Discovery Of Poly Research Articles

Takashi Sugimura: In Memoriam (1926–2020)–A Personal Perspective

![][1] Takashi Sugimura was a pioneer in cancer research and a figure recognized internationally for his seminal contributions to the understanding of mutagenicity and chemical carcinogenesis. Rather than focusing on the many accolades, honors, and influential positions that he held,

Thiophene-Based Aldehyde Derivatives for Functionalizable and Adhesive Semiconducting Polymers.

The pursuit for novelty in the field of (bio)electronics demands for new and better-performing (semi)conductive materials. Since the discovery of poly(3,4-ethylenedioxythiophene) (PEDOT), the ubiquitous golden standard, many studies have focused on its applications but only few on its structural modification and/or functionalization. This lack of structural variety strongly limits the versatility of PEDOT, thus hampering the development of novel PEDOT-based materials. In this paper, we present a short and simple strategy for introducing an aldehyde functionality in thiophene-based semiconducting polymers. First, through a two-step synthesis, an EDOT-aldehyde derivative was prepared and polymerized, both chemically and electrochemically. Next, to overcome the inability of thiophene-aldehyde to be polymerized by any means, we synthesized a trimer in which thiophene-aldehyde is enclosed between two EDOT groups. The successful chemical and electrochemical polymerization of this new trimer is presented. The polymer suspensions were characterized by ultraviolet-visible-near-infrared spectroscopy, while the corresponding films were characterized by Fourier transform infrared and four-point-probe conductivity measurements. Afterward, insoluble semiconducting films were formed by using ethylenediamine as a cross-linker, demonstrating in this way the suitability of the aldehyde group for the easy chemical modification of our material. The efficient reactivity conferred by aldehyde groups was also exploited for grafting fluorescent polyamine nanoparticles on the film surface, creating a fluorescent semiconducting polymer film. The films prepared by electropolymerization, as shown by means of a sonication test, exhibit strong surface adhesion on pristine indium tin oxide (ITO). This property paves the way for the application of these polymers as conductive electrodes for interfacing with living organisms. Thanks to the high reactivity of the aldehyde group, the aldehyde-bearing thiophene-based polymers prepared herein are extremely valuable for numerous applications requiring the facile incorporation of a functional group on thiophene, such as the functionalization with labile molecules (thermo-, photo-, and electro-labile, pH sensitive, etc.).

Synthetic Polymer with a Structure-Driven Hepatic Deposition and Curative Pharmacological Activity in Hepatic Cells

Synthetic polymers make strong contributions as tools for delivery of biological drugs and chemotherapeutics. The most praised characteristic of polymers in these applications is complete lack of pharmacological function such as to minimize the side effects within the human body. In contrast, synthetic polymers with curative pharmacological activity are truly rare. Moreover, such activity is typically nonspecific rather than structure-defined. In this work, we present the discovery of poly(ethylacrylic acid) (PEAA) as a polymer with a suit of structure-defined, unexpected, pharmacological, and pharmacokinetic properties not observed in close structural analogues. Specifically, PEAA reveals capacity to bind to albumin with ensuing natural hepatic deposition in vivo and exhibits concurrent inhibitory activity against the hepatitis C virus and inflammation in hepatic cells. Our findings provide a view on synthetic polymers as curative, functional agents and present PEAA as a unique biomedical tool with applications related to health of the human liver.

Enhanced catalytic activity towards hydrogen evolution on polythiophene via microstructural changes

The discovery of poly(2,2′-bithiophene) (PBTh) as a photo-electrochemical catalyst for the hydrogen evolution reaction (HER) presents a novel electrode material for the transition to a sustainable hydrogen energy economy. Nonetheless, it remains limited by a low hydrogen evolution rate. We here investigate two methods in which to increase the catalytic activity of PBTh: using humidity for alternative templating and substrate roughening. It was found that exposure of the oxidant solution to humidity prior to polymerisation causes the formation of new microstructures that was found to increase catalytic activity of the PBTh film by over four times, from 14 to 57 µA cm-2. It was also found that control of the atmospheric environment proved critical. In contrast, the roughening of the substrate did not consistently lead to an increase in performance and was attributed to poor adhesion and electrical contact of the film to the substrate. During these tests however, a photo-electrocatalytic current of 150 μA cm−2 was recorded in pH 7.0 and an underpotential of 0.12 V on an un-roughened PBTh sample. This represents the highest reported value for PBTh thus far and a significant achievement for its further development towards a low-cost and efficient HER catalyst.

