Enantioselective Detection of Gaseous Odorants with Peptide-Graphene Sensors Operating in Humid Environments.

Replicating the sense of smell presents an ongoing challenge in the development of biomimetic devices. Olfactory receptors exhibit remarkable discriminatory abilities, including the enantioselective detection of individual odorant molecules. Graphene has emerged as a promising material for biomimetic electronic devices due to its unique electrical properties and exceptional sensitivity.

Volatile Organic Compound Detection by Graphene Field-Effect Transistors Functionalized with Fly Olfactory Receptor Mimetic Peptides.

An olfactory receptor mimetic peptide-modified graphene field-effect transistor (gFET) is a promising solution to overcome the principal challenge of low specificity graphene-based sensors for volatile organic compound (VOC) sensing. Herein, peptides mimicking a fruit fly olfactory receptor, OR19a, were designed by a high-throughput analysis method that combines a peptide array and gas chromatography for the sensitive and selective gFET detection of the signature citrus VOC, limonene. The peptide probe was bifunctionalized via linkage of a graphene-binding peptide to facilitate one-step self-assembly on the sensor surface.

Designable peptides on graphene field-effect transistors for selective detection of odor molecules.

Gas sensing based on graphene field-effect transistors (GFETs) has gained broad interest due to their high sensitivity. Further progress in gas sensing with GFETs requires to detection of various odor molecules for applications in the environmental monitoring, healthcare, food, and cosmetic industries. To develop the ubiquitous odor-sensing system, establishing an artificial sense of smell with electronic devices by mimicking olfactory receptors will be key.

Discovery of a Highly Specific Anti-methotrexate (MTX) DNA Aptamer for Antibody-Independent MTX Detection.

High-dose methotrexate (MTX) therapy is used to treat a wide variety of cancers such as leukemia and lymphoma, while the resulting high blood concentration of MTX faces a risk of life-threatening side effects, so it is essential to monitor the concentration carefully. Currently, the MTX concentration is measured using antibody-based kits in a clinical setting; however, the heterogeneity and batch-to-batch variation of antibodies potentially compromise the detection limit. Here, we developed MTX detection systems with chemically synthesizable homogeneous oligonucleotides.

Molecular Interactions between an Enzyme and Its Inhibitor for Selective Detection of Limonene.

Researchers widely apply enzyme inhibition to chemicals such as pesticides, nerve gases, and anti-Alzheimer's drugs. However, application of enzyme inhibition to odorant sensors is less common because the corresponding reaction mechanisms have not yet been clarified in detail. In this study, we propose a new strategy for highly selective detection of odorant molecules by using an inhibitor-specific enzyme.

Wafer-scalable chemical modification of amino groups on graphene biosensors.

Graphene's remarkable attributes make it suitable for application to biosensors for biomolecular recognition. Specific and precise target detection is realized by designing robust methods for immobilization of probe molecules, such as oligonucleotides, antibodies, receptors, and sugar chains, to a device surface. In this research, we developed a chemical modification method with a plasma treatment of amino groups on natural defects of graphene, which is compatible with a wafer-scalable semiconductor process, to prevent deterioration of the carrier mobility.

Ionic Liquids with Wafer-Scalable Graphene Sensors for Biological Detection.

Ionic liquids, known as non-volatile solvents, have potential for realizing microanalysis with a minute quantity of sample. Here we report the measurement of the Id-Vg characteristics during the enzymatic catalytic reactions and streptavidin-biotin binding in ionic liquids by using the graphene FET sensors we fabricated, and successfully monitored the biological reactions in much smaller amount of solvents. These findings suggest the possibility of ionic liquids for application in bio-microanalysis with high sensitivity.