The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

James W Mcginity - One of the best experts on this subject based on the ideXlab platform.

  • bioadhesive properties of hydroxypropylcellulose topical films produced by hot melt extrusion
    Journal of Controlled Release, 2001
    Co-Authors: Michael A Repka, James W Mcginity
    Abstract:

    The objective of this study was to investigate the in vivo bioadhesive properties of hydroxypropylcellulose (HPC) films containing seven polymer additives on the epidermis of 12 human subjects, including two ethnic sub-groups. HPC films containing polyethylene glycol (PEG 3350) alone, Vitamin E TPGS (TPGS) 5%, sodium starch glycolate 5%, Eudragit E-100 5%, carbomer 974P and 971P 5%, and Polycarbophil 5%, all with and without plasticizer, were prepared by hot-melt extrusion utilizing a Randcastle Microtruder (Model #RCP-0750). Bioadhesion testing was performed using a Chatillon digital force gauge DFGS50 attached to a Chatillon TCD-200 motorized test stand to determine force of adhesion (FA), elongation at adhesive failure (EAF), and modulus of adhesion (MA) for the 12 films tested. In vivo, the TPGS-incorporated film exhibited a two-fold increase in FA when compared to the control film containing the PEG 3350 5%. The carbomer 971P and Polycarbophil containing films were determined to have the highest FA and EAF, and the lowest MA of all films tested. The film containing carbomer 971P had a higher FA than the film containing 974P. In addition, films in one ethnic sub-group exhibited higher FA and EAF than the other. Force--deflection profiles obtained from these experiments indicate that the force of adhesion, elongation at adhesive failure and modulus of adhesion are a function of the polymer additive in the HPC extruded films. The incorporation of carbomer 971P and a Polycarbophil into HPC films increased bioadhesion significantly when compared to the film containing HPC and PEG 3350. Differences in FA and EAF were discovered between two ethnic sub-groups tested.

  • bioadhesive properties of hydroxypropylcellulose topical films produced by hot melt extrusion
    Journal of Controlled Release, 2001
    Co-Authors: Michael A Repka, James W Mcginity
    Abstract:

    Abstract The objective of this study was to investigate the in vivo bioadhesive properties of hydroxypropylcellulose (HPC) films containing seven polymer additives on the epidermis of 12 human subjects, including two ethnic sub-groups. HPC films containing polyethylene glycol (PEG 3350) alone, Vitamin E TPGS (TPGS) 5%, sodium starch glycolate 5%, Eudragit E-100 5%, carbomer 974P and 971P 5%, and Polycarbophil 5%, all with and without plasticizer, were prepared by hot-melt extrusion utilizing a Randcastle Microtruder ® (Model #RCP-0750). Bioadhesion testing was performed using a Chatillon digital force gauge DFGS50 attached to a Chatillon TCD-200 motorized test stand to determine force of adhesion (FA), elongation at adhesive failure (EAF), and modulus of adhesion (MA) for the 12 films tested. In vivo, the TPGS-incorporated film exhibited a two-fold increase in FA when compared to the control film containing the PEG 3350 5%. The carbomer 971P and Polycarbophil containing films were determined to have the highest FA and EAF, and the lowest MA of all films tested. The film containing carbomer 971P had a higher FA than the film containing 974P. In addition, films in one ethnic sub-group exhibited higher FA and EAF than the other. Force–deflection profiles obtained from these experiments indicate that the force of adhesion, elongation at adhesive failure and modulus of adhesion are a function of the polymer additive in the HPC extruded films. The incorporation of carbomer 971P and a Polycarbophil into HPC films increased bioadhesion significantly when compared to the film containing HPC and PEG 3350. Differences in FA and EAF were discovered between two ethnic sub-groups tested.

