Difference between revisions of "AixSense 2019"

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== AixSense 2019 ==
 
== AixSense 2019 ==
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== Method ==
 
== Method ==
 +
Electro-Impedance Spectroscopy (EIS). Anti-Adalimumab (Anti-AM) is used to immobilize the surface of the graphene based transducers where the analyte then flows over. Changes in the impedance before and after the flow are measured using an Impedance Analyzer. Adalimumab specific transducers will then show increase of impedance against different concentrations of Adalimumab molecular binding within clinical ranges (0.1μg/ml to 10 μg/ml).
 +
 +
==Molecular Recognition ==
  
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A system consisting of graphene oxide (GO) coated screen-printed electrode (SPE) modified with a capture antibody specific for Humiran is used. Surface modification, as well as antibody binding events, lead to changes in the electrochemical properties of the electrode surface which can be used to determine the analyte concentration.
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The molecules used in the biosensor are the Anti-Adalimumab Type 1 Antibody, the TNF-α - Tumour Necrosis Factor alpha (TNF-α), and silver Nanoparticles.  
  
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==Molecular Recognition ==
+
The Type 1 anti-adalimumab (Anti-AM) antibodies inhibit the binding of the drug adalimumab(AM) to its target, TNF-α, and therefore detect the free drug. This protein was used to bio-immobilize the Graphene based transducers.
  
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The graphene oxide covered working electrode is activated using EDC/NHS chemistry. Unreacted active sites are then quenched with the addition of 4 μl of 0.5% BSA. An analyte sample is then added onto the electrode surface and allowed to incubate for 30 minutes. The electrode is then rinsed with PBS solution. Finally, a redox couple such as potassium ferrocyanide/ferricyanide is applied onto the electrode to enable a proper measurement.
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The tumour Necrosis Factor alpha (TNF-α), is an inflammatory cytokine produced by
 +
macrophages/monocytes during acute inflammation and is responsible for a diverse range
 +
of signalling events within cells, leading to necrosis or apoptosis.The
 +
affinity of TNF-α to adalimumab was taken advantage of by tagging it with optically active silver nanoparticles and then flowing it over the Graphene based transducers containing the Anti-AM complex.
  
 +
The Silver Nanoparticles (Ag NPs) were used as the optical tags with receptor
 +
proteins specific to AM.
  
 
== Physical Transduction ==
 
== Physical Transduction ==
 +
The graphene based transducers allows for electrical readouts for the specific binding of AM and the optical readout for the recording of optical emissions from the labelled secondary antibodies of TNF- alpha which specifically binds to the Anti-AM AM complex bio that are immobilized on the Graphene transducers. Moreover, dedicated microfluidic circuits increasing the local concentrations of the analytes at the transducer enhance the optical signal and improve the bioassay readout.
 +
  
−
Differential pulse voltammetry (DPV) is used for the readout and an
+
An optical based detection has also been installed as a parallel detection platform for increased accuracy of the results.  
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equimolar mixture of the potassium ferricyanide/ferrocyanide redox couple acts as a probe for the signal generation.  
+
For the optical detection, Microscale Thermophoresis (MST) is utilised.  
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The current is measured as a function of time and potential between the indicator and reference electrode. As the potential increases  towards the redox potential of the probe, it starts undergoing redox and a current up to a peak value is produced. The current is subsequently brought into a diffusion-controlled state and as a result, the total current response takes its shape as a peak. The immunocomplex restricts the surface availability for the redox probe, which lowers the number of redox events and therefore reduces the current signal.
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Directed movement of particles in a microscopic temperature gradient leads to accumulation of analyte molecules and thus leads to an enhanced sensor signal due to the increased local fluorescence.  
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Measurements are performed after the immobilization procedure to achieve a baseline which is compared to the signal obtained after analyte incubation on the electrode.
 
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Samples with known concentrations of the analyte are used to prepare a calibration curve which can then be used to quantify the amount of the analyte in an unknown sample.
 
  
 
== Cartridge ==
 
== Cartridge ==
  
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The screen-printed electrodes are disposable. Incubation of the sample on the electrode is
+
For measuring the concentration of AM, blood samples containing the drug are injected into
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performed outside of the potentiostat. The sample is applied by the technician on the tabletop after which the sample is incubated in a sealed container in 4 degree celsius. After sample incubation, the electrode is manually washed off with PBS into a waste container. The electrode is inserted into the adapter on the potentiostat and quantification can be performed. After running the measurement, the electrode can
+
the disposable chips (having graphene electrodes functionalized with Anti-AM) and then the
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simply be discarded into biological waste. The electrode chips could potentially be regenerated and therefore, reused.
+
optically labelled TNFα is made to flow through it. Once the fluid is stationary, the electrical and optical measurements are made in the respective platforms and the chips are disposed after each measurement.
  
