POLYISOBUTYLENE-BASED THERMOPLASTIC BIORUBBERS

Abstract Linear triblock poly(styrene-b-isobutylene-b-styrene) (SIBS), the first representative of polyisobutylene (PIB)-based biomaterials, is approved by the Food and Drug Administration for use in the Taxus® Drug Eluting stent. SIBS and the new generation of dendritic or arborescent D_SIBS are self-assembling thermoplastic elastomers (TPEs), or “biorubbers.” D_SIBS has lower creep and improved fatigue life. We recently produced composites of novel D_PIB-based TPEs with carbon and silica. These composites had 2–10 times higher tensile strength than that of the neat polymer. The composite with 37.5 wt. % carbon black was nonconductive, demonstrating excellent filler dispersion. Transmission electron microscopy and atomic force microscopy analysis supported the formation of a nanocomposite with nanosized surface topology. The water contact angle of the biorubbers was significantly lower than that of silicone rubber. The carbon nanocomposite showed excellent biocompatibility in vivo, having thinner capsules than silicone after 180 days implantation into rabbits. Bone compatibility was also excellent. The improved biocompatibility was most likely due to a combination of hydrophilicity and surface nanotopology. Fundamental studies of the effect of surface properties of these biorubbers on biocompatibility are ongoing in our laboratory.

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Preparation and Time Resolved Photoluminescence of Nanoscale InP Islands in In0.48Ga0.52P

MRS Proceedings ◽

10.1557/proc-379-185 ◽

1995 ◽

Vol 379 ◽

Cited By ~ 3

Author(s):

K. Eberl ◽

A. Kurtenbach ◽

K. HÄusler ◽

F. Noll ◽

W.W. RÜhle

Keyword(s):

Lattice Mismatch ◽

Excitation Power ◽

Buffer Layers ◽

Time Resolved ◽

Force Microscopy ◽

Self Assembling ◽

Atomic Force ◽

Transmission Electron ◽

Decay Times ◽

Time Resolved Photoluminescence

ABSTRACTNanoscale InP islands are formed during InP/In0 48Ga0.52P heteroepitaxy due to the lattice mismatch of about 3.7%. The samples are prepared by solid source molecular beam epitaxy on (001) GaAs substrate. Atomic force microscopy measurements show that the size of the islands is typically 15 to 50 nm in diameter and about 5 to 10 nm high depending on the nominally deposited InP layer thickness, which is between 1 and 7.5 monolayers. Transmission electron micrographs show the coherent incorporation into the In0.48Ga0.52P matrix for InP islands with 2.5 monolayers. Resonantly excited time-resolved photoluminescence (PL) measurements of the self assembling InP dots are performed for optical characterisation. The decay times are typically 400 ps. The dependence on excitation power and temperature indicates the quantum dot nature of the InP islands. Finally a pronounced alignment of the InP islands is obtained on strained In0.61Ga0.39P buffer layers.

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Polyisobutylene-Based Thermoplastic Elastomers for Manufacturing Polymeric Heart Valve Leaflets: In Vitro and In Vivo Results

Applied Sciences ◽

10.3390/app9224773 ◽

2019 ◽

Vol 9 (22) ◽

pp. 4773 ◽

Cited By ~ 4

Author(s):

Evgeny Ovcharenko ◽

Maria Rezvova ◽

Pavel Nikishau ◽

Sergei Kostjuk ◽

Tatiana Glushkova ◽

...

Keyword(s):

Mechanical Properties ◽

Heart Valve ◽

Heart Valves ◽

Reference Sample ◽

Sample Surface ◽

Thermoplastic Elastomers ◽

Water Contact ◽

Promising Alternative

Superior polymers represent a promising alternative to mechanical and biological materials commonly used for manufacturing artificial heart valves. The study is aimed at assessing poly(styrene-block-isobutylene-block-styrene) (SIBS) properties and comparing them with polytetrafluoroethylene (Gore-texTM, a reference sample). Surface topography of both materials was evaluated with scanning electron microscopy and atomic force microscopy. The mechanical properties were measured under uniaxial tension. The water contact angle was estimated to evaluate hydrophilicity/hydrophobicity of the study samples. Materials’ hemocompatibility was evaluated using cell lines (Ea.hy 926), donor blood, and in vivo. SIBS possess a regular surface relief. It is hydrophobic and has lower strength as compared to Gore-texTM (3.51 MPa vs. 13.2/23.8 MPa). SIBS and Gore-texTM have similar hemocompatibility (hemolysis, adhesion, and platelet aggregation). The subcutaneous rat implantation reports that SIBS has a lower tendency towards calcification (0.39 mg/g) compared with Gore-texTM (1.29 mg/g). SIBS is a highly hemocompatible material with a promising potential for manufacturing heart valve leaflets, but its mechanical properties require further improvements. The possible options include the reinforcement with nanofillers and introductions of new chains in its structure.

