scholarly journals Low Molecular Weight and Polymeric Modifiers as Toughening Agents in Poly(3-Hydroxybutyrate) Films

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2446
Author(s):  
Adriana Nicoleta Frone ◽  
Cristian Andi Nicolae ◽  
Mihaela Carmen Eremia ◽  
Vlad Tofan ◽  
Marius Ghiurea ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Photoelectron Spectroscopy ◽  
Biomedical Applications ◽  
Low Molecular Weight ◽  
Elongation At Break ◽  
Force Microscopy ◽  
In Vitro Biocompatibility ◽  
Atomic Force ◽  
Lower Temperature

The inherent brittleness of poly(3-hydroxybutyrate) (PHB) prevents its use as a substitute of petroleum-based polymers. Low molecular weight plasticizers, such as tributyl 2-acetyl citrate (TAC), cannot properly solve this issue. Herein, PHB films were obtained using a biosynthesized poly(3-hydroxyoctanoate) (PHO) and a commercially available TAC as toughening agents. The use of TAC strongly decreased the PHB thermal stability up to 200 °C due to the loss of low boiling point plasticizer, while minor weight loss was noticed at this temperature for the PHB-PHO blend. Both agents shifted the glass transition temperature of PHB to a lower temperature, the effect being more pronounced for TAC. The elongation at break of PHB increased by 700% after PHO addition and by only 185% in the case of TAC; this demonstrates an important toughening effect of the polymeric modifier. Migration of TAC to the upper surface of the films and no sign of migration in the case of PHO were highlighted by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) results. In vitro biocompatibility tests showed that all the PHB films are non-toxic towards L929 cells and have no proinflammatory immune response. The use of PHO as a toughening agent in PHB represents an attractive solution to its brittleness in the case of packaging and biomedical applications while conserving its biodegradability and biocompatibility.

Low Molecular Weight Microfibers with Light Sensing Properties

2017 ◽  
Vol 54 (4) ◽  
pp. 655-658
Author(s):  
Andrei Bejan ◽  
Dragos Peptanariu ◽  
Bogdan Chiricuta ◽  
Elena Bicu ◽  
Dalila Belei
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
X Ray ◽  
Force Microscopy ◽  
Light Sensing ◽  
Sensing Applications ◽  
Atomic Force ◽  
Low Molecular Weight Compounds

Microfibers were obtained from organic low molecular weight compounds based on heteroaromatic and aromatic rings connected by aliphatic spacers. The obtaining of microfibers was proved by scanning electron microscopy. The deciphering of the mechanism of microfiber formation has been elucidated by X-ray diffraction, infrared spectroscopy, and atomic force microscopy measurements. By exciting with light of different wavelength, florescence microscopy revealed a specific optical response, recommending these materials for light sensing applications.

Electrically-Controlled Penicillin/Streptomycin Release from Nanostructured Polypyrrole Coated on Titanium for Orthopedic Implants

2009 ◽  
Vol 151 ◽  
pp. 197-202 ◽  
Author(s):  
Sirinrath Sirivisoot ◽  
Rajesh A. Pareta ◽  
Thomas J. Webster
Keyword(s):  
Photoelectron Spectroscopy ◽  
Orthopedic Implants ◽  
Nanometer Scale ◽  
Force Microscopy ◽  
Atomic Force ◽  
Osteoblast Adhesion ◽  
Antibiotic Release ◽  
Orthopedic Applications ◽  
Scale Roughness

Implant infection leading to revision surgery can be avoided by incorporating controllable antibiotic release from titanium (Ti) implant surfaces. In this study, penicillin/streptomycin (P/S) and dexamethasone (Dex) were successfully immobilized via electropolymerization within polypyrrole membranes coated on the surface of Ti, which is widely used in orthopedic applications. In vitro results showed that greater numbers of osteoblasts adhered on these polymer-coated substrates than on currently-used unmodified Ti. X-ray photoelectron spectroscopy was used to monitor and compare the reaction effectiveness and the yield of electropolymerization. Polypyrrole membranes conjugated with P/S and Dex, and then coated with PLGA, all possessed nanometer scale roughness, as analyzed by atomic force microscopy. In summary, this study demonstrated that drugs incorporated within electroactive polypyrrole membranes, whose release was controlled by applying voltages, supported osteoblast adhesion and could potentially fight bacterial infection.

