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Macromolecular Rapid Communications Feb 2014Photoresponsive azobenzene-containing systems ranging from molecular to macroscopic material levels have greatly been increasing their significance in materials... (Review)
Review
Photoresponsive azobenzene-containing systems ranging from molecular to macroscopic material levels have greatly been increasing their significance in materials chemistry. This review focuses on the studies on light induced or triggered motions in azobenzene liquid crystalline (LC) polymer films at mesoscopic and microscopic levels. Due to the cooperative nature of liquid crystalline materials, highly efficient photoalignment and photo-triggered migrating motions are realized in mostly repeated manners. Here, recent advances in surface-grafted LC polymer brushes, LC block copolymer films, and LC polymer films that exhibit mass migrations are overviewed. Such newly emerged photoresponsive systems are expected to provide new possibilities and applications in polymer thin film technologies.
Topics: Light; Liquid Crystals; Polymers; Surface Properties
PubMed: 24343758
DOI: 10.1002/marc.201300763 -
Journal of Controlled Release :... Aug 2007Gene therapy holds tremendous promise in the treatment of many genetic and acquired diseases. The future of gene therapy in humans, however, is contingent upon the... (Comparative Study)
Comparative Study Review
Gene therapy holds tremendous promise in the treatment of many genetic and acquired diseases. The future of gene therapy in humans, however, is contingent upon the discovery of safe and effective carriers of genetic material. Polymers represent a class of materials that can be extensively modified to meet the needs of a particular gene delivery system. A variety of polymer formulations have been proposed in the literature as potential carriers, most of which facilitate gene delivery by encapsulating, and in some cases, condensing nucleic acids into nano-sized particles which can then be taken up by cells. Crucial to successful delivery of the gene to a cell is the polymer's ability to protect its contents from degradation in the extracellular environment. A well-designed carrier will also promote cellular uptake and intracellular release of the nucleic acid. In the past, a common approach to gene therapy has been to transfect cells with a polymer-encapsulated DNA plasmid designed to replace a defective gene in the target-cell genome. Within the last few years, however, RNA interference (RNAi) has emerged as a novel therapeutic pathway by which harmful genes can be "silenced" by delivering complementary short interfering RNA (siRNA) to target cells. siRNA delivery facilitated by polymers, although very promising, suffers from many of the same limitations as DNA delivery. This review will (1) highlight the similarities and differences between these two methods of gene therapy and (2) discuss how some of the remaining challenges in siRNA delivery facilitated by polymers can be addressed by applying knowledge from the longer-studied problem of DNA delivery.
Topics: Animals; Cell Line, Tumor; DNA; Gene Transfer Techniques; Genetic Therapy; Humans; Inhibitory Concentration 50; Models, Genetic; Polyamines; Polyelectrolytes; Polymers; RNA Interference; RNA, Small Interfering
PubMed: 17588702
DOI: 10.1016/j.jconrel.2007.05.021 -
Molecules (Basel, Switzerland) Sep 2022The interaction of water with polymers is an intensively studied topic. Vibrational spectroscopy techniques, mid-infrared (MIR) and Raman, were often used to investigate...