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Novel Thermoplastic Elastomers Based on Acrylonitrile-Butadiene-Styrene Terpolymer (ABS) from Waste Computer Equipment and Nitrile Rubber

Rubber Chemistry and Technology ◽

10.5254/1.3547793 ◽

2003 ◽

Vol 76 (5) ◽

pp. 1145-1163 ◽

Cited By ~ 22

Author(s):

S. Anandhan ◽

P. P. De ◽

S. K. De ◽

Anil K. Bhowmick ◽

S. Bandyopadhyay

Keyword(s):

Acrylonitrile Butadiene Styrene ◽

Thermoplastic Elastomers ◽

Nitrile Rubber ◽

Dynamic Vulcanization ◽

Force Microscopy ◽

Atomic Force ◽

Computer Equipment ◽

Transmission Electron ◽

Engineering Plastics ◽

Butadiene Styrene

Abstract Acrylonitrile-butadiene-styrene terpolymer (ABS) is one of the engineering plastics most frequently used as outer casings for computer equipment such as monitors, keyboards and other similar components. In an attempt to recycle, blends of scrap computer plastics (SCP) based on ABS with nitrile rubber (NBR) were prepared and mechanical properties and morphology were studied. Effect of dynamic vulcanization on the properties of 60/40, 70/30, and 80/20 NBR/SCP blends was assessed. These blends show the thermoplastic elastomeric behavior. Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) studies show that the dynamically vulcanized NBR particles are dispersed in the ABS matrix. The thermoplastic elastomeric blends show excellent swelling resistance in IRM # 93 oil.

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Zirconia Coating of Carbon Nanotubes by a Hydrothermal Method

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.211 ◽

2008 ◽

Vol 8 (11) ◽

pp. 5678-5683 ◽

Cited By ~ 6

Author(s):

N. Garmendia ◽

L. Bilbao ◽

R. Muñoz ◽

G. Imbuluzqueta ◽

A. García ◽

...

Keyword(s):

Carbon Nanotubes ◽

Electron Microscope ◽

Crack Propagation ◽

Single Wall Carbon Nanotubes ◽

X Ray ◽

Multi Wall Carbon Nanotubes ◽

Force Microscopy ◽

Atomic Force ◽

Transmission Electron

Carbon nanotubes have unique mechanical properties that open attractive possibilities in many fields, such as the biomedical one. Currently, zirconia ceramics are widely used as femoral heads, but case studies show that delayed failure can occur in vivo due to crack propagation. Nanotubes could avoid the slow crack propagation and enhance the toughness of the ceramic material used for prostheses fabrication. In this work, single-wall carbon nanotubes and multi-wall carbon nanotubes have been partially coated with nanozirconia via hydrothermal synthesis and characterized by several techniques: X-ray diffraction, infrared spectroscopy, scanning electron microscope, transmission electron microscope, electron energy loss spectra, X-ray photoelectronic spectroscopy and atomic force microscopy. By means of these techniques, the existence of bonds between zirconium and the carbon nanotube has been proved. The as covered nanotubes should offer a better wettability in the ceramic matrix and improve the dispersion of the carbon nanotubes, to obtain the desired new ceramic biomaterial with a longer lifetime and better reliability.

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Self-Assembling Poly(ethylene glycol)/Poly-γ-glutamic Acid Nanoparticles for Targeted Drug Delivery and Plasmid DNA

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.721.105 ◽

2013 ◽

Vol 721 ◽

pp. 105-108

Author(s):

Yang Ge ◽

Ke Shuai Lu ◽

Xue Yan Su

Keyword(s):

Drug Delivery ◽

Digital Processing ◽

Spherical Particles ◽

Aqueous Environment ◽

Force Microscopy ◽

Feeding Experiments ◽

Self Assembling ◽

Intracellular Drug Delivery ◽

Transmission Electron ◽

Poly Ethylene

These stable self-assembled nanoparticles were characterized by dynamic light scattering, transmission electron microscopy, and atomic force microscopy,which demonstrated that the nanosystem consists of spherical particles with a smooth surface both in aqueous environment and in dried state. Toxicity measurements showed that the composition is nontoxic when tested either on cell cultures or in animal feeding experiments. To evaluate the potential of the nanosystem for intracellular drug delivery and gene, the nanoparticles were fluorescently labeled and folic acid was attached as a cancer cell-specific targeting moiety. The quantitative data obtained by digital processing of the intensity of green color of each pixel in the pictures inside the cell boundaries and total intensity of fluorescence inside the cells showed thattargeted particles internalized into the cells significantly faster and the total accumulation of these particles was substantially higher in the cancer cells.

