Effect of Enzyme and Cofactor Immobilization on the Response of Ethanol Oxidation in Zirconium Phosphate Modified Biosensors

Abstract

Two different self-contained ethanol amperometric biosensors incorporating layered [Ru(phend) 2 bpy] 2þ -intercalated zirconium phosphate (ZrP) as the mediator as well as yeast-alcohol dehydrogenase (y-ADH) and its cofactor nicotinamide adenine dinucleotide (NAD þ ) were constructed to improve upon a design previously reported where only this mediator was immobilized in the surface of a modified electrode. In the first biosensor, a [Ru(phend) 2 bpy] 2þ -intercalated ZrP modified carbon paste electrode (CPE) was improved by immobilizing in its surface both y-ADH and NAD þ using quaternized Nafion membrane. In the second biosensor, a glassy carbon electrode was modified with [Ru(phend) 2 bpy] 2þ -intercalated ZrP, y-ADH, and NAD þ using Nafion as the holding matrix. Calibration plots for ethanol sensing were constructed in the presence and absence of ZrP. In the absence of ZrP in the surface of the modified glassy carbon electrode, leaching of ADH was observed as detected by UV-vis spectrophotometry. Ethanol sensing was also tested in the presence and absence of ascorbate to measure the selectivity of the sensor for ethanol. These two ethanol biosensors were compared to a previously reported one where the y-ADH and the NAD þ were in solution, not immobilized.

Preparation of Zirconium Phosphate Nanomaterials and Their Applications as Inorganic Supports for the Oxygen Evolution Reaction

“…As the intercalation proceeds, the intercalant enters the interlayer space though the edges and diffuses into the center of the solid [73]. The direct intercalation of several guest species into θ-ZrP has been successfully used to produce composite materials for different applications [18,20,[74][75][76][77][78][79]. Reproduced from [13], with permission from the American Chemical Society, 2003.…”

“…Ion-exchange in ZrP occurs at the Brönsted acid groups (P-OH) which are also present at the surface of the nanoparticles, opening another pathway for the modification of this material: surface modification [ 9 , 10 , 11 ]. These composite materials have been used for several applications including photocatalysis [ 12 , 13 ], drug delivery [ 14 , 15 , 16 , 17 ], amperometric biosensors [ 18 , 19 , 20 ], catalysis [ 7 , 21 , 22 , 23 , 24 , 25 , 26 ], flame retardancy [ 27 , 28 , 29 ], and others. We encourage the reader to also see other recent reviews on the topic of the synthesis of ZrP and its applications [ 7 , 8 , 30 , 31 ].…”

Water Splitting Electrocatalysis within Layered Inorganic Nanomaterials

“…ZrP has been used for the intercalation of several photo-, bio-and redox-active compounds for a wide variety of applications including artificial photosynthesis, amperometric biosensors, and drug delivery [27,[30][31][32][33][34][35][36][37][38][39][40][41][42]. Even though ZrP has previously been studied for catalysis [43][44][45][46][47], membrane composites for proton exchange water electrolyzers [48][49][50][51][52], and as additive for catalytic layers for OER in order to protect metal oxide catalysts [53], our work is, to the best of our knowledge, the first time ZrP is used as an inorganic support for catalysts for the OER.…”

Zirconium Phosphate Catalysts in the XXI Century: State of the Art from 2010 to Date

“…It exists in a hydrated form of α-ZrP containing approximately six hydration water molecules and exhibits a larger interlayer distance (about 10.3-10.4 Å) with respect to the monohydrated form (7.6 Å). This form was first observed by Clearfield et al in 1969 [6], while Colon et al developed a systematic approach for the use of -ZrP for the intercalation of bulky molecules [7][8][9].…”