  • physical mechanical moisture absorption and bioadhesive properties of hydroxypropylcellulose hot melt extruded films
    Biomaterials, 2000
    Co-Authors: Michael A Repka, James W Mcginity
    Abstract:

    Abstract The objective of this study was to investigate the moisture absorption, physical–mechanical and bioadhesive properties of hot-melt extruded hydroxypropylcellulose (HPC) films containing polymer additives. These additives included polyethylene glycol (PEG) 5%, Polycarbophil 5%, carbomer 5%, Eudragit E-100 5%, and sodium starch glycolate (SSG) 5%. Relative humidity (RH) and temperature parameters of the films studied included 25°C at 0, 50, 80 and 100% RH, and 40°C at 0 and 100% RH, stored for 2 weeks. Tensile strength and percent elongation were determined on an Instron according to the ASTM standards. The bioadhesive properties of the HPC/PEG 3350 5% film and the Polycarbophil 5% containing films, with and without PEG, were investigated in vivo on the human epidermis. Although all films studied exhibited an increase in percent water content as the percent RH increased, the SSG containing film exhibited an almost three-fold increase in percent water content compared to that of the HPC/PEG film. The temperature storage condition of 40°C/100% RH (versus 25°C/100% RH) increased the percent water content of the SSG containing film. Percent elongation was highest for films containing Polycarbophil 5% (without PEG). In addition, the HPC film containing Polycarbophil 5% exhibited a greater force of adhesion and elongation at adhesive failure in vivo, and a lower modulus of adhesion when compared to the HPC/PEG film. A novel approach to determine bioadhesion of films to the human epidermis is presented.

  • physical mechanical moisture absorption and bioadhesive properties of hydroxypropylcellulose hot melt extruded films
    Biomaterials, 2000
    Co-Authors: Michael A Repka, James W Mcginity
    Abstract:

    The objective of this study was to investigate the moisture absorption, physical-mechanical and bioadhesive properties of hot-melt extruded hydroxypropylcellulose (HPC) films containing polymer additives. These additives included polyethylene glycol (PEG) 5%, Polycarbophil 5%, carbomer 5%, Eudragit E-100 5%, and sodium starch glycolate (SSG) 5%. Relative humidity (RH) and temperature parameters of the films studied included 25 degree C at 0, 50, 80 and 100% RH, and 40 degrees C at 0 and 100% RH, stored for 2 weeks. Tensile strength and percent elongation were determined on an Instron according to the ASTM standards. The bioadhesive properties of the HPC/PEG 3350 5% film and the Polycarbophil 5% containing films, with and without PEG, were investigated in vivo on the human epidermis. Although all films studied exhibited an increase in percent water content as the percent RH increased, the SSG containing film exhibited an almost three-fold increase in percent water content compared to that of the HPC/PEG film. The temperature storage condition of 40 degrees C/100% RH (versus 25 degrees C/100% RH) increased the percent water content of the SSG containing film. Percent elongation was highest for films containing Polycarbophil 5% (without PEG). In addition, the HPC film containing Polycarbophil 5% exhibited a greater force of adhesion and elongation at adhesive failure in vivo, and a lower modulus of adhesion when compared to the HPC/PEG film. A novel approach to determine bioadhesion of films to the human epidermis is presented.

Michael A Repka - One of the best experts on this subject based on the ideXlab platform.

  • production and characterization of hot melt extruded films containing clotrimazole
    Drug Development and Industrial Pharmacy, 2003
    Co-Authors: Michael A Repka, Suneela Prodduturi, Steven P Stodghill
    Abstract:

    AbstractHot-melt extrusion technology (HME) was used to prepare muco-adhesive matrix films containing 10% w/w clotrimazole (CT) intended for local drug delivery applications for the oral cavity. This study was aimed at the production and characterization of these drug delivery systems for the prophylaxis and treatment of oral candidiasis. The film system's formulation contained hydroxypropyl cellulose and poly(ethylene oxide) as polymeric carriers, the bioadhesive Polycarbophil, and other excipients. The CT formulation was processed at a temperature range of 125–130°C utilizing a Killion extruder (Model KLB-100) equipped with a 6-inch flex-lip die. The films were evaluated for postextrusion drug content, physical and chemical content uniformity, drug release, thermal and crystalline behavior, and bioadhesive strength. The extruded films demonstrated excellent content uniformity and a postprocessing drug content of 93.3% (± 1.0). The degradation product, (o-chlorophenyl)diphenyl methanol, was also identifi...

