Spraying Enzymes in Microemulsions of AOT in Nonpolar Organic Solvents for Fabrication of Enzyme Electrodes

Abstract

A new technique suitable for automated, large-scale fabrication of enzyme electrodes by air-spraying enzymes in organic inks is presented. Model oxidoreductases, tyrosinase (Tyr) and glucose oxidase (GOx), were adapted to octane-based ink by entrapment in a system of reverse micelles (RM) of surfactant AOT in octane to separate and stabilize the catalytically active forms of the enzymes in nonpolar organic media. Nonpolar caoutchouk polymer was also used to create a kind of "dry micelles" at the electrode/solution interface. Enzyme/RM/polymer-containing organic inks were air-brushed onto conductive supports and were subsequently covered by sprayed Nafion membranes. The air-brushed enzyme electrodes exhibited relevant bioelectrocatalytic activity toward catechol and glucose, with a linear detection range of 0.1-100 microM catechol and 0.5-7 mM glucose; the sensitivities were 2.41 A M(-1) cm(-2) and 2.98 mA M(-1) cm(-2) for Tyr and GOx electrodes, respectively. The proposed technique of air-brushing enzymes in organic inks enables automated construction of disposable enzyme electrodes of various designs on a mass-production scale.

A bienzyme channeling glucose sensor with a wide concentration range based on co-entrapment of enzymes in SBA-15 mesopores

“…The average relative standard deviation (RSD) of the plots was 3.6%. This linear range of four orders of magnitude was much wider than the ranges of 0.5-7 mM for GOD in microemulsions of microemulsions of dioctyl sulfosuccinate sodium salt (AOT) in nonpolar organic solvents (Shipovskov et al, 2005), 1.0-10 mM for a ribbon-like masssensitive magnetoelastic sensor (Cai et al, 2004) and 2.5 M to 0.5 mM in the enzyme-immobilized magnetic microreactor for the flow injection analysis (Nomura et al, 2004). It had a high sensitivity of 90 A cm −2 mM −1 , which was much higher than those of 50 A cm −2 mM −1 in perfluorosulfonated ionomer membranes (Karyakin et al, 2002) and 2.98 A cm −2 mM −1 for GOD in microemulsions of AOT in nonpolar organic solvents (Shipovskov et al, 2005).…”

“…This linear range of four orders of magnitude was much wider than the ranges of 0.5-7 mM for GOD in microemulsions of microemulsions of dioctyl sulfosuccinate sodium salt (AOT) in nonpolar organic solvents (Shipovskov et al, 2005), 1.0-10 mM for a ribbon-like masssensitive magnetoelastic sensor (Cai et al, 2004) and 2.5 M to 0.5 mM in the enzyme-immobilized magnetic microreactor for the flow injection analysis (Nomura et al, 2004). It had a high sensitivity of 90 A cm −2 mM −1 , which was much higher than those of 50 A cm −2 mM −1 in perfluorosulfonated ionomer membranes (Karyakin et al, 2002) and 2.98 A cm −2 mM −1 for GOD in microemulsions of AOT in nonpolar organic solvents (Shipovskov et al, 2005). Although the similar upper limits of detection for glucose have been reported to be 20, 30 and 35 mM at GOD immobilized carbon nanotubes Rubianes and Rivas, 2003;Lin et al, 2004), our bienzyme-channeling sensor with an upper limit of 34 mM can detect glucose down to 3.0 M, which is much lower than 2.0, 0.08 and 0.6 mM at these carbon nanotubes Lin et al, 2004;Rubianes and Rivas, 2003).…”

Activation of laccase bioelectrocatalysis of O2 reduction to H2O by carbon nanoparticles

“…For catechol oxidation 0.1-5 nm laccase was added to a solution containing 0.5 mM catechol in 0.1 M sodium citrate-sulphate buffer, pH 5. A molar absorption coefficient of catechol e 405 = 760 M À1 cm À1 was used [32,33]. One substrate unit (U) is equivalent to the amount of laccase that catalyses the oxidation of 1 lmol of a substrate (catechol) min À1 .…”

Mesocarpo De Babaçu (Orbinya Sp) Como Adsorvente Do Dodecil Benzeno Sulfonato De Sódio (Sdbs)

“…Os surfactantes conhecidos também com tensoativos são moléculas que possuem características anfifílicas, ou seja, possuem na mesma molécula uma porção hidrofílica ou polar, denominada cabeça, e uma cadeia hidrofóbica ou apolar, a qual é referida como cauda (SHIPOVSKOV et al, 2005).…”