Bone Marrow Mesenchymal Stromal Cells on Silk Fibroin Scaffolds to Attenuate Polymicrobial Sepsis Induced by Cecal Ligation and Puncture.

Suitable scaffolds with appropriate mechanical and biological properties can improve mesenchymal stromal cell (MSC) therapy. Because silk fibroins (SFs) are biocompatible materials, they were electrospun and applied as scaffolds for MSC therapy. Consequently, interferon (IFN)-primed human bone marrow MSCs on SF nanofibers were administered into a polymicrobial sepsis murine model. The IL-6 level gradually decreased from 40 ng/mL at 6 h after sepsis to 35 ng/mL at 24 h after sepsis. The IL-6 level was significantly low as 5 ng/mL in primed MSCs on SF nanofibers, and 15 ng/mL in primed MSCs on the control surface. In contrast to the acute response, inflammation-related factors, including HO-1 and COX-2 in chronic liver tissue, were effectively inhibited by MSCs on both SF nanofibers and the control surface at the 5-day mark after sepsis. An in vitro study indicated that the anti-inflammatory function of MSCs on SF nanofibers was mediated through enhanced COX-2-PGE2 production, as indomethacin completely abrogated PGE2 production and decreased the survival rate of septic mice. Thus, SF nanofiber scaffolds potentiated the anti-inflammatory and immunomodulatory functions of MSCs, and were beneficial as a culture platform for the cell therapy of inflammatory disorders.

Silk fibroin scaffolds potentiate immunomodulatory function of human mesenchymal stromal cells.

Although mesenchymal stromal cells (MSCs) show great potential for use in regenerative medicine, their therapeutic efficacy remains limited because of their low adaptation efficiency and viability observed in clinical trials. To potentiate the adaptation and survival efficiency of MSCs after administration in vivo, silk fibroin nanofibers (SFNs) were applied as a scaffold. SFNs are biocompatible, biodegradable polymers with tunable architectures and mechanical properties. Treatment with interferon (IFN)-γ for 18 h increased the expression of immunomodulatory functional cytokines, IDO and COX2 in MSCs. Further, the MSCs grown on SFN sheets showed enhanced IDO1 and COX2 expression following IFN-γ treatment. MSCs showed significantly greater migratory ability on SFN sheets than on glass surfaces or PLGA control sheets. Though IFN-γ treatment slightly reduced the migration ability of MSCs cultured on glass or poly(lactic-co-glycolic acid) (PLGA) nanofiber sheets, it did not alter MSC motility on SFN sheets. Furthermore, MSCs cultured on SFN sheets dramatically suppressed TNF-α secretion from lipopolysaccharide-activated murine splenocytes, suggesting that the immunomodulatory function of MSCs was enhanced by the SFN sheets. Taken together, these data demonstrate that SFN sheets potentiate the reparative and regenerative properties of MSCs.

Toxicity of graphene nanoflakes evaluated by cell-based electrochemical impedance biosensing.

Graphene nanoflake toxicity was analyzed using cell-based electrochemical impedance biosensing with interdigitated indium tin oxide (ITO) electrodes installed in a custom-built mini-incubator positioned on an inverted optical microscope. Sensing with electrochemical measurements from interdigitated ITO electrodes was highly linear (R(2) = 0.93 and 0.96 for anodic peak current (Ipa) and cathodic peak current (Ipc), respectively). Size-dependent analysis of Graphene nanoflake toxicity was carried out in a mini-incubator system with cultured HeLa cells treated with Graphene nanoflakes having an average size of 80 or 30 nm for one day. Biological assays of cell proliferation and viability complemented electrochemical impedance measurements. The increased toxicity of smaller Graphene nanoflakes (30 nm) as measured by electrochemical impedance sensing and optical monitoring of treated cells was consistent with the biological assay results. Cell-based electrochemical impedance biosensing can be used to assess the toxicity of nanomaterials with different biomedical and environmental applications.

Reduction in oxidative stress during cellular responses to chemically functionalised graphene.

The two-dimensional nanocarbon material graphene (Gr) has been extensively studied due to its many potential biomedical applications including regenerative medicine, drug delivery, bioimaging, and biosensing. The effects of nitrogen-functionalisation on chemically driven Gr (CDG) cellular responses were studied by investigating the generation of reactive oxygen species (ROS) and mitochondrial morphology as well as focal adhesion, shape, proliferation and viability of HeLa cells grown on functionalised CDG (f-CDG) films. The drop casting of CDG nanosheets formed thin CDG films and the formation of nitrogen groups on the f-CDG thin films was mediated by N2 plasma treatment without the formation of observable surface defects. N-containing functional groups on the CDG thin films contributed to an increase in hydrophilicity. The proliferation and viability of HeLa cells grown on the f-CDG thin films were enhanced compared to those grown on CDG films alone and control samples. N-functionalisation of CDG thin films effectively reduced the ROS generated from cells on the f-CDG films. These results indicate that N2 plasma treatment of CDG is very useful in improving biocompatibility for the bio-application of graphene materials.

Electrical graphene aptasensor for ultra-sensitive detection of anthrax toxin with amplified signal transduction.

