Thermal Stabilization of Polyoxymethylene by PEG-Functionalized Hydroxyapatite: Examining the Effects of Reduced Formaldehyde Release and Enhanced Bioactivity

Nanostructured hydroxyapatite (HA) functionalized with poly(ethylene glycol) (HA-g-PEG) of different molar mass was used as a thermal stabilizer to prepare polyoxymethylene (POM) composites by a melt processing method. The chemical and crystalline structure of (HA-g-PEG) and POM/HA-g-PEG composites was investigated by means of FTIR and XRD. The thermal properties, degree of crystallinity, and melting behaviour of POM-based composites were analysed with TG, DSC, and TOPEM DSC methods. The tensile strength, Young’s modulus, toughness, and wettability of POM were investigated as well. A preliminary assessment of bioactivity, in vitro chemical stability, and formaldehyde release from POM/HA-g-PEG composites by Schiff’s test was also performed. An SEM/EDX method was used to observe the morphology of POM/HA-g-PEG composites. The results indicate that the addition of 1% HA-g-PEG slightly increases the melting temperature and degree of crystallinity. In small amounts, HA-g-PEG particles probably act as nucleating agents for the POM crystallization process. Incorporation of 5% HA-g-PEG to POM caused a decrease in the crystallinity of the polymer matrix, as a result, some mechanical properties of POM/HA-g-PEG composites also decreased. The thermal stability of POM/HA-g-PEG composites improved significantly from 309°C for unmodified POM to 342°C for POM/10.0% HA-g-PEG 600. The most effective thermal stabilizer was synthesized with the lowest mass-average molar mass PEG. The in vitro bioactivity test confirmed that, as the average molar mass of PEG in HA-g-PEG hybrids increased, POM-based composites indicated higher bioactivity. The in vitro chemical stability analysis results showed that both the POM matrix and the HA-g-PEG additive remain stable during the whole incubation time. Importantly, after seven days of dynamic incubation, no formaldehyde was detected in all filtrates, which is crucial in biomedical applications, among others.

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Hyaluronic Acid in the Intestinal Tract: Influence of Structure, Rheology, and Mucoadhesion on the Intestinal Uptake in Rats

Biomolecules ◽

10.3390/biom10101422 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1422

Author(s):

Alexandro Barbosa de Souza ◽

Marco Vinícius Chaud ◽

Thais Francine Alves ◽

Juliana Ferreira de Souza ◽

Maria Helena Andrade Santana

Keyword(s):

Hyaluronic Acid ◽

Intestinal Tract ◽

Molar Mass ◽

Hydrodynamic Diameter ◽

Average Molar Mass ◽

Intestinal Membrane ◽

Mixed Formulations ◽

Jejunum Segment

Oral hyaluronic acid (HA) is a ubiquitous biopolymer that has gained attention as a treatment for local or systemic diseases. Here, we prepared and characterized structures of free HA (f-HA) with a high (>105 Da), intermediate (≤105 Da), and low (≤104 Da) average molar mass (MM); nanoparticles crosslinked with adipic dihydrazide (n-HA); and mixed formulations (mixed-HA) containing f-HA and n-HA. MM distribution determined the structure, hydrodynamic diameter, and zeta potential of the f-HAs. Crosslinking changed the physicochemical properties in n-HA. In vitro tack adhesion assays, using mucin tablets or a viable rat intestinal mucosa, showed better mucoadhesion with f-HA (intermediate MM) and mixed-HA (25% n-HA), especially in the jejunum segment. High MM f-HA presented negligible mucoadhesion. n-HA showed the deepest diffusion into the porous of the membranes. In vivo results showed that, except for high MM f-HA, there is an inverse relationship between rheological changes in the intestinal membrane macerates resulting from mucoadhesion and the effective intestinal permeability that led to blood clearance of the structures. We conclude that the n-HA formulations are promising for targeting other tissues, while formulations of f-HA (intermediate MM) and mixed-HA are better for treating dysbiosis.

