RESUMEN
Different fluorocarbon thin films were deposited on Si substrates using two different plasma polymerization methods. Fluorine-containing hydrophobic thin films were obtained using inductively coupled plasma (ICP) and capacitively coupled plasma (CCP) with a mixture of fluorocarbon precursors (C2F6, C3F8, or c-C4F8) and an unsaturated hydrocarbon (C2H2). Different process parameters for plasma polymerization (e.g., processing time) were used to generate various fluorocarbon thin films. The hydrophobic properties and mechanical properties of the new products were measured using a profilometer, water contact angle measurements, pencil hardness, and a 90° peel test. The chemical compositions of the fluorocarbon thin films were characterized using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The water contact angle results showed that the ICP technique provides a more hydrophobic surface compared to the CCP technique. XPS and FT-IR analyses indicated that the ICP technique generated more fluorine-related functional groups (i.e., CF-CFn, CF2, and CF3) in the surface region, while the CCP technique produced fewer fluorine-containing functional groups. However, the fluorocarbon thin films produced using the CCP technique showed greater adhesive strength than did the fluorocarbon thin films produced using the ICP technique. These results are useful to establish the optimal condition for the fabrication of fluorocarbon films and to develop the device in bio-sensing applications.
RESUMEN
In general, the formation of embryoid bodies (EBs) is a commonly known method for initial induction of human embryonic stem cells (hESCs) into their derivatives in vitro. Despite the ability of EBs to mimic developmental processing, the specification and classifications of EBs are not yet well known. Because EBs show various differentiation potentials depending on the size and morphology of the aggregated cells, specification is difficult to attain. Here, we sought to classify the differentiation potentials of EBs by morphologies to enable one to control the differentiation of specific lineages from hESCs with high efficiency. To induce the differentiation of EB formation, we established floating cultures of undifferentiated hESCs in Petri dishes with hESC medium lacking basic fibroblast growth factor. Cells first aggregated into balls; â¼10 days after suspension culture, some different types of EB morphology were present, which we classified as cystic-, bright cavity-, and dark cavity-type EBs. Next, we analyzed the characteristics of each type of EB for its capacity to differentiate into the 3 germ layers via multiplex polymerase chain reaction (PCR), real-time PCR, and immunocytochemistry. Our results indicated that most cells within the cystic EBs were composed of endoderm lineage populations, and both of the cavity EB types were well organized with 3 germ-layer cells. However, the differentiation capacity of the bright cavity EBs was faster than that of the dark cavity EBs. Thus, the bright cavity EBs in this study, which showed equal differentiation tendencies compared with other types of EBs, may serve as the standard for in vitro engineering of EBs. These results indicate that the classification of EB morphologies allows the estimation of the differentiation status of the EBs and may allow the delineation of subsets of conditions necessary for EBs to differentiate into specific cell types.
