Digital Biosensing by Foundry-Fabricated Graphene Sensors.

The prevailing philosophy in biological testing has been to focus on simple tests with easy to interpret information such as ELISA or lateral flow assays. At the same time, there has been a decades long understanding in device physics and nanotechnology that electrical approaches have the potential to drastically improve the quality, speed, and cost of biological testing provided that computational resources are available to analyze the resulting complex data. This concept can be conceived of as "the internet of biology" in the same way miniaturized electronic sensors have enabled "the internet of things.

Novel graphene-based biosensor for early detection of Zika virus infection.

We have developed a cost-effective and portable graphene-enabled biosensor to detect Zika virus with a highly specific immobilized monoclonal antibody. Field Effect Biosensing (FEB) with monoclonal antibodies covalently linked to graphene enables real-time, quantitative detection of native Zika viral (ZIKV) antigens. The percent change in capacitance in response to doses of antigen (ZIKV NS1) coincides with levels of clinical significance with detection of antigen in buffer at concentrations as low as 450pM.

Dual-mode operation of 2D material-base hot electron transistors.

Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (VCB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.

High-Current Gain Two-Dimensional MoS₂-Base Hot-Electron Transistors.

The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain.

Characterization of a computationally designed water-soluble human μ-opioid receptor variant using available structural information.

Background: The recent X-ray crystal structure of the murine μ-opioid receptor (MUR) allowed the authors to reengineer a previously designed water-soluble variant of the transmembrane portion of the human MUR (wsMUR-TM).

Methods: The new variant of water-soluble MUR (wsMUR-TM_v2) was engineered based on the murine MUR crystal structure. This novel variant was expressed in Escherichia coli and purified.

Scalable production of highly sensitive nanosensors based on graphene functionalized with a designed G protein-coupled receptor.

We have developed a novel, all-electronic biosensor for opioids that consists of an engineered μ-opioid receptor protein, with high binding affinity for opioids, chemically bonded to a graphene field-effect transistor to read out ligand binding. A variant of the receptor protein that provided chemical recognition was computationally redesigned to enhance its solubility and stability in an aqueous environment. A shadow mask process was developed to fabricate arrays of hundreds of graphene transistors with average mobility of ∼1500 cm(2) V(-1) s(-1) and yield exceeding 98%.

Continuous growth of hexagonal graphene and boron nitride in-plane heterostructures by atmospheric pressure chemical vapor deposition.

Graphene-boron nitride monolayer heterostructures contain adjacent electrically active and insulating regions in a continuous, single-atom thick layer. To date structures were grown at low pressure, resulting in irregular shapes and edge direction, so studies of the graphene-boron nitride interface were restricted to the microscopy of nanodomains. Here we report templated growth of single crystalline hexagonal boron nitride directly from the oriented edge of hexagonal graphene flakes by atmospheric pressure chemical vapor deposition, and physical property measurements that inform the design of in-plane hybrid electronics.

Detecting Lyme disease using antibody-functionalized single-walled carbon nanotube transistors.

We examined the potential of antibody-functionalized single-walled carbon nanotube (SWNT) field-effect transistors (FETs) to use as a fast and accurate sensor for a Lyme disease antigen. Biosensors were fabricated on oxidized silicon wafers using chemical vapor deposition grown carbon nanotubes that were functionalized using diazonium salts. Attachment of Borrelia burgdorferi (Lyme) flagellar antibodies to the nanotubes was verified by atomic force microscopy and electronic measurements.

Differentiation of complex vapor mixtures using versatile DNA-carbon nanotube chemical sensor arrays.

Vapor sensors based on functionalized carbon nanotubes (NTs) have shown great promise, with high sensitivity conferred by the reduced dimensionality and exceptional electronic properties of the NT. Critical challenges in the development of NT-based sensor arrays for chemical detection include the demonstration of reproducible fabrication methods and functionalization schemes that provide high chemical diversity to the resulting sensors. Here, we outline a scalable approach to fabricating arrays of vapor sensors consisting of NT field effect transistors functionalized with single-stranded DNA (DNA-NT).

Toward quantifying the electrostatic transduction mechanism in carbon nanotube molecular sensors.

Despite the great promise of carbon nanotube field-effect transistors (CNT FETs) for applications in chemical and biochemical detection, a quantitative understanding of sensor responses is lacking. To explore the role of electrostatics in sensor transduction, experiments were conducted with a set of highly similar compounds designed to adsorb onto the CNT FET via a pyrene linker group and take on a set of known charge states under ambient conditions. Acidic and basic species were observed to induce threshold voltage shifts of opposite sign, consistent with gating of the CNT FET by local charges due to protonation or deprotonation of the pyrene compounds by interfacial water.

Hybrids of a genetically engineered antibody and a carbon nanotube transistor for detection of prostate cancer biomarkers.

We developed a novel detection method for osteopontin (OPN), a new biomarker for prostate cancer, by attaching a genetically engineered single-chain variable fragment (scFv) protein with high binding affinity for OPN to a carbon nanotube field-effect transistor (NT-FET). Chemical functionalization using diazonium salts is used to covalently attach scFv to NT-FETs, as confirmed by atomic force microscopy, while preserving the activity of the biological binding site for OPN. Electron transport measurements indicate that functionalized NT-FET may be used to detect the binding of OPN to the complementary scFv protein.

Biomimetic chemical sensors using nanoelectronic readout of olfactory receptor proteins.

We have designed and implemented a practical nanoelectronic interface to G-protein coupled receptors (GPCRs), a large family of membrane proteins whose roles in the detection of molecules outside eukaryotic cells make them important pharmaceutical targets. Specifically, we have coupled olfactory receptor proteins (ORs) with carbon nanotube transistors. The resulting devices transduce signals associated with odorant binding to ORs in the gas phase under ambient conditions and show responses that are in excellent agreement with results from established assays for OR-ligand binding.