The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform
Alexander M Seifalian - One of the best experts on this subject based on the ideXlab platform.
-
surface functionalization and Grafting of heparin and or rgd by an aqueous based process to a poly carbonate urea urethane Cardiovascular Graft for cellular engineering applications
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Henryk J Salacinski, G Hamilton, Alexander M SeifalianAbstract:An aqueous-based process is reported for surface functionalization and Grafting of anticoagulant and cell attachment moieties, such as heparin and/or arginine–glycine– aspartate (RGD) onto the lumenal surface of a prefabricated Cardiovascular Graft (5 mm i.d.) made of poly(carbonate- urea)urethane (MyoLink™). It is a three-stage process, all aqueous: (1) hydroxylation using an azobis compound, particularly 2,2′-azobis(2-methylpropionamidine)dihydrochloride, which abstracts hydrogen via an electron transfer process from the polyurethane surface (strong oxygen purging); (2) Grafting using the as-generated hydroxide groups to allow attachment of an acrylamide monomer using a conventional ceric ion technique (strong nitrogen purging); and (3) moiety attachment, preactivated with [1-ethyl-3-(3-dimethylaminopropyl)carbodiimide] in acidic solution. The technique was validated by attaching heparin and RGD/heparin to the MyoLink™ polymer. Following bonding, the Graft segments were exposed to prolonged physiologic shear force in a flow circuit (10 h). The Grafts first were analyzed by X-ray photoelectron spectroscopy (XPS) to determine the degree of attachment of the moieties and then by materials methods to assess whether any degradation of the Graft material itself had occurred since polyurethanes with carbonate amorphous segments are readily susceptible to hydrolytic degradation following functionalization processes. XPS showed the moieties were present on the surface at a concentration of 10%. The S2p3/2 states of sulfur indicated that there were high degrees of ionic covalent bonding, indicating high degrees of moiety bioactivity. Heparin was found to be present from the sulfur signal, namely NSO3. RGD was found to be present from the nitrogen signal present at the binding energy of 399 eV. Macroscopic analysis and ESEM showed no signs of polyurethane degradation or small protuberances indicative of microgel formation. Quality control (QC) showed that the internal diameters and wall thicknesses of all the respective Grafts postbonding remained within normal batch release limits (5 ± 0.1mm, i.d.; 0.9 ± 0.05 mm, wall thickness). Gel permeation chromatography (GPC) showed there were no statistical differences between the control, which was nonbonded (MN 45,300, MW 98,500, D 2.17) and all of the bonded samples, respectively (MN 41,800, MW 104,000, D 2.45). Radial tensile strength (RTS) analysis also showed that all of the respective samples postbonding (1.48N/mm) remained within batch release specifications (>1N/mm). A simple aqueous polymer surface functionalization and Grafting technique has been developed for covalent bonding of anticoagulant and cell-attachment moieties onto poly(carbonate-urea)urethane(s) and has been validated by surface and materials analyses. The moieties were attached uniformly and were bioactive at a high surface density. No degradation in terms of a loss in mechanical properties was evident following bonding of the polyurethane. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 688–697, 2003
-
Surface functionalization and Grafting of heparin and/or RGD by an aqueous‐based process to a poly(carbonate‐urea)urethane Cardiovascular Graft for cellular engineering applications