  • bioadhesive properties of hydroxypropylcellulose topical films produced by hot melt extrusion
    Journal of Controlled Release, 2001
    Co-Authors: Michael A Repka, James W Mcginity
    Abstract:

    The objective of this study was to investigate the in vivo bioadhesive properties of hydroxypropylcellulose (HPC) films containing seven polymer additives on the epidermis of 12 human subjects, including two ethnic sub-groups. HPC films containing polyethylene glycol (PEG 3350) alone, Vitamin E TPGS (TPGS) 5%, sodium starch glycolate 5%, Eudragit E-100 5%, carbomer 974P and 971P 5%, and Polycarbophil 5%, all with and without plasticizer, were prepared by hot-melt extrusion utilizing a Randcastle Microtruder (Model #RCP-0750). Bioadhesion testing was performed using a Chatillon digital force gauge DFGS50 attached to a Chatillon TCD-200 motorized test stand to determine force of adhesion (FA), elongation at adhesive failure (EAF), and modulus of adhesion (MA) for the 12 films tested. In vivo, the TPGS-incorporated film exhibited a two-fold increase in FA when compared to the control film containing the PEG 3350 5%. The carbomer 971P and Polycarbophil containing films were determined to have the highest FA and EAF, and the lowest MA of all films tested. The film containing carbomer 971P had a higher FA than the film containing 974P. In addition, films in one ethnic sub-group exhibited higher FA and EAF than the other. Force--deflection profiles obtained from these experiments indicate that the force of adhesion, elongation at adhesive failure and modulus of adhesion are a function of the polymer additive in the HPC extruded films. The incorporation of carbomer 971P and a Polycarbophil into HPC films increased bioadhesion significantly when compared to the film containing HPC and PEG 3350. Differences in FA and EAF were discovered between two ethnic sub-groups tested.

  • bioadhesive properties of hydroxypropylcellulose topical films produced by hot melt extrusion
    Journal of Controlled Release, 2001
    Co-Authors: Michael A Repka, James W Mcginity
    Abstract:

    Abstract The objective of this study was to investigate the in vivo bioadhesive properties of hydroxypropylcellulose (HPC) films containing seven polymer additives on the epidermis of 12 human subjects, including two ethnic sub-groups. HPC films containing polyethylene glycol (PEG 3350) alone, Vitamin E TPGS (TPGS) 5%, sodium starch glycolate 5%, Eudragit E-100 5%, carbomer 974P and 971P 5%, and Polycarbophil 5%, all with and without plasticizer, were prepared by hot-melt extrusion utilizing a Randcastle Microtruder ® (Model #RCP-0750). Bioadhesion testing was performed using a Chatillon digital force gauge DFGS50 attached to a Chatillon TCD-200 motorized test stand to determine force of adhesion (FA), elongation at adhesive failure (EAF), and modulus of adhesion (MA) for the 12 films tested. In vivo, the TPGS-incorporated film exhibited a two-fold increase in FA when compared to the control film containing the PEG 3350 5%. The carbomer 971P and Polycarbophil containing films were determined to have the highest FA and EAF, and the lowest MA of all films tested. The film containing carbomer 971P had a higher FA than the film containing 974P. In addition, films in one ethnic sub-group exhibited higher FA and EAF than the other. Force–deflection profiles obtained from these experiments indicate that the force of adhesion, elongation at adhesive failure and modulus of adhesion are a function of the polymer additive in the HPC extruded films. The incorporation of carbomer 971P and a Polycarbophil into HPC films increased bioadhesion significantly when compared to the film containing HPC and PEG 3350. Differences in FA and EAF were discovered between two ethnic sub-groups tested.

