Three-dimensional Polymer Matrix Research Articles

Evaluating polyanthranilic acid as a polymeric template for the production of Prussian blue nanoclusters

AbstractThe electropolymerization of anthranilic acid (2-aminobenzoic acid) has been shown to lead to the production of a redox polymer functionalized with carboxylate groups capable of complexing metal ions. The polymer was exploited as a means of capturing ferric ion from solution with the iron decorated polymer chains used as seeding points for the formation of Prussian blue (PB). Nanoclusters of PB were dispersed throughout the three-dimensional polymer matrix with deposition achieved through direct electrochemical means or via a dip process. The latter exploited the chemical combination of Fe(III) + Ferrocyanide to yield PB allowing its dispersal of the PB throughout the polymer film. The polymer film and its subsequent modification have been characterized by electron microscopy, X-ray analysis, Raman spectroscopy and electrochemical analysis. The stability toward peroxide has also been explored. Graphical Abstract

Characterization of Nitrogen-Rich Coating Films with Atmospheric-Pressure Plasma Generated by Re-Entrant Microwave Cavity

The deposition and characterization of nitrogen-rich coating films using atmospheric-pressure plasma generated with a re-entrant cylindrical microwave cavity is presented. This system enables simple matching, stable plasma, and free space under the orifice of plasma steam. Allylamine and acetonitrile are employed as monomers, whereas argon is used as the carrier gas. The effective area of the hydrophilic coating film is 55 mm in diameter and the deposition rate is 10 nm min–1. X-ray photoelectron spectroscopy measurements show that the surfaces of these films contain a high concentration of nitrogen atoms and primary amine groups. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry shows that the coating films have a large molecular weight (>200 kDa). The surface morphology is very flat (ca. 1 nm). The experimental results indicate that a highly cross-linked three-dimensional polymer matrix is formed and atmospheric-pressure plasma deposition is successfully achieved.

Microwave-assisted atmospheric pressure plasma polymerization of hexamethyldisiloxane

Microwave-assisted atmospheric pressure plasma polymerization is presented. A system with a re-entrant microwave cavity realizes simple matching, stable plasma, and free space under the orifice of plasma steam. Hexamethyldisiloxane is employed as a monomer, while argon is used as a carrier gas. The effective area of the hydrophobic coating film used corresponds to a circle of 20 mm diameter and the deposition rate considered is 5 nm/min. Matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy shows that the coating film has a large molecular weight (>200 kDa), suggesting that a high-crosslinking and three-dimensional polymer matrix is formed and microwave-assisted atmospheric pressure plasma polymerization is fulfilled.

Evaluation of TRI-726 as a drug delivery matrix

Background: The TRI-726 polymeric drug delivery matrix is a newly-developed biocompatible hydrogel exhibiting in situ reverse-thermal gelling, mucoadhesivity, and sustained-erosion properties.Methods: Using two model drugs, clindamycin hydrochloride and acetaminophen, we determined the gelling temperatures, in vitro release profiles, kinetics of matrix erosion, rheological properties, mucoadhesive strength, microbiological activity of released clindamycin, and biocompatibility when in contact with cells.Results: It was demonstrated that none of the excipients contained in the TRI-726 polymer matrix caused any loss in clindamycin’s antimicrobial activity following incorporation into the polymer matrix. Thus, the new patent pending TRI-726 drug delivery matrix was both inert and non-reactive toward the incorporated clindamycin in terms of chemical degradation (<10% degradation under accelerated conditions over 6 months) and antimicrobial activity.Conclusions: This new drug delivery matrix is capable of releasing a wide variety of water-soluble drug compounds over an approximate 10-day period, due primarily to protracted dissolution/erosion of the three-dimensional polymer matrix in an aqueous-based biophase. Additionally, TRI-726 exhibits excellent mucoadhesive properties that would allow a candidate drug/TRI-726 formulation to adhere and remain at a potential application site for an extended period of time. Lastly, the biocompatibility tests affirmed the non-toxic and biocompatible nature of TRI-726 when in contact with cells, which suggests its suitability and versatility as a drug delivery matrix for the targeted administration of a wide range of pharmaceutical compounds where in situ gelation, protracted release of the active, and mucoadhesion of the formulation are desired.

UV-radiation-induced formation of gold nanoparticles in a three-dimensional polymer matrix

The possibility of generation of a surface plasmon resonance by gold nanoparticles in a 3D network polymer matrix upon irradiation of a liquid acrylic composition containing a dissolved Au3+ salt is demonstrated for the first time. UV-irradiation of the solution simultaneously causes gold photoreduction to Au0 and acrylate photopolymerization. The possibility of preparing transparent colorless films that, when heated or exposed to light, give rise to a visible-spectrum absorption band belonging to a plasmon resonance of metal nanoparticles is demonstrated. The intensity and position of the plasmon resonance band depend on the parameters of the 3D polymer network, chemical structure of the oligomer, type of the support, and conditions of formation of Au0 particles. The formation of reduced gold nanoparticles responsible for the plasmon resonance band occurs more effectively in low-density networks with a large interchain length and containing oligomer block capable of complexation with the metal. The formation of nanoparticles is affected by the chlorine-containing products of the reduction of the gold salt.