Journal of biomedical materials research. Part A, 2003Co-Authors: Henryk J Salacinski, G Hamilton, Alexander M SeifalianAbstract:An aqueous-based process is reported for surface functionalization and Grafting of anticoagulant and cell attachment moieties, such as heparin and/or arginine–glycine– aspartate (RGD) onto the lumenal surface of a prefabricated Cardiovascular Graft (5 mm i.d.) made of poly(carbonate- urea)urethane (MyoLink™). It is a three-stage process, all aqueous: (1) hydroxylation using an azobis compound, particularly 2,2′-azobis(2-methylpropionamidine)dihydrochloride, which abstracts hydrogen via an electron transfer process from the polyurethane surface (strong oxygen purging); (2) Grafting using the as-generated hydroxide groups to allow attachment of an acrylamide monomer using a conventional ceric ion technique (strong nitrogen purging); and (3) moiety attachment, preactivated with [1-ethyl-3-(3-dimethylaminopropyl)carbodiimide] in acidic solution. The technique was validated by attaching heparin and RGD/heparin to the MyoLink™ polymer. Following bonding, the Graft segments were exposed to prolonged physiologic shear force in a flow circuit (10 h). The Grafts first were analyzed by X-ray photoelectron spectroscopy (XPS) to determine the degree of attachment of the moieties and then by materials methods to assess whether any degradation of the Graft material itself had occurred since polyurethanes with carbonate amorphous segments are readily susceptible to hydrolytic degradation following functionalization processes. XPS showed the moieties were present on the surface at a concentration of 10%. The S2p3/2 states of sulfur indicated that there were high degrees of ionic covalent bonding, indicating high degrees of moiety bioactivity. Heparin was found to be present from the sulfur signal, namely NSO3. RGD was found to be present from the nitrogen signal present at the binding energy of 399 eV. Macroscopic analysis and ESEM showed no signs of polyurethane degradation or small protuberances indicative of microgel formation. Quality control (QC) showed that the internal diameters and wall thicknesses of all the respective Grafts postbonding remained within normal batch release limits (5 ± 0.1mm, i.d.; 0.9 ± 0.05 mm, wall thickness). Gel permeation chromatography (GPC) showed there were no statistical differences between the control, which was nonbonded (MN 45,300, MW 98,500, D 2.17) and all of the bonded samples, respectively (MN 41,800, MW 104,000, D 2.45). Radial tensile strength (RTS) analysis also showed that all of the respective samples postbonding (1.48N/mm) remained within batch release specifications (>1N/mm). A simple aqueous polymer surface functionalization and Grafting technique has been developed for covalent bonding of anticoagulant and cell-attachment moieties onto poly(carbonate-urea)urethane(s) and has been validated by surface and materials analyses. The moieties were attached uniformly and were bioactive at a high surface density. No degradation in terms of a loss in mechanical properties was evident following bonding of the polyurethane. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 688–697, 2003
-
development of a hybrid Cardiovascular Graft using a tissue engineering approach
The FASEB Journal, 2002Co-Authors: Alok Tiwari, Henryk J Salacinski, Geoffrey Punshon, G Hamilton, Alexander M SeifalianAbstract:Tissue engineering of endothelial cells (EC) and chemical engineering with anticoagulant moieties has been undertaken in order to improve prosthetic Graft patency and thrombogenicity. This was done by covalently bonding a compliant poly(carbonate-urea)urethane Graft (MyoLink™) with arginine-glycine-aspartate (RGD) or/and heparin (Hep) to ascertain whether EC retention could be improved. The retention of these moieties and EC was assessed after exposure to pulsatile flow. We covalently bonded RGD, Hep, and RGD/Hep onto the luminal surface of MyoLink using spacer arm technology. Narrow-beam X-ray photoelectron spectroscopy was carried out to check the efficiency of the bonding. EC were radiolabeled and seeded onto native MyoLink and with 1) RGD-, 2) Hep-, and 3) RGD/Hep-bonded Grafts and exposed to shear stress in a physiological flow circuit for 6 h, which reproduces femoral artery flow waveforms and pulsatility. Results were recorded on a gamma camera imaging system. Viability of cells was tested with a m...
Henryk J Salacinski - One of the best experts on this subject based on the ideXlab platform.
