Abstract
Graphene oxide (GO) is a two-dimensional material with peculiar photoluminescence emission and good dispersion in water, that make it an useful platform for the development of label-free optical biosensors. In this study, a GO-porous silicon (PSi) hybrid device is realized using a covalent chemical approach in order to obtain a stable support for biosensing applications. Protein A, used as bioprobe for biosensing purposes, is covalently linked to the GO, using the functional groups on its surface, by carbodiimide chemistry. Protein A bioconjugation to GO-PSi hybrid device is investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), water contact angle (WCA) measurements, Fourier transform infrared (FTIR) spectroscopy, steady-state photoluminescence (PL), and fluorescence confocal microscopy. PSi reflectance and GO photoluminescence changes can thus be simultaneously exploited for monitoring biomolecule interactions as in a multi-parametric hybrid biosensing device.
Highlights
Graphene oxide (GO) is the oxidized counterpart of graphene, characterized by oxygen-bearing functional groups in the form of epoxy, hydroxyl, and carboxyl acids groups on both the basal plane and edges (Dreyer et al, 2010)
GO can be processed in aqueous solution in order to directly link biomolecules to its surface for the realization of a biosensor, whose sensing mechanism could be based on changes of GO photoluminescence (Morales-Narváez and Merkoçi, 2012)
GO solubility could be not assured in presence of a biological molecule, so that in Supplementary Information (SI) the interaction of free GO sheets and a FITC labeled PrA∗, dispersed in demineralized water, is reported
Summary
Graphene oxide (GO) is the oxidized counterpart of graphene, characterized by oxygen-bearing functional groups in the form of epoxy, hydroxyl, and carboxyl acids groups on both the basal plane and edges (Dreyer et al, 2010). The oxygen-containing functional groups on the GO sheets make this material more hydrophilic than graphene. GO can be functionalized with biomolecules without using cross-linkers in aqueous solution, so that this material is interesting for biosensing applications (Jung et al, 2010; Loh et al, 2010; Liu et al, 2012; Zhang et al, 2013). Carboxylic acid groups on the GO sheets can be used as reactant sites for immobilization or conjugation of several biological molecules such as proteins, peptides, antibodies, DNA, and so on (Zhang et al, 2010; Wu et al, 2011). The PL of a thin layer of GO nanosheets is too weak, mainly due to the oxygen-functional groups producing non-radiative recombination between their electrons
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