine, chemical detection and electrocatalysis.
The properties of biosensors such as response time, electrical sensing and sensitivity are enhanced by the inclusion of 2D layered nanomaterials. Promising transduction elements that have been identified to improve the selectivity of devices with low detection limits include MXenes, 2D graphite and graphene-like materials, and molybdenum disulfide. This property facilitates the early diagnosis of disease biomarkers and, as such, is in high demand by the biosensor industry.
Additionally, these materials exhibit improved thermal, electroactive and mechanical properties, making them ideal for nanosystems / advanced capabilities. The recent Covid-19 pandemic has highlighted the need for point-of-care and diagnostic biosensing devices with advanced properties and features that facilitate early detection of infections. Fast, selective, sensitive and portable smart biosensors are in demand by the healthcare industry.
Use of 2D graphene for nanosensors
Recently, progress in the field of biodetection has led to the development of several devices, in particular microelectrochemical systems, field effect transistors, electrochemical and colorimetric biosensors. Designs using different advanced materials have been explored in numerous research studies.
2D graphene has become a pioneer in the search for materials that can be used for smart biosensors. It is easily synthesized into many structures such as nanosheets, tapes, foams and films is cost effective, scalable, and has superior properties such as high ion mobility and mechanical strength. In addition, it has a large area and high thermal conductivity.
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Graphene-based sensors have good mechanical flexibility and are ultra-thin, making them ideal for portable applications where the device deals with mechanical deformation. These sensors can receive high quality signals without disturbance, contamination or discomfort, and they can maintain close contact with the body. They can be used for both invasive and non-invasive applications.
The synthesis of 2D graphene can be achieved via several methods, including chemical vapor deposition and ball milling. The deposition of graphene on sensors is accomplished by techniques such as drop molding, spin coating and dip coating. Coating and casting methods are the most widely used. Nanocomposites of graphene and other carbon-based materials using polymers, metals, metal oxides and other molecules are a stimulating and emerging area of materials research and biomedical science.
The first graphene-based biosensor was developed in 2007. This innovative sensor was used to successfully detect NO2. Since then, 2D graphene biosensors have been developed to detect a multitude of gases and volatile compounds.
A recent advance in graphene nanosensors has been their use to detect SARS-CoV-2 in patients. The system developed was an antibody-coated 2D graphene field-effect transistor, and it was able to detect the virus spike protein from nasal swabs with a high degree of accuracy. The limit of detection was 1 fg / ml concentrations in buffer liquid and 100 fg / ml in clinical transport medium.
Another recent advance has been the development of a nanosensor using a DIDC detection chip. The sensitivity and selectivity of the system have been improved by the 2D graphene material. The device had a short response time and a low detection limit. However, the device had a complex structure and several key areas for improvement were identified.
The future of portable graphene nanobiosensors
The study published in Materials Letters provided a comparative study for layered nanocomposite biosensors to improve knowledge gaps in the field. The team identified that portable graphene-based biosensors would offer significant benefits for early biomarker detection and point-of-care diagnostics.
However, a key challenge identified was that research should not only aim to improve the performance of nanosensors, but also to develop unified portable systems that can perform as well as current devices. Recently, a significant breakthrough has been made by Gao et al. who developed a portable and flexible 2D graphene-scale biosensor that can examine lactate, temperature and glucose for real-time humidity analysis.
The team concluded that 2D graphene nanobiodetection devices offer advantages for future point-of-service applications due to their electrical and mechanical properties, as well as portability, scalability, cost-effectiveness, ease of manufacture and advanced engineering techniques.
Rawat, P et al. (2021) Emergence of an ultra-efficient and ultra-fast 2D graphene nano-biodetection system [online] Materials Letters 131241 | sciencedirect.com. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0167577X2101939X