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Biasing of FET01:22

Biasing of FET

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Biasing a Junction Field Effect Transistor (JFET) is crucial for setting operational parameters and ensuring efficient functioning in electronic circuits. JFETs are characterized by using a single carrier type in N-channel or P-channel configurations, where the channel is surrounded by PN junctions. These junctions are central to the device's ability to control current flow.
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Enzyme-linked receptors are proteins that act as both receptor and enzyme, activating multiple intracellular signals. This is a large group of receptors that include the receptor tyrosine kinase (RTK) family. Many growth factors and hormones bind to and activate the RTKs.
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The use of enzymes by humans dates to 7000 BCE. Humans first used enzymes to ferment sugars and produce alcohol without knowing that this was an enzyme-catalyzed reaction. Wilhelm Kuhne coined the term 'enzyme' in 1877 from the Greek words ‘en’ meaning ‘in’ or ‘within’ and ‘zyme’ meaning ‘yeast.’
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Enzyme Multilayers on Graphene-Based FETs for Biosensing Applications.

Christina Bliem1, Esteban Piccinini2, Wolfgang Knoll1

  • 1AIT Austrian Institute of Technology GmbH, Biosensor Technologies, Vienna, Austria.

Methods in Enzymology
|September 25, 2018
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Summary

Portable electrochemical sensors using reduced graphene oxide (rGO) field-effect transistors (FETs) enable rapid, low-cost urea detection. These biosensors also quantify heavy metals by monitoring enzyme inhibition, offering versatile point-of-care diagnostics.

Keywords:
BiosensorsField-effect transistorGrapheneUrease

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Area of Science:

  • Electrochemistry
  • Materials Science
  • Biotechnology

Background:

  • Electrochemical sensors are vital for real-time analyte measurement in clinical diagnostics and food technology.
  • Point-of-care devices are crucial for bedside and online monitoring in clinical settings.
  • Urea detection is clinically significant, necessitating sensitive and reliable measurement tools.

Purpose of the Study:

  • To develop portable, low-cost electrochemical sensors for rapid and reliable urea detection.
  • To utilize the pH sensitivity of reduced graphene oxide (rGO)-based field-effect transistors (FETs) for monitoring enzymatic urea hydrolysis.
  • To enable quantification of heavy metals like Cu2+ via enzyme inhibition.

Main Methods:

  • Fabrication of rGO-based FETs for electrochemical sensing.
  • Functionalization of the sensor platform using layer-by-layer technique for enzyme immobilization.
  • Exploiting urease enzyme's selectivity and rGO-FET sensitivity for urea detection.
  • Utilizing urease inhibition by heavy metals for Cu2+ quantification.

Main Results:

  • Developed urea biosensors with a limit of detection (LOD) of 1μM and a linear range up to 1mM.
  • Achieved quantification of Cu2+ with a LOD down to 10nM.
  • Demonstrated preservation of enzyme integrity and rGO surface during functionalization.
  • Showcased the potential for label-free detection of various clinically relevant analytes.

Conclusions:

  • Portable, low-cost rGO-FET based biosensors offer sensitive and selective detection of urea.
  • These versatile platforms can be adapted for detecting heavy metals through enzyme inhibition.
  • The developed technology holds significant promise for advancing point-of-care diagnostics and real-time monitoring.