The interaction of water with polymers is an intensively studied topic. Vibrational spectroscopy techniques, mid-infrared (MIR) and Raman, were often used to investigate the properties of water-polymer systems. On the other hand, relatively little attention has been given to the potential of using near-infrared (NIR) spectroscopy (12,500-4000 cm; 800-2500 nm) for exploring this problem. NIR spectroscopy delivers exclusive opportunities for the investigation of molecular structure and interactions. This technique derives information from overtones and combination bands, which provide unique insights into molecular interactions. It is also very well suited for the investigation of aqueous systems, as both the bands of water and the polymer can be reliably acquired in a range of concentrations in a more straightforward manner than it is possible with MIR spectroscopy. In this study, we applied NIR spectroscopy to investigate interactions of water with polymers of varying hydrophobicity: polytetrafluoroethylene (PTFE), polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC), polyoxymethylene (POM), polyamide 6 (PA), lignin (Lig), chitin (Chi) and cellulose (Cell). Polymer-water mixtures in the concentration range of water between 1-10%(/) were investigated. Spectra analysis and interpretation were performed with the use of difference spectroscopy, Principal Component Analysis (PCA), Median Linkage Clustering (MLC), Partial Least Squares Regression (PLSR), Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) and Two-Dimensional Correlation Spectroscopy (2D-COS). Additionally, from the obtained data, aquagrams were constructed and interpreted with aid of the conclusions drawn from the conventional approaches. We deepened insights into the problem of water bands obscuring compound-specific signals in the NIR spectrum, which is often a limiting factor in analytical applications. The study unveiled clearly visible trends in NIR spectra associated with the chemical nature of the polymer and its increasing hydrophilicity. We demonstrated that changes in the NIR spectrum of water are manifested even in the case of interaction with highly hydrophobic polymers (e.g., PTFE). Furthermore, the unveiled spectral patterns of water in the presence of different polymers were found to be dissimilar between the two major water bands in NIR spectrum ( + and + ).
Topics: Cellulose; Chitin; Lignin; Polymers; Polypropylenes; Polystyrenes; Polytetrafluoroethylene; Polyvinyl Chloride; Spectroscopy, Near-Infrared; Water
PubMed: 36144616
DOI: 10.3390/molecules27185882 -
Proceedings of the National Academy of... Apr 2023Biomolecular phase separation has emerged as an essential mechanism for cellular organization. How cells respond to environmental stimuli in a robust and sensitive...
Biomolecular phase separation has emerged as an essential mechanism for cellular organization. How cells respond to environmental stimuli in a robust and sensitive manner to build functional condensates at the proper time and location is only starting to be understood. Recently, lipid membranes have been recognized as an important regulatory center for biomolecular condensation. However, how the interplay between the phase behaviors of cellular membranes and surface biopolymers may contribute to the regulation of surface condensation remains to be elucidated. Using simulations and a mean-field theoretical model, we show that two key factors are the membrane's tendency to phase-separate and the surface polymer's ability to reorganize local membrane composition. Surface condensate forms with high sensitivity and selectivity in response to features of biopolymer when positive co-operativity is established between coupled growth of the condensate and local lipid domains. This effect relating the degree of membrane-surface polymer co-operativity and condensate property regulation is shown to be robust by different ways of tuning the co-operativity, such as varying membrane protein obstacle concentration, lipid composition, and the affinity between lipid and polymer. The general physical principle emerged from the current analysis may have implications in other biological processes and beyond.
Topics: Polymers; Cell Membrane; Membranes; Membrane Proteins; Lipids
PubMed: 37018196
DOI: 10.1073/pnas.2212516120 -
Advances in Colloid and Interface... Nov 1998When a polymer is in contact with a liquid, generally some matter transfers take place: the liquid enters the polymer, while some additives leave the polymer. This fact... (Review)
Review
When a polymer is in contact with a liquid, generally some matter transfers take place: the liquid enters the polymer, while some additives leave the polymer. This fact is responsible for a reduction in the properties of the polymer and pollution of the liquid food is obtained. However, it is sure that, on account of their outstanding properties, food packages are becoming more and more based on polymers. The process of mass transfers is controlled by transient diffusion, and these theoretical problems are so complex that only numerical models are able to resolve them. New difficult problems appear with the desire of recycling old food packages made of polymers by reusing them as new food packages. Of course, because of the potential contamination brought with this recycled polymer, the package is made of bi-layer or tri-layer films where the reused polymer is located between two virgin polymer layers. As it takes some time for the contaminant to diffuse through the virgin layer, this latter plays the role of a functional barrier to pollution. The various difficulties in the whole problem are considered in succession: the coextrusion of the films where a contaminant transfer already occurs; and the effect of the liquid food which may enhance the diffusion of the contaminant. Various master curves are drawn by using dimensionless numbers, so as to make the results quite general and of use from a practical point of view.
