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Recent innovations in nanotechnology have led to the development of novel electrochemical and optical sensors using a new class of nano polymers known as Metal-organic frameworks (MOFs) and 2-dimensional (2D) materials.
These cutting-edge materials offer significant potential for creating low-cost, point-of-care devices capable of rapidly and accurately detecting various health conditions, food quality parameters, and environmental pollutants. Such devices are poised to revolutionise the detection and screening of diseases like anaemia and cancer, as well as ensure food safety and environmental protection.
Over the past few decades, nanomaterials have played a crucial role in the advancement of sensing technologies. Among these, MOFs and 2D materials stand out due to their unique features, such as large surface area, functional versatility, and exceptional optoelectronic properties. These characteristics make them ideal candidates for developing a wide range of sensors, including disposable electrodes, optical kits, fibre optic sensors, and colourimetric strips.
Researchers from the Institute of Nano Science and Technology (INST) in Mohali, an autonomous institute under the Department of Science and Technology, have leveraged these materials to create a variety of electrochemical and optical biosensors. These sensors, based on multifunctional MOFs and 2D materials like MoS2 nanosheets and MXenes, offer enhanced sensitivity and multimodal detection capabilities, making them suitable for a broad spectrum of applications.
The integration of biorecognition molecules with MOFs and 2D materials has proven particularly effective, resulting in sensors with robust performance and high sensitivity. Published in leading scientific journals, these sensors have demonstrated the ability to detect various analytes, including harmful bacteria, aflatoxins, and heavy metals, with remarkable accuracy and reliability.
For instance, one of the developed electrochemical biosensors has shown great promise in detecting Aflatoxin B1 (AFB1), a toxic secondary metabolite commonly found in contaminated food and water. Utilising electrochemical impedance spectroscopy (EIS), this sensor, which incorporates anti-AFB1 antibodies, can detect AFB1 levels as low as 8 pg/mL.
The sensor has also exhibited excellent stability, specificity, reproducibility, and effectiveness in detecting AFB1 in spiked samples of pistachios, highlighting its potential as a critical tool for ensuring food safety.
Another significant development involves the detection of zearalenone (ZEN), a toxin found in agricultural products and animal feed that poses a global public health risk. Researchers have created a highly accurate and rapid assay that demonstrates excellent specificity and repeatability across a ZEN concentration range of 0.01–100 ng/mL, with a detection limit of just 5 pg/mL.
The sensor has also performed well in spiked samples of wheat and corn flour, achieving recovery rates between 85% and 114%, thereby offering a new, cost-effective method for ensuring food safety.
Beyond food safety, these innovative sensors are also crucial for monitoring environmental contaminants, such as heavy metals. Hexavalent chromium (Cr(VI)), a common and hazardous pollutant in the environment and agriculture, can now be detected using a biocompatible, luminescent MOF-based nanoprobe.
Functionalised with ascorbic acid (AA), this “turn-on” nanoprobe offers rapid and sensitive optical detection of Cr(VI) over a concentration range of 0.02 to 20 ng/mL, with a detection limit of 0.01 ng/mL. The nanoprobe has proven effective in real water and spiked food samples, making it a promising tool for on-field environmental monitoring.
The integration of MOFs, 2D materials, and their composites into sensor technology marks a significant advancement in the field of analytical chemistry. These materials not only offer greater sensitivity and multimodal detection capabilities but also pave the way for the development of accessible, low-cost sensors that can be deployed across various sectors, including healthcare, food safety, and environmental protection.
As research continues, these innovative sensors are expected to play a pivotal role in addressing global challenges related to health, food security, and environmental sustainability.
