Polymers

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6144 KiB

Open AccessArticle

2-(Dimethylamino)ethyl Methacrylate/(2-Hydroxyethyl) Methacrylate/α-Tricalcium Phosphate Cryogels for Bone Repair, Preparation and Evaluation of the Biological Response of Human Trabecular Bone-Derived Cells and Mesenchymal Stem Cells

by Tiago Volkmer, Joana Magalhães, Vania Sousa, Luis A. Santos, Elena F. Burguera, Francisco J. Blanco, Julio San Román and Luis M. Rodríguez-Lorenzo

Polymers 2014, 6(10), 2510-2525; https://doi.org/10.3390/polym6102510 - 29 Sep 2014

Cited by 14 | Viewed by 7192

Abstract

The aim of this work is to evaluate the potential of cryogels to be used as scaffolds in tissue engineering. Scaffolds based on the α-tricalcium phosphate reinforced PDMAEMA (Poly(dimethyl aminoethyl methacrylate))/PHEMA (poly(hydroxyethyl methacrylate)) system were prepared and human trabecular bone-derived cells (HTBs) and [...] Read more.

The aim of this work is to evaluate the potential of cryogels to be used as scaffolds in tissue engineering. Scaffolds based on the α-tricalcium phosphate reinforced PDMAEMA (Poly(dimethyl aminoethyl methacrylate))/PHEMA (poly(hydroxyethyl methacrylate)) system were prepared and human trabecular bone-derived cells (HTBs) and bone marrow derived-mesenchymal stem cells (BM-MSCs) cultured on them. Several features, such as porosity, pore shape, molecular weight between crosslinks and mesh size, are studied. The most suitable PDMAEMA/PHEMA ratio for cell proliferation has been assessed and the viability, adhesion, proliferation and expression of osteoblastic biochemical markers are evaluated. The PDMAEMA/PHEMA ratio influences the scaffolds porosity. Values between 53% ± 5.7% for a greater content in PHEMA and 75% ± 5.5% for a greater content in PDMAEMA have been obtained. The polymer ratio also modifies the pore shape. A greater content in PDMAEMA leads also to bigger network mesh size. Each of the compositions were non-cytotoxic, the seeded cells remained viable for both BM-MSCs and HTBs. Thus, and based on the structural analysis, specimens with a greater content in PDMAEMA seem to provide a better structural environment for their use as scaffolds for tissue engineering. The α-tricalcium phosphate incorporation into the composition seems to favor the expression of the osteogenic phenotype. Full article

(This article belongs to the Special Issue Biomimetic Polymers)

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339 KiB

Open AccessArticle

Azetidinium Functionalized Polytetrahydrofurans: Antimicrobial Properties in Solution and Application to Prepare Non Leaching Antimicrobial Surfaces

by Subrata Chattopadhyay, Elisabeth Heine, Helmut Keul and Martin Moeller

Polymers 2014, 6(5), 1618-1630; https://doi.org/10.3390/polym6051618 - 23 May 2014

Cited by 18 | Viewed by 8526

Abstract

In this work, we report the antimicrobial efficacy of azetidinium functionalized polytetrahydrofurans in solution and their application in the preparation of non leaching, antimicrobial surfaces. The excellent antimicrobial efficacy of these water soluble polymers both in solution and on surfaces (>99.99%–100% bacterial growth [...] Read more.

In this work, we report the antimicrobial efficacy of azetidinium functionalized polytetrahydrofurans in solution and their application in the preparation of non leaching, antimicrobial surfaces. The excellent antimicrobial efficacy of these water soluble polymers both in solution and on surfaces (>99.99%–100% bacterial growth inhibition) makes them excellent candidates for solving the hygiene related problems in the medical and hospital environment. Full article

(This article belongs to the Special Issue Biomimetic Polymers)

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1020 KiB

Open AccessArticle

Phase Transformation of Adefovir Dipivoxil/Succinic Acid Cocrystals Regulated by Polymeric Additives

by Sungyup Jung, Jeong-Myeong Ha and Il Won Kim

Polymers 2014, 6(1), 1-11; https://doi.org/10.3390/polym6010001 - 20 Dec 2013

Cited by 12 | Viewed by 7966

Abstract

The polymorphic phase transformation in the cocrystallization of adefovir dipivoxil (AD) and succinic acid (SUC) was investigated. Inspired by biological and biomimetic crystallization, polymeric additives were utilized to control the phase transformation. With addition of poly(acrylic acid), the metastable phase newly identified through [...] Read more.

