Proceedings of the 38th Annual Biochemical Engineering Symposium

The 38th Annual Biochemical Engineering Symposium was held at the Pingree Park Campus and Conference Center, Colorado State University, 22-23 May 2009. The following institutions were represented; Colorado State University, Iowa State University, Kansas State University and the South Dakota School of Mines. This Proceeding contains papers based on most of the oral presentations. The first symposium was first held in 1971. It has been held annually since then except for a one year break. The following institutions have hosted the symposium. Contents History of the Annual Biochemical Engineering Symposium - Larry E. Erickson, Department of Chemical Engineering Kansas State University, Manhattan, Kansas 66506 Enhanced Solid-Liquid Clarification of Lignocellulosic Slurries Using Polyelectrolyte Flocculating Agents - Devon R. Burke, Jason Anderson, Patrick C. Gilcrease and Todd J. Menkhaus, Department of Chemical and Biological Engineering South Dakota School of Mines and Technology, Rapid City, SO 57701 Removal and Recovery of Inhibitory Compounds from Pine Slurry Hydrolysates using a Polyelectrolyte Flocculating Agent - Brian Carter, Todd J. Menkhaus, and Patrick C. Gilcrease Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SO 57701 The thioesterases: A new perspective based on their primary and tertiary structures - David C. Cantu, Yingfei Chen, and Peter J. Reilly Department of Chemical and Biological Engineering, Iowa State University, Ames, lA 50011 Tailoring Polysaccharide-Based Nanostructured Biomaterials for Guided Mesenchymal Stem Cell (MSC) Response - Jorge Almodóvar, Matt J. Kipper, Department of Chemical and Biological Engineering, Colorado State University, School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523-1370 Nanoassembly of polysaccharide based polyelectrolytes: Tuning morphology and Size - Soheil Boddohit, Jorge Almodóvar, Hao Zhang, Patrick A. Johnson, and Matt J. Kipper, Department of Chemical and Biological Engineering, Colorado State University, School of Biomedical Engineering, Colorado State University, Fort Collins CO, 80523, Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie WY, 82071 Vertical Cell Assembly of Colloidal Crystal Films for Making Inverse Colloidal Crystal Membrane: A New Generation Ultrafiltration Membrane for Protein Separation - Xinying Wang, Scott M. Husson, Xianghong Qian, S. Ranil Wickramasinghe, Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523https://lib.dr.iastate.edu/bce_proceedings/1037/thumbnail.jp

128 - Mohammadhasan Hedayati

Biomaterials and medical devices induce tissue responses when they get into contact with human blood and rapidly becomes covered with a layer of nonspecifically adsorbed proteins. For blood contacting devices, protein adsorption is undesirable and is generally the first event in blood coagulation. The polymer coating on solid surfaces is an efficient approach for modification of materials to design protein resistant biomaterials. The aim of this work is to mimic the endothelial glycocalyx layer on the surface of blood vessels, which is responsible for anticoagulant activity by restricting molecules such as proteins from reaching the endothelium.Great Minds in Research - 1st Place

Improved in vitro endothelialization on nanostructured titania with tannin/glycosaminoglycan-based polyelectrolyte multilayers

Abstract Purpose Blood compatibility of cardiovascular implants is still a major concern. Rapid endothelialization of these implant surfaces has emerged as a promising strategy to enhance hemocompatibility and prevent complications such as thrombus formation and restenosis. The successful endothelialization of implant surfaces mostly depends on the migration of endothelial cells (ECs), the differentiation of stem cells, and the inhibition of smooth muscle cell (SMC) proliferation. Our previous study demonstrated that nanostructured titania surfaces modified with polyelectrolyte multilayers based on tanfloc (a cationic tannin derivative) and glycosaminoglycans (heparin and hyaluronic acid) have improved antithrombogenic properties. Methods In this work, we used in vitro cell culture of ECs and SMCs to investigate the outcomes of these surface modifications on endothelialization. The cells were seeded on the surfaces, and their viability, adhesion, and proliferation were evaluated after 1, 3, and 5 days. Indirect immunofluorescent staining was used to determine the cellular expression of ECs through the presence of specific marker proteins after 7 and 10 days, and EC migration on the NT surfaces was also investigated. Results The surfaces modified with tanfloc and heparin showed enhanced EC adhesion, proliferation, and migration. However, SMC proliferation is not promoted by the surfaces. Therefore, these surfaces may promote endothelialization without stimulating SMC proliferation, which could improve the hemocompatibility without enhancing the risk of SMC proliferation leading to restenosis. Conclusions The surface modification here proposed is a promising candidate to be used in cardiovascular applications due to enhanced antithrombogenic and endothelialization properties

