Bone tissue engineering typically involves the use of porous, bioresorbable scaffolds to serve as temporary, three-dimensional scaffolds to guide cell attachment, differentiation, proliferation, and subsequent tissue regeneration. In this study we developed a composite membrane scaffold by phase inversion technique by using biodegradable polyester, Polycaprolactone (PCL), with hydroxyapatite (HA) in order to develop novel controlled nanostructured biomaterials for bone tissue engineering applications.After preparation, membrane scaffolds were characterized in order to evaluate its morphological, physico-chemical and mechanical properties and then used for the cell culture.

Our experimental design consists to apply the knowledge of natural bone tissue remodelling in an in vitro membrane biohybrid system. We used human mesenchymal stem cells for culture in the membrane scaffolds inducing the differentiation in osteoblasts and human monocytes to trigger osteoclastogenesis. Osteoclastic resorption of the scaffold material would lead to subsequent induction of osteoblasts and faster bone formation with mesenchymal stem cells. Our results show that osteoblasts and osteoclasts were successfully differentiated in the developed PCL-HA membrane scaffold. This membrane system will lead to insights in the creation of a controllable osteoinductive microenvironment based on the specific properties (e.g. basic composition, surface chemistry, architecture) and on the function (resorption coupled to proliferation and differentiation) of defined cellular systems.

The Renewable Fuels Standard (RFS) and Energy Independence and Security Act of 2007 (EISA) mandated that 36 billion gallons of biofuels should be blended into transportation fuel by 2022. Implementing this will help reduce greenhouse gas emissions, reduce petroleum imports and encourage the development and expansion of US renewable fuels sector within rural America. Of the 36 billion gallons of biofuels, 16 billion gallons is expected to be from lignocellulosic biomass such as trees and grasses. The Black Hills of South Dakota is rich in ponderosa pine. This feedstock for bioethanol production, which is widely available due to recent pine beetle infestation, will not only add to the RFS requirement, it will also have a positive impact on rural economies in South Dakota. From the wood chips of pine, after acid pretreatment and enzymatic hydrolysis, the fermentable sugars obtained are relatively dilute in concentration (∼20-30 g/L). Hence, within a biorefinery, to increase the fermentation efficiency and decrease downstream processing cost of the biofuels, concentrating the sugars can be beneficial. In this study, Reverse Osmosis (RO) and Nanofiltration (NF) membranes were tested with complex lignocellulosic hydrolysate samples for their ability to concentrate sugars prior to fermentation. Fouling analysis and membrane characterization for both RO and NF membranes were performed by SEM, AFM, BET, contact angle and FTIR spectroscopy. Efficiency of membranes for their ability to separate fermentation inhibitors (e.g., organic and mineral acids, furans and phenolic compounds) from sugars, while simultaneously concentrating the sugars was studied to make the bio-ethanol production process cost and energy efficient. Three commercial nanofiltration membranes GE-R, TS40 and SR100 showed very promising results. GE-R concentrated sugars to more than 2.5 fold in the retentate, and simultaneously separated more than 50% of the inhibitory components into permeate. These results will increase the fermentation efficiency and reduce downstream purification costs of the produced fuel.

We describe a hybrid organic-inorganic fuel cell membrane material based on silica colloidal crystal and using EEMA/SPM co-polymers. We demonstrate that there is an S-shaped dependence of proton conductivity on the amount of sulfonyl groups in the copolymer for the copolymer-modified membranes and that there is no significant increase in proton conductivity with increasing amount of sulfonated monomer content above 60%. The studies of fuel cell potential dependence on the degree of sulfonation show that the presence of non-ionic moieties improves the performance of fuel cell, likely due to the reduction of methanol cross-over through the membrane. The fuel cells using the polymer-modified silica colloidal membranes perform better than Nafion 117.

We prepared colloidal crystals by self-assembly of gold-coated silica nanospheres, and formed free-standing nanoporous membranes by sintering these colloidal crystals. We modified the nanopore surface with ionizable functional groups, by forming a monolayer of L-cysteine or by surface-initiated polymerization of methacrylic acid. Diffusion experiments for neutral and cationic dyes showed that transport through these surface-modified Au-coated colloidal membranes can be controlled by pH and presence of metal cations.