Effect of magnetization on the gel structure and protein electrophoresis in polyacrylamide hydrogel nanocomposites

Abstract

In this study, polyacrylamide nanocomposite hydrogels were formulated in combination with sodium montmorillonite (MMT) in the presence of a 2-T magnetic field. This top-down nanomanufacturing approach led to interesting changes in the internal structure of the gel and ultimately to a dramatic improvement in the ability of the composite to separate the two protein probes, ovum serum albumin and carbonic anhydrase. The morphology of the nanocomposite hydrogel was analyzed with cryogenic scanning and transmission electron microscopy, wide-angle X-ray diffraction, and small-angle scattering to determine whether morphological changes would correlate with this improved separation. As the volume fractions of MMT were well under 1% in this study (because of aqueous swelling), scattering data were dominated by the polymer structure. Significant morphological changes were noted at two length scales: (1) the hydrogel cell structure, at hundreds of nanometers, appeared to ex-hibit changes in the anisotropic orientation with magnetization, and (2) the polyamide structure, at tens of nanometers, exhibited decreasing pore size (small-angle Xray scattering). The separation data correlated most closely with a reduction in pore size; however, an additional contribution to separation from local electrostatic effects from the presence of charged MMT in the cell walls could not be discounted. The change in the pore size associated with processing may have been due to the MMT presence altering the diffusion rates of the reactants during polymer formation. The method demonstrated herein could be used ultimately to separate proteins in their native state, with the potential retention of function for downstream applications, such as novel detection techniques or purification.

Choosing the Optimal Gel Morphology in Electrophoresis Separation by a Differential Evolution Approach (Dea)

“…In particular, and as an overall conclusion, this study suggests that the magnetic alignment of nanoparticles within the gels achieved by Thompson et al (2012) and that showed potential for improving separation has now a possibly fundamental explanation based on the study reported here. This study also suggests (for the first time and to the best of our knowledge) a possible useful approach to choose both a favorable hydrogel morphology as well as optimal values of the operating parameters for a given type of separation medium The use of nanoparticles (Thompson et al, 2010;Thompson et al, 2012) such as ceramic, metallic or polymer types might be an excellent way to achieve this objective by orienting them during the gels manufacture with the use of magnetic fields, for example.…”

“…Therefore, a systematic optimization-based approach is appealing because an optimal separation of practical use can be achieved efficiently from a complete understanding of all possibilities. This (overall) morphology-based optimization could be helpful in assisting potential new designs that work towards systematically generating a multidimensional structure having broader tunability (Thompson et al, 2008) for a given type of molecule.…”

“…From the analysis, we can infer the following key observations: 1-All the parameters mentioned above had an effect on the separation resolution for electrophoresis; however, the DEA does an excellent performance in handling the multiparameter space to suggest optimal values; 2-The highest possible separation resolution can be obtained when the angle of deviation of the microvoid domain is relatively small; and 3-Imperfections in microvoids, i.e. deviations from an ideal type of geometry such as rectilinear channels or cells (obtained by a magnetic orientation of the nanoparticle in the gels, see Thompson et al, 2012) should be avoided in order to increase separation efficiency.…”

Magneto-optical harmonic susceptometry of superparamagnetic materials

“…20,21 However, these techniques measure the total magnetic response of the probed region of the sample, and a large dia-or paramagnetic response can make the detection of a small superparamagnetic contribution difficult and time-consuming. Nanocomposites, composite materials where at least one constituent has a size on the order of nanometers, have become important materials with many current and future applications, 22 such as in batteries, 23 antibacterial materials, 24 biochemistry, 25 magnetic-field controlled electrical devices, 26 and many others. Nanocomposite material properties not only depend on the properties of their constituent materials but also strongly depend on their morphology, dispersion, and interfacial characteristics of the constituents.…”

“…Nanocomposite material properties not only depend on the properties of their constituent materials but also strongly depend on their morphology, dispersion, and interfacial characteristics of the constituents. [22][23][24][25][26][27] The increase in research on nanoscale materials has been driven by the ability to characterize these materials. 28 In order to further advance the field, new characterization techniques are necessary that are accessible to many researchers.…”