Evaluation of a Novel Biodegradable Polymer for the Generation of a Dermal Matrix

Dermal skin substitutes can be used to overcome the immediate problem of donor site shortage in the treatment of major skin loss conditions, such as burn injury. In this study, the biocompatibility, safety, and potential of three variants of NovoSorb (a family of novel biodegradable polyurethanes) as dermal scaffolds were determined in a series of in vitro and in vivo systems. All three polymers exhibited minimal cytotoxic effects on human skin cells, allowing keratinocytes, dermal fibroblasts, and microvascular endothelial cells to grow normally in coculture. Subcutaneous implantation of the polymers in rats demonstrated no systemic toxic effects of the materials or their degradation products. The anticipated local foreign body reaction compared favorably with commercially available medical sutures. Assessment of a three-dimensional polymer matrix followed. The success of sequential culturing of dermal fibroblasts and keratinocytes within the matrix indicated that the generation of a cultured skin substitute is achievable. The polymeric matrix also provided a scaffold for the guided formation of a cultured microvasculature. When engrafted onto a surgically created full-thickness sheep wound, the noncellular matrix integrated, healed with an epidermis supported by a basement membrane, and was capable of withstanding wound contraction. The resistance to contraction compared favorably with a commercially available collagen-based dermal matrix (Integra). These results suggest that the NovoSorb matrix could form the basis of an elegant two-stage burn treatment strategy, with an initial noncellular biodegradable temporizing matrix to stabilize the wound bed followed by the application of cultured skin substitute.

Effect of the Textile Structure of Polyacrylonitrile Fibres on Formation of a Three-Dimensional Polymer Matrix Network in “Polikon” Materials

The effect of the textile structure of PAN fibre on formation of a three-dimensional network in the polymer matrix in Polikon-A chemisorption material was investigated. The basic process methods and parameters for manufacturing modified Polikon-A materials were developed. Service life tests were performed on experimental-laboratory batches of materials. The effect of the textile structure of the fibre base on the selective power of Polikon-A chemisorption materials was noted.

Salt fusion: an approach to improve pore interconnectivity within tissue engineering scaffolds.

Macroporous scaffolds composed of biodegradable polymers have found extensive use as three-dimensional substrates either for in vitro cell seeding followed by transplantation, or as conductive substrates for direct implantation in vivo. Methods abound for creation of macroporous scaffolds for tissue engineering, and common methods typically employ a solid porogen within a three-dimensional polymer matrix to create a well-defined pore size, pore structure, and total scaffold porosity. This study describes an approach to impart improved pore interconnectivity to polymer scaffolds for tissue engineering by partially fusing the solid porogen together prior to creation of a continuous polymer matrix. Three dimensional, porous scaffolds of the copolymer 85:15 poly(lactide-co-glycolide) were fabricated via either a solvent casting/particulate leaching process, or a gas foaming/particulate leaching process. Prior to creation of a continuous polymer matrix the NaCl crystals, which serve as the solid porogen, are partially fused via treatment in 95% humidity. Scanning electron micrographs clearly display fused salt crystals and an enhancement in pore interconnectivity in the salt fused scaffolds prepared via both solvent casting and gas foaming, and the extent of pore interconnectivity is enhanced with longer treatment times. Fusion of salt crystal for 24 h increased the radius of curvature of salt crystals, and led to a twofold increase in the compressive modulus of solvent cast scaffolds (total porosity of 97 +/- 1%). Fusion of NaCl crystals prior to gas foaming resulted in a decrease in scaffold compressive modulus from 277 +/- 60k Pa to 187 +/- 30k Pa (total porosity of 94 +/- 1%). The resulting highly interconnected scaffolds have implications for facilitated cell migration, abundant cell-cell interaction, and potentially improved neural and vascular growth within tissue engineering scaffolds.

Immobilization of yeast cells in acrylamide gel matrix

Entrapment of yeast cells in a three-dimensional polymer matrix was achieved, and various properties of the polymer matrix as well as the invertase activity of the yeast cells were studied. When the matrix was highly cross-linked or synthesized from concentrated polymer solutions, its swelling ratio decreased. Invertase activity was found to increase with water content of the matrix. Cell content of the gel was found to affect adversely enzyme activity. The enzyme was found to retain its activity after seven runs with the same sample.