Topics: Conservation of Natural Resources; Food Contamination; Food Packaging; Polymers
PubMed: 9828353
DOI: 10.1016/s0001-8686(98)00065-7 -
The Journal of Physical Chemistry. B Jan 2022Nanoparticle surfaces, such as cylindrical nanowires and carbon nanotubes, are commonly coated with adsorbed polymer corona phases to impart solution stabilization and...
Nanoparticle surfaces, such as cylindrical nanowires and carbon nanotubes, are commonly coated with adsorbed polymer corona phases to impart solution stabilization and to control molecular interactions. These adsorbed polymer molecules (biological or otherwise), also known as the corona phase, are critical to engineering particle and molecular interactions. However, the prediction of its structure and the corresponding properties remains an unresolved problem in polymer physics. In this work, we construct a Hamiltonian describing the adsorption of an otherwise linear polymer to the surface of a cylindrical nanorod in the form of an integral equation summing up the energetic contributions corresponding to polymer bending, confinement, solvation, and electrostatics. We introduce an approximate functional that allows for the solution of the minimum energy configuration in the strongly bound limit. The functional is shown to predict the pitch and surface area of observed helical corona phases in the literature based on the surface binding energy and persistence length alone. This approximate functional also predicts and quantitatively describes the recently observed ionic strength-mediated phase transitions of charged polymer corona at carbon nanotube surfaces. The Hamiltonian and the approximate functional provide the first theoretical link between the polymer's mechanical and chemical properties and the resulting adsorbed phase configuration and therefore should find widespread utility in predicting corona phase structures around anisotropic nanoparticles.
Topics: Adsorption; Nanoparticles; Nanotubes, Carbon; Osmolar Concentration; Polymers; Protein Corona
PubMed: 34962804
DOI: 10.1021/acs.jpcb.1c09998 -
Advances in Colloid and Interface... 2009It is well established that colloidal polymer particles can be used to create organised structures by methods of horizontal deposition, vertical deposition,... (Review)
Review
It is well established that colloidal polymer particles can be used to create organised structures by methods of horizontal deposition, vertical deposition, spin-casting, and surface pattern-assisted deposition. Each particle acts as a building block in the structure. This paper reviews how two-phase (or hybrid) polymer colloids can offer an attractive method to create nanocomposites. Structure in the composite can be controlled at the nanoscale by using such particles. Methods to create armored particles, such as via methods of hetero-flocculation and Pickering polymerization, are of particular interest here. Polymer colloids can also be blended with other types of nanoparticles, e.g. nanotubes and clay platelets, to create nanocomposites. Structure can be controlled over length scales approaching the macroscopic through the assembly of hybrid particles or particle blends via any of the various deposition methods. Colloidal nanocomposites can offer unprecedented long-range 2D or 3D order that provides a periodic modulation of physical properties. They can also be employed as porous templates for further nanomaterial fabrication. Challenges in the design and control of the macroscopic properties, especially mechanical, are considered. The importance of the internal interfacial structure (e.g. between inorganic and polymer particles) is highlighted.
Topics: Colloids; Nanoparticles; Particle Size; Polymers; Surface Properties
PubMed: 18757049
DOI: 10.1016/j.cis.2008.06.002 -
Nucleosides, Nucleotides & Nucleic Acids 2013Nucleosides and their analogues play important roles in biological research and clinical therapeutics. Polymer-assisted structural modifications of nucleosides and... (Review)
Review
Nucleosides and their analogues play important roles in biological research and clinical therapeutics. Polymer-assisted structural modifications of nucleosides and nucleotides enable parallel and rapid construction of nucleoside library. For some nucleosides, higher chemical selectivity and regioselectivity can be achieved using solid-phase synthesis when compared to classic solution-phase synthesis.
