Electrical detection of immobilized proteins with ungated AlGaN∕GaN high-electron-mobility Transistors

Kang, B. S.; Ren, F.; Wang, L.; Lofton, Charles; Tan, Weihong; Pearton, S. J.; Dabiran, A. M.; Osinsky, A.; Chow, P. P.

doi:10.1063/1.1994951

Cited by 141 publications

(101 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Results, though contrary to classical assessment [13,[15][16][17][18], are congruent with recent HFET protein-sensing results [20,21,24,25,29,30,40]. Nonetheless, the notion that some immunoHFETs are feasible in physiological environments is not widely accepted, motivating direct demonstration of the proposition here.…”

Section: Resultsmentioning

confidence: 38%

ImmunoFET feasibility in physiological salt environments

Casal

Wen

Gupta

et al. 2012

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

Field-effect transistors (FETs) are solid-state electrical devices featuring current sources, current drains and semiconductor channels through which charge carriers migrate. FETs can be inexpensive, detect analyte without label, exhibit exponential responses to surface potential changes mediated by analyte binding, require limited sample preparation and operate in real time. ImmunoFETs for protein sensing deploy bioaffinity elements on their channels (antibodies), analyte binding to which modulates immunoFET electrical properties. Historically, immunoFETs were assessed infeasible owing to ion shielding in physiological environments. We demonstrate reliable immunoFET sensing of chemokines by relatively ion-impermeable III-nitride immunoHFETs (heterojunction FETs) in physiological buffers. Data show that the specificity of detection follows the specificity of the antibodies used as receptors, allowing us to discriminate between individual highly related protein species (human and murine CXCL9) as well as mixed samples of analytes (native and biotinylated CXCL9). These capabilities demonstrate that immunoHFETs can be feasible, contrary to classical FET-sensing assessment. FET protein sensors may lead to point-of-care diagnostics that are faster and cheaper than immunoassay in clinical, biotechnological and environmental applications.

show abstract

Section: Resultsmentioning

confidence: 38%

ImmunoFET feasibility in physiological salt environments

Casal

Wen

Gupta

et al. 2012

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

show abstract

“…Pioneering work has been carried out by Bermudez,10,11 who has analyzed the adsorption of different organic molecules, such as anilines or octanethiols on GaN surfaces, from the gas phase. In a recent publication Kang et al 12 have reported the electrical detection of immobilized proteins on AlGaN / GaN transistors, modified with aminopropyltriethoxysilane ͑APTES͒ molecules in a liquid phase reaction. However, the covalent immobilization of molecules was not proven.…”

mentioning

confidence: 99%

Chemical functionalization of GaN and AlN surfaces

Baur

Steinhoff

Hernando

et al. 2005

Applied Physics Letters

126

View full text Add to dashboard Cite

The covalent functionalization of GaN and AlN surfaces with organosilanes is demonstrated. Both octadecyltrimethoxysilane and aminopropyltriethoxysilane form self-assembled monolayers on hydroxylated GaN and AlN surfaces, confirmed by x-ray photoelectron spectroscopy and atomic force microscopy. The monolayer thickness on GaN was determined to 2.5± 0.2 nm by x-ray reflectivity. Temperature-programmed desorption measurements reveal a desorption enthalpy of 240 kJ/ mol. The application of these devices for electronic detection of specific biomolecular processes is a promising approach for novel biosensors based on molecular recognition, such as specific antibody detection or label-free detection of deoxyribonucleic acid ͑DNA͒ hybridization. For this purpose, the covalent attachment of specific molecules with controlled structural order and composition on group III-nitride devices is a basic requirement.Covalent coupling of biomolecules to oxidized and hydrogen-terminated silicon surfaces has been investigated in numerous works during recent decades. 3,4 Covalent grafting of self-assembled monolayers ͑SAMs͒ of organosilanes on oxidized silicon surfaces 5-7 is widely used as the first step of surface functionalization with biomolecules for electronic detection of enzyme activity and DNA hybridization with Si-based field effect transistors. 8,9 In contrast, the surface chemistry on AlGaN alloys has not yet been studied in great detail. Pioneering work has been carried out by Bermudez, 10,11 who has analyzed the adsorption of different organic molecules, such as anilines or octanethiols on GaN surfaces, from the gas phase. In a recent publication Kang et al. 12 have reported the electrical detection of immobilized proteins on AlGaN / GaN transistors, modified with aminopropyltriethoxysilane ͑APTES͒ molecules in a liquid phase reaction. However, the covalent immobilization of molecules was not proven.In this letter, we report the covalent attachment of SAMs of octadecyltrimethoxysilane ͑ODTMS͒ and APTES on hydroxylated GaN and AlN surfaces. Complementary analysis by x-ray photoelectron spectroscopy ͑XPS͒, atomic force microscopy ͑AFM͒, and temperature-programmed desorption mass spectrometry proves covalent coupling of the SAMs to the surface. Immobilization of single-stranded 20-mer oligonucleotides on APTES-modified nitride surfaces and hybridization is demonstrated by fluorescence microscopy.GaN and AlN layers with a thickness of 2 m were grown by metalorganic chemical vapor deposition ͑MOCVD͒ on c-plane sapphire substrates. AFM over a scan area of 4 m 2 revealed a root-mean-square surface roughness of 0.2 nm for GaN and 0.3 nm for AlN, respectively.The presence of hydroxyl groups on the hydrophilic surface is an essential requirement for the silanization process. 5-7 Therefore, the substrates were immersed in H 2 SO 4 :H 2 O 2 ͑3:1͒ solution for 20 min, rinsed with deionized water ͑18 M⍀ cm, Millipore͒ and dried under nitrogen flux prior to silanization. In addition to the activation of surface hydroxyl groups, this...

show abstract

“…They are a Pd ring Schottky diode structure [34] and an open gate FET structure [41] and both are formed on a standard AlGaN/GaN HFET wafer so that future co-integration with signal processing HFETs is easily accomplished.…”

Section: Leakage Currents In Algan Schottky Diodesmentioning

confidence: 99%