Surface Active Protein Polymers Research (Evolved from KSU Targeted Excellence Program) (X. Susan Sun (PI), John Tomich, Donghai Wang, Bruce Law, Kevin Lease, Amit Chakrabarti, Jianhan Chen):
We focus on design and discover novel protein polymers with desirable commercial properties for industrial applications, including protein structure design, thermal dynamics, theory and modeling, rheology and mechanics, surface chemistry, and reaction pathways. Protein polymers at peptides scale are designed and synthesized by using both chemical and physical methods. Protein polymers at polymer scale are designed and synthesized using biosynthesis method. Various chemical reaction pathways are applied to these protein polymers at both peptide and polymer scales. These materials are characterized for structure, thermal dynamics, rheology, adhesion mechanics, surface chemistry, and other functional properties for adhesives and coating materials. Computer simulation and percolation modeling will be used to develop theoretical equations at both peptides and polymer scales. In coupling with experimental data, structures desirable for surface active polymers for adhesive and coating applications are identified. Protein polymer structures and properties as surface active polymers should be predictable by designing the protein polymers at peptide scale.
Soft Matter Physics ((Chakrabarti, Flanders, Law, Sorensen and Szoszkiewicz): Five physics faculty are involved in soft matter physics at the nano/bio interface. This research group enjoys interdisciplinary collaborations with faculty in chemistry, biology and biochemistry. Research includes nanoparticle synthesis and assembly into ordered two and three dimensional arrays (super-crystals), the physical chemistry of nanoparticle solutions, gel formation, wetting and lubrication properties of solutions of nanoparticles, electronic and optical properties of nanostructures, liquid surface nanostructures, biopolymer mechanical properties and physical properties of living cells. Equipment in our laboratories includes light scattering devices, spectrometers, X-ray diffraction, transmission electron microscopy, ellipsometers, aerosol generators, combustion apparatus, and atomic force microscopes.
Nanometer Stoichiometric Particle Compound Solutions and Control of their Self-Assembly into the Condensed Phase (NSF/NIRT) (Chris Sorensen (PI), Aakeroy, Amit Chakrabarti, Ken Klabunde, Bruce Law):
Our goal is to create a new family of nanometer “stoichiometric particle compounds,” or what could also be called nanoparticles of all the same size, and control their active assembly into condensed phases. In order to do this, understanding and control of solution phase and interfacial properties is needed. Understanding of particulate self-assembly to yield two and three dimensional superlattices, films and gels is also needed. To achieve this goal a series of nanomaterials will be synthesized in large amounts and will be “nanomachined” (digestively ripened) to molecular stoichiometry and stabilized with selected surface ligands. The ligands will be chosen for their tendencies to be hydrophobic or hydrophilic, their ability to form ordered monolayers, and to hydrogen bond and/or interdigitate with neighbors. In this way solution phase behavior, aggregation, crystallization to form superlattices, and assembly into various structures will be controlled.
Physics-based modeling of biomolecules (Jianhan Chen, John Tomich, Ahlam Al-Rawi):
We are specialized in physics-based modeling of biomolecules at atomic and larger scales. These computer simulations can provide the critical insights that are otherwise inaccessible by experiments, and often serve as a foundation for generating new hypotheses and new directions for further research. At present, we are mainly interested in two important classes of peptides, namely, membrane-inserting peptides and intrinsically disordered peptides. Spontaneous membrane insertion of peptides is essential in a vast array of crucial cellular processes, including those involved in antimicrobial defense and viral membrane
fusion. Intrinsic disorder in proteins has been recently recognized to play critical roles in crucial biological processes involved in cellular regulation and signal transduction. The computational
techniques developed in our research will be directly applicable to rational design of new functional biopolymers, in particular, a new generation of peptide-based antibiotics.
Bio-based Adhesive Research, (DOE/USDA/DOD/USB/KS Soy Commission) (X. Susan Sun (PI), Donghai Wang): Large amount of petroleum based and synthetic adhesives and coatings are used worldwide. These materials contain hazardous chemicals including formaldehyde, isocyanate, vinyl acetate or acetaldehyde and polyvinyl alcohol and many other chemicals. There is a need to develop alternatives from biobased materials. Biobased materials from agriculture feedstock and biofuel residues are used as raw materials. We chemically modified the biobased materials and develop a variety of biobased adhesives for various applications. We are specialized to turn soy protein polymers into materials that have potential for adhesives and coating applications. We characterize protein structure, amino acids composition, and reaction pathways against adhesive performance. We have developed technologies using the soy protein based adhesives for wood products (plywood, wood veneer, fiberboard), silicon sand, cellulosic fiber, ceramics, and glass for labeling and packaging applications..
