Macroporous polymeric materials for bioanalytical microchips

Macroporous copolymers derived from 2-cyanoethyl methacrylate were prepared using low-molecular-weight and polymeric porogens. The influence of the polymerization conditions on the pore characteristics and surface morphology of the macroporous materials was examined. The possibility of efficiently using the synthesized polymeric matrices for protein assay was evaluated with a model biocomplementary couple as example.     

Gradient polymers and copolymers

Gradient polymers are two component polymeric systems in which the concentration of one component varies in a continuous way from one side to the other in systems with plane-parallel geometry. Such systems can be obtained from an amorphous polymeric matrix by diffusing into another monomer creating a gradient of concentration, which is fixed by, for example, photo-polymerization. Properties of such systems with plane-parallel geometry are discussed. Paricular attention is given to the systems with cylindrical geometry in which the gradient of the second polymer varies from the center to outside. This class of gradient polymers has a great practical application as gradient optical polymeric fibers and multifocal lenses. An interesting and new class of gradient polymers are systems systems consisting of semicrystalline polymeric matrices in which a gradient of structure is created by appropriate thermal treatment and an amorphous polymer gradient is formed by diffusion of a monomer and its subsequent polymerization. The structural, thermal and mechanical properties are discussed mainly for a model system consisting of polyethylene and polystyrene. The polymeric gradient systems, consisting of an oriented semicrystalline polymer and amorphous gradient polymer, are discussed showing that the structurally gradient matrices and amorphous polymer offer a great variety of factors which can influence the properties of multicomponent gradient polymers. Recently obtained gradient copolymers in which the chemical composition varies from one end to the other a macromolecule are presented. It is shown how such macromolecules can be obtained with different type of changes of the composition. The unusual properties of gradient copolymers are discussed considering their mechanical and thermal properties as well their specific behaviour as compatibilizers. © 1998 John Wiley & Sons, Ltd.     

Penetration of3H-glycerol trinitrate through silicone-hydroxyethyl methacrylate matrices

The possibility of use of a powder-like polymeric hydrogel of 2-hydroxyethyl methacrylate with 33 wt.% methacrylic acid as potential pharmaceutical adjuvant in the form of a composite powdered material, with silicone rubber in the form of matrices for transdermal therapeutic system has been studied. The effect of solvents and the content of composite hydrogel in matrices on the rate of permeation of an antianginic drug, radioactive labeled glycerol trinitrate (GTN) was evaluated. The results show that hydrogel copolymers are prospective adjuvants for transdermal therapeutic systems.     

Modification of solids with polymer nanolayers as a process for manufacture of novel biomaterials

The results of study on the chemical deposition of polymeric coatings of a nanoscale thickness on porous and flat inorganic matrices and encapsulation of nano-and microparticles in polymer shells are discussed. Procedures for the deposition of homogeneous defect-free coatings are detailed by using polytetrafluoroethylene, polyaniline, and their derivatives as examples. The matrices modified with nanosized polytetrafluoroethylene and polyaniline layers are promising biomaterials for one-step isolation of nucleic acids from complex biological mixtures (cell and tissue lysates, whole blood, plant feedstock), as well as for high-performance chromatography of proteins and other biopolymers. Approaches to the fabrication of polymer shells on luminescent nanocrystals of (CdSe)ZnS via the inclusion of the nanocrystals in micrometer-sized particles based on acrolein-styrene copolymers and the formation of polymer shells directly on nanoparticles are discussed. It was shown that polymer-functionalized luminescent nanocrystals hold promise as bioanalytical reagents.     

Macroreticular resins. III. Formation of macroreticular styrene–divinylbenzene copolymers

Experimental evidence is presented that describes the mechanism of formation of macroreticular styrene–divinylbenzene copolymers in which phase separation occurs during a suspension polymerization. The mode of formation of the macroreticular structure is described as a three-stage process in which each droplet of the organic phase behaves as an individual in a bulk polymerization that results in a bead of copolymer. Macroreticular structure formation is described by changes in copolymer swelling ratios, infrared absorption spectra of vinyl groups pendent to the polymeric matrices, surface area, total porosity, and pore-size distribution. The proposed mechanism of formation is also substantiated by electron micrographs of the copolymers during various stages of the copolymerization.     

