Coated-wall microreactor for continuous biocatalytic transformations using immobilized enzymes.

Area of Science:

• Biocatalysis and enzyme immobilization
• Microfluidics and reactor design
• Chemical engineering and process development

Background:

• Microstructured flow reactors offer advantages for biocatalysis, but active enzyme immobilization on surfaces remains a challenge.
• Coated-wall reactors, where enzymes form a surface layer, are a promising design.
• Existing materials like poly(dimethylsiloxane) have limitations due to hydrophobic interactions.

Purpose of the Study:

• To develop a robust stainless steel microreactor for efficient covalent enzyme immobilization.
• To create a highly active and stable wall biocatalyst for continuous hydrolysis.
• To overcome limitations of existing microreactor materials in biocatalytic applications.

Main Methods:

• Covalent immobilization of thermophilic beta-glycosidase CelB onto a stainless steel microreactor using aminopropyl triethoxysilane and glutardialdehyde.
• Utilizing a macroporous gamma-aluminum oxide wash-coat layer to support enzyme attachment.
• Surface functionalization and activation for enhanced enzyme binding.

Main Results:

• Achieved high catalyst loading (500 U/mL) with retained enzyme activity (50% of free enzyme).
• Demonstrated efficient continuous lactose hydrolysis (500 mg glucose/(mL h) space-time yield) at >70% conversion.
• Immobilized enzyme exhibited a half-life of 15 days and compatibility with alternative substrates and products.

Conclusions:

• The developed stainless steel microreactor with a functionalized wash-coat provides a stable and active platform for enzyme immobilization.
• This system overcomes material limitations of previous microreactors, enabling broader biocatalytic applications.
• The microreactor design is suitable for continuous enzymatic hydrolysis processes with high efficiency and longevity.