Immobilized Enzyme Studies in a Microscale Bioreactor

Abstract

Novel microreactors with immobilized enzymes were fabricated using both silicon and polymer-based microfabrication techniques. The effectiveness of these reactors was examined along with their behavior over time. Urease enzyme was successfully incorporated into microchannels of a polymeric matrix of polydimethylsiloxane and through layer-bylayer self-assembly techniques onto silicon. The fabricated microchannels had cross-sectional dimensions ranging from tens to hundreds of micrometers in width and height. The experimental results for continuous-flow microreactors are reported for the conversion of urea to ammonia by urease enzyme. Urea conversions of >90% were observed.

Enzymatic microreactors in biocatalysis: history, features, and future perspectives

“…Tyrosinase Fused-silica capillary Immobilized by ionic binding technique with hexadimethrine bromide [129]. Urease Poly(dimethylsiloxane) Entrapped in a mono- [105,158,159], or multi-layer [106] polymeric matrix Polymer-activated silicon wafer…”

“…Bound by a multilayer technique with poly(dimethyldiallyl ammonium chloride) and poly(styrenesulfonate) [106]. Low temperature co-fired ceramics Immobilized on commercial glass beads and introduced into the microreactor [108,160].…”

“…Thomsen and B. Nidetzky developed a microstructured plate for lactose hydrolysis by immobilizing β-glycosidase via APTES/GA activation [104], while F. Jones at al. affixed polydimethylsiloxane/urease bioplastic on a silicon wafer [105,106]. Bio-microreactors with enzymes immobilized on beads have been prepared by filling the reaction chamber with enzyme-immobilized particles.…”

The effects of engineering design on heterogeneous biocatalysis in microchannels

“…The kinetics of the heterogeneous chemical reaction that takes place at the solid-liquid interfaces is described using the Michaelis-Menten model: (4) where v is reaction rate (mol/[s·m 2 ]), [S] is substrate concentration at the solid surface (M), V max is the maximum reaction rate (mol/[s·m 2 ]) V max = k cat [E], k m is Michaelis constant (concentration that gives v = V max /2) (M), k cat is turnover number (s -1 ), and [E] is enzyme concentration at the solid surface (mol/m 2 ). The kinetics of the heterogeneous chemical reaction that takes place at the solid-liquid interfaces is described using the Michaelis-Menten model: (4) where v is reaction rate (mol/[s·m 2 ]), [S] is substrate concentration at the solid surface (M), V max is the maximum reaction rate (mol/[s·m 2 ]) V max = k cat [E], k m is Michaelis constant (concentration that gives v = V max /2) (M), k cat is turnover number (s -1 ), and [E] is enzyme concentration at the solid surface (mol/m 2 ).…”

Silica‐immobilized enzymes for multi‐step synthesis in microfluidic devices

“…The dramatically increased surface to volume ratios lead to rapid mass transfer and greatly reduced analysis time and sample consumption. There is increasing interest in the integration of enzymes into microfluidic systems for applications in medical diagnostics, biosensing and natural product and organic synthesis (Hadd et al, 1997;Jones et al, 2004;Krenkova and Foret, 2004;Ku et al, 2006;Lee et al, 2003;Srinivasan et al, 2003Srinivasan et al, , 2004. Such biocatalytic systems are typically enabled by covalent attachment of the biocatalysts to channel walls, physical absorption onto solid matrices, or copolymerization (Holden et al, 2004(Holden et al, , 2005Honda et al, 2005;Mao et al, 2002;Sakia-Kato et al, 2004).…”