1. Biomass Fundamentals Module 14: Lignin II: Specialty Applications A capstone course for BioSUCCEED: Bioproducts Sustainability: a University Cooperative Center of Excellence in EDucation The USDA Higher Education Challenge Grants program gratefully acknowledged for support

2. This course would not be possible without support from: USDA Higher Education Challenge (HEC) Grants Program www.csrees.usda.gov/funding/rfas/hep_challenge.html

3. What is “lignin?” The amorphous glue that binds carbohydrate bundles A complex, polydisperse (weight average MW/Number average MW  measure of distribution of individual MWs) polymer A source of endless discussion for the exact nature of its biosynthesis in plants (enzyme controlled vs. random radical coupling) C 9 polypropylphenol derivative

4. Lignin Biosynthesis

5. Structures of Lignin Precursors

7. Flavonoids: Chemical Offshoots of Lignin Biosynthesis 15 carbon atom compounds (C 6 - C 3 -C 6 ) – over 4000! Polyphenol Phytochemicals (phenolic acids, stilbenes, polyphenols) Antioxidants CV health: reduce agglomeration of platelets in endothelia Assist lignification of cell walls in plants in response to injury Antimicrobials

8. Biologically Active Isoflavonoid Rotenone comes from Derris root and Lonchocarpus species Insecticide Fish poison Topical treatment of head lice, scabies, and ectoparasites

9. Rheological Properties of Lignin Schematic illustration of secondary cell wall of spruce tracheids Between ordered cellulose fibrils is the lignin-hemicellulose matrix Various vibrational studies (static & dynamic FT-IR) of lignin functional groups suggest lignin is ordered in plane with the plane of cell wall surface Distribution, however, is not ISOTROPIC in fiber wall

10. Rheological Properties of Lignin, Part Deux Monolignols couple/polymerize under environmental constraints along fiber axis to ordered polysaccharide matrix Polysaccharides templates*? A high response in a 90° out-of-phase spectrum with lignin peaks indicates a more viscoelastic behavior for lignin over carbohydrates – also can move freely in matrix unperturbed by carbohydrates *

11. Lignin in Composite/Industrial Applications Lignosulfonates Extrusion moldings Fuel Fertilizer/agricultural adjuvant Potential raw material for fine chemical production

12. Lignin as a Medical “Tissue” Wood and bone possess unique structural motifs that fulfill requirements of support & transport of nutrients Is it possible, therefore, to use wood as a implantable material? Can it be used, for example, as a femoral replacement?

13. Technical Hurdles to Address Toxicity Compatibility Adsorption Functionality Mechanical Properties

14. What is Bone? Ceramic-polymer composite Calcium phosphate (hydroxyapatite) and collagen The apatite has different metal ions that adjust solubility and availability of mineral elements to rest of body Small apatite platelets crystallize in preferred locations on collagen

15. Ultrastructure of Bone

16. Attempts to Mimic Bone MOE: *Hydroxyapatite + polyethylene – middle ear implants, maxillofacial reconstruction, & bone repair; possesses MOE similar to bone Porosity: Porites (coral species) have similar pore size & interconnectivity; CaCO 3 (aragonite in coral)  hydroxyapatite by hydrothermal process Hierarchical Structure: tendon, muscle, WOOD, and bamboo *

17. van Leeuwenhoek’s Famous Comment When he first recognized the Haversian canals in bone in 1693, he made reference to other hierarchical structures:

18. Structure & Function of Wood Wood is a polymer of 20-30% lignin and the virtual remainder carbohydrates Tracheid (osteocyte in bone) is “cell” Tracheids consists of 5-30 nm wide microfibrillar elements composes of cellulosic strands (2.5 nm diameter) Wood is porous and operates on negative pressure osmotic gradients in lumens and valves in pits – transport in bone is positive pressure from circulation of nutrients

19. Morphological Structure of Juniperus communis A: annual rings; B: rays & pits; C: pirs in a ray connecting adjacent tracheid; D: Helical texture of spiraling cellulose strands outside a tracheid

20. Bone & Wood Collagen is bone’s counterpart to wood’s cellulose Alternating fibrillar orientation in the various lamellae in bone and wood imparts strength & toughness Pore networks differ only in size and connectivity

21. Material Property Chart for Orthopedics

22. Histological Section of Juniper Wood A: cortical bone after 3 mos. B: cortical bone after 6 mos. C: trabecular bone after 6 mos. D: Cortical bone after 1.5 years E: cortical bone after 3 years

23. Conclusions from Medical Study No infection, serendipitously due to wood oils Boiling wood to remove excess oil and any microorganisms lowered MOE, better mechanical fit to wood (see chart) Wood well tolerated by body – surrounded by bone Even bone growth into open pores and artificial microchannels (a priori machining) for improved integration