  • physical mechanical moisture absorption and bioadhesive properties of hydroxypropylcellulose hot melt extruded films
    Biomaterials, 2000
    Co-Authors: Michael A Repka, James W Mcginity
    Abstract:

    Abstract The objective of this study was to investigate the moisture absorption, physical–mechanical and bioadhesive properties of hot-melt extruded hydroxypropylcellulose (HPC) films containing polymer additives. These additives included polyethylene glycol (PEG) 5%, Polycarbophil 5%, carbomer 5%, Eudragit E-100 5%, and sodium starch glycolate (SSG) 5%. Relative humidity (RH) and temperature parameters of the films studied included 25°C at 0, 50, 80 and 100% RH, and 40°C at 0 and 100% RH, stored for 2 weeks. Tensile strength and percent elongation were determined on an Instron according to the ASTM standards. The bioadhesive properties of the HPC/PEG 3350 5% film and the Polycarbophil 5% containing films, with and without PEG, were investigated in vivo on the human epidermis. Although all films studied exhibited an increase in percent water content as the percent RH increased, the SSG containing film exhibited an almost three-fold increase in percent water content compared to that of the HPC/PEG film. The temperature storage condition of 40°C/100% RH (versus 25°C/100% RH) increased the percent water content of the SSG containing film. Percent elongation was highest for films containing Polycarbophil 5% (without PEG). In addition, the HPC film containing Polycarbophil 5% exhibited a greater force of adhesion and elongation at adhesive failure in vivo, and a lower modulus of adhesion when compared to the HPC/PEG film. A novel approach to determine bioadhesion of films to the human epidermis is presented.

  • physical mechanical moisture absorption and bioadhesive properties of hydroxypropylcellulose hot melt extruded films
    Biomaterials, 2000
    Co-Authors: Michael A Repka, James W Mcginity
    Abstract:

    The objective of this study was to investigate the moisture absorption, physical-mechanical and bioadhesive properties of hot-melt extruded hydroxypropylcellulose (HPC) films containing polymer additives. These additives included polyethylene glycol (PEG) 5%, Polycarbophil 5%, carbomer 5%, Eudragit E-100 5%, and sodium starch glycolate (SSG) 5%. Relative humidity (RH) and temperature parameters of the films studied included 25 degree C at 0, 50, 80 and 100% RH, and 40 degrees C at 0 and 100% RH, stored for 2 weeks. Tensile strength and percent elongation were determined on an Instron according to the ASTM standards. The bioadhesive properties of the HPC/PEG 3350 5% film and the Polycarbophil 5% containing films, with and without PEG, were investigated in vivo on the human epidermis. Although all films studied exhibited an increase in percent water content as the percent RH increased, the SSG containing film exhibited an almost three-fold increase in percent water content compared to that of the HPC/PEG film. The temperature storage condition of 40 degrees C/100% RH (versus 25 degrees C/100% RH) increased the percent water content of the SSG containing film. Percent elongation was highest for films containing Polycarbophil 5% (without PEG). In addition, the HPC film containing Polycarbophil 5% exhibited a greater force of adhesion and elongation at adhesive failure in vivo, and a lower modulus of adhesion when compared to the HPC/PEG film. A novel approach to determine bioadhesion of films to the human epidermis is presented.

Hans E. Junginger - One of the best experts on this subject based on the ideXlab platform.

  • Mucoadhesive polymers in peroral peptide drug delivery. IV. Polycarbophil and chitosan are potent enhancers of peptide transport across intestinal mucosae in vitro
    Journal of Controlled Release, 1997
    Co-Authors: H.l. Lueßen, A G De Boer, Claus-michael Lehr, J.c. Verhoef, A F Kotze, C.-o. Rentel, Hans E. Junginger
    Abstract:

    Abstract The purpose of the study was to evaluate the inhibitory effect of the mucoadhesive polymers Polycarbophil, chitosan and chitosan glutamate on trypsin and carboxypeptidase B (CPB) activity as well as their potential to improve the intestinal transport of the peptide drug 9-desglycinamide, 8- l -arginine vasopressin (DGAVP) in vitro. The degradation of the model substrates N-α-benzoyl- l -arginine ethylester by trypsin and hippuryl- l -arginine by CPB in the presence of the polymers was studied. Furthermore, the effect of the polymers on intestinal DGAVP transport was investigated using Caco-2 cell monolayers and the rat vertically perfused intestinal loop model. Uniquely, Polycarbophil in a concentration of 1% (w/v) was able to inhibit both trypsin and CPB activities. Chitosan glutamate in concentrations of 0.4 and 1% (w/v) strongly increased the transport of DGAVP across Caco-2 cell monolayers, whereas 1% (w/v) Polycarbophil showed only low transport enhancement. All polymers in concentrations of 1% (w/v), however, showed a pronounced and comparable improvement of DGAVP transport across intestinal mucosae in the vertically perfused loop model. It is concluded that the chitosans enhance the transport of DGAVP solely by increasing the paracellular permeability due to opening of intercellular junctions. The observed comparable transport effect of Polycarbophil in the intestinal loop model is mainly ascribed to protection of DGAVP against proteolytic degradation in the intestinal lumen, which allows for sufficient concentration and thus transport of the peptide drug when Polycarbophil induced paracellular transport is less enhanced.

  • Mucoadhesive polymers in peroral peptide drug delivery. V. Effect of poly(acrylates) on the enzymatic degradation of peptide drugs by intestinal brush border membrane vesicles
    International Journal of Pharmaceutics, 1996
    Co-Authors: Henrik L. Lueβen, A G De Boer, J.c. Verhoef, V. Bohner, D. Pérard, Peter Langguth, Hans P. Merkle, Hans E. Junginger
    Abstract:

    The purpose of the study was to evaluate the inhibitory effect of the mucoadhesive poly(acrylates) Polycarbophil and carbomer on the activity of proteolytic enzymes bound to the intestinal brush border. To that end, the degradation of a number of peptide drugs in the presence or absence of the poly(acrylates) was investigated, using rat brush border membrane vesicles (BBMV) as the protease preparation. Both carbomer and Polycarbophil in concentrations of 0.25 and 0.5% (w/v) reduced rather weakly the enzymatic degradation of the peptide 9-desglycinamide, 8-arginine vasopressin (DGAVP), and only 0.5% (w/v) carbomer inhibited metkephamid degradation, but not Polycarbophil. More pronounced inhibitory effects on DGAVP breakdown were found following a 30 min preincubation of the BBMV suspension with 0.5% (w/v) carbomer. However, the poly(acrylic acid) derivatives were unable to inhibit the degradation of buserelin at all. On the other hand, the polypeptide hormone insulin was remarkably stable in the BBMV preparations. In conclusion, the poly(acrylic acid) derivatives Polycarbophil and carbomer show rather weak inhibitory effects on enzymes of the intestinal brush border cell membranes responsible for DGAVP and metkephamid degradation.

  • mucoadhesive polymers in peroral peptide drug delivery ii carbomer and Polycarbophil are potent inhibitors of the intestinal proteolytic enzyme trypsin
    Pharmaceutical Research, 1995
    Co-Authors: H L Luesen, Gerrit Borchard, Coos J Verhoef, A G De Boer, Claus-michael Lehr, Hans E. Junginger
    Abstract:

    Purpose. The evaluation of the inhibitory action of two mucoadhesive poly(acrylates), Polycarbophil and carbomer, registered by the Food and Drug Administration (FDA), on the intestinal proteolytic enzyme trypsin.