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Crystallization Processes In Poly (Ethylene Terephthalate) / Polycarbonate Blends

MRS Proceedings ◽

10.1557/proc-321-543 ◽

1993 ◽

Vol 321 ◽

Author(s):

Veronika E. Reinsch ◽

Ludwig Rebenfeld

Keyword(s):

Ethylene Terephthalate ◽

Crystallization Rate ◽

Melt Processing ◽

Degree Of Crystallinity ◽

Processing Temperature ◽

Scanning Calorimetry ◽

Processing Times ◽

Poly Ethylene Terephthalate ◽

Poly Ethylene ◽

Crystallization From The Melt

ABSTRACTBlends of poly (ethylene terephthalate), or PET, and polycarbonate (PC) over a range of compositions were studied in isothermal crystallizations from the melt using differential scanning calorimetry (DSC). Both crystallization rate and degree of crystallinity of PET depend on blend composition. The glass transition temperature, Tg, of PET and PC in blends and pure polymer were also measured by DSC. Elevation of the Tg of PET and depression of the Tg of PC are observed upon blending. In cooling scans, dynamic crystallization from the melt was observed. In PET/PC blends with high PC content, a novel dual-peak crystallization of PET was observed. The effects of thermal history on crystallization kinetics and degree of crystallinity were also determined in isothermal crystallization studies. For Melt processing times between 1 and 30 Min and for processing temperatures between 280 and 300 °C, Melt processing temperature was seen to have a stronger effect than processing time.

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Degradation process of low molar mass poly(ethylene terephthalate)/organically modified montmorillonite nanocomposites

Journal of Thermoplastic Composite Materials ◽

10.1177/0892705715604678 ◽

2016 ◽

Vol 30 (4) ◽

pp. 504-520 ◽

Cited By ~ 6

Author(s):

Juliana A de Lima ◽

Lays B Fitaroni ◽

Daniel VA Chiaretti ◽

Manuela LQA Kaneko ◽

Sandra A Cruz

Keyword(s):

Ethylene Terephthalate ◽

Molar Mass ◽

Degradation Process ◽

Melt Processing ◽

Platelet Surface ◽

Modified Montmorillonite ◽

Organically Modified Montmorillonite ◽

Poly Ethylene Terephthalate ◽

Organically Modified ◽

Poly Ethylene

The aim of this work is to investigate the degradation of low molar mass poly(ethylene terephthalate) (PET)/organically modified montmorillonite (OMMT) clay nanocomposites prepared by melt processing. The rheological behavior in combination with transmission electron microscopic images suggests an intercalation and therefore a percolating network. Furthermore, the results indicate that the increase of organoclay content caused a degradation of PET during processing of PET/OMMT nanocomposites, once it was observed the PET molar mass decreases. The effect mentioned could be attributed to an increase of Brønsted acidic sites on the platelet surface, which is produced by the Hofmann elimination reaction of ammonium, and also the presence of residual metal compounds on clay surface might possibly favored the polymer matrix degradation process.

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NaYF4-based upconverting nanoparticles with optimized phosphonate coatings for chemical stability and viability of human endothelial cells

Methods and Applications in Fluorescence ◽

10.1088/2050-6120/ac41ba ◽

2021 ◽

Author(s):

Darja Lisjak ◽

Maša Vozlič ◽

Uliana Kostiv ◽

Daniel Horak ◽

Boris Majaron ◽

...

Keyword(s):