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Hydrophobic performance of electrospun fibers functionalized with TiO2 nanoparticles

Textile Research Journal ◽

10.1177/00405175211010669 ◽

2021 ◽

pp. 004051752110106

Author(s):

Vânia Pais ◽

Miguel Navarro ◽

Catarina Guise ◽

Rui Martins ◽

Raul Fangueiro

Keyword(s):

Electron Microscopy ◽

Polymer Concentration ◽

Water Repellent ◽

Scanning Calorimetry ◽

Hydrophobic Properties ◽

Water Contact ◽

Force Microscopy ◽

Transmission Electron ◽

Biodegradable Poly ◽

Needle Diameter

The development of materials with hydrophobic properties has been widely explored in areas such as textiles, healthcare, sports, and personal protective equipment. Hydrophobic properties that arise from nanoparticles (nPs) directly promote other valuable properties, including self-cleaning capabilities, decreased bacterial growth, and increased comfort. In this study, biodegradable poly(ε-caprolactone) (PCL) nanofibers were functionalized by the incorporation of titanium dioxide (TiO2) nPs to develop water-repellent materials. The membranes were produced through electrospinning, and variables such as the polymer concentration, nP concentration, and needle diameter were optimized to achieve PCL/TiO2 composite fibers with water-repellent capabilities. The nanofibers were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and the water contact angle (WCA). In general, it was observed that the nanofibers presented higher roughness values when TiO2 nPs were present and that this result promoted higher WCA values. The highest WCA value (156°) was obtained for the nanofiber mat produced with 20% weight-to-volume (w/v) PCL and 0.6% (w/v) TiO2.

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A New Noncoding RNA Arranges Bacterial Chromosome Organization

mBio ◽

10.1128/mbio.00998-15 ◽

2015 ◽

Vol 6 (4) ◽

Cited By ~ 12

Author(s):

Zhong Qian ◽

Mirjana Macvanin ◽

Emilios K. Dimitriadis ◽

Ximiao He ◽

Victor Zhurkin ◽

...

Keyword(s):

Dna Sequences ◽

Noncoding Rna ◽

Chromosome Conformation ◽

Content Type ◽

Force Microscopy ◽

Transmission Electron ◽

Bacterial Nucleoid ◽

Dna Elements

ABSTRACTRepeated extragenic palindromes (REPs) in the enterobacterial genomes are usually composed of individual palindromic units separated by linker sequences. A total of 355 annotatedREPs are distributed along theEscherichia coligenome. RNA sequence (RNAseq) analysis showed that almost 80% of theREPs inE. coliare transcribed. The DNA sequence ofREP325showed that it is a cluster of six repeats, each with two palindromic units capable of forming cruciform structures in supercoiled DNA. Here, we report that components of theREP325element and at least one of its RNA products play a role in bacterial nucleoid DNA condensation. These RNA not only are present in the purified nucleoid but bind to the bacterial nucleoid-associated HU protein as revealed by RNA IP followed by microarray analysis (RIP-Chip) assays. Deletion ofREP325resulted in a dramatic increase of the nucleoid size as observed using transmission electron microscopy (TEM), and expression of one of theREP325RNAs, nucleoid-associated noncoding RNA 4 (naRNA4), from a plasmid restored the wild-type condensed structure. Independently, chromosome conformation capture (3C) analysis demonstrated physical connections among variousREPelements around the chromosome. These connections are dependent in some way upon the presence of HU and theREP325element; deletion of HU genes and/or theREP325element removed the connections. Finally, naRNA4 together with HU condensed DNAin vitroby connectingREP325or other DNA sequences that contain cruciform structures in a pairwise manner as observed by atomic force microscopy (AFM). On the basis of our results, we propose molecular models to explain connections of remote cruciform structures mediated by HU and naRNA4.IMPORTANCENucleoid organization in bacteria is being studied extensively, and several models have been proposed. However, the molecular nature of the structural organization is not well understood. Here we characterized the role of a novel nucleoid-associated noncoding RNA, naRNA4, in nucleoid structures bothin vivoandin vitro. We propose models to explain how naRNA4 together with nucleoid-associated protein HU connects remote DNA elements for nucleoid condensation. We present the first evidence of a noncoding RNA together with a nucleoid-associated protein directly condensing nucleoid DNA.

