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G.R.A.S.S. – Mengfei Huang (Klier/Schiffman Group) and Yongkuk Park (Lee Group)

Date/Time: 

Tuesday, October 8, 2019 - 11:30am

Location: 

LGRT 201

Details: 

Mengfei Huang – John Klier/Jessica Schiffman Lab

 

High-Performance Coatings Featuring Methylene Malonate Derivatives

Mengfei Huang1, Yuan Liu1, Aniruddha Palsule,2 John Klier1, Jessica Schiffman1,

1 Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, MA 01003, USA

2 Sirrus, Inc., 422 Wards Corner Rd., Loveland, OH 45140

 

Novel methylene malonate (MM) monomers can be synthesized economically using petro-based or renewable feedstocks. Interestingly, they undergo reactive anionic polymerization in an ambient environment in water. This attribute provides a powerful and simple new approach to enhance the properties of emulsion polymers, waterborne coatings and related applications that would benefit from greener chemistries. In this work, we have demonstrated the direct emulsion polymerization of MM initiation in aqueous solutions at various pH values and functional groups. Polymerization was also readily initiated from latex particle surfaces. This strategy was employed to introduce high functional group densities to the latex particles, providing attributes, such as ultraviolet (UV) crosslinking, free radical crosslinking, antifouling and mechanical properties to the latexes and coatings derived therefrom. Systematic studies were conducted on the UV curing of methacrylate functionalized latex films to determine their thermal properties, mechanical strength, crosslinking density and composition. Rapid UV curing and high crosslinking densities enabled the synthesis of high-performance coatings based on a very simple in-situ latex modification. This study provides a simple, new, in-situ and readily scalable chemistry and methodology to significantly enhance the performance of emulsion polymers, latex systems, pigments and the resulting coatings and other materials.

 

 

Yongkuk Park – Jungwoo Lee Lab

 

Development of in vitro bone models on demineralized compact bone slices

Yongkuk Park1, Jungwoo Lee1,2

1Department of Chemical Engineering, Institute for Applied Life Sciences,

2Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003.

 

The trabecular bone undergoes repeated surface remodeling throughout the lifetime by bone-forming osteoblasts and bone-resorbing osteoclasts to maintain the mechanical and mineral homeostasis. Furthermore, osteocytes buried in bone matrix and comprising more than 90% of total bone cells play critical roles in regulating many aspects of the bone tissue biology. However, it’s hard to study the detailed mechanism due to anatomical inaccessibility of the inner bone cavity in living animals. Alternatively, in vitro models have been developed but there exists no experimental method that addresses natural bony extracellular matrix structure and material as well as optical accessibility. Here, we propose that a thin slice of demineralized compact bone retaining intrinsic complexity of bony extracellular matrix with semi-optical transparency would be a novel biomaterial platform for in vitro bone modeling. Osteoblasts on the bone slice deposited much higher amount of mineral than the osteoblast on well plate, indicating that microenvironments of culture condition could influence on the cell activity and physiology. In addition to osteoblasts culture, mature osteoclasts and their resorption were also confirmed by the real-time imaging. Osteoclasts formed two different resorption patterns, trench and pit. Our results demonstrated that the bone slice provides suitable microenvironment for the osteoblasts and osteoclasts culture. Their activities were successfully captured through the real-time imaging. Moreover, we developed novel method to achieve osteoblast-to-osteocyte differentiation by taking advantage of native bony biomaterials and tissue engineering strategies. We hypothesize that the progressive changes mechanical and physical environment is required to induce osteoblast-to-osteocyte differentiation in vitro. We tested the hypothesis by stacking 5 layers of bone slice to mimic the inner structure of bone tissue. As a further step, the multi-layered bone slice with osteoblasts was cultured in bioreactor under hypoxia, which is much similar to the microenvironment of inner bone tissue. In the multi-layered bone slice, osteoblasts entrapped by collagen matrix and deposited mineral, then, the osteoblasts underwent the osteocyte differentiation. Well-aligned cell morphology of osteoblasts was dramatically turned into the dendritic-like shape. Dendrites of cells connected to each other, which is very similar to the osteocyte in vivo. Furthermore, DMP-1 and SOST gene expressions of isolated osteoblasts highly increased after mechano-culture under hypoxic condition, indicating that mechanical stress and hypoxic condition accelerate the osteocyte differentiation by making similar microenvironment to in vivo condition. We envision that the demineralized bone slice will be an enabling tool for studying bone tissue biology in vitro.

 
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