Cell Culture ◽

Endothelial Cells ◽

Chemical Stability ◽

Culture Medium ◽

Cell Culture Medium ◽

Human Endothelial Cells ◽

Surface Quenching ◽

Poly Ethylene ◽

Amorphous Surface

Abstract The increasing interest in upconverting nanoparticles (UCNPs) in biodiagnostics and therapy fuels the development of biocompatible UCNPs platforms. UCNPs are typically nanocrystallites of rare-earth fluorides codoped with Yb3+ and Er3+ or Tm3+. The most studied UCNPs are based on NaYF4 but are not chemically stable in water. They dissolve significantly in the presence of phosphates. To prevent any adverse effects on the UCNPs induced by cellular phosphates, the surfaces of UCNPs must be made chemically inert and stable by suitable coatings. We studied the effect of various phosphonate coatings on chemical stability and in vitro cytotoxicity of the Yb3+,Er3+-codoped NaYF4 UCNPs in human endothelial cells obtained from cellular line Ea.hy926. Cell viability of endothelial cells was determined using the resazurin-based assay after the short-term (15 min), and long-term (24 h and 48 h) incubations with UCNPs dispersed in the cell-culture medium. The coatings were obtained from tertaphosphonic acid (EDTMP), sodium alendronate, and poly(ethylene glycol)-neridronate. Regardless of the coating conditions, 1−2 nm-thick amorphous surface layers were observed on the UCNPs with transmission electron microscopy. The upconversion fluorescence was measured in the dispersions of all synthesized UCNPs. Surface quenching in aqueous suspensions of the UCNPs was reduced by the coatings. The dissolution degree of the UCNPs was determined from the concentration of dissolved fluoride measured with ion-selective electrode after the aging of UCNPs in water, physiological buffer (i.e., phosphate-buffered saline – PBS), and cell-culture medium. The phosphonate coatings prepared at 80 °C significantly suppressed the dissolution of UCNPs in PBS, while only minor dissolution of bare and coated UCNPs was measured in water and cell-culture medium. The viability of human endothelial cells was significantly reduced when incubated with UCNPs, but it increased with the improved chemical stability of UCNPs by the phosphonate coatings with negligible cytotoxicity when coated with EDTMP at 80 °C.

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Developing and Evaluating In Vitro Effect of Poly(Ethylene Glycol) Conjugated Curcumin on Human Cancer Cell Lines

Current Drug Discovery Technologies ◽

10.2174/1570163813666161018131228 ◽

2016 ◽

Vol 13 (4) ◽

pp. 254-266 ◽

Cited By ~ 1

Author(s):

Bui Thanh Tung ◽

Nguyen Thanh Hai ◽

Phan Ke Son

Keyword(s):

Ethylene Glycol ◽

Cell Lines ◽

Cancer Cell ◽

Human Cancer ◽

Human Cancer Cell ◽

Poly Ethylene Glycol ◽

Human Cancer Cell Lines ◽

Poly Ethylene ◽

Vitro Effect

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Fabrication of Doxorubicin Conjugated Methoxy Poly(ethylene glycol)-block-poly(ε-caprolactone) Nanoparticles and Study on Their in vitro Antitumor Activities

Journal of Biomaterials Science Polymer Edition ◽

10.1080/09205063.2021.1937462 ◽

2021 ◽

pp. 1-11

Author(s):

Hongdan Shen ◽

Quan Liu ◽

Deju Liu ◽

Shasha Yu ◽

Xiao Wang ◽

...

Keyword(s):

Ethylene Glycol ◽

Poly Ethylene Glycol ◽

Antitumor Activities ◽

Poly Ethylene

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Comparative Analysis of Morphological and Release Profiles in Ocular Implants of Acetazolamide Prepared by Electrospinning

Pharmaceutics ◽

10.3390/pharmaceutics13020260 ◽

2021 ◽

Vol 13 (2) ◽

pp. 260

Author(s):

Mariana Morais ◽

Patrícia Coimbra ◽

Maria Eugénia Pina

Keyword(s):

Drug Release ◽

In Vitro Release ◽

Morbidity Rate ◽

Coating Film ◽

Sustained Drug Release ◽

Coated Implant ◽

Poly Ethylene ◽

Coaxial Fibers ◽

Release Profiles

The visual impairment that often leads to blindness causes a higher morbidity rate. The goal of this work is to create a novel biodegradable polymeric implant obtained from coaxial fibers containing the dispersed drug—acetazolamide—in order to achieve sustained drug release and increase patient compliance, which is of the highest importance. Firstly, during this work, uncoated implants were produced by electrospinning, and rolled in the shape of small cylinders that were composed of uniaxial and coaxial fibers with immobilized drug inside. The fibers were composed by PCL (poly ε-caprolactone) and Lutrol F127 (poly (oxyethylene-b-oxypropylene-b-oxyethylene)). The prepared implants exhibited a fast rate of drug release, which led to the preparation of new implants incorporating the same formulation but with an additional coating film prepared by solvent casting and comprising PCL and Lutrol F127 or PCL and Luwax EVA 3 ((poly (ethylene-co-vinyl acetate)). Implants were characterized and in vitro release profiles of acetazolamide were obtained in phosphate buffered saline (PBS) at 37 °C. The release profile of the acetazolamide from coated implant containing Luwax EVA 3 is considerably slower than what was observed in case of coated implants containing Lutrol F127, allowing a sustained release and an innovation relatively to other ocular drug delivery systems.

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