  • bioadhesive polymers for the peroral delivery of peptide drugs
    Journal of Controlled Release, 1994
    Co-Authors: H L Luesen, A G De Boer, Claus-michael Lehr, J.c. Verhoef, C.-o. Rentel, A B J Noach, Hans E. Junginger
    Abstract:

    Abstract Two different classes of bioadhesive excipients which have been approved by the FDA, the anionic charged poly (acrylic acid) derivatives and the cationic charged chitosans, have been investigated with respect to their ability to improve intestinal peptide drug absorption. It was found that both Polycarbophil and the chitosan derivatives Daichitosan ® VH and chitosan-glutamate (SeaCure ® + 210) enhance the absorption of the peptide drug 9-desglycinamide, 8-arginine vasopressin (DGAVP) in the vertically perfused intestinal loop model of the rat. Recent studies demonstrated that the two poly (acrylates) Polycarbophil and Carbopol ® 934P are able to inhibit the activity of the proteolytic enzyme trypsin at pH 6.7, which may lead to an increased stability of the peptide drug in the intestine. The depletion of Ca 2+ out of the incubation medium due to the Ca 2+ binding properties of the poly (acrylates) is discussed as a possible mechanism of action. Because of the observation that depletion of Ca 2+ can additionally cause an opening of tight junctions, the influence of Polycarbophil on the paracellular integrity of Caco-2 monolayers was also investigated by measurements of transepithelial electrical resistance (TEER) as well as by visualization studies using confocal laser scanning microscopy. At pH 4.0, apically applied Polycarbophil tended to decrease TEER values stronger than the control solution, whereas at pH 7.0 no pronounced changes of TEER could be observed. At pH 7.4, Polycarbophil was only able to increase the paracellular permeability of the hydrophilic model compound fluorescein-isothiocyanate-dextran ( M w 4000) when applied to the basolateral side of the Caco2 cell monolayer. In conclusion, bioadhesive polymers are promising absorption promoting agents for peroral delivery of peptide drugs, and their mechanism of action is probably a combination of inhibiting protease activities and modulating the intestinal epithelial permeability.

  • effects of the mucoadhesive polymer Polycarbophil on the intestinal absorption of a peptide drug in the rat
    Journal of Pharmacy and Pharmacology, 1992
    Co-Authors: Claus-michael Lehr, Douwe D. Breimer, Josef J. Tukker, Albertus G De Boer, Coos J Verhoef, Johanna A. Bouwstra, Hans E. Junginger
    Abstract:

    — The absorption across rat intestinal tissue of the model peptide drug 9-desglycinamide, 8-arginine vasopressin from bioadhesive formulations was studied in-vitro, in a chronically isolated internal loop in-situ and after intraduodenal administration in-vivo. A controlled-release bioadhesive drug delivery system was tested, consisting of microspheres of poly(2-hydroxyethyl methacrylate) with a mucoadhesive Polycarbophil-coating, as well as a fast-release formulation consisting of an aqueous solution of the peptide in a suspension of Polycarbophil particles. Using the controlled-release system, a slight improvement of peptide absorption was found in-vitro in comparison with a non-adhesive control system, but not in-situ or in-vivo. In contrast, bioavailability was significantly increased in all three models from the Polycarbophil suspension in comparison with a solution of the drug in saline. The effect appeared to be dose-dependent, indicative of intrinsic penetration-enhancing properties of the mucoadhesive polymer. A prolongation of the absorption phase in-vitro and in the chronically isolated loop in-situ suggested that the polymer was able to protect the peptide from proteolytic degradation. This could be confirmed by degradation studies in-vitro. The duration of the penetration enhancing/enzyme inhibiting effect was diminished with increasing complexity of the test model, in the same way as was previously found for the bioadhesive effect. This interrelationship suggests that the observed improvement in peptide absorption and the mucoadhesive properties of this polymer are associated. The development of a fast-release oral dosage form for peptide drugs on the basis of Polycarbophil appears to be possible.

Nicholas A. Peppas - One of the best experts on this subject based on the ideXlab platform.

