The Experts below are selected from a list of 3063 Experts worldwide ranked by ideXlab platform
Maria Nowakowska - One of the best experts on this subject based on the ideXlab platform.
-
alginate Hydroxypropylcellulose hydrogel microbeads for alkaline phosphatase encapsulation
Journal of Microencapsulation, 2014Co-Authors: Anna Karewicz, Dorota Bielska, Katarzyna Zasada, Timothy Douglas, John A Jansen, Sander C G Leeuwenburgh, Maria NowakowskaAbstract:There is a growing interest in using proteins as therapeutics agents. Unfortunately, they suffer from limited stability and bioavailability. We aimed to develop a new delivery system for proteins. ALP, a model protein, was successfully encapsulated in the physically cross-linked sodium alginate/Hydroxypropylcellulose (ALG-HPC) hydrogel microparticles. The obtained objects had regular, spherical shape and a diameter of similar to 4 mu m, as confirmed by optical microscopy and SEM analysis. The properties of the obtained microbeads could be controlled by temperature and additional coating or crosslinking procedures. The slow, sustained release of ALP in its active form with no initial burst effect was observed for chitosan-coated microspheres at pH = 7.4 and 37 degrees C. Activity of ALP released from ALG/HPC microspheres was confirmed by the occurance of effectively induced mineralization. SEM and AFM images revealed formation of the interpenetrated three-dimensional network of mineral, originating from the microbeads' surfaces. FTIR and XRD analyses confirmed formation of hydroxyapatite.
-
Hydroxypropylcellulose-graft-poly(N-isopropylacrylamide)—novel water-soluble copolymer with double thermoresponsivity
Polimery, 2013Co-Authors: Magdalena Motyl, Dominik Drozd, Kamil Kamiński, Dorota Bielska, Anna Karewicz, Krzysztof Szczubiałka, Maria NowakowskaAbstract:Summary — A copolymer showing two cloud points was obtained by grafting poly(N-isopropylacrylamide) (PNIPAM) onto Hydroxypropylcellulose (HPC). The structure of the polymer was verified using 1 H NMR, FT-IR, GPC, and elemental analysis. The values of cloud points could be changed by increasing ionic strength and as a result of the interactions with surfactants.
-
Hydrogel membranes based on genipin-cross-linked chitosan blends for corneal epithelium tissue engineering
Journal of Materials Science: Materials in Medicine, 2012Co-Authors: Maria Grolik, Krzysztof Szczubiałka, Bogumił Wowra, Dariusz Dobrowolski, Bogusława Orzechowska-wylęgała, Edward Wylęgała, Maria NowakowskaAbstract:Novel polymeric hydrogel scaffolds for corneal epithelium cell culturing based on blends of chitosan with some other biopolymers such as Hydroxypropylcellulose, collagen and elastin crosslinked with genipin, a natural substance, were prepared. Physicochemical and biomechanical properties of these materials were determined. The in vitro cell culture experiments with corneal epithelium cells have indicated that a membrane prepared from chitosan–collagen blend (Ch–Col) provided the regular stratified growth of the epithelium cells, good surface covering and increased number of the cell layers. Ch–Col membranes are therefore the most promising material among those studied. The performance of Ch–Col membranes is comparable with that of the amniotic membrane which is currently recommended for clinical applications.
-
zwitterionically modified Hydroxypropylcellulose for biomedical applications
European Polymer Journal, 2010Co-Authors: Kamila Gawel, Krzysztof Szczubialka, Szczepan Zapotoczny, Maria NowakowskaAbstract:Novel polyelectrolytes have been synthesized by grafting sulfobetaine side chains onto Hydroxypropylcellulose backbone. Polymers with various degrees of grafting have been obtained. The polymers do not interact with model anionic, cationic and zwitterionic surfactants as found in fluorescence studies using pyrene as a molecular probe. Dynamic light scattering (DLS) studies indicated that in the graft polymer solution two types of polymers are present. The films were formed from the grafted polymers. Using atomic force microscopy (AFM) technique it was found that they are resistant to the adhesion of proteins and can be used for the preparation of antiadhesive surfaces which may find biomedical applications.
