Study of the calcification of PHEMA hydrogels using a two compartment permeation cell

Zainuddin, Zainuddin -; Chirilă, Traian V.; Hill, David J. T.; Whittaker, Andrew K.

doi:10.1016/j.molstruc.2004.06.038

Cited by 16 publications

(8 citation statements)

References 28 publications

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“…The tentative explanations of biomaterials calcification assign the main cause to dead cells. According to this hypothesis, the accumulation of calcium deposits originates from the cells or tissues that have degenerated or become necrotic [25,26]. However, some authors showed that, even without direct contact with cells, calcification of biomaterials occurs through the formation of a protein-calcium complex layer on the surface of biomaterials, this being the key event in biomaterial calcification [27,28].…”

Section: Discussionmentioning

confidence: 99%

Bacterial Cellulose: Long-Term Biocompatibility Studies

Pértile

Moreira

Costa

et al. 2012

Journal of Biomaterials Science, Polymer Edition

124

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The bacterial cellulose (BC) secreted by Gluconacetobacter xylinus is a network of pure cellulose nanofibres which has high crystallinity, wettability and mechanical strength. These characteristics make BC an excellent material for tissue-engineering constructs, noteworthy for artificial vascular grafts. In this work, the in vivo biocompatibility of BC membranes produced by two G. xylinus strains was analyzed through histological analysis of long-term subcutaneous implants in the mice. The BC implants caused a mild and benign inflammatory reaction that decreased along time and did not elicit a foreign body reaction. A tendency to calcify over time, which may be related to the porosity of the BC implants, was observed, especially among the less porous BC-1 implants. In addition, the potential toxicity of BC nanofibres - obtained by chemical-mechanical treatment of BC membranes - subcutaneously implanted in mice was analysed through bone marrow flow cytometry and histological analyses. At 2 and 4 months post-implantation, the nanofibres implants were found to accumulate intracellularly, in subcutaneous foamy macrophages aggregates. Moreover, no differences were observed between the controls and implanted animals in thymocyte populations and in B lymphocyte precursors and myeloid cells in the bone marrow.

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Section: Discussionmentioning

confidence: 99%

Bacterial Cellulose: Long-Term Biocompatibility Studies

Pértile

Moreira

Costa

et al. 2012

Journal of Biomaterials Science, Polymer Edition

124

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“…It is proposed that water molecules bonded close to the surface of the PMMA can attract ions to adhere to the surface. Previous studies have shown that diffusion triggers the process of calcification, whereby calcium containing deposits may be noticed on the PMMA surface after just seven days [19]. Therefore if we are able to hinder diffusion we may in turn delay calcification, or even prevent it.…”

Section: Resultsmentioning

confidence: 94%

The Effect of Direct Gas Fluorination on Medical Grade Poly(methyl methacrylate)

Ghatora¹,

Barton²,

Foot³

et al. 2014

OJOPM

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Medical-grade poly(methyl methacrylate) (PMMA) is extensively employed in the fabrication of a variety of medical implants, including intraocular lenses (IOLs). However, a postoperative complication that leads to the failure of the implanted intraocular lenses has been recently identified. This process, termed calcification, occurs when calcium-containing deposits accumulate on the surface of the IOL. In this study direct gas fluorination was used to modify the surface of PMMA in an attempt to increase the service lifetime of the material in optical applications. PMMA discs exposed to a 20% fluorine/nitrogen gas mixture for 24 h were compared with untreated PMMA discs serving as control samples. Over time, both surface-fluorinated and untreated PMMA samples immersed in a simulated aqueous humour solution (SAHS) (pH 7.4, 35˚C) were used to carry out in vitro studies. Attenuated total refractive Infrared spectroscopy (ATR-IR) Scanning electron microscopy (SEM), coupled with Energy dispersive X-ray analysis (EDX), showed that calcium-containing surface deposits were less abundant on surface-fluorinated PMMA compared with the control samples, indicating that the fluorinated surface was acting as a barrier to the deposits. Gravimetric analysis data showed that the decreased rate of diffusion compared with that of a control sample was due to the fluorinated surface.

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“…The in vitro calcification of PHEMA has been studied to a lesser extent 110–118. Some of our own previous investigations suggested that enhanced local supersaturation within the polymer network due to salting‐out solute effects,119 and the presence of diffusion gradients120 may contribute to triggering nucleation and crystal growth of calcium phosphate phases. Consequently, it was implied121 that the abiogenic calcification of synthetic hydrogels may have, after all, a level of complexity not much lower that that of the calcification of typical biogenic substrata, such as collagen.…”

Section: Resultsmentioning

confidence: 99%

Sequential homo‐interpenetrating polymer networks of poly(2‐hydroxyethyl methacrylate): Synthesis, characterization, and calcium uptake

Chirilă

George

Ghafor

et al. 2012

J of Applied Polymer Sci

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Formation of homo-interpenetrating polymer networks (homo-IPNs) of poly(2-hydroxyethyl methacrylate) (PHEMA) and their capacity for calcification are investigated. A sequential method is established to generate IPNs of rank I and II, containing two or three crosslinked networks. Although the networks are chemically identical, thermo-mechanical analysis (DSC, DMA) suggests some phase separation. Calcification of PHEMA hydrogels, thought to be controlled by the free volume pathways accessible to calcium ions, is investigated by positron annihilation lifetime spectroscopy (PALS) and experimental calcium deposition. While calcium uptake is reduced in IPNs, the size of the free volume elements estimated by PALS remain constant at radii of 2.6 Å (dry) and 2.9 Å (hydrated), both in PHEMA and IPNs. The reduction of calcium uptake cannot be therefore associated with the size reduction of the angstrom-size free volume elements detectable by PALS, and is attributed to the effect of chain packing on pores too large to be detected by PALS. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 126: E455-E466, 2012

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Study of the calcification of PHEMA hydrogels using a two compartment permeation cell

Cited by 16 publications

References 28 publications

Bacterial Cellulose: Long-Term Biocompatibility Studies

Bacterial Cellulose: Long-Term Biocompatibility Studies

The Effect of Direct Gas Fluorination on Medical Grade Poly(methyl methacrylate)

Sequential homo‐interpenetrating polymer networks of poly(2‐hydroxyethyl methacrylate): Synthesis, characterization, and calcium uptake

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