-
surface functionalization and Grafting of heparin and or rgd by an aqueous based process to a poly carbonate urea urethane Cardiovascular Graft for cellular engineering applications
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Henryk J Salacinski, G Hamilton, Alexander M SeifalianAbstract:An aqueous-based process is reported for surface functionalization and Grafting of anticoagulant and cell attachment moieties, such as heparin and/or arginine–glycine– aspartate (RGD) onto the lumenal surface of a prefabricated Cardiovascular Graft (5 mm i.d.) made of poly(carbonate- urea)urethane (MyoLink™). It is a three-stage process, all aqueous: (1) hydroxylation using an azobis compound, particularly 2,2′-azobis(2-methylpropionamidine)dihydrochloride, which abstracts hydrogen via an electron transfer process from the polyurethane surface (strong oxygen purging); (2) Grafting using the as-generated hydroxide groups to allow attachment of an acrylamide monomer using a conventional ceric ion technique (strong nitrogen purging); and (3) moiety attachment, preactivated with [1-ethyl-3-(3-dimethylaminopropyl)carbodiimide] in acidic solution. The technique was validated by attaching heparin and RGD/heparin to the MyoLink™ polymer. Following bonding, the Graft segments were exposed to prolonged physiologic shear force in a flow circuit (10 h). The Grafts first were analyzed by X-ray photoelectron spectroscopy (XPS) to determine the degree of attachment of the moieties and then by materials methods to assess whether any degradation of the Graft material itself had occurred since polyurethanes with carbonate amorphous segments are readily susceptible to hydrolytic degradation following functionalization processes. XPS showed the moieties were present on the surface at a concentration of 10%. The S2p3/2 states of sulfur indicated that there were high degrees of ionic covalent bonding, indicating high degrees of moiety bioactivity. Heparin was found to be present from the sulfur signal, namely NSO3. RGD was found to be present from the nitrogen signal present at the binding energy of 399 eV. Macroscopic analysis and ESEM showed no signs of polyurethane degradation or small protuberances indicative of microgel formation. Quality control (QC) showed that the internal diameters and wall thicknesses of all the respective Grafts postbonding remained within normal batch release limits (5 ± 0.1mm, i.d.; 0.9 ± 0.05 mm, wall thickness). Gel permeation chromatography (GPC) showed there were no statistical differences between the control, which was nonbonded (MN 45,300, MW 98,500, D 2.17) and all of the bonded samples, respectively (MN 41,800, MW 104,000, D 2.45). Radial tensile strength (RTS) analysis also showed that all of the respective samples postbonding (1.48N/mm) remained within batch release specifications (>1N/mm). A simple aqueous polymer surface functionalization and Grafting technique has been developed for covalent bonding of anticoagulant and cell-attachment moieties onto poly(carbonate-urea)urethane(s) and has been validated by surface and materials analyses. The moieties were attached uniformly and were bioactive at a high surface density. No degradation in terms of a loss in mechanical properties was evident following bonding of the polyurethane. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 688–697, 2003
-
Surface functionalization and Grafting of heparin and/or RGD by an aqueous‐based process to a poly(carbonate‐urea)urethane Cardiovascular Graft for cellular engineering applications
Journal of biomedical materials research. Part A, 2003Co-Authors: Henryk J Salacinski, G Hamilton, Alexander M SeifalianAbstract:An aqueous-based process is reported for surface functionalization and Grafting of anticoagulant and cell attachment moieties, such as heparin and/or arginine–glycine– aspartate (RGD) onto the lumenal surface of a prefabricated Cardiovascular Graft (5 mm i.d.) made of poly(carbonate- urea)urethane (MyoLink™). It is a three-stage process, all aqueous: (1) hydroxylation using an azobis compound, particularly 2,2′-azobis(2-methylpropionamidine)dihydrochloride, which abstracts hydrogen via an electron transfer process from the polyurethane surface (strong oxygen purging); (2) Grafting using the as-generated hydroxide groups to allow attachment of an acrylamide monomer using a conventional ceric ion technique (strong nitrogen purging); and (3) moiety attachment, preactivated with [1-ethyl-3-(3-dimethylaminopropyl)carbodiimide] in acidic solution. The technique was validated by attaching heparin and RGD/heparin to the MyoLink™ polymer. Following bonding, the Graft segments were exposed to prolonged physiologic shear force in a flow circuit (10 h). The Grafts first were analyzed by X-ray photoelectron spectroscopy (XPS) to determine the degree of attachment of the moieties and then by materials methods to assess whether any degradation of the Graft material itself had occurred since polyurethanes with carbonate amorphous segments are readily susceptible to hydrolytic degradation following functionalization processes. XPS showed the moieties were present on the surface at a concentration of 10%. The S2p3/2 states of sulfur indicated that there were high degrees of ionic covalent bonding, indicating high degrees of moiety bioactivity. Heparin was found to be present from the sulfur signal, namely NSO3. RGD was found to be present from the nitrogen signal present at the binding energy of 399 eV. Macroscopic analysis and ESEM showed no signs of polyurethane degradation or small protuberances indicative of microgel formation. Quality control (QC) showed that the internal diameters and wall thicknesses of all the respective Grafts postbonding remained within normal batch release limits (5 ± 