Aligning Bacterial Cellulose

Transcription

1 2006 International Conference on Nanotechnology, April 26-28, 2006 Atlanta, GA Aligning Bacterial Cellulose Nicole R. Brown Assistant Professor The School of Forest Resources The Materials Research Institute Penn State University

2 Acknowledgements Collaborator: Prof. Jeffrey Catchmark -Assistant Professor, College of Engineering & College of Agricultural Sciences -Operations Manager, PSU Nanofabrication facility, NSF NNIN Site Undergrads Michelle & Mariel Cruz

3 Assembly in Plant Cell Walls Native hierarchical assembly Cellulose microfibril Vincent Enzyme rosette Microtubule Cote

4 Specific Mechanisms of Assembly in Plant Tissues Not well understood Recent Developments Cellulose microfibril Vincent Enzyme rosette Microtubule

5 Motivation for studying nano-scale fiber assembly? 1. Understand what is happening in nature Watch/monitor natural fiber assembly process Effects of our treatments? 2. Address needs relating to cellulose fibers/industry: Efficient fiber utilization Improved properties (physical, chemical, environmental) for composites

6 Motivation for studying nano-scale fiber assembly? 3. Value-added products from natural materials: Biomedical: filters, sensors, anti-microbial surfaces Electronic: RFIDs on fiber based substrates like paper Optical: Optical indicators or displays on paper

7 Assembly Efforts Acetobacter xylinum Simple system No lignin! Easy to culture Manipulations to system can be investigated rather easily Acetobacter xylinum producing cellulose (A. Hirai)

8 Assembly Efforts Acetobacter xylinum Key Question: Do electric fields influence the alignment of cellulose fibers?

9 Applied potential in buffered solution The Experiment 20 mv, DC Investigate biofilm via SEM Bacteria culture in sugar water (buffered)

10 Preliminary Result Control

11 Preliminary Result Film after perturbation Location of electrodes

12 Preliminary Result Control Film after perturbation Location of electrodes Preliminary results in our laboratory suggest DC electric fields are capable of aligning cellulose fibers.

13 Future work Varying ph conditions Use of AC current potential for novel morphologies? Mechanical effects of alignment

14 Future milestones Design a system where bacteria are fixed in a given position and extrude cellulose that can be harvested Bacterium Cellulose Facilitating growth of the biofilm Others

15 Biomotors Assembly Attempt #2 Biomotors Transport intercellular cargo on microtubules Chemically powered hydrolysis of adenosine triphosphate (ATP) Microtubules Cylindrical polymers which form dynamically inside cells to enable transport Biomotors walk uni-directionally on microtubules Newt lung cell Centrosome Cooper, 2nd ed.

16 Background Biomotors & microtubules are proteins Families: kinesin, dynein, myosin and others Microtubules polymerize and depolymerize according to presence of GTP/GDP 25 nm Plus end 7 nm Kozielski et al. Nogales et al. Cooper, 2nd ed.

17 Biomotors are Studied using Motility Assays Bead assay (Biomotor in solution): - End + End Gliding assay (Biomotor is bound to surface): - End + End Glass Substrate Microtubule Direction Casein of motion Kinesin Cargo protein

18 Motility Assays Gliding Motility Assay Bead Assay Microtubules labeled with rhodamine

19 Microtubule Aster Fireworks Rhodamine-labeled microtubule asters assembled with 4-kinesin motor assembly interacting with motor coated surface which tears assembly apart

20 Microtubule Aster Fireworks

21 Summary Assembly studies: Could help us understand natural assembly Could give us means of producing novel cellulosic materials

22 Thank you! Nicole R. Brown Jeff Catchmark