-
smart alginate Hydroxypropylcellulose microbeads for controlled release of heparin
International Journal of Pharmaceutics, 2010Co-Authors: Anna Karewicz, Krzysztof Szczubialka, Szczepan Zapotoczny, Katarzyna Zasada, Radoslaw Lach, Maria NowakowskaAbstract:Abstract “Smart” (thermosensitive) alginate–Hydroxypropylcellulose (Alg/HPC) microbeads for controlled release of heparin were synthesized and the release profiles at various temperatures and for various alginate/HPC compositions were measured. Microbeads of regular spherical shape (ca. 3 μm in diameter) containing efficiently encapsulated heparin were obtained using an emulsification method. The internal structure of the bead was estimated by fluorescence microscopy using dansyl alginate as a labelled component. The microbeads surface structure and morphology were imaged in a dry state using scanning electron microscopy (SEM) and in water using atomic force microscopy (AFM). The microbead surface was shown to be covered by the regular network of pores with a mesh of ca. 30–60 nm. Lower critical solution temperature (LCST) of the Alg/HPC systems was measured spectrophotometrically (cloud point measurements). Heparin release profiles were obtained based on spectrophotometric detection of heparin complex with Azure A. Three-stage sustained release for at least 16 days was observed at 37 °C. This was correlated with the size of the pores present at the surface of microbeads. The release profile can be controlled by the temperature and composition of the Alg/HPC microbeads.
Hui Li - One of the best experts on this subject based on the ideXlab platform.
-
Swelling Characterization of Double Sensitive Hydroxypropylcellulose / Sodium Alginate Hydrogel
Advanced Materials Research, 2011Co-Authors: Guo-li Gong, Hui LiAbstract:A series of temperature and pH responsive hydrogels was synthesized by using Hydroxypropylcellulose (HPC) as temperature sensitivity material and the natural material, sodium alginate (SA) as pH sensitivity material. The effect of SA to LCST has been studied and the mechanism of the influence has been presented. In addition, the swelling ratio and controlling factor of swelling process were all researched in this paper. The main results obtained are as follows: the LCST decreased gradually as added SA into HPC; the HPC/SA hydrogel responded both temperature and pH value of the medium; the swelling ratio reached maximum value as pH value of 6.
-
Synthesis and characterization of temperature/pH-sensitive Hydroxypropylcellulose/ sodium alginate hydrogel
E-polymers, 2010Co-Authors: Hui Li, Guo-li GongAbstract:A series of temperature and pH responsive hydrogels were synthesized by using Hydroxypropylcellulose (HPC) as temperature natural sensitive material, sodium alginate (SA) as pH sensitive material. The effect of SA to LCST has been studied and the mechanism of the influence has been presented. In addition, the swelling ratio and controlling factor of swelling process were all researched in this paper. The main results obtained are as follows: the LCST decreased gradually as SA was added into HPC; the HPC/SA hydrogel responded to both temperature and pH value of the medium; the swelling ratio reached maximum value at pH value of 6.
-
compatibility studies with blends based on Hydroxypropylcellulose and polyacrylonitrile
Carbohydrate Polymers, 2008Co-Authors: Hui Li, Guo-li Gong, Xinyuan Shen, Dong WangAbstract:Abstract The solubility parameters of Hydroxypropylcellulose (HPC) were measured with the viscosity method and estimated from proposing a group contribution approach for the prediction of δ based on the separation of the solubility parameter into three components (dispersion, polarity, and hydrogen bonding contributions). Hansen’s three dimensional solubility parameters were calculated approximately through the contributions of the structural groups. The compatibility of the HPC and polyacrylonitrile (PAN) blend system was studied with theoretical calculations as well as experimental measurements. Viscometric methods, polarized optical microscopy (POM), scanning electron microscopy (SEM), infrared spectrophotometric and thermogravimetry analysis (TGA) were employed for this investigation. The viscometric methods and polarized optical microscopy results were obtained from the blended solution in the range of 0–1.0 weight fraction of PAN, and the scanning electron microscopy, infrared spectrophotometric and thermogravimetry analysis results were obtained from the transparent films cast from the blended solutions that contained 0.2, 0.5 and 0.8 weight fractions of PAN, respectively. The results showed an excellent compatibility existed in the blends system, which may due to the strong hydrogen-bonding interaction between the hydroxyl group of HPC and the nitrile group of PAN.
Angel Concheiro - One of the best experts on this subject based on the ideXlab platform.