0.1mm, i.d.; 0.9 ± 0.05 mm, wall thickness). Gel permeation chromatography (GPC) showed there were no statistical differences between the control, which was nonbonded (MN 45,300, MW 98,500, D 2.17) and all of the bonded samples, respectively (MN 41,800, MW 104,000, D 2.45). Radial tensile strength (RTS) analysis also showed that all of the respective samples postbonding (1.48N/mm) remained within batch release specifications (>1N/mm). A simple aqueous polymer surface functionalization and Grafting technique has been developed for covalent bonding of anticoagulant and cell-attachment moieties onto poly(carbonate-urea)urethane(s) and has been validated by surface and materials analyses. The moieties were attached uniformly and were bioactive at a high surface density. No degradation in terms of a loss in mechanical properties was evident following bonding of the polyurethane. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 688–697, 2003
-
development of a hybrid Cardiovascular Graft using a tissue engineering approach
The FASEB Journal, 2002Co-Authors: Alok Tiwari, Henryk J Salacinski, Geoffrey Punshon, G Hamilton, Alexander M SeifalianAbstract:Tissue engineering of endothelial cells (EC) and chemical engineering with anticoagulant moieties has been undertaken in order to improve prosthetic Graft patency and thrombogenicity. This was done by covalently bonding a compliant poly(carbonate-urea)urethane Graft (MyoLink™) with arginine-glycine-aspartate (RGD) or/and heparin (Hep) to ascertain whether EC retention could be improved. The retention of these moieties and EC was assessed after exposure to pulsatile flow. We covalently bonded RGD, Hep, and RGD/Hep onto the luminal surface of MyoLink using spacer arm technology. Narrow-beam X-ray photoelectron spectroscopy was carried out to check the efficiency of the bonding. EC were radiolabeled and seeded onto native MyoLink and with 1) RGD-, 2) Hep-, and 3) RGD/Hep-bonded Grafts and exposed to shear stress in a physiological flow circuit for 6 h, which reproduces femoral artery flow waveforms and pulsatility. Results were recorded on a gamma camera imaging system. Viability of cells was tested with a m...
Gary L Bowlin - One of the best experts on this subject based on the ideXlab platform.
-
electrospun polydioxanone elastin blends potential for bioresorbable vascular Grafts
Biomedical Materials, 2006Co-Authors: Scott A Sell, Michael J Mcclure, Catherine P Barnes, D C Knapp, Beat H Walpoth, David G Simpson, Gary L BowlinAbstract:An electrospun Cardiovascular Graft composed of polydioxanone (PDO) and elastin has been designed and fabricated with mechanical properties to more closely match those of native arterial tissue, while remaining conducive to tissue regeneration. PDO was chosen to provide mechanical integrity to the prosthetic, while elastin provides elasticity and bioactivity (to promote regeneration in vitro/in situ). It is the elastic nature of elastin that dominates the low-strain mechanical response of the vessel to blood flow and prevents pulsatile energy from being dissipated as heat. Uniaxial tensile and suture retention tests were performed on the electrospun Grafts to demonstrate the similarities of the mechanical properties between the Grafts and native vessel. Dynamic compliance measurements produced values that ranged from 1.2 to 5.6%/100 mmHg for a set of three different mean arterial pressures. Results showed the 50:50 ratio to closely mimic the compliance of native femoral artery, while Grafts that contained less elastin exceeded the suture retention strength of native vessel. Preliminary cell culture studies showed the elastin-containing Grafts to be bioactive as cells migrated through their full thickness within 7 days, but failed to migrate into pure PDO scaffolds. Electrospinning of the PDO and elastin-blended composite into a conduit for use as a small diameter vascular Graft has extreme potential and warrants further investigation as it thus far compares favorably to native vessel.
-
Electrospun polydioxanone–elastin blends: potential for bioresorbable vascular Grafts*
Biomedical materials (Bristol England), 2006Co-Authors: Scott A Sell, Michael J Mcclure, Catherine P Barnes, D C Knapp, Beat H Walpoth, David G Simpson, Gary L BowlinAbstract:An electrospun Cardiovascular Graft composed of polydioxanone (PDO) and elastin has been designed and fabricated with mechanical properties to more closely match those of native arterial tissue, while remaining conducive to tissue regeneration. PDO was chosen to provide mechanical integrity to the prosthetic, while elastin provides elasticity and bioactivity (to promote regeneration in vitro/in situ). It is the elastic nature of elastin that dominates the low-strain mechanical response of the vessel to blood flow and prevents pulsatile energy from being dissipated as heat. Uniaxial tensile and suture retention tests were performed on the electrospun Grafts to demonstrate the similarities of the mechanical properties between the Grafts and native vessel. Dynamic compliance measurements produced values that ranged from 1.2 to 5.6%/100 mmHg for a set of three different mean arterial pressures. Results showed the 50:50 ratio to closely mimic the compliance of native femoral artery, while Grafts that contained less elastin exceeded the suture retention strength of native vessel. Preliminary cell culture studies showed the elastin-containing Grafts to be bioactive as cells migrated through their full thickness within 7 days, but failed to migrate into pure PDO scaffolds. Electrospinning of the PDO and elastin-blended composite into a conduit for use as a small diameter vascular Graft has extreme potential and warrants further investigation as it thus far compares favorably to native vessel.