Multivariate processing of atomic-force microscopy images for detection of the response of plasticized polymeric membranes

The possibility of using the atomic-force microscopy as a method for detection of the analytical signal from plasticized polymeric sensor membranes was analyzed. The surfaces of cadmium-selective membranes based on two polymeric matrices were examined. The digital images were processed with multivariate image analysis techniques. A correlation was found between the surface profile of an ion-selective membrane and the concentration of the ion in solution.     

New chelating sorbents for noble metals

The properties of the new ehelate-forming “POLYORGS” sorbents for concentration of noble metals are discussed. POLYORGS are made from different polymeric matrices (polystyrene, copolymers of styréne with divinylbenzene, fibrous materials). They contain heterocyclic amine and amidoxime groups, and are selective for noble metals. Some methods of noble metal determination after preliminary concentration of POLYORGS sorbents are given.     

The photochemistry of polymers containing anthrylmethyl vinyl ketone

The photolysis of copolymers of anthrylmethyl vinyl ketone (AMVK) with styrene and methyl methacrylate has been studied, both in solution and in the solid phase. Quantum yields of the order of 0.01 were observed in both cases for release of the major product, methyl anthracene (MA). Photolysis of an aqueous emulsion of a styrene-AMVK copolymer showed similar yields of MA. The results indicate the possibility of using the Norrish type I process as a means of releasing drugs or other biologically active compounds from polymeric matrices. © 1995 John Wiley & Sons, Inc.     

On the effect of the polyketone structure on the strength properties of thermoplastic-matrix fiber glass composites

The physical, mechanical, and structural-relaxation properties of composite microplastics based on thermoplastic (polyethylene and polyamide) matrices, in which the alternating ethylene-CO, diene-CO, and ethylene-CO-α-olefin copolymers are used as a finish, were studied. An important role of the interface between the components in the formation of the mechanical properties of thermoplastic-matrix composites and the possibility of controlling adhesive interactions by means of polymeric finishes based on poly(diene-ketone)s and aliphatic polyketones with different side-chain lengths are shown.     

Phase behavior of binary blends of diblock copolymer/homopolymer confined in spherical nanopores

Binary blends of a diblock copolymer (AB) and an incompatible homopolymer (C) confined in spherical cavities are studied using a simulated annealing technique. The phase behavior of the blends is examined for four typical cases, representing the different selectivity of the pore surface to the A, B, and C species. The internal morphology of the spherical polymeric particles is controlled by the homopolymer volume fraction, the degree of confinement, and the composition of the copolymer. Inside a particle, the homopolymers segregate to form one or, under some conditions, two domains; thus, the homopolymers may act as an additional controlling parameter of the shape and symmetry of the copolymer domain. A rich array of confinement-induced novel diblock copolymer morphologies is predicted. In particular, core-shell particles with the copolymers as the shell wrapping around a homopolymer core or a copolymer-homopolymer combined core and Janus-like particles with the copolymers and the homopolymers on different sides are obtained.     

The Influence of Crosslinking Amylose-Methacrylic Acid Graft Copolymers on the Release of BSA

Summary: One of the biggest challenges in the drug delivery field is to obtain oral systems for the release of peptides and proteins, enabling their use as therapeutic agents for clinical applications. The aim of this work is to obtain biodegradable copolymers suitable for the development of matrices which offer controlled release of proteins to be administered orally.Graft copolymers of amylose-methacrylic acid were synthesized using different amounts of the crosslinker N, N′-methylenediacrylamide. The influence on the release profiles of bovine serum albumin (BSA) was researched.     

