Studies on preparations and pH/redox responsiveness of zwitterionic nanomicelles of poly[lysine-co-N,N-bis(acryloyl)cystamine-co-dodecylamine]

Poly[L-lysine-co-N,N-bis(acryloyl) cystamine-co-dodecylamine] nanomicelles (NMs) were synthesized through Michael addition terpolymerization in one pot. The NMs showed spheric morphology and uniform size distributions. The NMs had excellent nonspecific protein adsorption ability at pH 7.4. Doxorubicin (DOX) was loaded in the NMs for the investigation of controlled release. The drug delivery results showed that the DOX-loaded NMs displayed apparent pH and reduction sensitivities in response to the environment of tumor cells due to the existence of carboxyl groups, amino groups, and disulfide bonds in the NMs. The NMs were biocompatible, biodegradable, and could be potentially used as drug vehicles in controlled release.     

Polymeric micelle nanocarriers in cancer research

Amphiphilic block copolymers (ABCs) assemble into a spherical nanoscopic supramolecular core/shell nanostructure termed a polymeric micelle that has been widely researched as an injectable nanocarrier for poorly water-soluble anticancer agents. The aim of this review article is to update progress in the field of drug delivery towards clinical trials, highlighting advances in polymeric micelles used for drug solubilization, reduced off-target toxicity and tumor targeting by the enhanced permeability and retention (EPR) effect. Polymeric micelles vary in stability in blood and drug release rate, and accordingly play different but key roles in drug delivery. For intravenous (IV) infusion, polymeric micelles that disassemble in blood and rapidly release poorly water-soluble anticancer agent such as paclitaxel have been used for drug solubilization, safety and the distinct possibility of toxicity reduction relative to existing solubilizing agents, e.g., Cremophor EL. Stable polymeric micelles are long-circulating in blood and reduce distribution to non-target tissue, lowering off-target toxicity. Further, they participate in the EPR effect in murine tumor models. In summary, polymeric micelles act as injectable nanocarriers for poorly water-soluble anticancer agents, achieving reduced toxicity and targeting tumors by the EPR effect.

Open image in new window

     

Computational linguistics: A new tool for exploring biopolymer structures and statistical mechanics

Unlike homopolymers, biopolymers are composed of specific sequences of different types of monomers. In proteins and RNA molecules, one-dimensional sequence information encodes a three-dimensional fold, leading to a corresponding molecular function. Such folded structures are not treated adequately through traditional methods of polymer statistical mechanics. A promising new way to solve problems of the statistical mechanics of biomolecules comes from computational linguistics, the field that uses computers to parse and understand the sentences in natural languages. Here, we give two examples. First, we show that a dynamic programming method of computational linguistics gives a fast way to search protein models for native structures. Interestingly, the computational search process closely resembles the physical folding process. Second, linguistics-based dynamic programming methods are also useful for computing partition functions and densities of states for some foldable biopolymers - helix-bundle proteins are reviewed here. In these ways, computational linguistics is helping to solve problems of the searching and counting of biopolymer conformations.     

DNA-inorganic hybrid material as selective absorbent for harmful compounds

Double-stranded DNA is one of functional polymers, but the large amounts of DNA sources, such as salmon milt and shellfish gonads, have been discarded as industrial wastes. Therefore, conversion of this discarded DNA to be a useful material would be beneficial to utilize the unique property of DNA. These materials including DNA have been prepared by mixing with the organic polymers, such as alginic acid, collagen, and chitosan. However, since these materials have consisted from entirely organic components, these do not have the mechanical strength for a material. So, we prepared the organic-inorganic hybrid materials by mixing DNA with silane coupling reagents bis(trimethoxysilylpropyl)amine or bis[(3-trimethoxysilyl)propyl]ethylenediamine. These hybrid materials with the flexibility were water-insoluble and resistant to hydrolysis by nuclease. In addition, the mechanical strength of this hybrid material was approximately twice as high as that of DNA without mixing with silane coupling reagents. Furthermore, the double-stranded DNA in the hybrid materials has been maintained in a B-form structure in aqueous solution. Thus, we demonstrated the utilization of DNA as a functional material. As a result, this material could selectively accumulate harmful DNA-intercalating compounds with the planar structure, such as dibenzo-p-dioxin, dibenzofuran, and ethidium bromide. Organic-inorganic hybrid material including double-stranded DNA has potential to serve as a useful biomaterial for medical, engineering, and environmental applications.     