G Hamilton - One of the best experts on this subject based on the ideXlab platform.
-
surface functionalization and Grafting of heparin and or rgd by an aqueous based process to a poly carbonate urea urethane Cardiovascular Graft for cellular engineering applications
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Henryk J Salacinski, G Hamilton, Alexander M SeifalianAbstract:An aqueous-based process is reported for surface functionalization and Grafting of anticoagulant and cell attachment moieties, such as heparin and/or arginine–glycine– aspartate (RGD) onto the lumenal surface of a prefabricated Cardiovascular Graft (5 mm i.d.) made of poly(carbonate- urea)urethane (MyoLink™). It is a three-stage process, all aqueous: (1) hydroxylation using an azobis compound, particularly 2,2′-azobis(2-methylpropionamidine)dihydrochloride, which abstracts hydrogen via an electron transfer process from the polyurethane surface (strong oxygen purging); (2) Grafting using the as-generated hydroxide groups to allow attachment of an acrylamide monomer using a conventional ceric ion technique (strong nitrogen purging); and (3) moiety attachment, preactivated with [1-ethyl-3-(3-dimethylaminopropyl)carbodiimide] in acidic solution. The technique was validated by attaching heparin and RGD/heparin to the MyoLink™ polymer. Following bonding, the Graft segments were exposed to prolonged physiologic shear force in a flow circuit (10 h). The Grafts first were analyzed by X-ray photoelectron spectroscopy (XPS) to determine the degree of attachment of the moieties and then by materials methods to assess whether any degradation of the Graft material itself had occurred since polyurethanes with carbonate amorphous segments are readily susceptible to hydrolytic degradation following functionalization processes. XPS showed the moieties were present on the surface at a concentration of 10%. The S2p3/2 states of sulfur indicated that there were high degrees of ionic covalent bonding, indicating high degrees of moiety bioactivity. Heparin was found to be present from the sulfur signal, namely NSO3. RGD was found to be present from the nitrogen signal present at the binding energy of 399 eV. Macroscopic analysis and ESEM showed no signs of polyurethane degradation or small protuberances indicative of microgel formation. Quality control (QC) showed that the internal diameters and wall thicknesses of all the respective Grafts postbonding remained within normal batch release limits (5 ± 0.1mm, i.d.; 0.9 ± 0.05 mm, wall thickness). Gel permeation chromatography (GPC) showed there were no statistical differences between the control, which was nonbonded (MN 45,300, MW 98,500, D 2.17) and all of the bonded samples, respectively (MN 41,800, MW 104,000, D 2.45). Radial tensile strength (RTS) analysis also showed that all of the respective samples postbonding (1.48N/mm) remained within batch release specifications (>1N/mm). A simple aqueous polymer surface functionalization and Grafting technique has been developed for covalent bonding of anticoagulant and cell-attachment moieties onto poly(carbonate-urea)urethane(s) and has been validated by surface and materials analyses. The moieties were attached uniformly and were bioactive at a high surface density. No degradation in terms of a loss in mechanical properties was evident following bonding of the polyurethane. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 688–697, 2003
-
Surface functionalization and Grafting of heparin and/or RGD by an aqueous‐based process to a poly(carbonate‐urea)urethane Cardiovascular Graft for cellular engineering applications
Journal of biomedical materials research. Part A, 2003Co-Authors: Henryk J Salacinski, G Hamilton, Alexander M SeifalianAbstract:An aqueous-based process is reported for surface functionalization and Grafting of anticoagulant and cell attachment moieties, such as heparin and/or arginine–glycine– aspartate (RGD) onto the lumenal surface of a prefabricated Cardiovascular Graft (5 mm i.d.) made of poly(carbonate- urea)urethane (MyoLink™). It is a three-stage process, all aqueous: (1) hydroxylation using an azobis compound, particularly 2,2′-azobis(2-methylpropionamidine)dihydrochloride, which abstracts hydrogen via an electron transfer process from the polyurethane surface (strong oxygen purging); (2) Grafting