Presence of poly(A) tails at the 3'-termini of some mRNAs of a double-stranded RNA virus, southern rice black-streaked dwarf virus.

Southern rice black-streaked dwarf virus (SRBSDV), a new member of the genus Fijivirus, is a double-stranded RNA virus known to lack poly(A) tails. We now showed that some of SRBSDV mRNAs were indeed polyadenylated at the 3' terminus in plant hosts, and investigated the nature of 3' poly(A) tails. The non-abundant presence of SRBSDV mRNAs bearing polyadenylate tails suggested that these viral RNA were subjected to polyadenylation-stimulated degradation. The discovery of poly(A) tails in different families of viruses implies potentially a wide occurrence of the polyadenylation-assisted RNA degradation in viruses.

Phosphorus containing hydrogels

AbstractSince the discovery of poly(2‐hydroxyethyl methacrylate) by Wichterle and Lim in 1960, hydrogels have been of great interest to biomedical scientists. Hydrogels are three dimensional hydrophilic polymer networks capable of swelling in water or biological fluids and retaining a large amount of fluids in the swollen state. In the last decade, hydrogels containing organophosphorus moieties were synthesized and used for proton conducting membrane, drug carriers, and scaffold for tissue engineering, pharmaceutical formulation, cosmetics, and bioseparation. One of the most versatile and rapidly developing classes of biomedical polymers is a family of polymers with a nitrogen and phosphorus backbone—polyphosphazenes. The advantage of the phosphorus–nitrogen backbone is that it can be rendered hydrolytically unstable when combined with appropriate side groups. Because of the tremendous variety of substituents that can be introduced in their structure, phosphazene polymers exhibit a very broad and sophisticated spectrum of chemical and physical properties leading to almost unlimited possibilities in the preparation of biodegradable materials Copyright © 2009 John Wiley & Sons, Ltd.

Phthalazinones 2: Optimisation and synthesis of novel potent inhibitors of poly(ADP-ribose)polymerase

We have previously described the discovery of poly(ADP-ribose)polymerase-1 (PARP-1) inhibitors based on a phthalazinone scaffold. Subsequent optimisation of inhibitory activity, metabolic stability and pharmacokinetic parameters has led to a novel series of meta-substituted 4-benzyl-2 H-phthalazin-1-one PARP-1 inhibitors which retain low nM cellular activity and show good stability in vivo and efficacy in cell based models.

“SENSELESS” ANTIVIRAL POLYRIBONUCLEOTIDES: POLY (1-PROPARGYLINOSINIC ACID)

ABSTRACT Previous work has shown that novel amphipathic oligo and polyribo-nucleotides exhibiting secondary structure in solution are potent inhibitors of HIV and HCMV replication and cytopathicity in tissue culture. It was hypothesized that the mechanism(s) of action for these compounds might be inhibition of retroviral reverse transcriptase (RT) and/or viral uptake by cells. Pursuit of the essential pharmacophore has led to the discovery of poly (1-propargylinosinic acid) (10), an HIV and HCMV-active polyribonucleotide lacking the secondary structure previously thought to be essential for the observed antiviral activity.

Preparation and Photoluminescence Characteristics of Carbazole-Poly(p-phenylenevinylene)s

Organic conjugated polymers for light-emitting diodes (LEDs) attract much attention for good optical applications. Organic conjugated polymers have been synthesized for development of photoluminescence (PL) properties.1–3 Since the discovery of poly(pphenylenevinylene) (PPV) exhibiting photoluminescence a variation of conventional PPV was investigated in which backbone conjugation is partially modified using spacers. In 1993, Karasz et al. demonstrated the block copolymer, which has specified units of PPV copolymer with alkyl spacer.4 As mentioned in a lots of papers, progress for achievement of blue-emitting organic polymers has been concentrated on the introduction of side group or newly designed backbones by insertion of heterocycles. We recently synthesized PPV copolymers that have shorter backbone conjugations and examined their luminescence.5, 6 They showed emission spectra in far-blue region and exhibited specific luminescence effect by conjugation length of main chain and methoxy substituents on the phenyl ring. Although hundreds of studies have been conducted using conventional phenylenevinylene-phenylen-vinylene-phenylene unit, effective works need variation of backbones to find a blueemitting polymer showing low turn-on voltage simultaneously. Recently PPV derivatives containing a carbazole moiety in the backbone or side chain have been reported.7–9 In particular, these carbazole-containing PPV copolymers are good materials for making optical and electronic devices due to high hole-transporting capability of carbazole unit.10–12 The introduction of new organic polymers based on the carbazole molecule and exploration of applications in the fabrication of organic light-emitting devices will further interest on carbazole-PPVs for possible optoelectronic applications. So we synthesized three carbazol-PPV derivatives that contain a carbazole unit as a part of main chain and examined luminescence properties. We herein report photoluminescence characteristics and alkoxy substituent effects of carbazole-containing PPV copolymers.

