Materials 2013, 6(11), 4946-4966; doi:10.3390/ma6114946
Article

Influence of a Thiolate Chemical Layer on GaAs (100) Biofunctionalization: An Original Approach Coupling Atomic Force Microscopy and Mass Spectrometry Methods

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Received: 29 July 2013; in revised form: 29 August 2013 / Accepted: 18 October 2013 / Published: 25 October 2013
(This article belongs to the Special Issue Functional Materials and Proteins for Bio-Sensing Applications)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Widely used in microelectronics and optoelectronics; Gallium Arsenide (GaAs) is a III-V crystal with several interesting properties for microsystem and biosensor applications. Among these; its piezoelectric properties and the ability to directly biofunctionalize the bare surface, offer an opportunity to combine a highly sensitive transducer with a specific bio-interface; which are the two essential parts of a biosensor. To optimize the biorecognition part; it is necessary to control protein coverage and the binding affinity of the protein layer on the GaAs surface. In this paper; we investigate the potential of a specific chemical interface composed of thiolate molecules with different chain lengths; possessing hydroxyl (MUDO; for 11-mercapto-1-undecanol (HS(CH2)11OH)) or carboxyl (MHDA; for mercaptohexadecanoic acid (HS(CH2)15CO2H)) end groups; to reconstitute a dense and homogeneous albumin (Rat Serum Albumin; RSA) protein layer on the GaAs (100) surface. The protein monolayer formation and the covalent binding existing between RSA proteins and carboxyl end groups were characterized by atomic force microscopy (AFM) analysis. Characterization in terms of topography; protein layer thickness and stability lead us to propose the 10% MHDA/MUDO interface as the optimal chemical layer to efficiently graft proteins. This analysis was coupled with in situ MALDI-TOF mass spectrometry measurements; which proved the presence of a dense and uniform grafted protein layer on the 10% MHDA/MUDO interface. We show in this study that a critical number of carboxylic docking sites (10%) is required to obtain homogeneous and dense protein coverage on GaAs. Such a protein bio-interface is of fundamental importance to ensure a highly specific and sensitive biosensor.
Keywords: GaAs; self-assembled thiolate monolayers; proteins grafting; AFM; MALDI-TOF MS
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MDPI and ACS Style

Bienaime, A.; Leblois, T.; Gremaud, N.; Chaudon, M.-J.; Osta, M.E.; Pecqueur, D.; Ducoroy, P.; Elie-Caille, C. Influence of a Thiolate Chemical Layer on GaAs (100) Biofunctionalization: An Original Approach Coupling Atomic Force Microscopy and Mass Spectrometry Methods. Materials 2013, 6, 4946-4966.

AMA Style

Bienaime A, Leblois T, Gremaud N, Chaudon M-J, Osta ME, Pecqueur D, Ducoroy P, Elie-Caille C. Influence of a Thiolate Chemical Layer on GaAs (100) Biofunctionalization: An Original Approach Coupling Atomic Force Microscopy and Mass Spectrometry Methods. Materials. 2013; 6(11):4946-4966.

Chicago/Turabian Style

Bienaime, Alex; Leblois, Therese; Gremaud, Nicolas; Chaudon, Maxime-Jean; Osta, Marven E.; Pecqueur, Delphine; Ducoroy, Patrick; Elie-Caille, Celine. 2013. "Influence of a Thiolate Chemical Layer on GaAs (100) Biofunctionalization: An Original Approach Coupling Atomic Force Microscopy and Mass Spectrometry Methods." Materials 6, no. 11: 4946-4966.

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