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ANTI-MELANOMA BIO-EFFICACY OF THE PLANT MADHUCA LONGIFOLIA AND ITS ENHANCEMENT USING BIOACTIVE PRINCIPLE LOADED GOLD NANOPARTICLE

Asian Journal of Pharmaceutical and Clinical Research ◽

10.22159/ajpcr.2020.v13i10.38832 ◽

2020 ◽

pp. 142-149

Author(s):

SAURABH YADAV ◽

MUKTI SHARMA ◽

NARAYANAN GANESH ◽

SHALINI SRIVASTAVA ◽

M. M. SRIVASTAVA

Keyword(s):

Gold Nanoparticles ◽

Bark Extract ◽

X Rays ◽

Experimental Conditions ◽

Force Microscopy ◽

Transmission Electron ◽

Madhuca Longifolia ◽

C57bl Mice ◽

Histopathological Studies

Objective: Unexplored in-vivo anti-melanoma bio-efficacy of the plant Madhuca longifolia (bark) has been carried out against C57BL/6 mice. Methods: Optimized experimental conditions of phytofabrication of gold nanoparticles were as follows: flavonoid content (1 ml, 0.5 mg/ml), sodium tetrachloroaurate dihydrate solution (2 ml, 1 mM), and sonication (15 min, 20 KHz) at pH 4. The optical properties; ultraviolet-visible spectrophotometer (UV-Vis), particles size and zeta potential (Zetasizer), miller indices; X-ray diffraction (XRD), morphology; field emission-scanning electron microscope (FE-SEM), particle size; high resolution-transmission electron microscopy (HR-TEM), surface roughness; atomic force microscopy (AFM) and elemental composition; and energy dispersive X-rays (EDX) of flavonoid loaded gold nanoparticles. In-vivo anti-melanoma bio-efficacy has been carried out against C57BL mice. Radioisotopic, hematological, and histopathological studies were carried out using standard procedures. Results: Redox potential of the total flavonoid extracted from the bark of the plant (Madhuca longifolia) has been used for the fabrication of flavonoid loaded gold nanoparticles (F@AuNp) and confirmed for the first time their significant anti-melanoma bio-efficacy. The finding is supported by hematological and histopathological studies carried out in the organs (liver, kidney, and intestine) of C57BL mice. The significant enhancement in phytofabricated F@AuNp compared to native bark extract of the plant has been assigned to enhanced stay period and nanosizing, biocompatibility, nontoxic nature, and enhanced beneficial payload to the cancerous cells. Conclusion: Such phytofabricated gold nanoparticles possess an admirable prospect for the expansion of herbal nanomedicine for anti-melanoma bio-efficacy.

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Evaluation of the In Vitro Biocompatibility of PEDOT:Nafion Coatings

Nanomaterials ◽

10.3390/nano11082022 ◽

2021 ◽

Vol 11 (8) ◽

pp. 2022

Author(s):

Sonia Guzzo ◽

Stefano Carli ◽

Barbara Pavan ◽

Alice Lunghi ◽

Mauro Murgia ◽

...

Keyword(s):

Neutral Red ◽

In Vitro Cytotoxicity ◽

Water Contact ◽

Promising Alternative ◽

Force Microscopy ◽

In Vitro Biocompatibility ◽

Angle Measurements ◽

Organic Bioelectronics

Poly(3,4-ethylenedioxythiophene)-Nafion (PEDOT:Nafion) is emerging as a promising alternative to PEDOT-polystyrene sulfonate (PEDOT:PSS) in organic bioelectronics. However, the biocompatibility of PEDOT:Nafion has not been investigated to date, limiting its deployment toward in vivo applications such as neural recording and stimulation. In the present study, the in vitro cytotoxicity of PEDOT:Nafion coatings, obtained by a water-based PEDOT:Nafion formulation, was evaluated using a primary cell culture of rat fibroblasts. The surface of PEDOT:Nafion coating was characterized by Atomic Force Microscopy (AFM) and water contact angle measurements. Fibroblasts adhesion and morphology was investigated by scanning electron microscopy (SEM) and AFM measurements. Cell proliferation was assessed by fluorescence microscopy, while cell viability was quantified by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT), lactate dehydrogenase (LDH) and neutral red assays. The results showed that PEDOT:Nafion coatings obtained by the water dispersion were not cytotoxic, making the latter a reliable alternative to PEDOT:PSS dispersion, especially in terms of chronic in vivo applications.

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Combinatorial Approach to Materials Fabrication from Higher Hierarchies of Rosette Nanotubes

MRS Proceedings ◽

10.1557/proc-1057-ii05-36 ◽

2007 ◽

Vol 1057 ◽

Author(s):

Grigory Tikhomirov ◽

Hicham Fenniri

Keyword(s):

Electron Microscopy ◽

Self Assembly ◽

The Self ◽

Combinatorial Approach ◽

X Ray ◽

Force Microscopy ◽

Rosette Nanotubes ◽

Self Assembling ◽

Atomic Force ◽

Transmission Electron

ABSTRACTThe self-assembly of six self-complimentary Guanine – Cytosine hybrid heterocycles bearing hydrophobic substituents has been studied using combinatorial approach in eight solvents under different conditions. The parameters that were varied include: the structure of the self-assembling module, its concentration, the solvent, temperature, and time of self-assembly. scanning electron microscopy (SEM) was used as a screening tool. A wide variety of interesting morphologies was found. The most interesting structures were studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray powder diffraction (XRD).

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