| 1. |
- Aggarwal, N., et al.
(författare)
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Study on multilayer structures prepared from heparin and semi-synthetic cellulose sulfates as polyanions and their influence on cellular response
- 2014
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 116, s. 93-103
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Tidskriftsartikel (refereegranskat)abstract
- Multilayer coatings of polycationic chitosan paired with polyanionic semi-synthetic cellulose sulfates or heparin were prepared by the layer-by-layer method. Two different cellulose sulfates (CS) with high (CS2.6) and intermediate (CS1.6) sulfation degree were prepared by sulfation of cellulose. Multilayers were fabricated at pH 4 and the resulting films were characterized by several methods. The multilayer 'optical' mass, measured by surface plasmon resonance, showed little differences in the total mass adsorbed irrespective of which polyanion was used. In contrast, 'acoustic' mass, calculated from quartz crystal micro balance with dissipation monitoring, showed the lowest mass and dissipation values for CS2.6 (highest sulfation degree) multilayers indicating formation of stiffer layers compared to heparin and CS1.6 layers which led to higher mass and dissipation values. Water contact angle and zeta potential measurements indicated formation of more distinct layers with using heparin as polyanion, while use of CS1.6 and CS2.6 resulted into more fuzzy intermingled multilayers. CS1.6 multilayers significantly supported adhesion and growth of C2C12 cells where as only few cells attached and started to spread initially on CS2.6 layers but favoured long term cell growth. Contrastingly cells adhered and grew poorly on to the layers of heparin. This present study shows that cellulose sulfates are attractive candidates for multilayer formation as potential substratum for controlled cell adhesion. Since a peculiar interaction of cellulose sulfates with growth factors was found during previous studies, immobilization of cellulose sulfate in multilayer systems might be of great interest for tissue engineering applications.
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| 2. |
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| 3. |
- Allerbo, Oskar, 1985, et al.
(författare)
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Simulations of lipid vesicle rupture induced by an adjacent supported lipid bilayer patch
- 2011
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 82:2, s. 632-636
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Tidskriftsartikel (refereegranskat)abstract
- Using a simple phenomenological model of a lipid bilayer and a surface, simulations were performed to study the bilayer-induced vesicle rupture probability as a vesicle adsorbs adjacently to a bilayer patch already adsorbed on the surface. The vesicle rupture probability was studied as a function of temperature, vesicle size, and surface-bilayer interaction strength. From the simulation data, estimates of the apparent activation energy for bilayer-induced vesicle rupture were calculated, both for different vesicle sizes and for different surface-bilayer interaction strengths.
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| 4. |
- Allerbo, Oskar, et al.
(författare)
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Simulations of Lipid Vesicle Rupture Induced by an Adjacent Supported Lipid Bilayer Patch
- 2011
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 82, s. 632-636
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Tidskriftsartikel (refereegranskat)abstract
- Using a simple phenomenological model of a lipid bilayer and a surface, simulations were performed to study the bilayer-induced vesicle rupture probability as a vesicle adsorbs adjacently to a bilayer patch already adsorbed on the surface. The vesicle rupture probability was studied as a function of temperature, vesicle size, and surface-bilayer interaction strength. From the simulation data, estimates of the apparent activation energy for bilayer-induced vesicle rupture were calculated, both for different vesicle sizes and for different surface-bilayer interaction strengths.
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| 5. |
- Andersson, Martin, 1974, et al.