Aggrecan-Mimetic, Glycosaminoglycan-Containing Nanoparticles for Growth Factor Stabilization and Delivery

The direct delivery of growth factors to sites of tissue healing is complicated by their relative instability. In many tissues, the glycosaminoglycan (GAG) side chains of proteoglycans like aggrecan stabilize growth factors in the pericellular and extracellular space, creating a local reservoir that can be accessed during a wound healing response. GAGs also regulate growth factor-receptor interactions at the cell surface. Here we report the development of nanoparticles for growth factor delivery that mimic the size, GAG composition, and growth factor binding and stabilization of aggrecan. The aggrecan-mimetic nanoparticles are easy to assemble, and their structure and composition can be readily tuned to alter their physical and biological properties. We use basic fibroblast growth factor (FGF-2) as a model heparin-binding growth factor, demonstrating that aggrecan-mimetic nanoparticles can preserve its activity for more than three weeks. We evaluate FGF-2 activity by measuring both the proliferation and metabolic activity of bone marrow stromal cells to demonstrate that chondroitin sulfate-based aggrecan mimics are as effective as aggrecan, and heparin-based aggrecan mimics are superior to aggrecan as delivery vehicles for FGF-2

Mechanical Properties and Cell Compatibility of Agarose Hydrogels Containing Proteoglycan Mimetic Graft Copolymers

Proteoglycans have vital biochemical and biomechanical functions. Their proteolytic degradation results in loss of these functions. We have previously reported nonprotein proteoglycan-mimetic graft copolymers that stabilize and deliver growth factors and are not subject to proteases. Here we expand our investigation of these proteoglycan mimics by also investigating their effects on hydrogel mechanical properties. Four polysaccharide side chains, chondroitin sulfate, heparin, dextran, and dextran sulfate, are each grafted to a hyaluronan backbone. The polysaccharides and graft copolymers are added to agarose hydrogels. Cyclic compression and stress relaxation tests reveal how the addition of the polysaccharides and graft copolymers influence hydrogel modulus. Cells encapsulated in agarose hydrogels containing chondroitin sulfate and the chondroitin sulfate graft copolymer have decreased cell viability and metabolic activity compared to cells in unmodified agarose hydrogels. These multifunctional additives can be used to improve both the biochemistry and biomechanics of materials, warranting further optimization to overcome the potentially negative effects these may have on cell viability and activity

Synthesis and Characterization of Proteoglycan-Mimetic Graft Copolymers with Tunable Glycosaminoglycan Density

Proteoglycans (PGs) are important glycosylated proteins found on the cell surface and in the extracellular matrix. They are made up of a core protein with glycosaminoglycan (GAG) side chains. Variations in composition and number of GAG side chains lead to a vast array of PG sizes and functions. Here we present a method for the synthesis of proteoglycan-mimetic graft copolymers (or neoproteoglycans) with tunable GAG side-chain composition. This is done using three different GAGs: hyaluronan, chondroitin sulfate, and heparin. Hyaluronan is functionalized with a hydrazide-presenting linker. Either chondroitin sulfate or heparin is grafted by the reducing end on to the hyaluronan backbone through reductive amination. PG mimics with heparin or chondroitin sulfate side chains and four different ratios of GAG side chain result in graft copolymers with a wide range of sizes. The chemistry is confirmed through attentuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and ¹H NMR. Effective hydrodynamic diameter and zeta potential are determined using dynamic light scattering and electrophoretic mobility measurements. Graft copolymers were tested for their ability to bind and deliver basic fibroblast growth factor (FGF-2) to mesenchymal stem cells (MSCs). The chondroitin sulfate-containing graft copolymers successfully deliver FGF-2 to cells from surfaces. The lowest graft density of heparin-containing PG mimic also performs well with respect to growth factor delivery from a surface. This new method for preparation of GAG-based graft copolymers enables a wide range of graft density, and can be used to explore applications of PG mimics as new biomaterials with tunable biochemical and biomechanical functions