Multiscale Modulation of Nanocrystalline Cellulose Hydrogel via Nanocarbon Hybridization for 3D Neuronal Bilayer Formation.

Bacterial biopolymers have drawn much attention owing to their unconventional three-dimensional structures and interesting functions, which are closely integrated with bacterial physiology. The nongenetic modulation of bacterial (Acetobacter xylinum) cellulose synthesis via nanocarbon hybridization, and its application to the emulation of layered neuronal tissue, is reported. The controlled dispersion of graphene oxide (GO) nanoflakes into bacterial cellulose (BC) culture media not only induces structural changes within a crystalline cellulose nanofibril, but also modulates their 3D collective association, leading to substantial reduction in Young's modulus (≈50%) and clear definition of water-hydrogel interfaces.

Monolayer Graphene-Directed Growth and Neuronal Differentiation of Mesenchymal Stem Cells.

The development of an efficient platform for the growth and neuronal differentiation of stem cells is crucial for autologous cell therapy and tissue engineering to treat various neuronal disorders and neurodegenerative diseases. In this study, we describe the use of highly uniform graphene platforms that provide unique environments where unusual three-dimensional spheroids of human mesenchymal stem cells (hMSCs) are formed, which is advantageous for the differentiation of hMSCs into neurons. We suppose that graphene regulates the interactions at cell-substrate or cell-cell interfaces, consequently promoting the neurogenesis of hMSCs as well as the outgrowth of neurites, which was evidenced by the graphene-induced upregulation of early neurogenesis-related genes.

Stable n-type doping of graphene via high-molecular-weight ethylene amines.

We demonstrate a stable and strong n-type doping method to tune the electrical properties of graphene via vapor phase chemical doping with various high-molecular-weight ethylene amines. The resulting carrier concentration after doping with pentaethylenehexamine (PEHA) is as high as -1.01 × 10(13) cm(-2), which reduces the sheet resistance of graphene by up to ∼400% compared to pristine graphene.

In situ hybridization of carbon nanotubes with bacterial cellulose for three-dimensional hybrid bioscaffolds.

Carbon nanotubes (CNTs) have shown great potential in biomedical fields. However, in vivo applications of CNTs for regenerative medicine have been hampered by difficulties associated with the fabrication of three-dimensional (3D) scaffolds of CNTs due to CNTs' nano-scale nature. In this study, we devised a new method for biosynthesis of CNT-based 3D scaffold by in situ hybridizing CNTs with bacterial cellulose (BC), which has a structure ideal for tissue-engineering scaffolds.

Graphene oxide flakes as a cellular adhesive: prevention of reactive oxygen species mediated death of implanted cells for cardiac repair.

Mesenchymal stem cell (MSC) implantation has emerged as a potential therapy for myocardial infarction (MI). However, the poor survival of MSCs implanted to treat MI has significantly limited the therapeutic efficacy of this approach. This poor survival is primarily due to reactive oxygen species (ROS) generated in the ischemic myocardium after the restoration of blood flow.

Roll-to-roll continuous patterning and transfer of graphene via dispersive adhesion.

We present a roll-to-roll, continuous patterning and transfer of graphene sheets capable of residue-free and fast patterning. The graphene sheet is supported with dispersive adhesion. Graphene is continuously patterned by the difference in adhesion forces with a pre-defined embossed roller.

Graphene enhances the cardiomyogenic differentiation of human embryonic stem cells.

Graphene has drawn attention as a substrate for stem cell culture and has been reported to stimulate the differentiation of multipotent adult stem cells. Here, we report that graphene enhances the cardiomyogenic differentiation of human embryonic stem cells (hESCs) at least in part, due to nanoroughness of graphene. Large-area graphene on glass coverslips was prepared via the chemical vapor deposition method.

Graphene-regulated cardiomyogenic differentiation process of mesenchymal stem cells by enhancing the expression of extracellular matrix proteins and cell signaling molecules.

The potential of graphene as a mesenchymal stem cell (MSC) culture substrate to promote cardiomyogenic differentiation is demonstrated. Graphene exhibits no sign of cytotoxicity for stem cell culture. MSCs are committed toward cardiomyogenic lineage by simply culturing them on graphene.

Bacterial cellulose nanofibrillar patch as a wound healing platform of tympanic membrane perforation.

Bacterial cellulose (BC)-based biomaterials on medical device platforms have gained significant interest for tissue-engineered scaffolds or engraftment materials in regenerative medicine. In particular, BC has an ultrafine and highly pure nanofibril network structure and can be used as an efficient wound-healing platform since cell migration into a wound site is strongly meditated by the structural properties of the extracellular matrix. Here, the fabrication of a nanofibrillar patch by using BC and its application as a new wound-healing platform for traumatic tympanic membrane (TM) perforation is reported.

Graphene-incorporated chitosan substrata for adhesion and differentiation of human mesenchymal stem cells.

A simple method that uses graphene to fabricate nanotopographic substrata was reported for stem cell engineering. Graphene-incorporated chitosan substrata promoted adhesion and differentiation of human mesenchymal stem cells (hMSCs). In addition, we proposed that nanotopographic cues of the substrata could enhance cell-cell and cell-material interactions for promoting functions of hMSCs.

Use of magnetic nanoparticles to manipulate the metabolic environment of bacteria for controlled biopolymer synthesis.

Magnetic nanoparticles (MNPs) were covalently immobilized on the surface of Acetobacter xylinus and the location of the bacteria was controlled to manipulate bacterial bioactivation. The bacteria were positioned in the middle of an incubation tube by applying an external magnetic field, and the cellulose produced at the different metabolizing locations was characterized by X-ray diffraction, electron microscopy, and differential scanning calorimetry. To the best of our knowledge, this is the first experiment in which MNPs were employed in the control of cell metabolism.

Amphiphilic comb-like polymer for harvest of conductive nano-cellulose.

In this study, electrically conductive bacterial cellulose (BC) was prepared by culturing Gluconacetobacter xylinus in a carbon nanotube (CNT)-dispersed medium. The CNTs were dispersed by adopting a non-covalent approach in the presence of non-ionic amphiphilic comb-like polymer (CLP). Specifically, the hydrophobic backbone of CLP was chemophysically attached to the surface of the CNTs and the hydrophilic side chains were released freely toward the medium in an aqueous environment.

Amphiphilic comblike polymers enhance the colloidal stability of Fe(3)O(4) nanoparticles.

Stable colloidal dispersions of magnetite (Fe(3)O(4)) nanoparticles (MNPs) were obtained with the inclusion of an amphiphilic comblike polyethylene glycol derivative (CL-PEG) as an amphiphilic polymeric surfactant. Both the size and morphology of the resulting CL-PEG-modified MNPs could be controlled and were characterized by transmission electron microscopy (TEM). The interaction between MNPs and CL-PEG was confirmed by the presence of characteristic infrared absorption peaks, and the colloidal stability of the nanoparticle dispersion in water was evaluated by long-term observation of the dispersion using UV-visible spectroscopy.