Detection of the anthrax toxin, the protective antigen (PA), at the attomolar (aM) level is demonstrated by an electrical aptamer sensor based on a chemically derived graphene field-effect transistor (FET) platform. Higher affinity of the aptamer probes to PA in the aptamer-immobilized FET enables significant improvements in the limit of detection (LOD), dynamic range, and sensitivity compared to the antibody-immobilized FET. Transduction signal enhancement in the aptamer FET due to an increase in captured PA molecules results in a larger 30 mV/decade shift in the charge neutrality point (Vg,min ) as a sensitivity parameter, with the dynamic range of the PA concentration between 12 aM (LOD) and 120 fM. An additional signal enhancement is obtained by the secondary aptamer-conjugated gold nanoparticles (AuNPs-aptamer), which have a sandwich structure of aptamer/PA/aptamer-AuNPs, induce an increase in charge-doping in the graphene channel, resulting in a reduction of the LOD to 1.2 aM with a three-fold increase in the Vg,min shift.

pH sensing characteristics and biosensing application of solution-gated reduced graphene oxide field-effect transistors.

Solution-gated reduced graphene oxide field-effect transistors (R-GO FETs) were investigated for pH sensing and biochemical sensing applications. A channel of a networked R-GO film formed by self-assembly was incorporated as a sensing layer into a solution-gated FET structure for pH sensing and the detection of acetylcholine (Ach), which is a neurotransmitter in the nerve system, through enzymatic reactions. The fabricated R-GO FET was sensitive to protons (H(+)) with a pH sensitivity of 29 mV/pH in terms of the shift of the charge neutrality point (CNP), which is attributed to changes in the surface potential caused by the interaction of protons with OH surface functional groups present on the R-GO surface. The R-GO FET immobilized with acetylcholinesterase (AchE) was used to detect Ach in the concentration range of 0.1-10mM by sensing protons generated during the enzymatic reactions. The results indicate that R-GO FETs provide the capability to detect protons, demonstrating their applicability as a biosensing device for enzymatic reactions.

Reduced graphene oxide field-effect transistor for label-free femtomolar protein detection.

We report reduced graphene oxide field effect transistor (R-GO FET) biosensor for label-free ultrasensitive detection of a prostate cancer biomarker, prostate specific antigen/α1-antichymotrypsin (PSA-ACT) complex. The R-GO channel in the device was formed by reduction of graphene oxide nanosheets networked by a self-assembly process. Immunoreaction of PSA-ACT complexes with PSA monoclonal antibodies on the R-GO channel surface caused a linear response in the shift of the gate voltage, V(g,min), where the minimum conductivity occurs. The R-GO FET can detect protein-protein interactions down to femtomolar level with a dynamic range over 6-orders of magnitude in the V(g,min) shift as a sensitivity parameter. High association constants of 3.2 nM(-1) and 4.2 nM(-1) were obtained for the pH 6.2 and pH 7.4 analyte solutions, respectively. The R-GO FET biosensor showed a high specificity to other cancer biomarker in the phosphate buffered saline solutions as well as in the human serum.

Amine-modified single-walled carbon nanotubes protect neurons from injury in a rat stroke model.

Stroke results in the disruption of tissue architecture and is the third leading cause of death in the United States. Transplanting scaffolds containing stem cells into the injured areas of the brain has been proposed as a treatment strategy, and carbon nanotubes show promise in this regard, with positive outcomes when used as scaffolds in neural cells and brain tissues. Here, we show that pretreating rats with amine-modified single-walled carbon nanotubes can protect neurons and enhance the recovery of behavioural functions in rats with induced stroke. Treated rats showed less tissue damage than controls and took longer to fall from a rotating rod, suggesting better motor functions after injury. Low levels of apoptotic, angiogenic and inflammation markers indicated that amine-modified single-walled carbon nanotubes protected the brains of treated rats from ischaemic injury.

Construction of protein-resistant pOEGMA films by helicon plasma-enhanced chemical vapor deposition.

This paper describes the formation of protein-resistant, poly(ethylene glycol) methyl ether methacrylate (pOEGMA) thin films by helicon plasma-enhanced chemical vapor deposition (helicon-PECVD). pOEGMA was successfully grafted onto a silicon substrate, as a model substrate, without any additional surface initiators, by plasma polymerization of OEGMA. The resulting pOEGMA films were characterized by ellipsometry, FT-IR spectroscopy, X-ray photoelectron spectroscopy and contact angle goniometry. To investigate the protein-resistant property of the pOEGMA films, four different proteins, bovine serum albumin, fibrinogen, lysozyme and ribonuclease A, were tested as model proteins for ellipsometric measurements. The ellipsometric thickness change for all the model proteins was less than 3 A, indicating that the formed pOEGMA films are protein-resistant.

Kynurenic acid attenuates MPP(+)-induced dopaminergic neuronal cell death via a Bax-mediated mitochondrial pathway.

Kynurenic acid (KYNA), a tryptophan metabolite in the kynurenine pathway, is protective against various insults. However, the molecular mechanism of this protective effect has not been identified. In this study, we examined the protective effects of KYNA against 1-methyl-4-phenylpyridinium (MPP(+)), the best-characterized toxin inducing pathological changes resembling Parkinson's disease (PD), using SH-SY5Y and SK-N-SH human neuroblastoma cells. Pre-treatment of KYNA attenuated MPP(+)-induced neuronal cell death in SH-SY5Y and SK-N-SH cells. MPP(+)-induced cell death was preceded by increases in Bax expression and mitochondrial dysfunction, such as collapse of mitochondrial membrane potential (DeltaPsi(m)), release of cytochrome c from mitochondria into the cytoplasm, and increases in caspase-9/-3 activities. KYNA effectively inhibited all of these mitochondrial apoptotic processes. Our results indicate that KYNA plays a protective role by down-regulating Bax expression and maintaining mitochondrial function in MPP(+)-induced neuronal cell death, and suggest that KYNA may have therapeutic potential in PD.