Application of carbon nanotube-matrix assistant native polyacrylamide gel electrophoresis to the separation of apolipoprotein A-I and complement C3

Enhanced electrophoretic separation of proteins by tethered SiO2 nanoparticles in an SDS-polyacrylamide gel network

Nanoparticles (NPs) are able to improve the separation efficiency of proteins in SDS-polyacrylamide gel electrophoresis (SDS-PAGE) due to their capability of enhancing heat dissipation during electrophoresis. However, the intrinsic surface charges of NPs (at buffer pH or charge induced due to the SDS coating) make them acquire electrophoretic mobility and movement in the gel. Such a movement leads to viscosity and temperature gradients in the gel and deteriorates the separation. In this work, we proposed a novel method by using tethered NPs in the gel. Silica NPs, as the model NPs, were prepared and their surfaces were modified using 3-[(methacryloxy)propyl] trimethoxysilane (MPS) which locks the NPs in the gel via covalent bonds (M-SiO₂/PA (polyacrylamide)). SiO₂ NPs were embedded into the gel (SiO₂/PA) as the positive control, while pure PA gel was chosen as the negative control. The results showed that at a relatively high voltage of 250 V, although the Joule heat generated during electrophoresis disturbed the separation in the pure gel, the SiO₂/PA and M-SiO₂/PA nanocomposite gels showed better performances. In comparison with the pure PA gel, the resolution increased by 3 and 32% for SiO₂/PA and M-SiO₂/PA, respectively, in a relatively short separation time of 35 min. The gel with tethered NPs presented a more efficient separation in terms of band broadening and resolution compared with the gel with free NPs probably due to the movement of free charged particles in the gel. Evidently, the migration speed of protein bands in the gels decreased especially for larger proteins in the presence of the NPs compared to the pristine gel due to the steric hindrance of the NPs. Finally, we separated E. coli proteins, as a real sample. Among the three gels (pure PA, SiO₂/PA, and M-SiO₂/PA), the gel containing M-SiO₂ showed the best performance.

Heat dissipation in slab gel electrophoresis: The effect of embedded TiO2 nanoparticles on the thermal profiles

Despite the fast development of novel and high-resolution electrophoresis techniques such as capillary-based methods and microfluidic devices, the slab gel electrophoresis is still a popular method for the separation of biomolecules in medicine and biology. It is a low cost and simple method and offers high throughput. However, this technique is limited to low voltages leading to slow separations. Producing the heat during the electrophoresis known as Joule heating inevitably leads to a rise in the gel temperature. For the first time, this work offers a whole gel temperature measurement by using a thermal camera which presents accurate temperature profiles in the gel with a resolution of more than 10 pixel/mm² and a precision of 0.1 °C. Titania, TiO₂, nanoparticles (NPs) were embedded into the polyacrylamide (PA) gel to improve the electrophoretic separation of proteins. By embedding 0.025% w/v TiO₂ NPs, heat dissipation increases by 16.5% at applied voltage of 200 V compared with that of PA gel with no embedded TiO₂ NPs. The thermal images showed that the composite gel was 2.5 °C in average cooler than PA gel after 15 min of electrophoresis run at 200 V. The maximum separation voltage increased by 30 V in the composite PA/TiO₂ gel compared with the pure PA gel. Moreover, the average number of theoretical plates over the 10 protein peaks, as a criterion of separation performance, increased by about 63% at 180 V when TiO₂ NPs were included into the gel.

Understanding Collaborative Effects between the Polymer Gel Structure and the Applied Electrical Field in Gel Electrophoresis Separation

The collaborative effects between an applied orthogonal electrical field and the internal structure of polymer gels in gel electrophoresis is studied by using microscopic-based electrophoretic transport models that then are upscaled via the format of electro kinetics-hydrodynamics (EKHD). The interplay of the electrical field and internal gel morphology could impact the separation of biomolecules that, because of similar chemical properties, are usually difficult to separate. In this study, we focus on an irregular pore geometry of the polymer-gel structure by using an axially varying pore (i.e., an axially divergent section) and an orthogonal (to the main flow of solutes) applied electrical field. The microscopic-based conservation of species equation is formulated for the standard case of electrophoresis of charged particles within a geometrical domain, i.e., a pore, and upscaled to obtain macroscopic-based diffusion and mobility coefficients. These coefficients are then used in the calculation of the optimal time of separation to study the effect of the varying parameters of the pore structure under different values of the electrical field. The results are qualitatively consistent with those reported, in the literature, by using computational-based approaches as well as with experiments also reported in the literature, previously. The study shows the important collaborative effects between the applied electrical field and the internal geometry of the polymer gels that could lead to improving biomolecule separation in gel electrophoresis.

