Sol-Gel-Derived Silicate-Based Composite Electrode

Composite Silica‐Based Films as Platforms for Electrochemical Sensors

“…The amount of incorporated organic groups can be tuned by varying the R'-Si(OR) 3 /Si(OR) 4 molar ratio in the precursors solution, and multi-functionalized composite films can be obtained by adding one or more R'-Si(OR) 3 reagents in the medium. [17][18][19][20] Electrodeposition can be also implemented to generate such organically-modified deposits. [38] Other types of composite layers are obtained by exploiting the hosting properties of porous silica, and especially the versatility of the sol-gel process to enable the direct entrapment of biomolecules, nano-objects or even polymeric materials in the course of film formation, by simply dispersing these additives in the starting sol solution (see illustrations in part (b) of Figure 1B).…”

“…[42] Otherwise, several other nano-objects have been entrapped into silica films during their sol-gel processing. With respect to their attractiveness for the development of electrochemical sensors, they encompass primarily noble metal or metal oxide nanoparticles and carbon particles, giving birth respectively to metal-and carbon-ceramic composite electrodes, [9,20,43] which can be also prepared as thin films but mainly by electrochemically assisted deposition (EAD). [44][45][46][47][48] These modifiers are exploited in particular for their electrocatalytic properties and/or as an effective means of imparting electrical conductivity to the silica-based composite layer.…”

“…[14,17] They can be easily manufactured in the form of organic-inorganic hybrids or as nanocomposite materials by implementing the numerous possibilities offered by the sol-gel process. [17][18][19][20] Silica-based organic-inorganic nanocomposites have a long history and are usually classified into two categories depending on whether the organic and inorganic components are interacting via weak bonds (class I) or are linked by covalent or iono-covalent chemical bonds (class II). [21] The interest of the first category relies on the ability to entrap redox proteins or enzymes, nanocarbons or metal nanoparticles catalysts, electrochemiluminescence reagents, or electroactive polymers, which remain accessible to external reagents or target analytes owing to the rigid three-dimensional and porous inorganic network.…”

“…[21] The interest of the first category relies on the ability to entrap redox proteins or enzymes, nanocarbons or metal nanoparticles catalysts, electrochemiluminescence reagents, or electroactive polymers, which remain accessible to external reagents or target analytes owing to the rigid three-dimensional and porous inorganic network. [14,16,20,22] This is essential for the proper functioning of electrochemical sensors and biosensors. The second category is also very attractive in this field as the rich chemistry of organosilane reagents enables the covalent bonding of various organo-functional groups that can be exploited for the selective preconcentration and/or electrocatalytic sensing of target species, or for the attachment of suitable mediators necessary in electrochemical biosensors, for instance.…”

Electrogeneration of non-electroactive and non-conducting materials: a counterintuitive concept for the functionalization and nanostructuration of electrode surfaces

“…Sol-gel bioencapsulation, by keeping the biological activity of the immobilized biorecognition elements [201][202][203], leads to bioceramic materials that are attractive for the development of biosensors [249][250][251]. For bioelectrochemical applications, the bioceramic materials needs to be in contact with a conductive surface, which is usually achieved by dispersing biocomposite particles into conductive matrices or by coating bioceramic films formed by evaporation on electrodes [40,43,252], which is however not appropriate for uniform deposition on surfaces with complex morphologies. As briefly aforementioned, sol-gel bioencapsulation can be electrochemically induced to form biocomposite thin films, even on non-flat surfaces [156,204,205,253], leading to a novel one-step electrochemical approach of biomolecule immobilization for bioelectrochemical applications (beside electrodeposited polymers, for instance) [254].…”