两亲性共聚物的分子设计与合成及其共混膜性能

从分子结构设计出发,采用自由基聚合、醚化、酯化、原子转移自由基聚合(ATRP)、可逆加成断裂链转移自由基聚合(RAFT)等方法合成了一系列具有不同分子结构(包括接枝、嵌段、交替、超支化等)和链形态(包括直链、梳状、哑铃状、链球状等)的两亲性共聚物,并对这些聚合物进行了谱学表征和性能测试.将这些两亲性共聚物与聚合物膜材料(包括聚偏氟乙烯、聚氯乙烯、聚砜、聚醚砜、聚醚砜酮等)进行溶液共混,通过相转化法制备共混膜,在成膜热力学和动力学分析的基础上,对共混膜的结构和性能进行调控.研究发现,两亲性共聚物在成膜过程中自发地向膜表面迁移富集,并进行自组装,在膜表面形成两亲性共聚物包膜,显著改善了聚合物多孔膜的亲水性和抗污染性能.此外,两亲性共聚物中的功能基团还可赋予共混膜某些功能特性,如生物相容性、环境响应性(pH、温度敏感性)、酶活性等.     

Alternatives to Styrene- and Diisobutylene-Based Copolymers for Membrane Protein Solubilization via Nanodisc Formation

Styrene-maleic acid copolymers (SMAs), and related amphiphilic copolymers, are promising tools for isolating and studying integral membrane proteins in a native-like state. However, they do not exhibit this ability universally, as several reports have found that SMAs and related amphiphilic copolymers show little to no efficiency when extracting specific membrane proteins. Recently, it was discovered that esterified SMAs could enhance the selective extraction of trimeric Photosystem I from the thylakoid membranes of thermophilic cyanobacteria; however, these polymers are susceptible to saponification that can result from harsh preparation or storage conditions. To address this concern, we herein describe the development of α-olefin-maleic acid copolymers (αMAs) that can extract trimeric PSI from cyanobacterial membranes with the highest extraction efficiencies observed when using any amphiphilic copolymers, including diisobutylene-co-maleic acid (DIBMA) and functionalized SMA samples. Furthermore, we will show that αMAs facilitate the formation of photosystem I-containing nanodiscs that retain an annulus of native lipids and a native-like activity. We also highlight how αMAs provide an agile, tailorable synthetic platform that enables fine-tuning hydrophobicity, controllable molar mass, and consistent monomer incorporation while overcoming shortcomings of prior amphiphilic copolymers.     

Aliphatic polyester polymer stars: synthesis, properties and applications in biomedicine and nanotechnology

A critical review: the ring-opening polymerization of cyclic esters provides access to an array of biodegradable, bioassimilable and renewable polymeric materials. Building these aliphatic polyester polymers into larger macromolecular frameworks provides further control over polymer characteristics and opens up unique applications. Polymer stars, where multiple arms radiate from a single core molecule, have found particular utility in the areas of drug delivery and nanotechnology. A challenge in this field is in understanding the impact of altering synthetic variables on polymer properties. We review the synthesis and characterization of aliphatic polyester polymer stars, focusing on polymers originating from lactide, ε-caprolactone, glycolide, β-butyrolactone and trimethylene carbonate monomers and their copolymers including coverage of polyester miktoarm star copolymers. These macromolecular materials are further categorized by core molecules, catalysts employed, self-assembly and degradation properties and the resulting fields of application (262 references).     

Towards advanced chemical microsensors-an overview

The paper presents design and performance of miniaturized chemical sensors based on silicon transducers: ion-sensitive field effect transistor (ISFET) and solid-state electrode (SSE). The sensors were fabricated as back-side contact structures, which facilitate their mounting in a flow-cell. The role of an intermediate layer between the transducer and the ion-selective membrane is discussed. Various polymeric matrices were used to manufacture microsensors: polysiloxanes, polyacrylates (polymethacrylates), polyurethanes.     

