Interaction of Graphene and Polycaprolactone at Atomic Level

Polycaprolactone (PCL) is a material widely used in regenerative medicine because of biocompatibility, biodegradability, and low toxicity. Applications of PCL are mainly focused on tissue engineering, wound healing, drug encapsulation and delivery etc. PCL scaffolds have been used for stem cell differentiation into various cellular lineages. However, the hydrophobicity of PCL scaffolds possess some limitation to cellular attachment. Graphene which is a single sheet of sp2 hybridized carbon atoms can enhance cellular attachment by establishing π-π interaction. Here we investigate the interaction of PCL and graphene by molecular dynamics simulation and hence fabrication of PCL scaffolds with graphene nano-inclusions for neuronal differentiation. Correlated conformational and energetic analysis are implemented. During 10ns simulation, randomly assigned PCL chains adsorbed onto the surface of graphene and the size of PCL also tended to fit graphene sheet. Wrapping phenomenon was detected after 10ns interaction. The dominant force is Van der Waal’s force and hydrophobic interaction

Differentiation Of Mesenchymal Stem Cells (Mscs) To Functional Neuron On Graphene-Polycaprolactone Nanoscaffolds

Spinal cord is an important part of the central nervous system that controls all activities of the body. It is a tubular bundle of nerve fibers and tissues connecting brain to nearly all parts of the body. Nerve cells in an adult human body do not divide and make copies of themselves. Therefore, in case of an injury or damage to any part of spinal cord causes permanent changes to strength, sensation and other body functions. The field of tissue engineering and regenerative medicine which aims to replace and repair damaged tissues, organs or cells entails for effective methods for fabricating biological scaffolds. Here we present synthesis of fibrous scaffolds by a process called electrospinning that can provide a microenvironment in-vitro for differentiation and proliferation of functional neurons from mesenchymal stem cells. These nanofibrous PCL scaffolds with graphene as filler materials are engineered in such a way so as to provide topological, biochemical as well as electrical cues that can enhance neurite extension and penetration. Poly(ε-caprolactone) (PCL) is a FDA approved synthetic biodegradable polyester extensively used in biomedical applications. Graphene, a single layer carbon crystal, based nanomaterials have recently gained considerable interest for tissue engineering applications including osteogenic, neural and differentiation in other lineages due to their favorable chemical, electrical and mechanical properties. Our final aim is that the functional tissues or organs developed in vitro shall be implanted inside body to rehabilitate the biological function that was lost due to injury, abnormality or loss

A semi exact solution for a metallic phase in a Holstein-Hubbard chain at half filling with Gaussian anharmonic phonons

Abstract The nature of phase transition from an antiferromagnetic SDW polaronic Mott insulator to the paramagnetic bipolaronic CDW Peierls insulator is studied for the half-filled Holstein-Hubbard model in one dimension in the presence of Gaussian phonon anharmonicity. A number of unitary transformations performed in succession on the Hamiltonian followed by a general many-phonon averaging leads to an effective electronic Hamiltonian which is then treated exactly by using the Bethe-Ansatz technique of Lieb and Wu to determine the energy of the ground state of the system. Next using the Mott–Hubbard metallicity condition, local spin-moment calculation, and the concept of quantum entanglement entropy and double occupancy, it is shown that in a plane spanned by the electron–phonon coupling coefficient and onsite Coulomb correlation energy, there exists a window in which the SDW and CDW phases are separated by an intermediate phase that is metallic

Graphene Quantum Dot Oxidation Governs Noncovalent Biopolymer Adsorption.

Graphene quantum dots (GQDs) are an allotrope of carbon with a planar surface amenable to functionalization and nanoscale dimensions that confer photoluminescence. Collectively, these properties render GQDs an advantageous platform for nanobiotechnology applications, including optical biosensing and delivery. Towards this end, noncovalent functionalization offers a route to reversibly modify and preserve the pristine GQD substrate, however, a clear paradigm has yet to be realized. Herein, we demonstrate the feasibility of noncovalent polymer adsorption to GQD surfaces, with a specific focus on single-stranded DNA (ssDNA). We study how GQD oxidation level affects the propensity for polymer adsorption by synthesizing and characterizing four types of GQD substrates ranging ~60-fold in oxidation level, then investigating noncovalent polymer association to these substrates. Adsorption of ssDNA quenches intrinsic GQD fluorescence by 31.5% for low-oxidation GQDs and enables aqueous dispersion of otherwise insoluble no-oxidation GQDs. ssDNA-GQD complexation is confirmed by atomic force microscopy, by inducing ssDNA desorption, and with molecular dynamics simulations. ssDNA is determined to adsorb strongly to no-oxidation GQDs, weakly to low-oxidation GQDs, and not at all for heavily oxidized GQDs. Finally, we reveal the generality of the adsorption platform and assess how the GQD system is tunable by modifying polymer sequence and type