-
Interactions between Hydroxypropylcelluloses and vapour/liquid water
European Journal of Pharmaceutics and Biopharmaceutics, 2000Co-Authors: Carmen Alvarez-lorenzo, José Luis Gómez-amoza, Ramón Martínez-pacheco, Consuelo Souto, Angel ConcheiroAbstract:Abstract Understanding of the uptake of water vapour or liquid water by cellulose-based polymers is important because of the influence of these processes on many of the biologically or technologically relevant properties of these polymers. In this work we studied these processes in the cases of twelve Hydroxypropylcelluloses with low or medium-high degrees of substitution (L-HPCs and HPCs, respectively), characterization of which showed significant differences in structural and physical parameters (substitution pattern, crystallinity, particle size, specific surface area, and intraparticular porosity). Water vapour sorption–desorption isotherms determined to characterize the uptake of water vapour were fitted well by the Young–Nelson model, the optimized parameters of which indicated that at all relative humidities the capacity to bind water vapour as a surface monolayer is greater for HPCs than L-HPCs, but the capacity to absorb water vapour internally is greater for L-HPCs than HPCs. Guggenheim–Anderson–deBoer (GAB) models fitted the sorption–desorption isotherms less well. Differential scanning calorimetry (DSC) experiments showed all sorbed water vapour to be held as non-freezing water. Isoperibol microcalorimetry experiments carried out to investigate interactions with liquid water showed enthalpies of hydration/dissolution of between −62.86 and −71.35 J g −1 for L-HPCs and between −82.95 and −99.80 J g −1 for HPCs, and DSC showed average numbers of non-freezing water molecules per polymer repeat unit of 2.65–4.19 for L-HPCs and 18.10–22.42 for HPCs. DSC characterization of the kinetics of the water uptake by 10 mg compacts obtained by direct compression of Hydroxypropylcelluloses showed faster uptake by L-HPC compacts than by HPC compacts, among which there were significant differences in capacity for diffusive uptake. The explanations of the above differences in terms of the different substituent contents, particle sizes and porosities of the HPCs is supported by multiple linear regression analyses.
-
the stability of theophylline tablets with a Hydroxypropylcellulose matrix
Drug Development and Industrial Pharmacy, 2000Co-Authors: Carmen Alvarezlorenzo, J L Gomezamoza, R Martinezpacheco, C Souto, Angel ConcheiroAbstract:The behavior of 40:60 anhydrous theophylline/Hydroxypropylcellulose (HPC) direct compression tablets obtained using a variety of Hydroxypropylcelluloses with low or medium-high degrees of substitution (L-HPCs and HPCs, respectively) was determined immediately following their preparation and after storage for 6 months at 20°C and a relative humidity (RH) of either 70.4% or 93.9%. The lower relative humidity did not bring about hydration of the active principle in any formulation, but the higher relative humidity totally hydrated the drug in all except one L-HPC formulation, in which hydration remained incomplete. Both relative humidities caused significant tablet swelling, with L-HPC formulations being more affected than HPC formulations. Drug release was slowed by hydration of the active principle, but accelerated with tablet swelling. The lower relative humidity caused significant alteration of drug release characteristics in only two L-HPC formulations, release from which was accelerated, while the high...
-
degradation of Hydroxypropylcellulose by rhizomucor effects on release from theophylline Hydroxypropylcellulose tablets
International Journal of Pharmaceutics, 1999Co-Authors: Carmen Alvarezlorenzo, J L Gomezamoza, R Martinezpacheco, C Souto, R Duro, Angel ConcheiroAbstract:The stability of several varieties of Hydroxypropylcellulose was monitored during 3 years of storage (1) under the conditions recommended by manufacturers and official pharmacopoeias (simple storage in closed containers) and (2) at zero relative humidity. After 1 year, severe degradation of the varieties with lower initial pH and particle size stored at ambient relative humidity was shown by changes in their molecular weight and in the pH and apparent viscosity of 2% aqueous dispersions. Microbiological analyses showed the observed degradation to be attributable to the action of fungi of the genus Rhizomucor. The changes in apparent viscosity significantly affected the release of theophylline from direct compression tablets formulated with the degraded excipients.
Anna Karewicz - One of the best experts on this subject based on the ideXlab platform.
-
alginate Hydroxypropylcellulose hydrogel microbeads for alkaline phosphatase encapsulation
Journal of Microencapsulation, 2014Co-Authors: Anna Karewicz, Dorota Bielska, Katarzyna Zasada, Timothy Douglas, John A Jansen, Sander C G Leeuwenburgh, Maria NowakowskaAbstract:There is a growing interest in using proteins as therapeutics agents. Unfortunately, they suffer from limited stability and bioavailability. We aimed to develop a new delivery system for proteins. ALP, a model protein, was successfully encapsulated in the physically cross-linked sodium alginate/Hydroxypropylcellulose (ALG-HPC) hydrogel microparticles. The obtained objects had regular, spherical shape and a diameter of similar to 4 mu m, as confirmed by optical microscopy and SEM analysis. The properties of the obtained microbeads could be controlled by temperature and additional coating or crosslinking procedures. The slow, sustained release of ALP in its active form with no initial burst effect was observed for chitosan-coated microspheres at pH = 7.4 and 37 degrees C. Activity of ALP released from ALG/HPC microspheres was confirmed by the occurance of effectively induced mineralization. SEM and AFM images revealed formation of the interpenetrated three-dimensional network of mineral, originating from the microbeads' surfaces. FTIR and XRD analyses confirmed formation of hydroxyapatite.