Mechanically reinforced biodegradable nanocomposites. A facile synthesis based on PEGylated silica nanoparticles

Biodegradable nanocomposites consisting of poly(?-caprolactone) (PCL) reinforced by PEGylated silica (polyethylene-glycol/SiO₂) nanoparticles were prepared by a melt-extrusion process. The PEGylated silica nanoparticles were prepared in a facile, one-pot synthesis process. Transmission electron microscopy (TEM) observations of the PEGylated silica nanoparticles inside the PCL matrix indicated that a homogeneous dispersion had been achieved. As a result, the storage modulus (E′) in the rubbery plateau increased significantly with the filler contents at all temperatures studied, at values approximately 45% higher than the neat PCL, at a loading level of only 4 wt.%. In comparison, in the absence of polyethylene-glycol (PEG) the silica nanoparticles formed aggregates inside the PCL matrix, and the reinforcement was negligible. The results from X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR) analyses identified the location of the PEG at the PCL/silica interface.     

Soya protein as possible potential nanocarriers for in-vitro oral delivery of insulin in simulated gastric fluids (SGFs)

The present study aimed to prepare soya protein nanoparticles and employ them as nanocarriers for delivery of insulin. The nanoparticles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microcopy, zeta potential, and dynamic light scattering measurements. The particle size analysis revealed that the size of the nanoparticles lays in the range of 40–200?nm with surface charge of ?25.3?mV. The insulin-loaded nanoparticles were investigated in simulated gastric and simulated intestinal fluids and effect of percent drug loading chemical composition of nanoparticles, pH, temperature of the release media, and simulated physiologic fluids was studied on the release of insulin.     

Polymeric plasticizers for PVC

High molecular weight plasticizers can be used if they have a low T_g and are miscible with PVC. For example, linear polyesters exhibit miscibility with PVC when their [CH₂]/[COO] ratio is intermediate; in that range, as “miscibility window” has been found. However, the degree of miscibility of miscible polymer blends vary with the structure of the polymers involved and thier concentration. The miscibility of these systems is often assessed by the measurement of a single T_g as a function of composition. A careful examination of experimental data of polyester/chlorinated polymer blends, as well as the use of the free volume theory, indicates that several of these systems exhibit a cusp as a function of composition, which is characterized by a critical volume fraction and a critical temperature. Specific examples are given.     

Stochastic molecular descriptors for polymers. 4. Study of complex mixtures with topological indices of mass spectra spiral and star networks: The blood proteome case

The Quantitative Structure-Property Relationships (QSPRs) based on Graph or Network Theory are important for predicting the properties of polymeric systems. In the three previous papers of this series (Polymer 45 (2004) 3845-3853; Polymer 46 (2005) 2791-2798; and Polymer 46 (2005) 6461-6473) we focused on the uses of molecular graph parameters called topological indices (TIs) to link the structure of polymers with their biological properties. However, there has been little effort to extend these TIs to the study of complex mixtures of artificial polymers or biopolymers such as nucleic acids and proteins. In this sense, Blood Proteome (BP) is one of the most important and complex mixtures containing protein polymers. For instance, outcomes obtained by Mass Spectrometry (MS) analysis of BP are very useful for the early detection of diseases and drug-induced toxicities. Here, we use two Spiral and Star Network representations of the MS outcomes and defined a new type of TIs. The new TIs introduced here are the spectral moments (π_k) of the stochastic matrix associated to the Spiral graph and describe non-linear relationships between the different regions of the MS characteristic of BP. We used the MARCH-INSIDE approach to calculate the π_k(SN) of different BP samples and S2SNet to determine several Star graph TIs. In the second step, we develop the corresponding Quantitative Proteome-Property Relationship (QPPR) models using the Linear Discriminant Analysis (LDA). QPPRs are the analogues of QSPRs in the case of complex biopolymer mixtures. Specifically, the new QPPRs derived here may be used to detect drug-induced cardiac toxicities from BP samples. Different Machine Learning classification algorithms were used to fit the QPPRs based on π_k(SN), showing J48 decision tree classifier to have the best performance. These results suggest that the present approach captures important features of the complex biopolymers mixtures and opens new opportunities to the application of the idea supporting classic QSPRs in polymer sciences.     