Bioplastic Research, DOE/KS Wheat Commission/Industries
(X. Susan Sun (PI), Paul Seib, Ken Klabunde):
Humanity is facing a severe energy crisis due to limited fossil fuel resources.
Petrochemical based products industries are being challenged for raw material supplies. On the
other hand, the environment impact of persistent petroleum-based waste is of growing global
concern. Poly(lactice acid) (PLA) is a polyester derived from sugar based biomass through
bioconversion and polymerization. To reduce cost for raw materials, starch is used as a filler and co-polymer through thermal blending with PLA. Interface between starch granules and PLA was improved by using coupling reagents. Mechanical properties of PLA with 45% starch are similar to the neat PLA. Soy flour and wood flour are also used as fillers for PLA composites. Nanocrystals tetra-hydroxyl magnesium oxide has been incorporated into PLA. The incorporation of nanocrystals into PLA matrix improves tensile strength and modulus by 25%, and enhances the processability of the nanocomposites. We characterize thermal phase transitions, rheology, thermal dynamics, crystallinity, phase separation, physical aging, water resistance, plasticization, morphology, and degradability of PLA and its blends.
Next Generation of Bio/Nano Polymers (X. Susan Sun, Ken Klabunde, Duy Hua, Chris Sorensen, John Tomich, and Amit Chakrabarti):
The goals of this research program are to develop synthetic techniques to create plastics with both useful and desirable mechanical properties and programmable biodegradability from abundant biobased materials. There are a few examples of biobased plastics that have been synthesized in the past decade. However, these bioplastics are far behind the petroleum based plastics in terms of performance and processibility. We will use three well known and biodegradable biomaterials as sources for polymerization. We will explore novel synthetic pathways of biobased chemicals (i.e., lactic acid) by introducing structure-designed nanocrystals, peptides, and functionalized triglycerides during synthesis of lactic acid. Co-monomers of lactic acid with these structured and functionalized biopolymers and nanocrystals will also be synthesized and polymerized. We will also look at other selected bio-derived monomers, such as glycolic acid, succinic acid, and glutamic acid. We will test the macroscopic physical properties of our synthesized materials and correlate these properties to the microstructure and perform simulations to understand the causes of the material properties. Iteration between synthesis, characterization, microstructure analysis and simulation will allow us to develop new biobased materials with useful properties.
Viscoelastic Biopolymers, Industries (Duy Hua, Yongcheng Shi, X. Susan Sun):
Chewy candies and chewing gums are still popular consumer products. Current materials for chewing gum carrier are petroleum based polymers or synthetic materials. These materials are not edible nor biodegradable, but stick to carpets, walls, or anywhere it is disposed, which causes environmental problems and also cost to clean. The objective of this research is to discover and develop novel biobased polymer composites from grains (protein, starch, lipids) that can be used to replace or partially replace current chewing gum carrier materials. We do biopolymer isolation, modification, and functionalization. We characterize viscoelastic properties of the prepared biopolymer composites and their blends including tensile strength, elongation, cohesiveness, springness, chewiness, and adhesiveness using texture analyzer with a special extension accessory. We also characterize dynamic viscoelastic properties, thermal behavior, glass transition temperatures, denaturation, gelatinization, and melting temperatures and their enthalpies of the composites.
Computational modeling of biobased molecules and nanocrystals
(Christine Aikens, Amit Chakrabarti, Ken Klabunde):
The goal of this research is to study interactions of selected nanocrystals with biobased molecules (i.e., lactic acids, succinic acid, and glutamic acid, protein peptides, tryglycerides, and glucose). We have conducted modeling on reaction of lactic acid with MgO that will elucidate the initiation mechanism and thus aid in the structural determination of the polymer. First the reaction mechanism of biobased molecules (i.e., lactic acid) with free cluster of MgO will be examined. The minimum cluster size to be used in the calculations is (MgO)12 consisting of two layers each containing six MgO units. Initial calculations will employ this model cluster. A series of larger clusters will be examined in order to determine potential size effects. Multiple reaction mechanisms will be considered in order to explain the change in the polymer structure. In the beginning, PM3 semi-empirical calculations will be used to screen possible reaction mechanisms. PM3 results have previously been shown to be in agreement with density functional theory (DFT) calculations for the adsorption of water on nanocrystal surfaces. The semi-empirical method (MSINDO) will also be employed to screen potential reaction mechanisms.