using the as-generated hydroxide groups to allow attachment of an acrylamide monomer using a conventional ceric ion technique (strong nitrogen purging); and (3) moiety attachment, preactivated with [1-ethyl-3-(3-dimethylaminopropyl)carbodiimide] in acidic solution. The technique was validated by attaching heparin and RGD/heparin to the MyoLink™ polymer. Following bonding, the Graft segments were exposed to prolonged physiologic shear force in a flow circuit (10 h). The Grafts first were analyzed by X-ray photoelectron spectroscopy (XPS) to determine the degree of attachment of the moieties and then by materials methods to assess whether any degradation of the Graft material itself had occurred since polyurethanes with carbonate amorphous segments are readily susceptible to hydrolytic degradation following functionalization processes. XPS showed the moieties were present on the surface at a concentration of 10%. The S2p3/2 states of sulfur indicated that there were high degrees of ionic covalent bonding, indicating high degrees of moiety bioactivity. Heparin was found to be present from the sulfur signal, namely NSO3. RGD was found to be present from the nitrogen signal present at the binding energy of 399 eV. Macroscopic analysis and ESEM showed no signs of polyurethane degradation or small protuberances indicative of microgel formation. Quality control (QC) showed that the internal diameters and wall thicknesses of all the respective Grafts postbonding remained within normal batch release limits (5 ± 0.1mm, i.d.; 0.9 ± 0.05 mm, wall thickness). Gel permeation chromatography (GPC) showed there were no statistical differences between the control, which was nonbonded (MN 45,300, MW 98,500, D 2.17) and all of the bonded samples, respectively (MN 41,800, MW 104,000, D 2.45). Radial tensile strength (RTS) analysis also showed that all of the respective samples postbonding (1.48N/mm) remained within batch release specifications (>1N/mm). A simple aqueous polymer surface functionalization and Grafting technique has been developed for covalent bonding of anticoagulant and cell-attachment moieties onto poly(carbonate-urea)urethane(s) and has been validated by surface and materials analyses. The moieties were attached uniformly and were bioactive at a high surface density. No degradation in terms of a loss in mechanical properties was evident following bonding of the polyurethane. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 688–697, 2003
Udo Bakowsky - One of the best experts on this subject based on the ideXlab platform.
-
Immobilization and characterization of PLGA nanoparticles on polyethylene terephthalate Cardiovascular Grafts for local drug therapy of associated Graft complications
Journal of Drug Delivery Science and Technology, 2018Co-Authors: Bassam M. Al Meslmani, Gihan Mahmoud, Udo BakowskyAbstract:Abstract The Cardiovascular Graft associated complications limit the long-term patency of the Graft and restrict the patient's life quality. In the present study, PLGA nanoparticles were covalently immobilized onto the woven form of crimped polyethylene terephthalate (PET, Dacron®) Cardiovascular Graft to treat the early thrombosis, inflammation, or bacterial infection via local delivery of therapeutic agents. PET surface was firstly functionalized to produce reactive amino groups used as anchor sites for covalent immobilization of PLGA nanoparticles by end-point technique. The functionalized surface characterized by electro kinetic analyzer showed marked negative surface potential values up to −41 mV at high pH value indicating the presence of amino groups on PET surface. The scanning electron microscopy observations of nano-coated PET showed topographic architecture of homogenously distributed monolayer of PLGA nanoparticles on the PET surfaces. Profoundly, the immobilized nanoparticles manifested stability under blood flow-mimetic conditions for 24 h. The cytotoxicity and biocompatibility of the nano-coated PET in mouse L929 fibroblasts revealed adequate biocompatibility in terms of the cellular adhesion and growth pattern without remarkable cytotoxicity.
-
Development of expanded polytetrafluoroethylene Cardiovascular Graft platform based on immobilization of poly lactic-co-glycolic acid nanoparticles using a wet chemical modification technique.