A de novo formulation of metformin using chitosan-based nanomicelles for potential diabetes therapy

A de novo formulation of metformin (MET) was developed through the physical loading of drug into a chitosan-grafted-[poly(acryl amide)-block-poly(acrylic acid)] [CS-g-(PAAm-b-PAA)] terpolymer. For this purpose, CS was functionazed with phthalic anhydride followed by 4-cyano, 4-[(phenylcarbothioyl)sulfanyl]pentanoic acid to produc a macro-RAFT agent (CS-CTA). Afterward, acryl amide and acrylic acid monomers were graft and block copolymerized onto the synthesized CS-CTA through a reversible addition–fragmentation chain transfer (RAFT) polymerization technique to afford CS-g-PAAm copolymer and CS-g-(PAAm-b-PAA) terpolymer, respectively. The fabricated CS-g-(PAAm-b-PAA) terpolymer was loaded with MET as an anti-diabetic drug, and its drug release behavior was evaluated in the body simulated environment. As results, it was concluded that the fabricated CS-g-(PAAm-b-PAA) nanosystem has high potential as de novo drug delivery system (DDS) for diabetes therapy, mainly due to controlled drug release profile in comparison with conventional formulations of MET. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48037.     

Design and synthesis of perfluorinated amphiphilic copolymers: Smart nanomicelles for theranostic applications

Since decades, varieties of amphiphilic polymers have been widely investigated for improving aqueous solubility and bioavailability of the hydrophobic drugs. The upcoming approach is to develop more efficient advanced nano-carrier molecules capable of more than drug delivery. Herein, we report the design and synthesis of some novel carrier molecules with multiple applications including drug encapsulation, drug delivery and diagnosis (imaging). Copolymers were synthesized using dimethyl 5-hydroxy/aminoisophthalate, poly(ethylene glycols) and Candida antarctica lipase (CAL-B, Novozym 435). CAL-B selectively catalyses the trans esterification reaction under solvent less condition using primary hydroxyls of poly(ethylene glycols) and leaving behind phenolic hydroxyl for post polymerization modifications. The obtained copolymers were further tethered with perfluorinated aliphatic chains to make them amphiphilic. The synthesized materials were investigated for their micellar behavior, temperature dependent stability (in aqueous solution), encapsulation capacity, and imaging potential by measuring the sensitivity of these perfluorinated materials towards ¹⁹F NMR in NMR tube. It was observed that perfluorinated amphiphilic copolymers could encapsulate up to 14% (by wt) of hydrophobic drug and showed decent ¹⁹F NMR signals even at a very low concentration. Therefore, these perfluorinated copolymers hold considerable potential for further investigation as advanced nano-carrier molecules for biomedical applications.     

Polymeric plasticizers for gypsum-free cement

The influence of water solutions of polyvinyl alcohol, a copolymer of acrylamide/N-methylol-acrylamide, and six water-borne polymer dispersions made from vinyl acetate and acrylic comonomers on the hardening of cement paste and on chemical resistance of the obtained concert samples was investigated. The cement paste was obtained by mixing of pure, gypsum-free ground clinker with water, and lower or higher amount of plasticizer. The coils of water-soluble polymers or the particles of dispersions covered only from 7% to 17% of the surface of the cement particles. The plasticizers increased compressive strength by 17% at an age of 28 days and by 23% after treatment by aggressive solutions for 6 months.     

Polymeric Membranes for Medical Applications

The commercial application of membranes in dialysis treatment has started already 40 years ago. Today, dialysis is the application in medicine using the largest number of membrane surface area per year. Integration of the membrane production process into dialyzer manufacturing was the key element in the successful transition from small scale production to large scale dialyzer manufacturing. Automatization techniques are heavily integrated into this process to fulfill the high quality and safety demands in medical technology. This paper gives an overview on the different membrane applications in medical industry. The material selection for manufacturing dialysis membranes and the different membrane morphologies are discussed. In the second part the different manufacturing steps in dialyzer production are presented.     