(författare)
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Vesicle and bilayer formation of diphytanoylphosphatidylcholine (DPhPC) and diphytanoylphosphatidylethanolamine (DPhPE) mixtures and their bilayers' electrical stability
- 2011
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 82:2, s. 550-561
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Tidskriftsartikel (refereegranskat)abstract
- Lipid bilayers are of interest in applications where a cell membrane mimicking environment is desired. The performance of the lipid bilayer is largely dependent on the physical and chemical properties of the component lipids. Lipid bilayers consisting of phytanoyl lipids have proven to be appropriate choices since they exhibit high mechanical and chemical stability. In addition, such bilayers have high electrical resistances. Two different phytanoyl lipids, 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) and 1,2-diphytanoyl-sn-glycero-3-phosphoethanolamine(DPhPE), and various combinations of the two have been investigated with respect to their behavior in aqueous solutions, their interactions with solid surfaces, and their electrical stability. Dynamic light scattering, nuclear magnetic resonance diffusion, and cryogenic transmission electron microscopy measurements showed that pure DPhPC as well as mixtures of DPhPC and DPhPE consisting of greater than 50% (mol%) DPhPC formed unilamellar vesicles. If the total lipid concentration was greater than 0.15 g/l, then the vesicles formed solid-supported bilayers on plasma-treated gold and silica surfaces by the process of spontaneous vesicle adsorption and rupture, as determined by quartz crystal microbalance with dissipation monitoring and atomic force microscopy. The solid-supported bilayers exhibited a high degree of viscoelasticity, probably an effect of relatively high amounts of imbibed water or incomplete vesicle fusion. Lipid compositions consisting of greater than 50% DPhPE formed small flower-like vesicular structures along with discrete liquid crystalline structures, as evidenced by cryogenic transmission electron microscopy. Furthermore, electrophysiology measurements were performed on bilayers using the tip-dip methodology and the bilayers' capacity to retain its electrical resistance towards an applied potential across the bilayer was evaluated as a function of lipid composition. It was shown that the lipid ratio significantly affected the bilayer's electrical stability, with pure DPhPE having the highest stability followed by 3DPhPC:7DPhPE and 7DPhPC:3DPhPE in decreasing order. The bilayer consisting of 5DPhPC:5DPhPE had the lowest stability towards the applied electrical potential.
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| 6. |
- Arslan Yildiz, Ahu, et al.
(författare)
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Biomimetic membrane platform: Fabrication, characterization and applications
- 2013
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Ingår i: Colloids and Surfaces B. - : Elsevier. - 0927-7765 .- 1873-4367. ; 103, s. 510-516
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Tidskriftsartikel (refereegranskat)abstract
- A facile method for assembly of biomimetic membranes serving as a platform for expression and insertion of membrane proteins is described. The membrane architecture was constructed in three steps: (i) assembly/printing of alpha-laminin peptide (P19) spacer on gold to separate solid support from the membrane architecture; (ii) covalent coupling of different lipid anchors to the P19 layer to serve as stabilizers of the inner leaflet during bilayer formation; (iii) lipid vesicle spreading to form a complete bilayer. Two different lipid membrane systems were examined and two different P19 architectures prepared by either self-assembly or mu-contact printing were tested and characterized using contact angle (CA) goniometry, surface plasmon resonance (SPR) spectroscopy and imaging surface plasmon resonance (iSPR). It is shown that surface coverage of cushion layer is significantly improved by mu-contact printing thereby facilitating bilayer formation as compared to self-assembly. To validate applicability of proposed methodology, incorporation of Cytochrome bo(3) ubiquinol oxidase (Cyt-bo(3)) into biomimetic membrane was performed by in vitro expression technique which was further monitored by surface plasmon enhanced fluorescence spectroscopy (SPFS). The results showed that solid supported planar membranes, tethered by alpha-laminin peptide cushion layer, provide an attractive environment for membrane protein insertion and characterization.
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| 7. |
- Berlind, Torun, 1965-, et al.
(författare)
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Formation and cross-linking of fibrinogen layers monitored with in situ spectroscopic ellipsometry
- 2010
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 75:2, s. 410-417
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Thick matrices of fibrinogen with incorporation of a matrix metalloproteinaseinhibitor were covalently bonded on functionalized silicon surfaces using an ethyl-3-dimethyl-aminopropyl-carbodiimide and N-hydroxy-succinimide affinity ligand couplingchemistry. The growth of the structure was followed in situ using dynamic ellipsometryand characterized at steady-state with spectroscopic ellipsometry. The growth wascompared with earlier work on ex situ growth of fibrinogen layers studied by singlewavelength ellipsometry. It is found that in situ growth and ex situ growth yield differentstructural properties of the formed protein matrix. Fibrinogen matrices with thicknessesup to 58 nm and surface mass densities of 1.6 μg/cm2 have been produced.