The polymorphic phase transformation in the cocrystallization of adefovir dipivoxil (AD) and succinic acid (SUC) was investigated. Inspired by biological and biomimetic crystallization, polymeric additives were utilized to control the phase transformation. With addition of poly(acrylic acid), the metastable phase newly identified through the analysis of X-ray diffraction was clearly isolated from the previously reported stable form. Without additives, mixed phases were obtained even at the early stage of cocrystallization. Also, infrared spectroscopy analysis verified the alteration of the hydrogen bonding that was mainly responsible for the cocrystal formation between AD and SUC. The hydrogen bonding in the metastable phase was relatively stronger than that in the stable form, which indicated the locally strong AD/SUC coupling in the initial stage of cocrystallization followed by the overall stabilization during the phase transformation. The stronger hydrogen bonding could be responsible for the faster nucleation of the initially observed metastable phase. The present study demonstrated that the polymeric additives could function as effective regulators for the polymorph-selective cocrystallization. Full article

(This article belongs to the Special Issue Biomimetic Polymers)

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582 KiB

Open AccessArticle

Release of Potassium Ion and Calcium Ion from Phosphorylcholine Group Bearing Hydrogels

by Hanna R. Aucoin, A. Nolan Wilson, Ann M. Wilson, Kazuhiko Ishihara and Anthony Guiseppi-Elie

Polymers 2013, 5(4), 1241-1257; https://doi.org/10.3390/polym5041241 - 11 Nov 2013

Cited by 29 | Viewed by 9807

Abstract

In an attempt to recreate the microenvironment necessary for directed hematopoietic stem cell differentiation, control over the amount of ions available to the cells is necessary. The release of potassium ion and calcium ion via the control of cross-linking density of a poly(2-hydroxyethyl [...] Read more.

In an attempt to recreate the microenvironment necessary for directed hematopoietic stem cell differentiation, control over the amount of ions available to the cells is necessary. The release of potassium ion and calcium ion via the control of cross-linking density of a poly(2-hydroxyethyl methacrylate) (pHEMA)-based hydrogel containing 1 mol % 2-methacryloyloxyethyl phosphorylcholine (MPC) and 5 mol % oligo(ethylene glycol) (400) monomethacrylate [OEG(400)MA] was investigated. Tetra(ethylene glycol) diacrylate (TEGDA), the cross-linker, was varied over the range of 1–12 mol %. Hydrogel discs (ϕ = 4.5 mm and h = 2.0 mm) were formed by UV polymerization within silicone isolators to contain 1.0 M CaCl₂ and 0.1 M KCl, respectively. Isothermal release profiles, were measured at 37 °C in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid sodium salt (HEPES) buffer using either calcium ion or potassium ion selective electrodes (ISE). The resulting release profiles were found to be independent of cross-linking density. Average (n = 3) release profiles were fit to five different release models with the Korsmeyer-Peppas equation, a porous media transport model, exhibiting the greatest correlation (R² > 0.95). The diffusion exponent, n was calculated to be 0.24 ± 0.02 and 0.36 ± 0.04 for calcium ion and potassium ion respectively indicating non-Fickian diffusion. The resulting diffusion coefficients were calculated to be 2.6 × 10⁻⁶ and 11.2 × 10⁻⁶ cm²/s, which compare well to literature values of 2.25 × 10⁻⁶ and 19.2 × 10⁻⁶ cm²/s for calcium ion and potassium ion, respectively. Full article

(This article belongs to the Special Issue Biomimetic Polymers)

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Review

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2009 KiB

Open AccessReview

Addressing the Inflammatory Response to Clinically Relevant Polymers by Manipulating the Host Response Using ITIM Domain-Containing Receptors

by Joshua B. Slee, Abigail J. Christian, Robert J. Levy and Stanley J. Stachelek

Polymers 2014, 6(10), 2526-2551; https://doi.org/10.3390/polym6102526 - 29 Sep 2014

Cited by 19 | Viewed by 11565

Abstract

Tissue contacting surfaces of medical devices initiate a host inflammatory response, characterized by adsorption of blood proteins and inflammatory cells triggering the release of cytokines, reactive oxygen species (ROS) and reactive nitrogen species (RNS), in an attempt to clear or isolate the foreign [...] Read more.

Tissue contacting surfaces of medical devices initiate a host inflammatory response, characterized by adsorption of blood proteins and inflammatory cells triggering the release of cytokines, reactive oxygen species (ROS) and reactive nitrogen species (RNS), in an attempt to clear or isolate the foreign object from the body. This normal host response contributes to device-associated pathophysiology and addressing device biocompatibility remains an unmet need. Although widespread attempts have been made to render the device surfaces unreactive, the establishment of a completely bioinert coating has been untenable and demonstrates the need to develop strategies based upon the molecular mechanisms that define the interaction between host cells and synthetic surfaces. In this review, we discuss a family of transmembrane receptors, known as immunoreceptor tyrosine-based inhibitory motif (ITIM)-containing receptors, which show promise as potential targets to address aberrant biocompatibility. These receptors repress the immune response and ensure that the intensity of an immune response is appropriate for the stimuli. Particular emphasis will be placed on the known ITIM-containing receptor, Signal Regulatory Protein Alpha (SIRPα), and its cognate ligand CD47. In addition, this review will discuss the potential of other ITIM-containing proteins as targets for addressing the aberrant biocompatibility of polymeric biomaterials. Full article

(This article belongs to the Special Issue Biomimetic Polymers)

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4542 KiB

Open AccessReview

Function and Autonomous Behavior of Self-Oscillating Polymer Systems

by Yusuke Hara

Polymers 2014, 6(7), 1958-1971; https://doi.org/10.3390/polym6071958 - 9 Jul 2014

Cited by 5 | Viewed by 6516

Abstract

A novel gel undergoes the Belousov-Zhabotinsky (BZ) reaction in strong-acid-free conditions. Under such conditions, the gel can switch the BZ reaction on or off in conventional self-oscillating gels that undergo self-oscillation only in aqueous solutions with strong acids, such as HNO₃ or [...] Read more.