  • complexation graft copolymer networks swelling properties calcium binding and proteolytic enzyme inhibition
    Biomaterials, 1999
    Co-Authors: Flemming Madsen, Nicholas A. Peppas
    Abstract:

    Graft copolymer networks of poly(methacrylic acid-g-ethylene glycol) were prepared by free radical solution UV-polymerization of methacrylic acid (MAA) and poly(ethylene glycol) monomethacrylate. Dynamic swelling studies indicated that complexation/decomplexation processes occurred due to hydrogen bonding between the carboxylic groups of the poly(methacrylic acid) (PMAA) and the ether groups of poly(ethylene glycol) (PEG). The effects of copolymer composition, graft chain molecular weight, environmental pH and ion content on network structure and gel behavior were studied. The largest change in swelling ratio and mesh size of the gel structure was observed in gels containing the highest content of PEG and the longest molecular weight PEG grafts. Complexation was greatest in hydrogels containing the longest PEG grafts and equimolar amounts of MAA and PEG. The swelling was much less pronounced in the presence of calcium chloride compared to sodium chloride which could be attributed to the complexation of calcium of the carboxylic groups in the polymer. The copolymers showed significant but less binding of calcium compared to poly(acrylates) like Carbopol 934P and Polycarbophil. The P(MAA-g-EG) copolymers inhibited trypsin but to a lesser extent than the known protease inhibitors Carbopol 934P and Polycarbophil. Results suggest that P(MAA-g-EG) copolymers are good drug delivery carrier candidates due to their pH-sensitive and controllable swelling behavior. Additionally, they possess some protease inhibition effect along with their bioadhesive properties which make them promising carriers for peptides or proteins.

  • complexation graft copolymer networks swelling properties calcium binding and proteolytic enzyme inhibition
    Biomaterials, 1999
    Co-Authors: Flemming Madsen, Nicholas A. Peppas
    Abstract:

    Graft copolymer networks of poly(methacrylic acid-g-ethylene glycol) were prepared by free radical solution UV-polymerization of methacrylic acid (MAA) and poly(ethylene glycol) monomethacrylate. Dynamic swelling studies indicated that complexation/decomplexation processes occurred due to hydrogen bonding between the carboxylic groups of the poly(methacrylic acid) (PMAA) and the ether groups of poly(ethylene glycol) (PEG). The effects of copolymer composition, graft chain molecular weight, environmental pH and ion content on network structure and gel behavior were studied. The largest change in swelling ratio and mesh size of the gel structure was observed in gels containing the highest content of PEG and the longest molecular weight PEG grafts. Complexation was greatest in hydrogels containing the longest PEG grafts and equimolar amounts of MAA and PEG. The swelling was much less pronounced in the presence of calcium chloride compared to sodium chloride which could be attributed to the complexation of calcium of the carboxylic groups in the polymer. The copolymers showed significant but less binding of calcium compared to poly(acrylates) like Carbopol 934P and Polycarbophil. The P(MAA-g-EG) copolymers inhibited trypsin but to a lesser extent than the known protease inhibitors Carbopol 934P and Polycarbophil. Results suggest that P(MAA-g-EG) copolymers are good drug delivery carrier candidates due to their pH-sensitive and controllable swelling behavior. Additionally, they possess some protease inhibition effect along with their bioadhesive properties which make them promising carriers for peptides or proteins.

Flemming Madsen - One of the best experts on this subject based on the ideXlab platform.

  • complexation graft copolymer networks swelling properties calcium binding and proteolytic enzyme inhibition
    Biomaterials, 1999
    Co-Authors: Flemming Madsen, Nicholas A. Peppas
    Abstract:

    Graft copolymer networks of poly(methacrylic acid-g-ethylene glycol) were prepared by free radical solution UV-polymerization of methacrylic acid (MAA) and poly(ethylene glycol) monomethacrylate. Dynamic swelling studies indicated that complexation/decomplexation processes occurred due to hydrogen bonding between the carboxylic groups of the poly(methacrylic acid) (PMAA) and the ether groups of poly(ethylene glycol) (PEG). The effects of copolymer composition, graft chain molecular weight, environmental pH and ion content on network structure and gel behavior were studied. The largest change in swelling ratio and mesh size of the gel structure was observed in gels containing the highest content of PEG and the longest molecular weight PEG grafts. Complexation was greatest in hydrogels containing the longest PEG grafts and equimolar amounts of MAA and PEG. The swelling was much less pronounced in the presence of calcium chloride compared to sodium chloride which could be attributed to the complexation of calcium of the carboxylic groups in the polymer. The copolymers showed significant but less binding of calcium compared to poly(acrylates) like Carbopol 934P and Polycarbophil. The P(MAA-g-EG) copolymers inhibited trypsin but to a lesser extent than the known protease inhibitors Carbopol 934P and Polycarbophil. Results suggest that P(MAA-g-EG) copolymers are good drug delivery carrier candidates due to their pH-sensitive and controllable swelling behavior. Additionally, they possess some protease inhibition effect along with their bioadhesive properties which make them promising carriers for peptides or proteins.

