Aryl Diazonium Chemistry for the Surface Functionalization of Glassy Biosensors

Abstract

Nanostring resonator and fiber-optics-based biosensors are of interest as they offer high sensitivity, real-time measurements and the ability to integrate with electronics. However, these devices are somewhat impaired by issues related to surface modification. Both nanostring resonators and photonic sensors employ glassy materials, which are incompatible with electrochemistry. A surface chemistry approach providing strong and stable adhesion to glassy surfaces is thus required. In this work, a diazonium salt induced aryl film grafting process is employed to modify a novel SiCN glassy material. Sandwich rabbit IgG binding assays are performed on the diazonium treated SiCN surfaces. Fluorescently labelled anti-rabbit IgG and anti-rabbit IgG conjugated gold nanoparticles were used as markers to demonstrate the absorption of anti-rabbit IgG and therefore verify the successful grafting of the aryl film. The results of the experiments support the effectiveness of diazonium chemistry for the surface functionalization of SiCN surfaces. This method is applicable to other types of glassy materials and potentially can be expanded to various nanomechanical and optical biosensors.

Use of Selective Redox Cross-Inhibitors for the Control of Organic Layer Formation Obtained via Diazonium Salt Reduction

“…9,10 A plethora of methods have been developed to tailor the properties of conducting 11−13 and nonconducting surfaces. 14,15 In this regard, the reduction of diazonium salts has become a widespread procedure to functionalize a large number of surfaces because of its simplicity. 16 Briefly, the method consists in the reduction of a diazonium ion to produce an aryl radical, which attaches to the surface via the formation of a covalent bond.…”

“…The modification of surfaces at the nanometric level allows to introduce new functionalities on a wide range of substrates. This approach has led to the preparation of new materials with interesting properties in the fields of sensing, , catalysis, , corrosion, , energy storage, , and molecular electronics. , A plethora of methods have been developed to tailor the properties of conducting − and nonconducting surfaces. , In this regard, the reduction of diazonium salts has become a widespread procedure to functionalize a large number of surfaces because of its simplicity . Briefly, the method consists in the reduction of a diazonium ion to produce an aryl radical, which attaches to the surface via the formation of a covalent bond.…”

Integrated Affinity Biosensing Platforms on Screen-Printed Electrodes Electrografted with Diazonium Salts

“…Strategies involving conjugation of capture antibodies with 4-carboxy methylaniline followed by diazotization to the respective diazonium salt modified antibody [ 23 , 24 ] ( Figure 2 ), or with 4-carboxyphenyldiazonium salt to avoid the diazotization step in the presence of the protein, have been reported. Due to the high number of primary amines on the exterior, the proteins are indeed modified with several diazonium species.…”

“…Electrochemical grafting consisting of covalent modification of carbon surfaces by aryl radicals generated from electrochemical reduction of diazonium salts has demonstrated to facilitate the electron transfer and provide a highly stable binding surface with enhanced properties for selective and controlled immobilization of chemical and biological compounds [ 62 , 64 ]. Advantages of this method include the ease of diazonium preparation, a covalent attachment to the electrode, the speed of the chemistry involved [ 29 ] and the ability to modify closely-spaced electrodes with different biological entities (proteins, nucleic acid strands, and peptides) [ 23 , 29 ]. Moreover, the application of aryldiazonium salts for (bio)sensing has recently seen the integration of nanomaterials together with the recognition species into interfaces thus taking advantage of the nanomaterials properties.…”

“…In fact, conductive and semiconductive surfaces can be modified with a wide range of functional groups in aqueous solution at room temperature and without sophisticated equipment. Other advantages are the reproducibility, uniformity and stability of the covalently attached organic layer on the surface, which have made this method a suitable choice to develop a wide range of attractive electrochemical affinity biosensors by immobilizing proteins, antibodies, nucleic acids and anchoring nanomaterials [ 5 , 20 , 21 , 22 , 23 ]. In addition, the ability to create a diazonium-modified surface by application of an appropriate potential scan or previous modification of the biomolecules with aryl diazonium allows the selective functionalization of closely spaced microelectrode surfaces with different molecules leading to the construction of multianalyte biosensors [ 24 , 25 , 26 ].…”