Topics: Molecular Structure; Nucleosides; Nucleotides; Polymers; Solid-Phase Synthesis Techniques
PubMed: 23638922
DOI: 10.1080/15257770.2013.785561 -
Journal of Trace Elements in Medicine... May 2024Montmorillonite (MMT) is a biocompatible nanoclay and its incorporation into polymeric matrix not only improves the polymer's wettability/biodegradability, but also...
BACKGROUND
Montmorillonite (MMT) is a biocompatible nanoclay and its incorporation into polymeric matrix not only improves the polymer's wettability/biodegradability, but also enhances cellular proliferation, and differentiation. On the other hand, the positive effect of boron (B) on the healing cascade and its antibacterial properties have drawn the attention of researchers.
MATERIALS & METHODS
In this regard, B compounds in different chemical structures, boron nitride (BN), zinc borate (ZB), and phenylboronic acid (PBA), were adsorbed onto MMT and then, poly (lactic acid) (PLA) based MMT/B including micron/submicron fibers were fabricated by electrospinning.
RESULTS
The incorporation of MMT nanoparticles into the PLA demonstrated a porous fiber topography with enhanced thermal properties, water uptake capacity, and antibacterial effect. Furthermore, the composites including BN, ZB, and PBA showed bacteriostatic effects against Gram-negative and Gram-positive pathogenic bacteria (Escherichia coli and Staphylococcus aureus). In-vitro cell culture studies performed with human dermal fibroblasts (HDF) indicated the non-toxic effect of B compounds. The results showed that incorporation of MMT supported cell adhesion and proliferation, and further addition of B compounds especially PBA increased cell viability for 14 days.
CONCLUSION
The results illustrated the acceptable characteristics of the B-containing composites and their favorable effect on the cells, demonstrating their potential as a skin tissue engineering product.
Topics: Humans; Polymers; Biocompatible Materials; Nanofibers; Clay; Anti-Bacterial Agents; Polyesters; Boron Compounds; Bandages
PubMed: 38387426
DOI: 10.1016/j.jtemb.2024.127408 -
International Journal of Molecular... Sep 2022Using hybrid multi-particle collision dynamics (MPCD) and a molecular dynamics (MD) method, we investigate the effect of arms and shear flow on dynamical and structural...
Using hybrid multi-particle collision dynamics (MPCD) and a molecular dynamics (MD) method, we investigate the effect of arms and shear flow on dynamical and structural properties of the comb long-chain branched (LCB) polymer with dense arms. Firstly, we analyze dynamical properties of the LCB polymer by tracking the temporal changes on the end-to-end distance of both backbones and arms as well as the orientations of the backbone in the flow-gradient plane. Simultaneously, the rotation and tumbling behaviors with stable frequencies are observed. In other words, the LCB polymer undergoes a process of periodic stretched-folded-stretched state transition and rotation, whose period is obtained by fitting temporal changes on the orientation to a periodic function. In addition, the impact induced by random and fast motions of arms and the backbone will descend as the shear rate increases. By analyzing the period of rotation behavior of LCB polymers, we find that arms have a function in keeping the LCB polymer's motion stable. Meanwhile, we find that the rotation period of the LCB polymer is mainly determined by the conformational distribution and the non-shrinkable state of the structure along the velocity-gradient direction. Secondly, structural properties are numerically characterized by the average gyration tensor of the LCB polymer. The changes in gyration are in accordance with the LCB polymer rolling when varying the shear rate. By analyzing the alignment of the LCB polymer and comparing with its linear and star counterparts, we find that the LCB polymer with very long arms, like the corresponding linear chain, has a high speed to reach its configuration expansion limit in the flow direction. However, the comb polymer with shorter arms has stronger resistance on configuration expansion against the imposed flow field. Moreover, with increasing arm length, the comb polymer in shear flow follows change from linear-polymer-like to capsule-like behavior.
Topics: Molecular Conformation; Molecular Dynamics Simulation; Polymers; Rotation
PubMed: 36232591
DOI: 10.3390/ijms231911290