Novel delivery systems in contraception.

Contraception has mainly remained the responsibility of women. The sexually active time during the fertile period of life may last over 30 years and, increasingly, it is more than 10 years before the first baby. It is, therefore, natural that convenient long-acting contraceptive methods are becoming more and more appealing. The discovery of poly(dimethylsiloxane) as a carrier, and controlled release polymers for small molecule drugs allowed the development of contraceptive devices releasing steroids for several years. While contraceptive implants and intra-uterine systems are already marketed in many countries, contraceptive vaginal rings are in their late development phase. The key features of these long acting delivery systems are convenience, efficacy, reversibility and positive long-term health effects. Since these methods are based on new concepts, the provider needs to be prepared for extensive counselling.

Fluoroelastomers

Abstract The importance of fluorine in polymer chemistry has been known since the discovery of poly (tetrafluoroethylene) in 1938. Highly fluorinated polymers are very stable and have remarkable resistance to oxidative attack, flame, chemicals, and solvents. This stability has been attributed to the strength of the carbon—fluorine bond compared to that of the carbon—carbon bond, to steric hindrance, and to strong Van der Waals forces. The synthesis of elastomeric polymers containing enough fluorine to impart a significant degree of stability was not achieved until the mid-1950's. Since then a multitude of fluoroelastomers have been reported, but, of these, only certain copolymers of vinylidene fluoride, and fluorosilicone polymers have become commercially important. Recently, however, perfluoroelastomers based on perfluoro (alkyl vinyl ethers) and tetrafluoroethylene have been shown to possess an even greater degree of high temperature stability than do the fluoroelastomers hitherto available. These perfluoroelastomers also are essentially inert to most chemicals and solvents. Copolymers of perfluoro (alkyl vinyl ethers) with partially fluorinated monomers also have been developed that give better flexibility at low temperature. These polymers, now at the developmental stage, appear to be the forerunners of a new generation of superior high-performance elastomers. The discussion that follows will concern firstly, the commercial fluoroelastomers; secondly, those that show commercial promise and might be considered semi-commercial or at the developmental stage but which are available only in limited developmental quantities; and thirdly, those reported in the literature that, so far at least, have been of research interest only. In this last category, polymers will not be included which contain so little fluorine that performance characteristics are not substantially enhanced. For example fluoroprene [poly(2-fluorobutadiene)] and copolymers with nonfluorinated, olefin monomers in which the latter predominate will not be included.

Synthesis of DNA from vaccinia messenger RNA templates.

POLYADENYLIC acid sequences have been demonstrated in most messenger RNA molecules isolated from eukaryotic cells and animal viruses1–7. These sequences, ranging in size from 50 to 200 nucleotides, have been shown to occur on the 3-prime end of mRNA molecules of vaccinia virus and of HeLa cells (ref. 2 and unpublished results of W. Maloy and R. Perry and R. S. Sheldon, J. Kates and R. Perry). Aside from its intrinsic interest, the discovery of poly A sequences attached to messenger RNAs helps the study of gene expression in higher cells. For example, the ability of poly A containing mRNAs to bind quantitatively to immobilized poly U or poly dT is the basis of an extremely powerful method for the purification of most of the mRNA present in the polyribosomal fraction of cells2,6. Another potentially important application of the poly A sequence in mRNA, which will be the subject of this report, is its ability greatly to facilitate the synthesis of DNA copies of mRNA molecules using the RNA dependent DNA polymerase purified from oncornaviruses such as avian myeloblastosis virus (AMV) and Rous sarcoma virus (RSV)8–10. The simple principle involved depends on the fact that the reverse transcriptase enzyme functions very efficiently when an RNA template such as poly A is coupled with a small complementary DNA primer such as oligo dT11–13. The DNA product of this reaction is found covalently attached to the 3-prime end of the primer oligomer (David Baltimore, personal communication). We report here the success of the latter experimental approach in the efficient production of DNA complements of vaccinia virus messenger RNAs. Vaccinia virus mRNA was chosen purely as a model system in view of the fact that it can readily be synthesized in vitro in large quantities using the endogenous viral transcriptase15,16 and because about 90% of the RNA contains 3-prime poly A sequences.