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In this work, we fabricated a thermosensitive hydrogel based on NIPAM that incorporated an oxygen-permeable hyaluronic acid (HA) polysaccharide unit. The interpenetrating network (IPN) of NIPAM-HA-MA hydrogel was fabricated by using an ultraviolet (UV) cross-linking process. Importantly, we explored the real behavior kinetics of the hydrogel via the mechanical properties of Young's modulus and the shear strain. The mechanical properties were reduced when the temperature was raised from 25 to 35 °C, and lower temperatures increased the rigidity of the IPN gel. This dynamic change occurred because of NIPAM's thermosensitive character. Further, IPN hydrogel exhibits good transparency with the incorporation of MA-HA and this stimuli-responsive hydrogel was biocompatible with a human dermal fibroblasts cell line (HDF). The cells adherence was densest when the temperature reached 37 °C and was reduced when the temperature was lowered to 25 °C. We envision using such hydrogels as mimics of cell-instructive biomaterials in tissue engineering applications.

In this work, we studied the light induced self-assembly of F-actin and heavy meromyosin (HMM) in tubular vesicles or "tubularsomes" during initiation by ATP. To mimic nature, light-induced ATP synthesis was used for the F-actin/HMM self-assembly inside these vesicles created from a triblock copolymer reconstituted with the membrane protein bacteriorhodopsin (bR) and F1F0-ATPase along with F-actin and HMM in the core.

Synthesis, purification, and characterization of 3'-O-caged 2'-deoxyribonucleoside triphosphates (dNTPs), namely 3'-O-(2-nitrobenzyl)-2'-deoxy ribonucleoside triphosphates (NB-dNTPs) and 3'-O-(4,5-dimethoxy-2-nitrobenzyl)-2'-deoxy ribonucleoside triphosphates (DMNB-dNTPs), are discussed in detail. A total of eight 3'-O-caged dNTPs are synthesized with specific protocols depending on the nitrogenous base on the first carbon, i.e., adenine, guanine, thymine, and cytosine, as well as the photo-cleavable group, i.e, 2-nitrobenzyl and 4,5- dimethoxy-2-nitrobenzyl, to be attached in the 3'-O position. The purification of the synthesized compounds is done using ion-exchange and flash chromatography; this is followed by structural confirmation by nuclear magnetic resonance (NMR) and mass spectroscopy (MS). The efficiency of the designed compounds is tested by conducting and evaluating UV-cleaving experiments at 365 nm with proton NMR and LC-MS curves. Finally, the application of the 3'-O-cagged dNTPs in template-independent, enzyme-catalyzed, photo-mediated oligonucleotide synthesis is demonstrated. © 2017 by John Wiley & Sons, Inc.

The specific targeting ability of novel breast cancer targeting peptides as ligands coupled to polymeric micelles was evaluated in the present study. In this context, engineered breast cancer cell targeting peptides, denoted as peptide 11 (RGDPAYQGRFL) and peptide 18 (WXEAAYQRFL), were compared with the lead 12-mer p160 peptide and cyclic RGDfK peptide. All four peptides were conjugated individually to poly(ethylene oxide)-b-poly(caprolactone) (PEO-b-PCL) diblock polymeric micelles to obtain targeted carrier systems PM11, PM18, PM 160, and PM c-RGD. Physical blending of the peptides 11 and 18 with PEO-b-PCL was also done to yield combination micelles, comPM11 and comPM18. The structural confirmation of polymer was carried out using (1)H NMR and MALDI-TOF, and the size distribution and zeta potential of the micelles were determined using dynamic light scattering. Lipophilic cyanine fluorescent probe DiI was physically incorporated in the polymeric micelles to imitate the hydrophobic drug loaded in the micellar core. The cellular uptake of DiI-loaded peptide-containing polymeric micelles by MDA-MB-435, MDA-MB-231, and MCF7 breast cancer cell lines, as well as HUVEC and MCF10A noncancerous cells, were analyzed using flow cytometry and confocal microscopy techniques. Modification of polymeric micelles with peptide 11 or 18 led to an increase in micellar uptake specifically in breast cancer cells compared to p160, c-RGD modified, or naked micelles. The peptide-micelle combinations (comPM11 and comPM18) displayed better uptake by the cells compared to the covalently conjugated PM11 and PM18 micelles; however, the combinations were less selective toward cancer cells. The results point to a potential for peptides 11- and 18-micelle conjugates as attractive platforms for improved performance of a wide range of chemotherapeutic drugs and/or imaging agents in cancer therapy and diagnosis.

