Diacrylate Solution Research Articles

Determination of diffusion coefficient and partition coefficient of photoinitiator 2-hydroxy-2-methylpropiophenone in nanoporous polydimethylsiloxane network and aqueous poly(ethylene glycol) diacrylate solution

We determine diffusion and partition coefficients of 2-hydroxy-2-methylpropiophenone, a widely used photo-initiator, in nanoporous polydimethylsiloxane network and poly(ethylene glycol) diacrylate solution as model precursor solution. We spectroscopically measure average concentration of 2-hydroxy-2-methylpropiophenone in each media, which is compared to the one estimated from one-dimensional diffusion models to obtain diffusion coefficient. Partition coefficient is obtained by measuring saturated concentration of 2-hydroxy-2-methylpropiophenone in each media. Our results enables predicting concentration of 2-hydroxy-2-methylpropiophenone as it diffuses from precursor solution to crosslinked PDMS, which typically occurs when hydrogel is formed inside microfluidic device via photo-polymerization to create nano-structured or micro-structured hydrogel including microfluidic valves.

Simple Generation of Human Induced Pluripotent Stem Cells Using Poly-β-amino Esters As the Non-viral Gene Delivery System

Reprogramming of somatic cells to induced pluripotent stem (iPS) cells can be achieved by the delivery of a combination of transcription factors, including Oct4, Sox2, Klf4, and c-Myc. Retroviral and lentiviral vectors are commonly used to express these four reprogramming factors separately and obtain reprogrammed iPS cells. Although efficient and reproducible, these approaches involve the time-consuming and labor-intensive production of retroviral or lentiviral particles together with a high risk of working with potentially harmful viruses overexpressing potent oncogenes, such as c-Myc. Here, we describe a simple method to produce bona fide iPS cells from human fibroblasts using poly-β-amino esters as the transfection reagent for the delivery of a single CAG-driven polycistronic plasmid expressing Oct4, Sox2, Klf4, c-Myc, and a GFP reporter gene (OSKMG). We demonstrate for the first time that poly-β-amino esters can be used to deliver a single polycistronic reprogramming vector into human fibroblasts, achieving significantly higher transfection efficiency than with conventional transfection reagents. After a protocol of serial transfections using poly-β-amino esters, we report a simple methodology to generate human iPS cells from human fibroblasts avoiding the use of viral vectors.