Songtao Wu

Enzyme‐enabled responsive surfaces for anti‐contamination materials

Many real-life stains have origins from biological matters including proteins, lipids, and carbohydrates that act as gluing agents binding along with other particulates or microbes to exposed surfaces of automobiles, furniture, and fabrics. Mimicking naturally occurring self-defensive processes, we demonstrate in this work that a solid surface carrying partially exposed enzyme granules protected the surface in situ from contamination by biological stains and fingerprints. Attributed to the activities of enzymes which can be made compatible with a wide range of materials, such anti-contamination and self-cleaning functionalities are highly selective and efficient toward sticky chemicals. This observation promises a new mechanism in developing smart materials with desired anti-microbial, self-reporting, self-cleaning, or self-healing functions.

Poly(ethylene glycol) conjugated enzyme with enhanced hydrophobic compatibility for self-cleaning coatings

Enzyme-based smart materials constitute a rapidly growing group of functional materials. Often the natively evolved enzymes are not compatible with hydrophobic synthetic materials, thus significantly limiting the performance of enzymes. This work investigates the use of a polyethylene glycol (PEG)-conjugated detergent enzyme for self-cleaning coatings. As a result, PEG conjugated α-amylase demonstrated a much more homogeneous distribution in polyurethane coatings than the parent native enzyme as detected by both fluorescent microscopy and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (SEM-EDX). Additionally, the conjugated enzyme showed enhanced retention in the coating and much improved thermal stability with a halflife of 20 days detected at 80 °C and over 350 days under room temperature. Such coating-incorporated enzyme afforded interesting self-cleaning functionality against starch-based stains as examined through a slipping drop test.

Nanoporous silica glass for the immobilization of interactive enzyme systems.

Recent pursuit on utilization of nanoscale materials has manifested a variety of configurations of highly efficient enzymic biocatalyst systems for biotechnological applications. Nanoscale structures are particularly powerful in effecting multienzyme biocatalysis. Inherent properties of nanomaterials--primarily, the high surface area to volume ratio and atomic scale 3D configurations--enable higher enzyme loadings, microenvironment control surrounding enzyme molecules, regulation on mass transfer, and protein structural stabilization of the biocatalyst as compared to traditional immobilization systems. This chapter introduces one versatile nanoscale immobilization method via details demonstrated using the case of nanoporous silica glass (30 nm diameter) for the concomitant incorporation of lactate dehydrogenase (LDH), glucose dehydrogenase (GDH), and the cofactor (NADH).

Organic-Soluble Enzyme Nano-Complexes Formed by Ion-Pairing with Surfactants

The solubilization of enzymes in organic solvents for non-aqueous biocatalysis has attracted considerable attention since the homogeneous distribution accounts for a drastically improved reaction efficiency compared to enzymes dispersed as aggregates in an organic phase. This chapter highlights ion-pairing as a valuable and facile method to make enzymes soluble in organic solvents. Ion-pairing denotes the formation of a nano-complex, in which a single enzyme molecule in the core is surrounded by counter-charged surfactant molecules. The special architecture of this nano-complex exposes the surfactant hydrophobic group toward the bulk solvent and renders the complex sufficiently soluble in organic media. This chapter also describes the underlying principle of ion-pairing as well as simple preparation and characterization techniques to yield highly active enzyme-surfactant nano-complexes. The general applicability of this technique is demonstrated on the base of the hydrolytic enzyme α-chymotrypsin (α-CT) and the redox enzyme glucose oxidase (GO( x )).