The synthesis, characterization and potential application of eight 3'-O modified 2'-deoxyribonucleoside triphosphates (dNTPs) are discussed. These nucleotide analogues are modified by capping the 3'-OH with a photolabile protecting group which can temporarily cease DNA strand growth and can smoothly reinitiate the growth by the photodecomposition of the protecting group and setting the 3'-OH of dNTPs free to propagate. The synthesis of 3'-O-(2-nitrobenzyl)-2'-deoxyribonucleoside triphosphates (NB-dNTPs) and 3'-O-(4,5-dimethoxy-2-nitrobenzyl)-2'-deoxyribonucleoside triphosphates (DMNB-dNTPs) is discussed in detail with structural confirmation using NMR. The UV-cleaving studies are monitored and quantified using LCMS and (1)H NMR spectral traces. The synthesised nucleotides are employed for terminating and reinitiating template-less DNA synthesis, using primer independent Terminal Deoxynucleotidyl Transferase (TdT) enzyme. The use of this photolabile nucleotide in one step stop-start DNA synthesis is a novel strategy towards the precise assembly of dNTPs with the potential to reinforce present technologies.

A novel block copolymer of poly[N-isopropyl acrylamide]-co-polyurethane was designed, synthesized, and applied as controlled release fertilizer coating. Structural confirmation of the copolymer was performed using FTIR and 1H-NMR spectra and elemental analysis. The coating process consists essentially of immersing urea granules in molten polymer and removing the coated urea from the melt by centrifugal action. The morphology of the coated urea was studied using scanning electron microscope (SEM). The polymer coat of the urea granules was found to swell in water forming pores and enabling the release of urea. The urea released from the granule, monitored using a mass spectroscopy technique, was found to be governed by pH of the aqueous medium. The study anticipates development of a beneficiary fertilizer coat in terms of improving controlled release over a period of time which can be tailored by soil temperature, pH and moisture. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3236–3243, 2010

We report the effect of the amount of the mesoporous material, SBA-15, on the basic traits of fully aliphatic polyimides (API). For this purpose, water soluble, fully aliphatic poly(amic acid) triethyl amine salts (PAA(s)) were prepared and mixed with various amounts of SBA-15. Fully aliphatic polyimide hybrid composites containing the SBA 15-type mesoporous silica were synthesized successfully from bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and alicyclic diamine, 4,4′-methylene bis(2-methylcyclohexylamine). The structure of the hybrid composites was confirmed by IR spectroscopic analysis. Scanning electron microscopy revealed the morphology of the compounds. The hybrid composites exhibited good thermal stability, reasonable transparency, and a low dielectric constant.

Novel temperature-sensitive poly[N-isopropylacrylamide-co-2-hydroxyethylacrylate] [P(NIPAAm-HEAc)] colloidal crystals containing β-cyclodextrin (β-CD) were prepared. These reversibly tunable supramolecular inclusion complexes display brilliant colors, due to the self-assembly of several structured nanoparticles to form crystal structures. The hydrogels displayed rainbow colors upon the variation of the β-CD concentration and can be made either visible or invisible by simply changing the temperature. The inclusion complexes were characterized using NMR spectroscopy, laser light scattering, UV-visible spectroscopy, and viscometer measurements. Compared with the conventional poly(N-isopropylacrylamide) gel, the β-CD-incorporated hydrogels in aqueous solution showed a lower critical solution temperature of about 57°C, which can be attributed to the hydrogen bonding between P(NIPAAm-HEAc) included in β-CD and water, which is enhanced by the hydrophilic groups of β-CD. The use of these materials as drug carriers was also evaluated by making use of their thermo-responsive behavior. The release time of a model drug, 5-fluorouracil (5-FU), from the novel inclusion complexes was prolonged in comparison to that from P(NIPAAm-HEAc) without β-CD. The significance of the present drug delivery system is the mixing of the gel and drug without any chemical reaction at room temperature, resulting in a gelled drug depot for slow and controlled release.

Here, we report the synthesis and characterization of new soluble polyimides that are functionalized using carbazole moieties in their side chain. As a monomer for synthesizing the polyimides, 4″-carbazole-9-yl-[1,1′;2′,1″] terphenyl-4-4′-diamine and 2-(3-carbazol-9-yl-propyl)-biphenyl-4,4′-diamine were synthesized and then characterized using 1H NMR, 13C NMR, FTIR, UV–visible and photoluminescence spectroscopy, differential scanning calorimetry (DSC), and elemental analysis. The polyimides synthesized via chemical imidization processes were characterized with X-ray photoelectron spectroscopy, gel permeation chromatography, wide angle X-ray diffraction, thermogravimetric analysis, DSC, tensile strength measurement, and dielectric property measurement. Results showed that the synthesized polyimides were soluble in a variety of organic solvents, optically transparent in a visible range, thermally stable, mechanically strong, and considerably low dielectric. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8117–8130, 2008

