Enrichment Of Poly Research Articles

Surface collagen functionalization of electrospun poly(vinyl alcohol) scaffold for tissue engineering

The limited solubility of collagen is one of the main limitations to achieving electrospun mats based on this biomacromolecule. Postelectrospinning functionalization has emerged as a suitable alternative for effective collagen incorporation into biocompatible nanofiber mats without compromising their bioactivity. In this work, the enrichment of poly (vinyl alcohol) (PVA) nanofibers was attained by their postelectrospinning surface functionalization with nonsolubilized collagen through the esterification of hydroxyl groups of the PVA backbone via Steglich esterification using mild conditions. FTIR and XPS confirmed successful ester bond formation, while the thermal and mechanical results show the different behavior of PVA nanofibers after functionalization. Collagen functionalization enhanced the cytocompatibility behavior of PVA nanofibers, promoting the growth of HEK-293 cells. Thus, this novel methodology allows for the bioconjugation of nonsolubilized collagen to the surface of PVA nanofibrous mats, producing cytocompatible scaffolds while preserving the structural capabilities of collagen to support cell attachment and proliferation.

Enrichment of poly- and perfluoroalkyl substances (PFAS) in the surface microlayer and foam in synthetic and natural waters

Bench-scale experiments were performed to interrogate poly- and perfluoroalkyl substance (PFAS) enrichment in the water surface microlayer (SML). In initial experiments using electrolyte-only solutions, the perfluorooctane sulfonate (PFOS) and perfluorooctane carboxylate (PFOA) enrichment in the SML were reasonably (with a factor of 2) described by the Gibbs adsorption equation coupled with a Freundlich-based interfacial adsorption model. Enrichment in the SML among perfluorinated sulfonates and perfluorinated carboxylates of varying chain lengths was proportional to their surface activity. The PFOS enrichment factor (EF), defined as the PFAS concentration in the SML divided by the concentration in the bulk water, was 18 in a 200 mg/l NaCl solution. The presence of elevated organic carbon levels in synthetic surface waters inhibited PFAS accumulation in the SML, with resulting EF values of approximately 1 for all PFAS. However, in the presence of elevated organic levels coupled with foam, PFAS enrichment in the foam was observed, with a foam EF of 25 measured for PFOS in synthetic surface waters. PFAS EF values measured in several natural surface waters without foam showed little variation among the waters tested, with PFOS EF values ranging between 6 and 10. Together, these results suggest that PFAS accumulation in the SML is largely controlled by PFAS sorption at the air-water interface for the conditions examined in this study, and the presence of foam with natural organics enhances PFAS uptake at the water surface.

RNA-Seq approach for accurate characterization of splicing efficiency of yeast introns.

Introns in different genes, or even different introns within the same gene, often have different splice sites and differ in splicing efficiency (SE). One expects mass-transcribed genes to have introns with higher SE than weakly transcribed genes. However, such a simple expectation cannot be tested directly because variable SE for these genes is often not measured. Mechanistically, SE should depend on signal strength at key splice sites (SS) such as 5'SS, 3'SS and branchpoint site (BPS), i.e., SE = F(5'SS, 3'SS, BPS). However, without SE, we again cannot model how these splice sites contribute to SE. Here I present an RNA-Seq approach to quantify SE for each of the 304 introns in yeast (Saccharomyces cerevisiae) genes, including 24 in the 5'UTR, by measuring 1) number of reads mapped to exon-exon junctions (NEE) as a proxy for the abundance of spliced form, and 2) number of reads mapped to exon-intron junction (NEI5 and NEI3 at 5' and 3' ends of intron) as a proxy for the abundance of unspliced form. The total mRNA is NTotal = NEE + p * NEI5 + (1-p) * NEI3, with the simplest p = 0.5 but statistical methods were presented to estimate p from data. An estimated p is needed because NEI5 is expected to be smaller than NEI3 due to 1) step 1 splicing occurs before step 2 so EI5 is broken before EI3, 2) enrichment of poly(A) mRNA by oligo-dT, and 3) 5' degradation. SE is defined as the proportion (NEE/NTotal). Application of the method shows that ribosomal protein messages are efficiently and mostly cotranscriptionally spliced. Yeast genes with long introns are also spliced efficiently. HAC1/YFL031W is poorly spliced partly because its splicing involves a nonspliceosome mechanism and partly because Ire1p, which participate in splicing HAC1, is hardly expressed. Many putative yeast genes have low SE, and some splice sites are incorrectly annotated.

Gene expression profiling of non-polyadenylated RNA-seq across species.

Transcriptomes are dynamic and unique, with each cell type/tissue, developmental stage and species expressing a different repertoire of RNA transcripts. Most mRNAs and well-characterized long noncoding RNAs are shaped with a 5′ cap and 3′ poly(A) tail, thus conventional transcriptome analyses typically start with the enrichment of poly(A)+ RNAs by oligo(dT) selection, followed by deep sequencing approaches. However, accumulated lines of evidence suggest that many RNA transcripts are processed by alternative mechanisms without 3′ poly(A) tails and, therefore, fail to be enriched by oligo(dT) purification and are absent following deep sequencing analyses. We have described an enrichment strategy to purify non-polyadenylated (poly(A)−/ribo−) RNAs from human total RNAs by removal of both poly(A)+ RNA transcripts and ribosomal RNAs, which led to the identification of many novel RNA transcripts with non-canonical 3′ ends in human. Here, we describe the application of non-polyadenylated RNA-sequencing in rhesus monkey and mouse cell lines/tissue, and further profile the transcription of non-polyadenylated RNAs across species, providing new resources for non-polyadenylated RNA identification and comparison across species.

