Copolymers Derived from Two Active Esters: Synthesis, Characterization, Thermal Properties, and Reactivity in Post-Modification

Copolymers with two distinguished reactive repeating units are of great interest, as such copolymers might open the possibility of obtaining selective and/or consequent copolymers with different chemical structures and properties. In the present work, copolymers based on two active esters (pentafluorophenyl methacrylate and p-nitrophenyl methacrylate) with varied compositions were synthesized by Cu(0)-mediated reversible deactivation radical polymerization. This polymerization technique allows the preparation of copolymers with high to quantitative conversion of both comonomers, with moderate control over dispersity (Đ = 1.3–1.7). Additionally, by in-depth study on the composition of each copolymer by various techniques including elemental analysis, NMR, FT-IR, and XPS, it was possible to confirm the coherence between expected and obtained composition. Thermal analyses by DSC and TGA were implemented to investigate the relation between copolymers’ composition and their thermal properties. Finally, an evaluation of the difference in reactivity of the two monomer moieties was confirmed by post-modification of copolymers with a primary amine and a primary alcohol as the model.

Effects of electron beam sterilization on polyethylene terephthalate: Physico-chemical modifications and formation of non-volatile organic extractables

Our investigations hereby involve the effects of ionizing radiation as a sterilization method, and especially electron beams, on a medical grade Polyethylene Terephthalate (PET). Ionizing radiations are known to induce free radicals formation in the polymer that will then either degrade or crosslink, depending on its chemical nature, ionizing type and irradiation atmosphere (Charlesby, 1967; Dole, 1972 and Dole, 1973). The evaluation of packaging material modifications under radiation sterilization is of great interest and the objective of our paper is to focus on both PET volume modifications and extractable analyses after electron beam sterilization. As regards the polymeric matrix and after sterilization, we did not observe by means of spectral analyses, any single chemical modification whatsoever, whereas by thermal techniques we evidenced polymer chain scissions. As for the non-volatile organic extractables, we further substantiate the presence of numerous compounds, namely oligomers and trimers especially, along with benzoic and terephthalic acids in particular. With respect to pharmaceutical stakes however, we claim herein that the 25kGy sterilization dose used, triggers oligomers and extractables formation, a result which is promising for further risk analysis.

Characterization of the surface physico-chemistry of plasticized PVC used in blood bag and infusion tubing

Commercial infusion tubing and blood storage devices (tubing, blood and platelets bags) made of plasticized PVC were analyzed by spectroscopic, chromatographic and microscopic techniques in order to identify and quantify the additives added to the polymer (lubricants, thermal stabilizers, plasticizers) and to put into evidence their blooming onto the surface of the devices. For all the samples, deposits were observed on the surface but with different kinds of morphologies. Ethylene bis amide lubricant and metallic stearate stabilizers were implicated in the formation of these layers. In contact with aqueous media, these insoluble deposits were damaged, suggesting a possible particulate contamination of the infused solutions.

Impact of the nature and concentration of plasticizers on the ability of PVC to sorb drug

The sorption of a drug by an infusion set may dramatically reduce the drug delivery efficiency. In this paper, we investigated how the drug sorption, in static conditions, is affected by the plasticizer's nature and ratio in the case of plasticized PVC, one of the most common material for infusion set tubing. Within the study, the drug concentration in diazepam solutions was studied after contact with PVC films containing different amounts of DEHP, DEHT, TOTM and DINCH® plasticizers. Moreover the partition coefficients between material and water were calculated. The drug sorption levels were equivalent for the different plasticizers and there was a plasticizer ratio for which the drug uptake was enhanced. As a consequence, the amount of sorbed drug might not be only linked to the amount of plasticizer in the film and to the solubility of the drug in the plasticizer alone: it must probably depend on specific interactions between plasticizer and PVC.

A comprehensive study of apixaban's degradation pathways under stress conditions using liquid chromatography coupled to multistage mass spectrometry

The main degradation pathways of apixaban, a novel anticoagulant drug acting as factor Xa inhibitor, has been established based on the degradation products identification using liquid chromatography coupled to multistage high resolution mass spectrometry.