A set of functionalized polynorbornenes with various substituted pendant imide groups ( N -substituent imide group = adamantyl, cyclohexyl, tolyl, and phenyl) have been prepared via vinylic pathway by using di-μ-chloro-bis-(6-methoxybicyclo[2.2.1]-hept-2-ene- endo -5σ,2π)-palladium(II) catalyst as a means of developing materials for low dielectric constant. The effects of molar ratio of monomer to catalyst, solvent polarity, reaction time, and temperature on the polymerization of substituted norbornene-5,6-dicarboximide were investigated. Among the monomers used, exo - N -cyclohexyl-norbornene-5,6-dicarboximide recorded the highest activity, giving 90% conversion in 30 min. All the resulting functionalized polynorbornenes are characterized by good thermal properties (∼5% weight loss at 440 °C) and low dielectric constants (2.26–2.53), which are desirable for the next generation of microprocessors and memory for computers to provide insulation in the increasingly shrinking feature sizes of faster microprocessors.

Series of fully aliphatic polyimides were prepared from cyclobutane- 1,2,3,4-tetracarboxylic dianhydride and aliphatic diamines. The variations of the basic properties of these polyimides as a result of the incorporation of adamantyl and siloxane moieties are examined. The structure of the polyimides where confirmed by FT-IR spectroscopy. It was found that polyimides with appropriate ratio of adamantane and siloxane groups showed excellent solubility, good thermal stability, high glass transition temperature, low dielectric constant and beneficial transparencies.

Polyimides are one of the most important classes of polymers used in the microelectronics and photoelectronics industries. Because of their high thermal stability, chemical resistance, and good mechanical and electric properties, polyimides are often applied in photoresists, passivation and dielectric films, soft print circuit boards, and alignment films within displays. Recently, fully aliphatic and alicyclic polyimides have found applications as optoelectronics and inter layer dielectric materials, due to their good transparencies and low dielectric constants (e). The low molecular density, polarity and rare probability of forming inter- or intra-molecular charge transfers, resulting in lowering of the dielectric constant and high transparency, are the most striking characteristics of aliphatic polyimide. However, the ultimate end use of polyimides derived from aliphatic monomers is in their targeted applications that need less stringent thermal requirements. Much research effort has been exerted in the development of aliphatic polyimide with increased thermal and mechanical stabilities, while maintaining their transparencies and low dielectric constants, by the incorporation of rigid moieties. In this article, the recent research process in synthesizing fully aliphatic polyimides, with improved dimensional stability, high transparency and low e values, as well as the characterizations and future scope for their application in micro electric and photo-electronic industries, is reviewed.

A series of fully aliphatic polyimidosiloxanes (APISiO) were prepared by poly(addition/condensation) reaction of bicyclo (2,2,2) oct-7-ene-2,3,5,6-tetracarboxylic dianhydride or cyclobutane-1,2,3,4-tetracarboxylic dianhydride and varying composi- tions of 1,3-bis (3-amino propyl)-tetra methyl disiloxane and rigid adamantyl di- amines (1,3-diaminoadamantane or 3,3 0 -diamino-1,1 0 -diadamantane) or flexible alicy- clic diamines (4,4 0 -methylene bis(cyclohexylamine) or 4,4 0 -methylene bis(2-methylcy- clohexylamine)). High temperature one-step synthesis in m-cresol was employed to obtain APISiOs with intrinsic viscosity in the range of 0.28-0.59 dL/g. The final materials were characterized by 1 H and 13 C NMR, 29 Si-MAS-NMR and IR spectro- scopic analysis, thermogravimetric and differential scanning calorimetric analysis, and wide angle X-ray diffractometry. UV-visible spectra revealed the optical behavior of the polyimides. It was found that the APISiOs containing appropriate ratio of ada- mantyl moieties together with flexible aliphatic siloxane groups exhibit good thermal and mechanical stabilities, solubility, fair transparency, and low dielectric constant (2.4-2.7). V C 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5254-5270, 2006

