Fabrication of Porous Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Monoliths via Thermally Induced Phase Separation

Application of cellulose to chromatographic media: Cellulose dissolution, and media fabrication and derivatization

As the cornerstone of chromatographic technology, the development of high-performance chromatographic media is a crucial means to enhance the purification efficiency of biological macromolecules. Cellulose is a popular biological separation medium due to its abundant hydroxyl group on the surface, easy modification and, weak non-specific adsorption. In this paper, the development of cellulosic solvent systems, typical preparation methods of cellulosic chromatographic media, and the enhancement of chromatographic properties of cellulosic chromatographic media by polymeric ligand grafting strategies and their mechanism of action are reviewed. Ultimately, based on the current research status, a promising outlook for the preparation of high-performance cellulose-based chromatographic media was presented.

Role of pro-inflammatory cytokines in Alzheimer's disease and neuroprotective effects of pegylated self-assembled nanoscaffolds

Neurodegeneration and synaptic loss in Alzheimer's disease (AD) lead to impairment in memory functions. Neuroinflammation causes activation of microglia and astrocytes cells that locally and systemically produces inflammatory cytokines which can serve as early diagnostic markers or therapeutic targets in AD. Pro-inflammatory cytokines (Interleukins (IL-1β, IL-6 and IL-10) and tumor necrosis factor (TNF α)) levels were estimated in serum, cerebral tissue, hepatic tissue, and renal tissue in treatment groups of scopolamine-induced amnesia mice model using ELISA protocol. The results showed that cerebral tissue of AD mice exhibited elevated levels of IL1β, IL6, IL10 and TNFα which indicate contribution of pro-inflammatory cytokines in the progression of AD. A significant reduction in the concentration of IL1β, IL-10 and TNF-α were noticed in serum, cerebral tissue and hepatic tissue of animal group treated with marketed memantine tablet (Admenta), pure memantine drug (MEMp), memantine-poly (lactic-co-glycolic acid) self-assembled nanoscaffolds (MEM-PLGA) SANs, Polyethylene Glycol coated memantine-poly (lactic-co-glycolic acid) self-assembled nanoscaffolds [(PEG-MEM-PLGA) SANs] and Polyethylene Glycol coated memantine-poly [(lactic-co-glycolic acid)] self-assembled nanoscaffolds grafted with Bone Marrow Derived Stem Cell ((PEG-MEM-PLGA) SANs-BMSc), whereas a high level of IL-6 was observed in hepatic tissue, cerebral tissue and renal tissues of normal and AD induced mice which showed the emerging potential of IL-6 cytokines that can trigger either neurons survival after injury or causing neurodegeneration and cell apoptosis. The Neuroregenerative potential of stem cells helps in the proliferation of neuronal cell and thus improves cognition in AD animal model.

Morphology Control and Metallization of Porous Polymers Synthesized by Michael Addition Reactions of a Multi-Functional Acrylamide with a Diamine

Porous polymers have been synthesized by an aza-Michael addition reaction of a multi-functional acrylamide, N,N',N″,N‴-tetraacryloyltriethylenetetramine (AM4), and hexamethylene diamine (HDA) in H2O without catalyst. Reaction conditions, such as monomer concentration and reaction temperature, affected the morphology of the resulting porous structures. Connected spheres, co-continuous monolithic structures and/or isolated holes were observed on the surface of the porous polymers. These structures were formed by polymerization-induced phase separation via spinodal decomposition or highly internal phase separation. The obtained porous polymers were soft and flexible and not breakable by compression. The porous polymers adsorbed various solvents. An AM4-HDA porous polymer could be plated by Ni using an electroless plating process via catalyzation by palladium (II) acetylacetonate following reduction of Ni ions in a plating solution. The intermediate Pd-catalyzed porous polymer promoted the Suzuki-Miyaura cross coupling reaction of 4-bromoanisole and phenylboronic acid.

Polypropylene/lignin blend monoliths used as sorbent in oil spill cleanup

With increasing industrial development, frequent oil spillages in water; therefore, it is imperative and challenging to develop absorbents materials that are eco-efficiency, cost-effective, and pollution prevention. In this study, sorbents obtained from Lignin incorporated with Polypropylene in different levels loading 0, 10, 20 % wt using thermally induced phase separation Technique (TIPS). The Polypropylene/Lignin blend monoliths were fabricated and compared in terms of morphological, thermal, and wetting characterizations. The successfully blending of different lignin concentrations with preserved the chemical structure of the polymer was confirmed by FTIR analysis. Thermogravimetric tests displayed that the existence of Lignin has changed the onset temperature (Tonset) of the blending sorbents, decreasing as the loading of Lignin is increased. The contact angle measurement showed a decrease in the hydrophobicity of sorbents with increasing lignin loading, Polypropylene/Lignin blend monoliths showed better absorption toward oils (soybean - engine) as compared to Polypropylene itself. PP10L showed an improvement in the oil sorption capacity around 2 times compared to the Polypropylene. These excellent features make Polypropylene/Lignin blend monoliths more competitive promising candidates than commercial absorbent.

