Protein Transfer through Polyacrylamide Hydrogel Membranes Polymerized in Lyotropic Phases (original) (raw)
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Macromolecules, 1994
Pore-size distributions have been measured for cationic acrylamide-based hydrogels. We use the experimental mixed-solute-exclusion method, MSE (introduced by Kuga), to obtain the solute-exclusion curve representing the amount of imbibed liquid inside the gel inaccessible for a solute of radius r. We use the Brownian motion model (developed by Cassasa) to convert the size-exclusion curve into the pore-size distribution, which gives the frequency of pore radius R as a function of R. This theoretically-based interpretation of MSE data leads to the Fredholm integral equation that we solve numerically. Results are reported for a series of hydrogels containing acrylamide and 3 % MAPTAC; the hydrogels differed in extent of cross-linking and/or initial concentration of monomer. Pore-size distributions shift to lower pore sizes with rising initial monomer concentration and with rising cross-linker-to-monomer ratio.
Protein electrophoresis in polyacrylamide gels with templated pores
Electrophoresis, 1996
Protein electrophoresis in polyacrylamide gels with templated pores An approach is described for the synthesis of nanostructured hydrogels with defined size channels or pores for separations of biological macromolecules. Polyacrylamide gels (15-20% acrylamide) were cast in the presence of high concentrations (5 %-28%) of hydrophilic, macromolecular cosolutes either semirigid, rod-like polyelectrolytes (short fragments of DNA or xanthan) or spherical micelles of sodium dodecyl sulfate (SDS). Polyanionic cosolutes were then removed by a combination of diffusion and electrophoresis. These processes are expected to yield gels with 'templated' channels having dimensions near those of the double helical polymers (diameters = 2-3 nm, lengths of 50-200 nm) or pores near the size of the spherical SDS micelles (= 4-5 nm). This hypothesis was tested by comparing the relative electrophoretic mobilities of proteins (3400 to 43 000 Da) complexed with SDS on templated and conventional gels. Differences in electrophoretic mobilities were observed between all templated gels and control normal gels, demonstrating that the templating process altered the polyacrylamide network. No evidence was found for phase separation of cosolutes from the polyacrylamide network during polymerization. Templated pores are expected to enhance the mobilities of molecules in a particular size range relative to smaller and larger molecules. Gels templated with DNA or xanthan (8-10 O/ o final concentration) exhibited little size selectivity, but selectivity was observed for gels templated with SDS (17-20°/o final concentration). The degree of selectivity of gels templated with SDS varied with polyacrylamide concentration in a manner consistent with the creation of templated pores approximately the size of SDS micelles and larger than the average pore size in a surrounding polyacrylamide network.
Organic compatible polyacrylamide hydrogel fibers
Polymer, 2009
Ultra-fine fibrous PAAm hydrogel membranes were fabricated by electrospinning of aqueous solutions, followed by reaction with glutaraldehyde. A wide range of fiber diameters (267 nm to 2.8 mm) and morphologies (beaded, round, branched and ribbon) could be achieved by PAAm molecular weight and solution properties. The optimally glutaraldehyde-crosslinked membranes were highly stable in water as well as in organic solvents (methanol, ethanol, acetone, chloroform, DMF and cyclohexane). Glutaraldehyde formed imine with PAAm amide side groups in the form of crosslinking bridges as well as grafts with hydrolyzed carboxylic end groups. The fibrous membrane showed excellent thermal stability, hydrophilicity, super water absorbency and exceptional tensile strength. The fibrous membrane exhibited excellent ability to entrap b-galactosidase enzyme while allowing efficient diffusion of the substrate from and released products into surrounding media. The dual organic solvent and aqueous media compatible fibrous membranes have the promise for solid supported catalysis and diagnostic as well as a wide range of biomedical and industrial applications.
Journal of Applied Polymer Science, 2016
Separation processes are routinely used worldwide in biotechnology, chemical processing, wastewater treatment, and myriad other areas. Gel electrophoresis has been used for decades as a standard technique to separate charged biopolymers, such as DNA, RNA, and proteins. In this research, polyacrylamide hydrogels were synthesized in the presence of sodium dodecyl sulfate (SDS) micelles as nanotemplating agents in an effort to modify the internal porous microstructure of the gels. After removing these agents via a combination of passive and facilitated means, the gels were used during electrophoresis in order to assess the effects of its modified porous microstructure on protein separations. The results revealed that hydrogels containing 9% acrylamide and templated with SDS micelles in a 5-15% concentration range were the most effective materials in separating proteins in a range of 10-250 kDa. As expected, standard, nontemplated gels also resulted in separation of the proteins but not to the same extent as with the templated hydrogels. In summary, this research highlights the important role of the templating agent as possible useful tuning factors for achieving electrophoresis-based separation.