Flow induced surface enrichment of poly(ethylene-block-ethylene oxide) on polypropylene by capillary rheometer

In this study, we prepared polypropylene (PP) blends with commercially available amphiphilic diblock copolymer poly(ethylene-block-ethylene oxide) (P(E-b-EO)). Selective surface enrichment of the diblock copolymer used was observed only on the PP blend extrudates which were prepared using capillary rheometer with different wall shear rates showing that flow processes play an enormous role in surface migration.

Polyolefins functionalization by copolymerization of ethylene (propylene) with substituted norbornene

number of new copolymers of ethylene (propylene) and 5-ethylidene-2-norbornene (EN) containing 5-62 mol. % of the cyclic comonomer units in the main chain have been synthesized by employing of three ansa-metallocene catalytic systems, namely: Et[Ind]2ZrCl2/methylalumoxane, Et[IndH4]2ZrCl2/methylalumoxane or Me2Si[Ind]2ZrCl2/methylalumoxane. In this way side >C=CH-CH3 groups in the range up to 7ź10-3 mol/g were incorporated into a structure of polyolefin chain. As it was found by IR-spectroscopy, the side ethylidene groups of poly(ethylene-co-5-ethylidene-2-norbornene) were susceptible to ozonolysis reactions and converted into the polar carbonylic groups. According to DSC, X-ray diffraction and very cold neutrons scattering (VCN) data, enrichment of poly(ethylene-co-5-ethylidene-2-norbornene) with EN units has lead to eventual transformation of the studied copolymers from a partly crystalline state to a fully amorphous one. With the growing cyclic comonomer partial content the copolymers have exhibited progressively better optical transparency and higher glass transition temperatures (up to 85°C); they are characterized by a high density (d>1000kg/m3).

Surface modification of polypropylene. I. Surface enrichment of poly(ethylene glycol) on polypropylene/poly(ethylene glycol) blends

AbstractThe enrichment of poly(ethylene glycol) (PEG) on the surface of poly(ethylene glycol)/polypropylene (PEG/PP) blends was investigated by using attenuated total reflection infrared spectroscopy (ATR‐FTIR), contact angle measurement (CDA), and scanning electron microscopy (SEM). The preferred aggregation of the PEG component on the film surface of PP/PEG blends was affected mainly by the content, the molecular weight, and the segregated domains of PEG. Lower content and dies with higher surface energy favored the surface enrichment of PEG. The PEG with higher molecular weights was distributed in PP with larger phase domains, which resulted in a lower tendency toward preferred aggregation and surface enrichment. J. VINYL ADDIT. TECHNOL, 2008. © 2008 Society of Plastics Engineers

Enrichment of poly(butyl methacrylate) and its graft copolymer of polybutadiene on the surface of polypropylene blend

AbstractThe enrichment and diffusion of poly (butyl methacrylate) (PBMA) and its graft copolymer of polybutadiene on the surface of polypropylene (PP) blends were investigated using attenuated total reflection infrared spectroscopy (ATR‐FTIR), contact angle measurements (CDA), and scanning electron microscopy (SEM). It has been found that the selective aggregation of the PBMA and its copolymers on the surface of blends is mainly affected by the content, molecular weight, and the segregated domains. Lower content and higher surface energy die are in favor of the enrichment of additives on the surface of PP. PBMA with higher molecular weight has lower diffusivity and bigger phase domains, which results in its lower enrichment on the surface of PP blend film. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Enrichment of poly(methyl methacrylate) and its graft copolymer of polybutadiene on the surface of polypropylene blends

Poly(methyl methacrylate) (PMMA) and its graft copolymer of polybutadiene were used as the macromolecular surface modifiers of polypropylene. The enrichment and diffusion of the modifiers onto the surface of polypropylene blends were investigated using FTIR-ATR, CDA and SEM. It has been found that the selective aggregation of the modifier component on the surface of polypropylene was mainly affected by the content, molecular weight and size of the segregated domains. Lower content and higher surface energy die were in favor of the enrichment of the additive. PMMA with higher molecular weight showed larger domain phase and lower diffusion velocity which resulted in less enrichment on the surface of PP blends.

Selective binding of albumin on stearyl poly(ethylene oxide) coupling polymer-modified poly(ether urethane) surfaces

A tri-block-coupling polymer of stearyl poly(ethylene oxide)-4,4′-methylene diphenyl diisocyanate-stearyl poly(ethylene oxide)(MSPEO), was used as a surface modifying additive (SMA) and the MSPEO-modified poly(ether urethane) (PEU) surfaces were prepared by the process of dipcoating. The surface analysis by XPS revealed the surface enrichment of poly(ethylene oxide) (PEO). On the coating-modified surfaces, the bovine serum albumin (BSA) adsorption, respectively, from the low and high BSA bulk concentration solutions was correspondingly characterized by the methods of radioactive 125I-probe and ATR-FTIR. The bovine serum fibrinogen (Fg)-adsorption from the Fg bulk solution and the BSA-Fg competing adsorption from the BSA-Fg binary solutions were also characterized by radioactive 125I-probe. The reversible BSA-selective in situ adsorption on MSPEO-modified PEU surfaces were achieved, and the performance of blood compatibility on the coating-modified surfaces was also confirmed, respectively, by plasma recalcification time (PRT) and prothrombin time (PT) tests.