Carbon nanotubes: a novel material for multifaceted applications in human healthcare

Remarkable advances achieved in modern material technology, especially in device fabrication, have facilitated diverse materials to expand the list of their application fields.

Under the lens: carbon nanotube and protein interaction at the nanoscale

The combination of the very different chemical natures of carbon nanotubes (CNTs) and proteins gives rise to systems with unprecedented performance, thanks to a rich pool of very diverse chemical, electronic, catalytic and biological properties. Here we review recent advances in the field, including innovative and imaginative aspects from a nanoscale point of view. The tubular nature of CNTs allows for internal protein encapsulation, and also for their external coating by protein cages, affording bottom-up ordering of molecules in hierarchical structures. To achieve such complex systems it is imperative to master the intermolecular forces between CNTs and proteins, including geometry effects (e.g. CNT diameter and curvature) and how they translate into changes in the local environment (e.g. water entropy). The type of interaction between proteins and CNTs has important consequences for the preservation of their structure and, in turn, function. This key aspect cannot be neglected during the design of their conjugation, be it covalent, non-covalent, or based on a combination of both methods. The review concludes with a brief discussion of the very many applications intended for CNT-protein systems that go across various fields of science, from industrial biocatalysis to nanomedicine, from innovative materials to biotechnological tools in molecular biology research.

Embedded ceria nanoparticles in gel improve electrophoretic separation: a preliminary demonstration

Ceria NP embedded PAGE could improve the analytical figures of merit by reducing Joule heating and lowering the band broadening.

Improvement of heat dissipation in agarose gel electrophoresis by metal oxide nanoparticles

Joule heating is a primary limitation in slab gel electrophoresis which is a gold standard method in biochemistry and biotechnology.

Programmable self-assembly of carbon nanotubes assisted by reversible denaturation of a protein

Self-assembly of pristine multi-walled carbon nanotubes (CNTs) in aqueous dispersion using a protein, bovine serum albumin (BSA), has been demonstrated. Step-wise conformational changes in BSA as a function of temperature have been deployed to direct the assembly of nanotubes. More specifically, CNTs distributed randomly in native BSA at 35 °C as well as completely denatured BSA solution at 80 °C self-assemble in the intermediate temperature range of 45-65 °C, as evident from scanning and transmission electron microscopy. Fourier transform infrared (FTIR) and fluorescence studies indicate significant changes in the α-helical content of the protein with respect to the amide I and II bands and tryptophan emission intensity, respectively. The stability of CNT dispersion in BSA solution has been attributed to the hydrophobic interaction between nanotubes and the protein molecule by adding sodium cholate to the dispersion. Moreover, a mechanism based on electrostatic repulsion between BSA-bound CNTs has been proposed for the thermally reversible assembly of CNTs in BSA solution based on evidence from zeta potential measurements and FTIR spectroscopy. Thus the present report demonstrates bio-mimetic self-assembly of as-synthesized CNTs using changes in surface charge and conformation of an unfolding protein for biomedical applications and nanobiotechnology.

Carbon nanotubes-assisted polyacrylamide gel electrophoresis for enhanced separation of human serum proteins and application in liverish diagnosis

The application of pore-gradient polyacrylamide gel electrophoresis (PG-PAGE) incorporated with carbon nanotube modified by Triton X-100 and carboxylation so as to improve the separation of human serum proteins is reported. The novel PG-PAGE was made by adding water-soluble single-walled carbon nanotubes (CNTs) when preparing the polyacrylamide gel. Significant improvements in separation of complement C3 protein and haptoglobin (Hp) in human serum were achieved. It was estimated that the interactions between the hydrophilic groups on the proteins and the surface of the CNTs result in different adsorption kinetics of complement C3 and Hp subtype on the nanoparticles incorporated in the gel, thus enhancing the separation of the two proteins in serum. This new CNT matrix-assisted PG-PAGE method for enhanced separation of complement C3 and Hp in human serum was successfully applied to distinguish the samples from liverish patients and healthy people.