We have synthesized a series of fully alipha- tic polyimides (APIs) from bicyclo(2,2,2)oct-7-ene-2,3,5,6- tetracarboxylic dianhydride (BOCA) and various aliphatic diamines, including linear aliphatic, flexible alicyclic, and rigid adamantyl diamines. We performed the polymeriza- tion reactions using one-step syntheses in m-cresol at ele- vated temperatures without the isolation of poly(amic) acid. The chemical composition and structure of the poly- mers were characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectrometry. The characteriza- tion data are reported from analyses using gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), and wide-angle X-ray diffraction (WXAD) measurements. The polyimides are also subjected to solubility, solution viscosity, tensile strength, transparency, and dielectric constant measure- ments. The resultant polyimides possess well-controlled molecular weight, reasonable intrinsic viscosity, good transparency, enhanced solubility, low dielectric constants, and high glass transition temperature, together with mar- ginal thermal and mechanical stability. These properties were enhanced in copolyimides containing equimolar amounts of rigid and flexible moieties. These rigid-rod APIs derived from the alicyclic dianhydride and aliphatic diamines are promising candidates as advanced materials for future applications in micro- and photoelectronic de- vices. 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3316-3326, 2006

Fabrication of biodegradable polymer nanoparticles (NPs) is a fascinating research area because of their great potential in biomedical applications. In this work, apart from the well-reported di- or tri-block copolymer nanoassembly, homopolymers based on poly(caprolactone) were designed, synthesized and fabricated to obtain 200 nm size NPs, controlled by the duration of the ultraviolet (UV) cross-linking process. Furthermore, the encapsulated drug, doxorubicin, and the cross-linked NP system were produced via a UV cross-linking micro-emulsion process. Importantly, the drug-encapsulated NPs were taken up intracellularly and cytotoxicity studies were carried out in two different cell lines, HUVEC and SK-OV-3. The NP system reported here is a complimentary approach to existing therapeutic agents in biomedical engineering based on the straightforward utility of a single UV cross-linkable polymer with the ability to encapsulate and release drugs. It holds the promise of fine-tuning nano carriers for the targeted release of therapeutic moieties or growth factors, expanding the possibilities of tissue engineering.

The amazing scope of wartime applications accelerated the development and growth of polymers to meet the diverse needs of special materials in different fields of activity.[1, 2] Polyurethanes were developed in 1937, polyepoxides in 1947 and acryolonitrile-butadiene-styrene (ABS) terpolymer in 1948.[3,4] The discovery of the Zeigler-Natta catalyst in the 1950s brought about the development of linear polyethylene and stereoregular polypropylene.[4] Thereafter, the emergence of polyacetal, polyethylene terephthalate, polycarbonate, and many new copolymers, was noted. Commercial requirements paved the way for the development of highly temperature-resistant materials, which include polyphenylene oxides, polysulphones, polyimides, poly(amide-imide)s and polybenzimidazoles. These high performance polymers to which standard metal engineering equations can be applied are widely commercialized now. Polymers with properties of strength, heat-resistance or flame-resistance or chemical-resistance that far exceed those of more conventional polymers are termed “High Performance Polymers”. They are capable of sustaining high loads and stresses and are dimensionally stable.[5–7]

In this paper, we describe a novel method to screen peptides for specific recognition by cancer cells. Seventy peptides were synthesized on a cellulose membrane in an array format, and a direct method to study the peptide-whole cell interaction was developed. The relative binding affinity of the cells for different peptides with respect to a lead 12-mer p160 peptide, identified by phage display, was evaluated using the CyQUANT fluorescence of the bound cells. Screening allowed identification of at least five new peptides that displayed higher affinity (up to 3-fold) for MDA-MB-435 and MCF-7 human cancer cells compared to the p160 peptide. These peptides showed very little binding to the control (noncancerous) human umbilical vein endothelial cells (HUVECs). Three of these peptides were synthesized separately and labeled with fluorescein isothiocyanate (FITC) to study their uptake and interaction with the cancer and control cells using confocal laser scanning microscopy and flow cytometry. The results confirmed the high and specific affinity of an 11-mer peptide 11 (RGDPAYQGRFL) and a 10-mer peptide 18 (WXEAAYQRFL) for the cancer cells versus HUVECs. Peptide 11 binds different receptors on target cancer cells as its sequence contains multiple recognition motifs, whereas peptide 18 binds mainly to the putative p160 receptor. The peptide array-whole cell binding assay reported here is a complementary method to phage display for further screening and optimization of cancer targeting peptides for cancer therapy and diagnosis.

The present work is focused on investigating the controlled drug release behavior of Poly [N-isopropylacrylamide-co-2-Hydroxyethylacrylate] (P [NIPAm-HEAc])-based hydrogel. The synthesis process includes the preparation of monodispersed hydrogel nanoparticles containing specific functional groups, followed by cross-linking to neighboring spheres to stabilize the entire network. The color and volume of these crystalline hydrogel networks can reversibly change in response to external stimuli such as temperature, pH, and other environmental conditions. The feasibility of the hydrogel as a controlled release vehicle for 5-fluorouracil is evaluated.