Biomedical Processing of Polyhydroxyalkanoates

The rapidly growing interest on polyhydroxyalkanoates (PHA) processing for biomedical purposes is justified by the unique combinations of characteristics of this class of polymers in terms of biocompatibility, biodegradability, processing properties, and mechanical behavior, as well as by their great potential for sustainable production. This article aims at overviewing the most exploited processing approaches employed in the biomedical area to fabricate devices and other medical products based on PHA for experimental and commercial applications. For this purpose, physical and processing properties of PHA are discussed in relationship to the requirements of conventionally-employed processing techniques (e.g., solvent casting and melt-spinning), as well as more advanced fabrication approaches (i.e., electrospinning and additive manufacturing). Key scientific investigations published in literature regarding different aspects involved in the processing of PHA homo- and copolymers, such as poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), are critically reviewed.

The Effect of Diluent Mixture with Upper Critical Solution Temperature on Membrane Formation Process, Microstructure, and Performance of PVDF Hollow Fiber Membrane by TIPS Process

Thermally induced phase separation (TIPS) is a technique to prepare commercial membrane. However, the quick polymer crystallization during the quenching process will bring about a dense and thick skin layer and thus decrease permeability markedly. In this paper, a diluent mixture with upper critical solution temperature (UCST) was used to prepare polyvinylidene fluoride (PVDF) hollow fiber membrane. That is, the separation between diluent (propylene carbonate (PC)) and non-diluent (dioctyl terephthalate (DOTP)) occurred during the quenching process when the temperature of the dope was lower than 110 °C. The effects of separation between PC and DOTP and the resulting coalescence of DOTP on the PVDF crystallization process, microstructure, and the permeability of the membranes were analyzed. The results showed that the suitable PC/DOTP weight ratio reduced the thickness of the skin layer near the outer surface markedly and resulted in a porous outer surface, and the microstructure evolution process was proposed. The maximum pure water flux for the prepared membrane is up to 128.5 L·m-2·h-1 even in a dry mode without using a hydrophilizing agent. The rejection rate of the carbonic particle is nearly 100%. This study presents a novel and simple way to fabricate the microporous membrane with the interconnected pore structure.

Investigations on Green Blends Comprising Biodegradable Polymer and Ionic Liquid

The green blends of an ionic liquid, 1-ethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide {[EPrI][TFSI]}, and a biodegradable polymer, poly(3-hydroxybutyrate) (PHB), were investigated in this study. The influence of an ionic liquid on the crystallization behaviors of a biodegradable polymer was explored. In the blends, the presence of [EPrI][TFSI] decreased the Tg and Tm of PHB. Incorporating [EPrI][TFSI] in the blends reduced the degree of crystallinity of PHB, inferring that the [EPrI][TFSI] weakened the crystallization of PHB. It further showed retarded isothermal and non-isothermal crystallization for PHB with the presence of [EPrI][TFSI]. The smaller K and 1/t0.5 estimated by the Avrami equation for the blends indicated that [EPrI][TFSI] weakened the isothermal crystallization of PHB with exhibiting the slower crystallization rate. The present study also discussed non-isothermal crystallization of the blends. We found that the Mo model, which is generally used to discuss the non-isothermal crystallization, adequately described the non-isothermal behaviors of the [EPrI][TFSI]/PHB blends. By increasing the [EPrI][TFSI] content, the rate-related parameter F(T) systematically increased, inferring a decreased crystallization rate of PHB with the addition of [EPrI][TFSI] in the blends. The FTIR results suggested an ion⁻dipole interaction between [EPrI][TFSI] and PHB. This proposes the occurrence of possible complexation between [EPrI][TFSI] and PHB.

Comb-like temperature-responsive polyhydroxyalkanoate-graft-poly(2-dimethylamino-ethylmethacrylate) for controllable protein adsorption

Polyhydroxyalkanoates (PHA) are a family of diverse biopolyesters produced by many bacteria grown on sustainable bio-resources such as glucose or fatty acids.