Supramolecular Polymerization of Polymeric Nanorods Mediated by Block Copolymers

Introducing a second component is an effective way to manipulate polymerization behavior. However, this phenomenon has rarely been observed in colloidal systems, such as polymeric nanoparticles. Here, we report the supramolecular polymerization of polymeric nanorods mediated by block copolymers. Experimental observations and simulation results illustrate that block copolymers surround the polymeric nanorods and mainly concentrate around the two ends, leaving the hydrophobic side regions exposed. These polymeric nanorods connect in a side-by-side manner through hydrophobic interactions to form bundles. As polymerization progresses, the block copolymers gradually deposit onto the bundles and finally assemble into helical nanopatterns on the outermost surface, which terminates the polymerization. It is anticipated that this work could offer inspiration for a general strategy of controllable supramolecular polymerization.     

从聚酯合成聚酯-聚醚多嵌段共聚物

研究直接以聚酯为原料,合成聚酯-聚醚多嵌段共聚物。研究了反应机理、链段结构对反应的影响以及由此法制备的多嵌段共聚物的链段序列结构。实验结果表明,链段相容性对聚合物法的影响至为重要,链段相容性不仅决定了所得嵌段共聚物的组成均一性,而且还决定了某一链段结构的多嵌段共聚物能否用聚合物法制备。     

A supramolecular multi-block copolymer with a high propensity for alternation

Alternating, multi-block supramolecular copolymers were created using quadruple hydrogen bonding as the noncovalent binding force. One block consisted of two guanosine butyl urea (UG) units attached at the ends of a triethylene glycol linker or a PEG chain (MW = 2 kD). The other block contained a 2,7-diamido-1,8-naphthyridine (DAN) unit at each end of a short alkane diester linker or a 100 kD poly(butyl methacrylate) macromolecule. The UG unit presents an ADDA hydrogen bonding array that is complementary to the DAAD array of DAN, and these form a very strong complex (Kassoc approximately 5 x 107 M-1), whereas UG and DAN weakly self-associate. These recognition properties allowed a multi-block supramolecular polymer to form which exhibits a high propensity for alternation. The self-assembled polymeric structure was shown to be reversibly formed and it was characterized by a combination of dynamic light scattering (DLS), 1H NMR, size exclusion chromatography (SEC), and viscometry.     

Mesoporous membrane device for asymmetric biosensing

An array of micron size reactors has been designed and fabricated on a mesoporous membrane to create a platform for asymmetric biochemical sensing. Fabrication of this device required that a technique be developed to integrate the mesoporous alumina membrane with a polymeric layer that maintains the integrity of the membrane surface and permeability. This device was used to control an enzyme reaction at the surface of the membrane through the diffusion of the substrates from the opposite sides of the membrane. Asymmetric reactions promise new modes of sensing, enhanced stability of delicate biomolecular systems, and enhanced sensitivity and speed in sensing.     

Controlling the orientation of immobilized proteins on an affinity membrane through chelation of a histidine tag to a chitosan-Ni surface

The ability of histidine-tagged proteins to chelate to Ni⁺⁺ ions that are coordinated to functionalized polymeric matrices is the basis of affinity column separations. In this study, affinity membranes based on a Ni⁺⁺-chelating chitosan surface were fabricated to immobilize C-terminus hexahistidine-tagged green fluorescent protein (his-GFP). The binding of GFP antibody (antiGFP) to the immobilized his-GFP was measured and compared to a membrane with a chitosan surface to which his-GFP was immobilized through amine-glutaraldehyde chemistry as a control. Both membranes had comparable amounts of his-GFP immobilized on the surface. However, the amount of antiGFP bound to the Ni⁺⁺-chelated his-GFP at saturation was higher than that bound to the glutaraldehyde-immobilized his-GFP by a factor of five. Furthermore, fitting the data to a single-site Langmuir model resulted in an affinity constant for the Ni⁺⁺-chelated his-GFP towards antiGFP that was 14 times higher than the glutaraldehyde-immobilized his-GFP. The higher affinity suggests that immobilizing a protein at its C-terminus results in the proper orientation for subsequent antibody binding. At low antibody concentrations, the sensitivity of the affinity membrane is 70 times that of the control.