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| 8. |
- Bhatnagar, Amit, et al.
(författare)
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Biosorption optimization of nickel removal from water using Punica granatum peel waste
- 2010
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 76:2, s. 544-548
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Tidskriftsartikel (refereegranskat)abstract
- The present Study was undertaken to evaluate the feasibility of Punica granatum (pomegranate) peel waste for the removal of nickel from water. Batch experiments were performed to study the biosorption of nickel on prepared pomegranate peel adsorbent. The sorption process was well explained with pseudo-second-order kinetic model. The maximum sorption capacity of pomegranate peel adsorbent for nickel removal was ca. 52 mg g(-1). The sorption has been found to be endothermic and data conform to the Langmuir model. The Gibbs free energy was determined to be negative, indicating the spontaneous nature of the sorption process. The results of the present study suggest that pomegranate peel waste can be used beneficially for nickel removal from aqueous solution.
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| 9. |
- Chakraborty, Subhashis, et al.
(författare)
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Utilization of adsorption technique in the development of oral delivery system of lipid based nanoparticles
- 2010
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 81:2, s. 563-569
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the present study was to employ suitable adsorbent with free flowing characteristics for improving the stability and physical properties of solid lipid nanoparticles (SLN) for oral administration. Stearic acid based nanoparticles of carvedilol phosphate were fabricated by solvent emulsification evaporation technique in sodium taurocholate solution prepared in pH 7.2 buffers (I-KH2PO4/NaOH or II-NaH2PO4/Na2HPO4) with 1% polyvinyl alcohol. Nanoparticles were then adsorbed by passing the nanodispersion through a Neusilin US2 (adsorbent) column. Interestingly, scanning electron microscopy revealed round deformed and even collapsed nanoparticles in Buffer-I and discrete spherical to ellipsoidal nanoparticles in Buffer-II which indicates the inability of nanoemulsion to crystallize and form SLN in Buffer-I. The successful formation of SLN in Buffer-II was confirmed by differential scanning calorimetry and X-ray diffraction. The retention of SLN from the nanodispersion by adsorption on the adsorbent imparted good flow property and resulted in a marked stability improvement of the formulation in terms of drug retention efficiency and release profile as compared to the simple nanosuspension. In conclusion, the adsorbent technology would be instrumental in imparting additional features to the existing conventional colloidal system for pharmaceutical application which would ease the process of capsule filling at industrial scale, simplify the handling of formulations by patients and can significantly improve the shelf life of the product for a longer period of time as compared to liquid formulations
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| 10. |
- Costa, Diana, et al.
(författare)
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Swelling behavior of a new biocompatible plasmid DNA hydrogel
- 2012
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 1873-4367 .- 0927-7765. ; 92, s. 106-112
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Tidskriftsartikel (refereegranskat)abstract
- Chemical plasmid DNA (pDNA) gels were prepared by a cross-linking reaction with ethylene glycol diglycidyl ether (EGDE). Fluorescence microscopy (FM) and scanning electron microscopy (SEM) images of pDNA gels are reported. For the first time, the pDNA gels have been investigated with respect to their swelling in aqueous solution containing different additives, such as metal ions, polyamines, polycations and surfactants. The effect of the cationic surfactant tail length on the volume phase transition of pDNA gels was studied as a function of surfactant concentration: the critical aggregation concentration (cac), is found to decrease with increasing length of the hydrophobic tail. The deswelling appears to be reversible as exemplified by the addition of anionic surfactant subsequent to collapsing the gel by a cationic surfactant. Cell viability assays suggest that the plasmid DNA gels are non-toxic to cells and do not cause any distinct harm to them. This step contributes to the possibility of using these gels, as carriers, in real biological systems. (C) 2011 Elsevier B.V. All rights reserved.
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