Crystallization of low molecular weight atactic polystyrene

Soft Matter ◽  
2018 ◽  
Vol 14 (33) ◽  
pp. 6883-6891 ◽  
Author(s):  
Yu Chai ◽  
Adam N. Raegen ◽  
Shipei Zhu ◽  
James A. Forrest
Keyword(s):  
Molecular Weight ◽  
Atomic Force Microscopy ◽  
Low Molecular Weight ◽  
Force Microscopy ◽  
Atomic Force ◽  
Atactic Polystyrene

We observe and characterize the crystallization of atactic polystyrenes (PS) of nearly oligomeric Mw using atomic force microscopy.

Fibronectin modified TiO2 nanotubes modulate endothelial cell behavior

2018 ◽  
Vol 33 (1) ◽  
pp. 44-51 ◽  
Author(s):  
Ziyang Jin ◽  
Xufeng Yan ◽  
Guiyong Liu ◽  
Min Lai
Keyword(s):  
Photoelectron Spectroscopy ◽  
Umbilical Vein ◽  
Cell Counting ◽  
Cellular Functions ◽  
Force Microscopy ◽  
Angle Measurements ◽  
Atomic Force ◽  
Substrate Surfaces ◽  
Umbilical Vein Endothelial Cells

Cardiovascular disease has become a great threat to the health of mankind; current titanium (Ti) stents fail due to late stent thrombosis caused by the lack of re-endothelialization of the Ti stent. The objective of this study was to design a novel cardiovascular Ti implant with improved surface biocompatibility. TiO2 nanotubes with a diameter of 110 nm were anodized at a constant voltage of 30 V, and fibronectin was immobilized onto the TiO2 nanotubes using polydopamine. The element composition, morphology, and wettability of the different substrate surfaces were characterized by x-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and contact angle measurements, respectively, confirming the successful immobilization of fibronectin. In vitro experiments including immunofluorescence staining, Cell Counting Kit-8 (CCK-8), and nitric oxide (NO) and prostacyclin (PGI2) release demonstrate that fibronectin modified TiO2 nanotubes supported cell adhesion, proliferation, and normal cellular functions of human umbilical vein endothelial cells (HUVECs). These methodologies can be applied for future fabrication of cardiovascular stents.

Hydroxyapatite Coatings Produced by Right Angle Magnetron Sputtering for Biomedical Applications

2007 ◽  
Vol 1008 ◽  
Author(s):  
Zhendong Hong ◽  
Alexandre Mello ◽  
Tomohiko Yoshida ◽  
Lan Luan ◽  
Paula H. Stern ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Photoelectron Spectroscopy ◽  
Biomedical Applications ◽  
Titanium Substrate ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Hydroxyapatite Coatings

AbstractHydroxyapatite coatings have been widely recognized for their biocompatibility and utility in promoting biointegration of implants in both osseous and soft tissue. Conventional sputtering techniques have shown some advantages over the commercially available plasma spraying method; however, the as-sputtered coatings are usually non-stoichiometric and amorphous which can cause some serious problems such as poor adhesion and excessive coating dissolution rate. A versatile right-angle radio frequency magnetron sputtering (RAMS) approach has been developed to deposit HA coatings on various substrates at low power levels. Using this alternative magnetron geometry, as-sputtered HA coatings are nearly stoichiometric, highly crystalline, and strongly bound to the substrate, as evidenced by analyses using x-ray diffraction (XRD), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). In particular, coatings deposited on oriented substrates show a polycrystalline XRD pattern but with some strongly preferred orientations, indicating that HA crystallization is sensitive to the nature of the substrate. Post deposition heat treatment under high temperature does not result in a marked improvement in the degree of crystallinity of the coatings. To study the biocompatibility of these coatings, murine osteoblast cells were seeded onto various substrates. Cell density counts using fluorescence microscopy show that the best osteoblast proliferation is achieved on an HA RAMS-coated titanium substrate. These experiments demonstrate that RAMS is a promising coating technique for biomedical applications.