Identification of dabigatran etexilate major degradation pathways by liquid chromatography coupled to multi stage high-resolution mass spectrometry

The major degradation mechanisms of dabigatran etexilate were deduced in the context of stress testing. Under hydrolytic stress conditions, O-dealkylation may occur along with formation of benzimidic acid derivatives.

A multiscale approach to assess the complex surface of polyurethane catheters and the effects of a new plasma decontamination treatment on the surface properties

Polyurethane catheters made of Pellethane 2363-80AE® were treated with a low temperature plasma developed for the decontamination of reusable polymer devices in hospitals. We investigated the modifications of the polymer surface by studying the topographic modifications, the chemical modifications, and their consequences on the wettability and bacterial adhesion. This study showed that plasma treatment modified the topography and grafted oxygen and nitrogen species onto the surface, resulting in an increase in the surface polarity. This effect could be correlated to the number of nitrogen atoms interacting with the surface. Moreover, this study demonstrated the significance of multiscale heterogeneities, and the complexity of industrial medical devices made from polymers. Their surface can be heterogeneous, and they contain additives that can migrate and change the surface composition.

Busulfan loading into poly(alkyl cyanoacrylate) nanoparticles: Physico-chemistry and molecular modeling

The busulfan is an alkylating agent widely used for the treatment of haematological malignancies and nonmalignant disorders. For a long time, it has been available only in an oral form. This treatment leads to a wide variability in bioavailability and side effects such as the veino-occlusive disease. Thus, an intravenous formulation of busulfan-loaded nanoparticles may be considered as a major progress. This study deals with busulfan entrapment by nanoprecipitation into five different types of poly(alkyl cyanoacrylate) polymers. The polymers leading to the highest busulfan loading efficiencies were poly(isobutyl cyanoacrylate) (PIBCA) and poly(ethyl cyanoacrylate). Molecular modeling along with energy minimization process was employed to identify the nature of the interactions occurring between busulfan and PIBCA. Further, optimization studies enabled to obtain PIBCA nanoparticles displaying busulfan loading ratios equal to 5.9% (w/w) together with nanoparticle yields of 71% (w/w). Since busulfan is a highly reactive molecule, we performed (1)H-NMR spectroscopy experiments showing that chemical integrity of the drug was preserved after loading into nanoparticles. The in vitro release studies under sink conditions, in water, or in rat plasma showed a fast release in the first 10 min followed by a slower one over 6 h. This phenomenon could be explained by the semi-polar characteristics of busulfan.

Development of "heparin-like" polymers using swift heavy ion and gamma radiation. I. Preparation and characterization of the materials

The development of ideal antithrombogenic polymers, a major problem in biomaterials sciences, is a primary objective in the fields of cardiovascular prostheses, artificial hearts, and other devices. To decrease their thrombogenicity, which remains the major obstacle, we have developed polymeric materials endowed with a specific affinity for antithrombin III (ATIII) and thus able, like heparin, to catalyze the inhibition of thrombin by ATIII. Sulfonate and sulfonamide groups are introduced onto phenyl rings belonging to styrene residues, which are radiation grafted (using swift heavy ion and gamma radiation) onto poly(vinylidene difluoride) (PVDF) and also onto poly(vinylidene fluoride/hexafluoropropylene) [P(VDF-HFP)]. In contrast to gamma radiation, which leads to a homogeneous modification, the advantage of swift heavy ion grafting is that only small regions are modified; thus, the surface may present hydrophilic (corresponding to the modified areas) and hydrophobic microdomains (corresponding to the unmodified areas) of different sizes, depending on the absorbed dose and grafting yield. Surface topography and composition are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Sulfur, sodium, fluorine, and carbon are determined by scanning electron microscopy combined with energy-dispersive X-ray analysis (SEM-EDXA). The amount of fluorine decreases as polystyrene (PS) is grafted, whatever the kind of radiation and polymer. When the polymers are functionalized, the amount of fluorine also decreases while sodium and sulfur appear. Functionalization seems to increase the roughness of the surface, and its area.