Scaled-up separation of cellobiohydrolase1 from a cellulase mixture by ion-exchange chromatography.

Enzymatic hydrolysis of cellulose often involves cellulases produced by Trichoderma reesei, of which cellobiohydrolase1 (CBH1) is the most abundant (about 60% of total cellulases) and plays an important role in the hydrolysis of crystalline cellulose. A method for separating sufficient quantities from the bulk cellulase cocktail is highly desirable for many studies, such as those that aim to characterize binding and hydrolysis kinetics of CBH1. In this work, CBH1 was separated from other Spezyme CP cellulases by ion-exchange chromatography using an efficient modification of a smaller scale process.

Transition force measurement between two negligibly charged surfaces: a new perspective on nanoparticle halos.

Since 2001, silica microspheres have been reported to be stabilized by highly charged hydrous ZrO(2) nanoparticles which form halos around the microspheres at pH 1.5. However, the exact mechanisms behind this novel stabilization method in terms of the relevant interaction forces remain unclear.

Direct calibration of colloidal probe cantilevers via Derjaguin, Landau, Verwey, and Overbeek surface forces in electrolyte solution.

The development of colloidal probe microscopy has made it possible to directly measure the interaction forces between two different surfaces in solution. Cantilever calibration is presently a subject of intense experimental and theoretical interest due to the need for accurate force measurement. We developed a novel and direct calibration method for colloidal probe cantilevers to which a silica microsphere has been previously attached based on fitting experimental force curves for the interaction between the silica sphere and a silica flat in dilute KBr solutions to the theoretical Derjaguin, Landau, Verwey, and Overbeek force curves using the measured zeta potential of the silica surfaces.

The investigation of Protein A and Salmonella antibody adsorption onto biosensor surfaces by atomic force microscopy.

The investigation of Protein A and antibody adsorption on surfaces in a biological environment is an important and fundamental step for increasing biosensor sensitivity and specificity. The atomic force microscope (AFM) is a powerful tool that is frequently used to characterize surfaces coated with a variety of molecules. We used AFM in conjunction with scanning electron microscopy to characterize the attachment of protein A and its subsequent binding to the antibody and Salmonella bacteria using a gold quartz crystal.

Control of the anodic aluminum oxide barrier layer opening process by wet chemical etching.

In this work, it has been shown that, through a highly controlled process, the chemical etching of the anodic aluminum oxide membrane barrier layer can be performed in such a way as to achieve nanometer-scale control of the pore opening. As the barrier layer is etched away, subtle differences revealed through AFM phase imaging in the alumina composition in the barrier layer give rise to a unique pattern of hexagonal walls surrounding each of the barrier layer domes. These nanostructures observed in both topography and phase images can be understood as differences in the oxalate anion contaminated alumina versus pure alumina.

New Approach to the Study of Particle-Surface Adhesion Using Atomic Force Microscopy.

The colloidal probe technique is commonly employed to determine the adhesion force between a particle and a solid surface. Characterization of the adhesion of a particle across a surface can be as important, if not more so, as the determination of an average value for the adhesion. Unfortunately, the measurement of the variation in adhesion can be difficult at best.