 
== Reader Instrument ==
 
== Reader Instrument ==
  
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The size of the biosensor is 95mmx75mmx75mm. It consists of a sealed
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The entire setup is 20x20x40 cm^3 in dimensions.  
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potentiostat and an electrode chip. The only handling required by the user is related to the electrode chip.
 
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The output of the measurement can be viewed and analyzed with the PSTrace software (PalmSens).
 
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The data from known concentrations of the analyte can be used to externally produce a calibration curve which can then be used to infer the analyte concentrations of an unknown sample based on peak differences.
 
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Additionally, an app has been developed which can measure the raw data in real-time during the measurement using Bluetooth. The data obtained can be automatically converted to the concentration of adalimumab in blood. The app provides graphs on current and past measurements, making the interpretation of the optimal drug usage straightforward to assess.
 
  
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== Prizes==
 
  
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None
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The user administers the blood sample and TNFα in the chip and put the chip in the measurement system. The electrical readout is then measured using an Impedance Analyzer, where the impedance change obtained at a particular frequency will indicate the concentrations. The optical readout is an image of the fluorescence captured by the camera.
 +
Furthermore, there is an integrated optoelectronic read out platform in order to improve the accuracy and speed of measurement.

Latest revision as of 16:35, 19 August 2020

Logo of AixSense

AixSense 2019

AixSense is a team from the RWTH Aachen University competing in the SensUs 2019 event. For SensUs 2019, AixSense investigated the possibilities for creating a biosensor which is able to measure the concentration of Adalimumab. The full TRD can be found [ via this link]

Method

Electro-Impedance Spectroscopy (EIS). Anti-Adalimumab (Anti-AM) is used to immobilize the surface of the graphene based transducers where the analyte then flows over. Changes in the impedance before and after the flow are measured using an Impedance Analyzer. Adalimumab specific transducers will then show increase of impedance against different concentrations of Adalimumab molecular binding within clinical ranges (0.1μg/ml to 10 μg/ml).

Molecular Recognition

The molecules used in the biosensor are the Anti-Adalimumab Type 1 Antibody, the TNF-α - Tumour Necrosis Factor alpha (TNF-α), and silver Nanoparticles.

The Type 1 anti-adalimumab (Anti-AM) antibodies inhibit the binding of the drug adalimumab(AM) to its target, TNF-α, and therefore detect the free drug. This protein was used to bio-immobilize the Graphene based transducers.

The tumour Necrosis Factor alpha (TNF-α), is an inflammatory cytokine produced by macrophages/monocytes during acute inflammation and is responsible for a diverse range of signalling events within cells, leading to necrosis or apoptosis.The affinity of TNF-α to adalimumab was taken advantage of by tagging it with optically active silver nanoparticles and then flowing it over the Graphene based transducers containing the Anti-AM complex.

The Silver Nanoparticles (Ag NPs) were used as the optical tags with receptor proteins specific to AM.

Physical Transduction

The graphene based transducers allows for electrical readouts for the specific binding of AM and the optical readout for the recording of optical emissions from the labelled secondary antibodies of TNF- alpha which specifically binds to the Anti-AM AM complex bio that are immobilized on the Graphene transducers. Moreover, dedicated microfluidic circuits increasing the local concentrations of the analytes at the transducer enhance the optical signal and improve the bioassay readout.


An optical based detection has also been installed as a parallel detection platform for increased accuracy of the results. For the optical detection, Microscale Thermophoresis (MST) is utilised. Directed movement of particles in a microscopic temperature gradient leads to accumulation of analyte molecules and thus leads to an enhanced sensor signal due to the increased local fluorescence.

Cartridge

For measuring the concentration of AM, blood samples containing the drug are injected into the disposable chips (having graphene electrodes functionalized with Anti-AM) and then the optically labelled TNFα is made to flow through it. Once the fluid is stationary, the electrical and optical measurements are made in the respective platforms and the chips are disposed after each measurement.

Reader Instrument

The entire setup is 20x20x40 cm^3 in dimensions.


The user administers the blood sample and TNFα in the chip and put the chip in the measurement system. The electrical readout is then measured using an Impedance Analyzer, where the impedance change obtained at a particular frequency will indicate the concentrations. The optical readout is an image of the fluorescence captured by the camera. Furthermore, there is an integrated optoelectronic read out platform in order to improve the accuracy and speed of measurement.

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