Preparation and characterization of a novel gel polymer membrane based on a tetra-copolymer
2012
Innovative hydrogels obtained by physical and chemical crosslinking of deacylated Gellan gum have been characterized in terms of water uptake, rheological properties and compressibility, and the behaviour of the tested materials, according to the type of the obtained network, is thoroughly discussed. The release from the various gels of loaded model molecules of different steric hindrance was also investigated and the trend of the release profiles has been related to the structures proposed for the physical and the chemical hydrogel.
European Polymer Journal, 2002
Diffusion of aqueous sodium dodecyl sulfate (SDS) across cross-linked polyacrylamide hydrogel membranes has been studied by electrical conductivity measurements. Initial rapid sorption of SDS (as unimer) into the membranes is observed. The effect of SDS concentration, and of cross-linker fraction on the degree of swelling of the gels is studied and associated with binding of the surfactant to the polymer, with surface bound water suggested to be involved in these interactions. Below the surfactant critical micelle concentration, volume collapse of less cross-linked membranes is observed, and associated with aggregate formation. Fluorescence measurements using pyrene as a probe show that micellar aggregates do not diffuse through the membrane, and only overall unimer diffusion is observed. The effect of cross-linking on the diffusion process is discussed.
The Chemical Educator, 2001
It is well known that hydrogels can be suitable for biomedical, agricultural, and industrial applications. In particular, they have been widely used for the preparation of drug-delivery systems. The preparation and characterization of such a system should be useful for introducing students to these materials. This paper describes the preparation of polyacrylamide hydrogels having different crosslinking densities from the view
Overview of the Biological Activity of Polyacrylamide Hydrogels
مجلة مركز بحوث التقنيات الاحيائية, 2023
Background: Polyacrylamide hydrogels have emerged as a versatile class of materials with considerable potential within the domain of biomedicine. These hydrogels, comprising crosslinked polyacrylamide polymers, exhibit distinctive properties that render them highly appealing for a wide range of applications in tissue engineering, drug delivery, wound healing, and regenerative medicine. Objective: This article provides a comprehensive overview of polyacrylamide hydrogels and their properties. Discussion: Furthermore, it delves into the interactions between these hydrogels and living tissues, evaluates their biocompatibility, and underscores their diverse applications within the realm of biomedicine. Conclusion: By comprehending the intricate biological behavior and inherent potential of polyacrylamide hydrogels, researchers and practitioners can effectively explore their application in the development of advanced biomedical technologies.
Characterization of inhomogeneous polyacrylamide hydrogels
Journal of Polymer Science Part B: Polymer Physics, 1992
The physical and structural properties of acrylamide gels have been characterized by osmotic deswelling, mechanical compression, and x-ray scattering. These properties vary considerably with the concentration of the crosslinking agent bisacrylamide, at fixed total monomers concentration ( 10% wt/wt water). In particular, changes in the properties appear more prominent at a crosslinking level of about 5 6 % ( w t bisacrylamide/wt monomers). The compression modulus of as-prepared and swollen gels passes through a maximum at this level of crosslinking. The swelling pressure curves can be separated into osmotic and elastic contributions of the gel network. The elastic part exhibits similar behavior to the compression modulus. The scaling of the osmotic part with the gel concentration varies with the degree of crosslinking, changing from 2.33 to 3.09. This indicates that the solvent power of water decreases with increasing crosslinking level, towards 0 conditions. The scattering patterns from the gels have been analyzed as arising from additive contributions from a homogeneous gel matrix, and embedded heterogeneities having a higher crosslinking density. These heterogeneities become much more prominent a t the same level of crosslinking about 5-6%. Hysteresis observed in the sorption/desorption behavior of polyacrylamide gel suggests that further irreversible structural changes may occur at water activities lower than probed by osmotic deswelling. 0 1992 John Wiley & Sons, Inc. Keywords: hydrogels, polyacrylamide, characterization of inhomogeneity in polyacrylamide, inhomogeneous hydrogels of gels of polyacrylamide in water, physical and structural characteristics of Sci. .
Hydrodynamic Permeability of Hydrogels Stabilized within Porous Membranes
Industrial & Engineering Chemistry Research, 1996
The purpose of this work was to demonstrate that cross-linked polymer gels can be stabilized against mechanical and osmotic forces by confining them in a microporous support. The hydrodynamic (Darcy) permeability was measured for neutral and charged polyacrylamide (PA) gels synthesized in semirigid membranes having a hydraulic mean pore diameter of 0.5 µm and a porosity of 67%. The permeability was determined by measuring the flow rate of aqueous solutions as a function of pressure drop across the membranes. The membrane-supported gels were stable and yielded a constant permeability when the pressure drop was increased to 300 bar/cm. No swelling/deswelling was observed with the charged gels (0.3-0.4 equiv/L) when the ionic strength was varied between 0.01 and 1.0 M, and the permeability was essentially independent of ionic strength. The permeability of the neutral gel varied as φ -3.3 where φ is the polymer volume fraction, whereas literature data for bulk PA gels shows the dependence to be φ -1.4 . The permeability of the membrane-supported neutral PA gel was greater than the literature values for the bulk gel at low φ but comparable to the bulk gels when φ > 0.08.