Direct Label-Free Electrical Immunodetection of Transplant Rejection Protein Biomarker in Physiological Buffer Using Floating Gate AlGaN/GaN High Electron Mobility Transistors

Abstract

Monokine induced by interferon gamma (MIG/CXCL9) is used as an immune biomarker for early monitoring of transplant or allograft rejection. This paper demonstrates a direct electrical, label-free detection method of recombinant human MIG with anti-MIG IgG molecules in physiologically relevant buffer environment. The sensor platform used is a biologically modified GaN-based high electron mobility transistor (HEMT) device. Biomolecular recognition capability was provided by using high affinity anti-MIG monoclonal antibody to form molecular affinity interface receptors on short N-hydroxysuccinimide-ester functionalized disulphide (DSP) self-assembled monolayers (SAMs) on the gold sensing gate of the HEMT device. A floating gate configuration has been adopted to eliminate the influences of external gate voltage. Preliminary test results with the proposed chemically treated GaN HEMT biosensor show that MIG can be detected for a wide range of concentration varying from 5 ng/mL to 500 ng/mL.

AlGaN/GaN High Electron Mobility Transistor-Based Biosensor for the Detection of C-Reactive Protein

“…After the formation of the SAM layer, the device was exposed to CRP-antibody. The positive charge of the CRP-antibody amine group, which is closer to the gate surface, attracts electrons in the HEMT 2DEG channel [ 13 ]. Therefore, the drain current of the sensor increased by 1.68 mA when CRP-antibody bound to the SAM.…”

“…The AlGaN/GaN HEMT-based biosensor with null-balancing circuit could detect CRP molecules at concentrations as low as 10 ng/mL; because AlGaN/GaN HEMT has a high electron mobility induced by piezoelectric polarization. In addition; the strong polarization field in AlGaN/GaN material responds strongly to the biomolecule charges on the gate surface [ 13 ]. Moreover; the LOD of the device may be improved by using a differential structure for noise cancellation [ 16 , 17 ].…”

“…The conducting channel of the AlGaN/GaN high electron mobility transistor (HEMT) is very close to the surface and extremely sensitive under applied stress, which should enhance detection sensitivity [ 11 , 12 ]. The application of some external change in surface conditions, such as the binding of biomolecules to the gate region of the device, changes the piezoelectric-induced carrier density in the channel of the HEMT, which in turn alters the drain current [ 13 ]. Therefore, the HEMT-based biosensor provides high sensitivity to immobilized biomolecules.…”

Performance Analysis of MOS-HEMT as a Biosensor: A Dielectric Modulation Approach

“…The presence of high sheet charge density and mobility increases the sensitivity [3]. Various research has been done on HEMT based biosensor for pH detection [4] [5][6] [7], Immuno-detection using floating gate AlGaN HEMT [8],deoxyribonucleic acid (DNA) [9], Urea testing [10], Prostate-specific antigen testing [11] [12], Monokine induced by interferon gamma [13], CerbB2 detection [14], CO and H 2 detection [3] [15], C-reactive protein detection [16], troponin I testing [17] [18] and carcinoembryonic antigen (CEA) detection respectively. To enhance the sensitivity of the proposed HEMTs device, various structures are also optimized like Circular gate HEMT, Double gate, Gateless devices, Nano-cavity under the gate region towards the drain side, and Nano-cavity at the source and drain both sides, respectively.…”

Separative extended-gate AlGaAs/GaAs HEMT biosensors based on capacitance change strategy

“…[7][8][9] However, in early reports, the gate electrode at the top of the HEMTs was often chosen as the sensing element; 7,10 therefore, the HEMTs with relatively high manufacturing costs would inevitably come into contact with various biological solutions and, thus, their service life would be severely limited. Then, an extended-gate 7 / floating-gate 11 sensing pad was proposed to keep the HEMT devices away from the biological solutions, but this scheme was not very effective. The separative extended-gate configuration is thought to be capable of solving the solution erosion issue during the biomodification and biosensing processes because this design provides high independence between the transistor and the sensing pad in terms of fabrication/measurement conditions and substrates used.…”