Fabrication of micropatterns on polypropylene films via plasma pretreatment combined with UV-initiated graft polymerization

2017 ◽  
Vol 31 (10) ◽  
pp. 1346-1357 ◽  
Author(s):  
Liu Jiang ◽  
Huaming Qian ◽  
Gang Chen ◽  
Chunyan Li ◽  
Guangjun Yan ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Graft Polymerization ◽  
Cellular Adhesion ◽  
Hydroxyethyl Methacrylate ◽  
Force Microscopy ◽  
Atomic Force ◽  
Plasma Pretreatment ◽  
Polypropylene Films ◽  
Vitro Analysis

In this study, micropatterns on polypropylene films were fabricated via plasma pretreatment and UV-initiated graft polymerization. Firstly, radio-frequency plasma, which does not significantly influence bulk attributes of substrates due to limited penetration depth, was utilized to activate polypropylene films. Then, different sizes of micropatterns of poly(hydroxyethyl methacrylate) (PHEMA) were fabricated on the polypropylene films via UV-initiated graft polymerization of hydroxyethyl methacrylate by using photo-masks. Scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle (CA) were employed to characterize changes of pristine polypropylene films and modified ones in surface morphology, roughness, hydrophilicity, free energy and the surface chemical composition. All of these confirmed the successful grafting of different sizes of PHEMA micropatterns on the polypropylene surface. Furthermore, the influence of PHEMA micropatterns on cell proliferation and cytotoxicity was evaluated in vitro. Analysis of cell behaviour indicated that PHEMA micropatterns of the appropriate size can promote cellular adhesion and proliferation, and the PHEMA-micropatterned polypropylene films had good biocompatibility. The approach presented here provides an alternative to synthesize on the surface of polypropylene films’ micropatterns with the aim of using them in a diverse array of applications.

Characterization of Polymeric Microcapsules Containing a Low Molecular Weight Peptide for Controlled Release

2013 ◽  
Vol 19 (1) ◽  
pp. 213-226 ◽  
Author(s):  
Keith Moore ◽  
Jennifer Amos ◽  
Jeffrey Davis ◽  
Robert Gourdie ◽  
Jay D. Potts
Keyword(s):  
Molecular Weight ◽  
Connexin 43 ◽  
Diffusion Method ◽  
Low Molecular Weight ◽  
Therapeutic Effects ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surgical Implants ◽  
Loading Ratio ◽  
Polymeric Microcapsules

AbstractA need exists to prolong the release of rapidly metabolized peptides of a low molecular weight, while delivering this peptide without environmental interference. Previous studies have used bovine serum albumin (BSA) as a model peptide to study release characteristics from alginate microcapsules. BSA is 66 kDa in size, while the peptide of interest here, connexin-43 carboxyl-terminus mimetic peptide (αCT1), is only 3.4 kDa. Such a change in size results in a much different set of release parameters. Our overall goal is a sustained release over a 24+ h period. Prolonged application of the peptide to a wound site to investigate therapeutic effects is ideal. As a result, a diffusion method using alginate microcapsules, along with the addition of poly-l-lysine and poly-l-ornithine, has been explored. We first aimed to establish and characterize our parameters through a set of parametric tests. Variations in polymer coating, change in pH, and changes in loading ratio have previously been shown to effect release using model compounds. Here we test specific changes in these parameters to show effects on the release of αCT1. Additionally, the microcapsules were attached to several biomaterials and surgical implants by ultraviolet cross-linking to study the effectiveness of attachment and delivery. Analysis and measurements using phase contrast microscopy, scanning electron microscopy, and atomic force microscopy were used to characterize changes in microcapsule morphology.

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