International journal of pharmaceutics, 2017Co-Authors: Bassam M. Al Meslmani, Gihan Mahmoud, Udo BakowskyAbstract:Expanded polytetrafluoroethylene ePTFE Grafts are mostly employed to replace damaged blood vessels and to restore normal blood flow. However, the dilemma of early thrombosis, inflammation, and development of biofilms after implantation limit ePTFE long-term patency and restrict the patient's life quality. In this study, poly lactic-co-glycolic acid (PLGA) nanoparticles were covalently immobilized on ePTFE surface for local therapeutic purposes. First, the ePTFE surface was primarily oxidized by H2O2/H2SO4 solution to create hydroxyl groups. Consequently, free amino groups were introduced onto ePTFE surface by an aminolyzation reaction of the activated hydroxyl groups using 3-aminopropyl triethoxysilane. The produced amino groups were further used as anchor sites for covalent immobilization of previously prepared PLGA nanoparticles. The functional groups originated on ePTFE surface were confirmed by FTIR analysis. Furthermore, the scanning electron microscopy visualization evidenced a homogeneous distribution pattern of the immobilized PLGA nanoparticles on the surface. The immobilized PLGA nanoparticles showed stability on ePTFE surface under blood flow mimetic conditions. Additionally, light microscopy observation confirmed the biocompatibility of mouse L929 fibroblasts on the nano-coated ePTFE Graft. The cellular adhesion and growth did not reveal remarkable cytotoxicity in the tested modified ePTFE Grafts.
-
Covalent immobilization of lysozyme onto woven and knitted crimped polyethylene terephthalate Grafts to minimize the adhesion of broad spectrum pathogens
Materials science & engineering. C Materials for biological applications, 2015Co-Authors: Bassam M. Al Meslmani, Gihan Mahmoud, Frank Sommer, Michael Lohoff, Thomas Leichtweiß, Boris Strehlow, Udo BakowskyAbstract:Graft-associated infections entirely determine the short-term patency of polyethylene terephthalate PET Cardiovascular Graft. We attempted to enzymatically inhibit the initial bacterial adhesion to PET Grafts using lysozyme. Lysozyme was covalently immobilized onto woven and knitted forms of crimped PET Grafts by the end-point method. Our figures of merit revealed lysozyme immobilization yield of 15.7 μg/cm(2), as determined by the Bradford assay. The activity of immobilized lysozyme on woven and knitted PET manifested 58.4% and 55.87% using Micrococcus lysodeikticus cells, respectively. Noteworthy, the adhesion of vein catheter-isolated Staphylococcus epidermidis decreased by 6- to 8-folds and of Staphylococcus aureus by 11- to 12-folds, while the Gram-negative Escherichia coli showed only a decrease by 3- to 4-folds. The anti-adhesion efficiency was specific for bacterial cells and no significant effect was observed on adhesion and growth of L929 cells. In conclusion, immobilization of lysozyme onto PET Grafts can inhibit the Graft-associated infection.
-
Multifunctional network-structured film coating for woven and knitted polyethylene terephthalate against Cardiovascular Graft-associated infections.
International journal of pharmaceutics, 2015Co-Authors: Bassam M. Al Meslmani, Gihan Mahmoud, Frank Sommer, Michael Lohoff, Udo BakowskyAbstract:Multifunctional network-structured polymeric coat for woven and knitted forms of crimped polyethylene terephthalate PET Graft was developed to limit Graft-associated infections. A newly synthesized antibacterial sulfadimethoxine polyhexylene adipate-b-methoxy polyethylene oxide (SD-PHA-b-MPEO) di-block copolymer was employed. Our figures of merit revealed that the formed coat showed a porous topographic architecture which manifested paramount properties, mostly bacterial anti-adhesion efficiency and biocompatibility with host cells. Compared to untreated Grafts, the coat presented marked reduction of adhered Gram-positive Staphylococcus epidermidis previously isolated from a patient's vein catheter by 2.6 and 2.3 folds for woven and knitted Grafts, respectively. Similarly, bacterial anti-adhesion effect was observed for Staphylococcus aureus by 2.3 and 2.4 folds, and by 2.9 and 2.7 folds for Gram-negative Escherichia coli for woven and knitted Grafts, respectively. Additionally, adhesion and growth characteristics of L929 cells on the modified Grafts revealed no significant effect on the biocompatibility. In conclusion, coating of PET with (SD-PHA-b-MPEO) is a versatile approach offers the desired bacterial anti-adhesion effect and host biocompatibility.