Implementation of a Simple Nanostructured Bio‐electrode with Immobilized Rhus Vernicifera Laccase for Oxygen Sensing Applications

Abstract

In this work a simple nanostructured direct‐electron transfer bio‐electrode based on tree laccase from Rhus vernicifera is described. The electrode was implemented on a 2 mm diameter graphite mine casted with a reduced graphene surface presenting the specific capacitance of 195.8 F g−1. About 10 μl of mixture between 25 mg mL−1 laccase suspension and 5 mg mL−1 single‐walled carbon nanotubes in 2 % SDS is dropped over the surface followed by 5 μl of the biological friendly tetrakis(2,3‐dihydroxypropyl)‐silane monomer sol to provide physical entrapment in a silica matrix after gelation. The rigidity of enzyme encapsulation allowed to obtain a constant enzyme turnover of about 16 min−1 in the extended pH range of 6.0‐7.5, being the activity almost proportional to the temperature used in the interval between 25 and 40 °C. The graphite‐graphene/SWCNT‐laccase/sol‐gel electrode enabled a proportional response to molecular oxygen up to the concentration of 0.45 mmol L−1 and is capable to generate the maximum power of 4.5 μW cm−2 at 0.250 V vs the AgCl/Ag reference electrode in quiescent oxygen saturated solution.

Nanostructured pencil graphite electrodes for application as high power biocathodes in miniaturized biofuel cells and bio-batteries

“…3 a, surface modification with reduced graphene enabled voltammetric peaks three times higher (i pa = 3.52 ± 0.14 mA cm −2 ; i pc = -3.58 ± 0.14 mA cm −2 , n = 3) relative to results obtained for HB previously polished with alumina. They also performed better regarding PGEs modified with MWCNT or carbon black despite the larger background current ascribed to the higher specific capacitance of graphene, 195 ± 6 F g −1 26 . The performance obtained after surface treatment with MWCNT (i pa = 2.55 ± 0.09 mA cm −2 ; i pc = − 2.68 ± 0.09 mA cm −2 , n = 3) was also fairly good specially when compared to the bare and Vulcan modified PGEs (PGE-CB).…”

Microfluidic Platform with an Embedded Pencil Graphite Electrode Biosensor for the Detection of Glucose and Cadmium

“…The PGE surface was modified with reduced graphene since we have evidenced that graphene greatly enhances the current signals though increasing also the capacitance of the electrode. 32 The procedure implemented for biosensor preparation, known as enzyme precipitate coatings 28 or cross-linked enzyme clusters 34 comprises the covalent attachment of glucose oxidase enzyme onto MWCNT, its precipitation and further cross-linking of protein cluster to achieve optimal enzyme loading and stability. The coupling of nanomaterials to biomolecules can be accomplished using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS).…”

“…A transversal cut exposed then a pristine PGE surface which was polished mechanically using sandpaper (P1200) and washed with distilled water. The active surface area of the PGE was determined by chronoamperometry 32 and corresponded to about 0.034 cm 2 . This surface was modified with 10 μL of graphene oxide (1 mg mL −1 ) and afterward electrochemically reduced in 0.1 M Na 2 SO 4 solution at 50 mV s −1 along 100 scans performed within −1.2 V and 0.8 V (vs. Ag/AgCl).…”

Approaching Immobilization of Enzymes onto Open Porous Basotect®

“…Furthermore, the good solubility of the polymer in aqueous solution results in a hydrogel-like 3D swelling behavior of surface-bound PEMA and thus provides an optimal environment for hydrophilic enzymes [16]. Lipase and laccase immobilization have been extensively studied, particularly either for applications in the dairy industry, oil and fat processing and for producing fine chemicals or even biofuels [11,[17][18][19], or in case of laccase, in the pulp and paper industry, cosmetics or for dye synthesis and biosensors, as well as wastewater treatment [20][21][22][23]. Different carrier materials, e.g., zeolites, silica gel, polypropylene, polyethylene, octyl-agarose and cellulose ester, as well as silica-based mesoporous cements and fibers, ceramic membranes or polyacrylonitrile beads, and immobilization techniques were applied [24][25][26][27][28][29][30][31][32].…”