Poster Presentation 1A-14

Imaging Biomass Using Atomic Force Microscopy and Near Field

Scanning Optical Microscopy

Shi-You Ding*, Jun Feng, Peng Zhang, Steve Smith, Stephen R. Decker,

Steven R. Thomas, Tina Jeoh, Todd B. Vinzant, Stanley G. Bower, and Michael E. Himmel

National Bioenergy Center

National Renewable Energy Laboratory

1617 Cole Boulevard

Golden, CO 80401

Phone:  (303)384-7758

Fax:  (303)384-7752

E-mail: shi_you_ding@nrel.gov

A significant database of knowledge has steadily grown over the past two decades to support our understanding of the effects of thermal chemical pretreatment and enzyme action on energy biomass.  These data are largely focused on chemical compositional analysis and enzyme hydrolysis kinetics.  It is now apparent that the digestibility of pretreated biomass (especially corn stover) may not tightly correlate with the chemical composition of the sample.  In order to understand the action of enzymes on mixed biomass, it is first necessary to examine their effects on the specific anatomical features of the plant cell wall.  Atomic force microscopy (AFM) has provided nanometer scale information about surface structure.  By using different modes, AFM can measure topographic image and detect variations in composition of sample surface. We have used AFM to image the surface of cellulose 1α from Gluconoacetobacter xylinus as well as cellulose 1β from native and organosolv treated poplar and noted molecular scale features of the cellulose submicrofibril particles. Near-field scanning optical microscopy (NSOM) uses a sharpened optical fiber as scanning probe, which is energized with monochromatic light.  The probe is scanned a few tens of nanometers over the sample surface and the transmitted and/or reflected energy is measured. The resulting optical signals provide information about the local properties of the sample in the sub-wavelength scale.  We will also discuss preliminary studies of the impact of AFEX pretreatment and enzyme action on selected biomass surfaces using AFM.