Conversion of biomass sugars into chemicals with genetic engineered microorganisms
(Praveen Vadlani, Ken Klabunde, Susan Sun):
We will initially focus on two chemicals: succinic acid, and poly glutamic acid (PGA), which have both shown great potential as building blocks for several derivatives as surface active polymers. For example, poly butylene succinate (PBS) derived from succinic acid is a biodegradable aliphatic thermoplastic with excellent properties and wide applications including nanocomposites. In a collaborative project with Rice University researchers, the metabolic engineered E coli can improve production yield of succinic acid. PGA biopolymer has wide applications: medical adhesives, vaccines, PGA nanoparticles for on-site drug release in chemotherapy, and tissue engineering. γ-PGA will be produced from biomass sugars using a bacillus strain (bacillus amyloliquefaciens) isolated in the bioprocessing lab that has high cellulolytic activity. Other bacilli strains, such as B. licheniformis and B. subtilis, will also be investigated for γ-PGA biosynthesis. The precursor L-glutamic acid, required to be added for γ-PGA biosynthesis, will be produced microbially using either corynebacterium or brevibacterium strains in the lab. The biodegradable PBS and γ-PGA will be used to develop innovative applications for adhesives and coatings as well as bionanocomposites.
Enzymatic Conversion of Biomass into Fuels and Chemicals
(Keith Hohn, Donghai Wang, Dan Higgins)
The challenge to producing chemicals from cellulose is the difficulty in breaking down cellulosic matter to sugars. Both physical and chemical pretreatments have been used to break down the crystalline structure of biomass for sugar release. However, they are expensive and all of them are conducted under severe conditions. We propose three objectives to improve the conversion rate and reduce processing cost so that we can convert biomass into chemicals. We focus on design and acid-functionalization of nanoparticles as catalysis for biomass hydrolysis. Acid-functionalized nanoparticles can be synthesized to have specific chemical and physical properties that will make them ideal hydrolysis catalysts. The envisioned metal nanoparticle is functionalized with acidic ligands. In an aqueous solution, these ligands will dissociate to form protons that will then diffuse inside lignocellulose and catalyze hydrolysis of hemicellulose and/or cellulose. Once reaction is completed, the nanoparticles can be separated by magnetic separation because of the incorporation of a magnetic core.
(Yong-Cheng Shi, Hulya Dogan)
Mother Nature produces thousand billion tons of carbohydrate polymers (e.g. cellulose and starch) a year. Cellulose, hemicellulose, and starch based polymers are widely used in food, paper, adhesive, detergent, thermoplastic, pharmaceutical and cosmetic industries. Currently we are focusing on following projects:
The objective of this project is to develop novel lipophilic glucose polymers for emulsion, encapsulation and delivery applications. Glucose-based polymers are hydrophilic but can become lipophilic when they are substituted with alkenylsuccinic groups. Glucose polymers (e.g. starch) reacted with succinic anhydride containing a hydrophobic substitutent group yields products with emulsion stabilizing properties. Linear (alpha-1,4 linked), branched (alpha-1,4 and 1,6 linked), and cross-linked glucose polymers with different molecular weight, size and shape are experimentally designed and made. The length of the alkenyl hydrophobic group can vary from 1 to 20 carbons. Various degree of substitution can be achieved. The structure, solution, surface and inter-facial properties of these lipophilic glucose polymers are experimentally determined. The fundamental structure and properties relationship will be established for these carbohydrate polymers with hydrophobic groups.
The goal of this project is to understand the relationship between the structure of starch and its enzyme digestibility, and design starch molecules with controlled digestibility in foods. We examine how starch molecules are assembled into microcrystallites. The effects of chain length and crystallization conditions on crystal formation are investigated. The relationship between crystal type, degree of crystallinity, and crystal morphology of starch and its digestibility will be established.