Polymeric membranes for lipase immobilization

Lipase triacylglycerol acylhydrolase, (E.C. 3.1.1.3) is an enzyme that is fully active on aggregated substrates and practically inactive on monodisperse systems. A lipase immobilized on polymeric membranes has been applied for sunflower oil hydrolysis. The influence of membrane properties on enzyme activity is studied. Membranes made of poly(vinyl chloride), collagen, cellulose acetate and polytetrafluoroethylene were used for adsorption of lipase. The porosity and hydrophobicity of membranes did not influence the lipase activity. The difference of the work of adhesion for the water/membrane system and oil/membrane system reflected the activity data, while work of adhesion for water or oil (done separately) did not. For oil hydrolysis to occur on the membrane surface, accessibility of two liquid phases is important, and the lower the difference of work of adhesion between water and oil, the greater the activity of immobilized lipase.     

Biopolymers as Carriers for Nasal Drug Delivery

Biopolymers are the most abundant raw materials that can be obtained from natural sources including bacteria, fungi, plants and even humans. The biopolymers are easily available, non-toxic, biodegradable and Generally Regarded as Safe (GRAS). These natural polymers can play an important role in the formulation of drug delivery systems by influencing the release, residence time and permeation of the therapeutic agent. The present review gives an insight into the important biopolymers and their properties in the effective delivery of the therapeutic agents systemically as well as targeting the brain via the intranasal route.     

高分子材料抗静电技术

介绍了静电的产生、危害及其防止的方法,重点评述了高分子材料抗静电技术的研究进展.     

Polymeric composites for repair purposes

A broad assortment of adhesive compositions and compounds under the common trade mark ANATERM are presented. Their mechanical characteristics and practical applications are outlined.     

Polymeric nanostructured materials for biomedical applications

Polymeric nanostructured materials (PNMs), which are polymeric materials in nanoscale or polymer composites containing nanomaterials, have become increasingly useful for biomedical applications. In specific, advances in polymer-related nanoscience and nanotechnology have brought a revolutionary change to produce new biomaterials with tailored properties and functionalities for targeted biomedical applications. These materials, including micelles, polymersomes, nanoparticles, nanocapsules, nanogels, nanofibers, dendrimers and nanocomposites, have been widely used in drug delivery, gene therapy, bioimage, tissue engineering and regenerative medicine. This review presents a comprehensive overview on the various types of PNMs, their fabrication methods and biomedical applications, as well as the challenges in research and development of future PNMs.     

Morphology and properties of thermoplastic polyurethanes with dangling chains in ricinoleate-based soft segments

In our previous publication on the structure-property behavior of segmented polyurethanes based on castor oil [Petrovi? ZS, Xu Y, Zhang W. Polymer Preprints 2007;48(2):852-3.], the results showed that these materials which possessed a soft segment weight concentration (SSC) of 70% have both low tensile strength and elongation at break. This behavior is distinctly different from segmented polyurethanes of comparable soft segment content obtained from petrochemical polymeric diols that possess terminal hydroxyl groups. The poor elastic properties of these segmented polyurethanes were ascribed to the low molecular weight of the polymers as well as due to the presence of the six-carbon “dangling chain”, which may influence the morphology of the resulting segmented polyurethanes. To further understand this behavior, four segmented polyurethanes with the SSC of 70, 60, 50, and 40%, respectively, were synthesized from a polyricinoleate diol with an M_n of 2580, diphenylmethane diisocyanate (MDI) and butanediol. The objective of this work was to study the effect of SSC on the morphology of the resulting polyurethanes, and to correlate the morphology with the properties of these bio-based segmented polyurethanes. Polymers were characterized by GPC, viscometry and spectroscopic methods. Thermal and mechanical properties of the polymers indicated good microphase separation. Microphase morphology was also noted by SAXS and AFM. Finally, “spherulitic-like” superstructures were noted in the solution cast films that are believed to arise from the nucleation and crystallization of the hard segments.