A novel gel undergoes the Belousov-Zhabotinsky (BZ) reaction in strong-acid-free conditions. Under such conditions, the gel can switch the BZ reaction on or off in conventional self-oscillating gels that undergo self-oscillation only in aqueous solutions with strong acids, such as HNO₃ or H₂SO₄. The self-oscillation of the polymer chain can be controlled by varying the temperature, owing to its thermoresponsive property. Moreover, the polymer chain undergoes viscosity self-oscillations in strong-acid-free conditions. In this review, the direct observation of self-oscillations in polymer chains attached to glass or gold surfaces, by using scanning probe microscopy and quartz crystal microbalances with dissipation monitoring, is discussed. Full article

(This article belongs to the Special Issue Biomimetic Polymers)

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2091 KiB

Open AccessReview

Polyelectrolyte Multilayers: Towards Single Cell Studies

by Dmitry Volodkin, Regine Von Klitzing and Helmuth Moehwald

Polymers 2014, 6(5), 1502-1527; https://doi.org/10.3390/polym6051502 - 20 May 2014

Cited by 43 | Viewed by 9826

Abstract

Single cell analysis (SCA) is nowadays recognized as one of the key tools for diagnostics and fundamental cell biology studies. The Layer-by-layer (LbL) polyelectrolyte assembly is a rather new but powerful technique to produce multilayers. It allows to model the extracellular matrix in [...] Read more.

Single cell analysis (SCA) is nowadays recognized as one of the key tools for diagnostics and fundamental cell biology studies. The Layer-by-layer (LbL) polyelectrolyte assembly is a rather new but powerful technique to produce multilayers. It allows to model the extracellular matrix in terms of its chemical and physical properties. Utilization of the multilayers for SCA may open new avenues in SCA because of the triple role of the multilayer film: (i) high capacity for various biomolecules; (ii) natural mimics of signal molecule diffusion to a cell and (iii) cell patterning opportunities. Besides, light-triggered release from multilayer films offers a way to deliver biomolecules with high spatio-temporal resolution. Here we review recent works showing strong potential to use multilayers for SCA and address accordingly the following issues: biomolecule loading, cell patterning, and light-triggered release. Full article

(This article belongs to the Special Issue Biomimetic Polymers)

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52769 KiB

Open AccessReview

Polymeric Slippery Coatings: Nature and Applications

by Mohamed A. Samaha and Mohamed Gad-el-Hak

Polymers 2014, 6(5), 1266-1311; https://doi.org/10.3390/polym6051266 - 30 Apr 2014

Cited by 45 | Viewed by 21588

Abstract

We review recent developments in nature-inspired superhydrophobic and omniphobic surfaces. Water droplets beading on a surface at significantly high static contact angles and low contact-angle hystereses characterize superhydrophobicity. Microscopically, rough hydrophobic surfaces could entrap air in their pores resulting in a portion of [...] Read more.

We review recent developments in nature-inspired superhydrophobic and omniphobic surfaces. Water droplets beading on a surface at significantly high static contact angles and low contact-angle hystereses characterize superhydrophobicity. Microscopically, rough hydrophobic surfaces could entrap air in their pores resulting in a portion of a submerged surface with air–water interface, which is responsible for the slip effect. Suberhydrophobicity enhances the mobility of droplets on lotus leaves for self-cleaning purposes, so-called lotus effect. Amongst other applications, superhydrophobicity could be used to design slippery surfaces with minimal skin-friction drag for energy conservation. Another kind of slippery coatings is the recently invented slippery liquid-infused porous surfaces (SLIPS), which are one type of omniphobic surfaces. Certain plants such as the carnivorous Nepenthes pitcher inspired SLIPS. Their interior surfaces have microstructural roughness, which can lock in place an infused lubricating liquid. The lubricant is then utilized as a repellent surface for other liquids such as water, blood, crude oil, and alcohol. In this review, we discuss the concepts of both lotus effect and Nepenthes slippery mechanism. We then present a review of recent advances in manufacturing polymeric and non-polymeric slippery surfaces with ordered and disordered micro/nanostructures. Furthermore, we discuss the performance and longevity of such surfaces. Techniques used to characterize the surfaces are also detailed. We conclude the article with an overview of the latest advances in characterizing and using slippery surfaces for different applications. Full article

(This article belongs to the Special Issue Biomimetic Polymers)

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