-
Hydroxypropylcellulose-graft-poly(N-isopropylacrylamide)—novel water-soluble copolymer with double thermoresponsivity
Polimery, 2013Co-Authors: Magdalena Motyl, Dominik Drozd, Kamil Kamiński, Dorota Bielska, Anna Karewicz, Krzysztof Szczubiałka, Maria NowakowskaAbstract:Summary — A copolymer showing two cloud points was obtained by grafting poly(N-isopropylacrylamide) (PNIPAM) onto Hydroxypropylcellulose (HPC). The structure of the polymer was verified using 1 H NMR, FT-IR, GPC, and elemental analysis. The values of cloud points could be changed by increasing ionic strength and as a result of the interactions with surfactants.
-
smart alginate Hydroxypropylcellulose microbeads for controlled release of heparin
International Journal of Pharmaceutics, 2010Co-Authors: Anna Karewicz, Krzysztof Szczubialka, Szczepan Zapotoczny, Katarzyna Zasada, Radoslaw Lach, Maria NowakowskaAbstract:Abstract “Smart” (thermosensitive) alginate–Hydroxypropylcellulose (Alg/HPC) microbeads for controlled release of heparin were synthesized and the release profiles at various temperatures and for various alginate/HPC compositions were measured. Microbeads of regular spherical shape (ca. 3 μm in diameter) containing efficiently encapsulated heparin were obtained using an emulsification method. The internal structure of the bead was estimated by fluorescence microscopy using dansyl alginate as a labelled component. The microbeads surface structure and morphology were imaged in a dry state using scanning electron microscopy (SEM) and in water using atomic force microscopy (AFM). The microbead surface was shown to be covered by the regular network of pores with a mesh of ca. 30–60 nm. Lower critical solution temperature (LCST) of the Alg/HPC systems was measured spectrophotometrically (cloud point measurements). Heparin release profiles were obtained based on spectrophotometric detection of heparin complex with Azure A. Three-stage sustained release for at least 16 days was observed at 37 °C. This was correlated with the size of the pores present at the surface of microbeads. The release profile can be controlled by the temperature and composition of the Alg/HPC microbeads.
Guo-li Gong - One of the best experts on this subject based on the ideXlab platform.
-
Swelling Characterization of Double Sensitive Hydroxypropylcellulose / Sodium Alginate Hydrogel
Advanced Materials Research, 2011Co-Authors: Guo-li Gong, Hui LiAbstract:A series of temperature and pH responsive hydrogels was synthesized by using Hydroxypropylcellulose (HPC) as temperature sensitivity material and the natural material, sodium alginate (SA) as pH sensitivity material. The effect of SA to LCST has been studied and the mechanism of the influence has been presented. In addition, the swelling ratio and controlling factor of swelling process were all researched in this paper. The main results obtained are as follows: the LCST decreased gradually as added SA into HPC; the HPC/SA hydrogel responded both temperature and pH value of the medium; the swelling ratio reached maximum value as pH value of 6.
-
Synthesis and characterization of temperature/pH-sensitive Hydroxypropylcellulose/ sodium alginate hydrogel
E-polymers, 2010Co-Authors: Hui Li, Guo-li GongAbstract:A series of temperature and pH responsive hydrogels were synthesized by using Hydroxypropylcellulose (HPC) as temperature natural sensitive material, sodium alginate (SA) as pH sensitive material. The effect of SA to LCST has been studied and the mechanism of the influence has been presented. In addition, the swelling ratio and controlling factor of swelling process were all researched in this paper. The main results obtained are as follows: the LCST decreased gradually as SA was added into HPC; the HPC/SA hydrogel responded to both temperature and pH value of the medium; the swelling ratio reached maximum value at pH value of 6.
-
compatibility studies with blends based on Hydroxypropylcellulose and polyacrylonitrile
Carbohydrate Polymers, 2008Co-Authors: Hui Li, Guo-li Gong, Xinyuan Shen, Dong WangAbstract:Abstract The solubility parameters of Hydroxypropylcellulose (HPC) were measured with the viscosity method and estimated from proposing a group contribution approach for the prediction of δ based on the separation of the solubility parameter into three components (dispersion, polarity, and hydrogen bonding contributions). Hansen’s three dimensional solubility parameters were calculated approximately through the contributions of the structural groups. The compatibility of the HPC and polyacrylonitrile (PAN) blend system was studied with theoretical calculations as well as experimental measurements. Viscometric methods, polarized optical microscopy (POM), scanning electron microscopy (SEM), infrared spectrophotometric and thermogravimetry analysis (TGA) were employed for this investigation. The viscometric methods and polarized optical microscopy results were obtained from the blended solution in the range of 0–1.0 weight fraction of PAN, and the scanning electron microscopy, infrared spectrophotometric and thermogravimetry analysis results were obtained from the transparent films cast from the blended solutions that contained 0.2, 0.5 and 0.8 weight fractions of PAN, respectively. The results showed an excellent compatibility existed in the blends system, which may due to the strong hydrogen-bonding interaction between the hydroxyl group of HPC and the nitrile group of PAN.