  • complexation graft copolymer networks swelling properties calcium binding and proteolytic enzyme inhibition
    Biomaterials, 1999
    Co-Authors: Flemming Madsen, Nicholas A. Peppas
    Abstract:

    Graft copolymer networks of poly(methacrylic acid-g-ethylene glycol) were prepared by free radical solution UV-polymerization of methacrylic acid (MAA) and poly(ethylene glycol) monomethacrylate. Dynamic swelling studies indicated that complexation/decomplexation processes occurred due to hydrogen bonding between the carboxylic groups of the poly(methacrylic acid) (PMAA) and the ether groups of poly(ethylene glycol) (PEG). The effects of copolymer composition, graft chain molecular weight, environmental pH and ion content on network structure and gel behavior were studied. The largest change in swelling ratio and mesh size of the gel structure was observed in gels containing the highest content of PEG and the longest molecular weight PEG grafts. Complexation was greatest in hydrogels containing the longest PEG grafts and equimolar amounts of MAA and PEG. The swelling was much less pronounced in the presence of calcium chloride compared to sodium chloride which could be attributed to the complexation of calcium of the carboxylic groups in the polymer. The copolymers showed significant but less binding of calcium compared to poly(acrylates) like Carbopol 934P and Polycarbophil. The P(MAA-g-EG) copolymers inhibited trypsin but to a lesser extent than the known protease inhibitors Carbopol 934P and Polycarbophil. Results suggest that P(MAA-g-EG) copolymers are good drug delivery carrier candidates due to their pH-sensitive and controllable swelling behavior. Additionally, they possess some protease inhibition effect along with their bioadhesive properties which make them promising carriers for peptides or proteins.

  • Complexation graft copolymer networks: swelling properties, calcium binding and proteolytic enzyme inhibition, Biomaterials 20
    1999
    Co-Authors: Flemming Madsen
    Abstract:

    Graft copolymer networks of poly(methacrylic acid-g-ethylene glycol) were prepared by free radical solution UV-polymerization of methacrylic acid (MAA) and poly(ethylene glycol) monomethacrylate. Dynamic swelling studies indicated that complexation/decomplexation processes occurred due to hydrogen bonding between the carboxylic groups of the poly(methacrylic acid) (PMAA) and the ether groups of poly(ethylene glycol) (PEG). The e!ects of copolymer composition, graft chain molecular weight, environmental pH and ion content on network structure and gel behavior were studied. The largest change in swelling ratio and mesh size of the gel structure was observed in gels containing the highest content of PEG and the longest molecular weight PEG grafts. Complexation was greatest in hydrogels containing the longest PEG grafts and equimolar amounts of MAA and PEG. The swelling was much less pronounced in the presence of calcium chloride compared to sodium chloride which could be attributed to the complexation of calcium of the carboxylic groups in the polymer. The copolymers showed signi"cant but less binding of calcium compared to poly(acrylates) like Carbopol 934P and Polycarbophil. The P(MAA-g-EG) copolymers inhibited trypsin but to a lesser extent than the known protease inhibitors Carbopol 934P and Polycarbophil. Results suggest that P(MAA-g-EG) copolymers are good drug delivery carrier candidates due to their pH-sensitive and controllable swelling behavior. Additionally, they possess some protease inhibition e!ect along with their bioadhesive properties which make them promising carriers for peptides or proteins