High-performance graphene-titania platform for detection of phosphopeptides in cancer cells.

Phosphopeptides play a crucial role in many biological processes and constitute some of the most powerful biomarkers in disease detection. However they are often present in very low concentration, which makes their detection highly challenging. Here, we demonstrate the use of a solution-dispersible graphene-titania platform for the selective extraction of phosphopeptides from peptide mixtures. This is followed by direct analysis by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). The efficient charge and energy exchange between graphene and TiO(2) during laser irradiation in SELDI-TOF MS promotes the soft ionization of analytes and affords a detection limit in the attomole range, which is 10(2)-10(5) more sensitive than conventional platforms. The graphene-titania platform can also be used for detecting phosphopeptides in cancer cells (HeLa cells), where it shows high specificity (94%). An expanded library of 967 unique phosphopeptides is detected using significantly reduced loading of extraction matrixes compared to conventional TiO(2) bead-based assays.

Highly wrinkled cross-linked graphene oxide membranes for biological and charge-storage applications.

Inspired by the amphiphilicity of graphene oxide (GO), the surface of water is used as a template for the assembly of a GO film. Methacrylate-functionalized GO sheets can be cross-linked instantaneously at the water-air interface to form a highly wrinkled membrane spreading over an extended area. The multiple covalent linkages amongst the GO sheets enhances the in-plane stiffness of the film compared to noncovalently bonded GO films. The highly convoluted GO membrane can be used in two applications: the promoting of spontaneous stem-cell differentiation towards bone cell lineage without any chemical inducers, and for supercapacitor electrodes. Due to reduced van der Waals restacking, capacitance values up to 211 F g(-1) can be obtained. The scalable and inexpensive nature of this assembly route enables the engineering of membranes for applications in regenerative medicine and energy-storage devices where secondary structures like nanotopography and porosity are important performance enhancers.

Origin of enhanced stem cell growth and differentiation on graphene and graphene oxide.

The culture of bone marrow derived mesenchymal stem cells (MSCs), as well as the control of its differentiation toward different tissue lineage, is a very important part of tissue engineering, where cells are combined with artificial scaffold to regenerate tissues. Graphene (G) and graphene oxide (GO) sheets are soft membranes with high in-plane stiffness and can potentially serve as a biocompatible, transferable, and implantable platform for stem cell culture. While the healthy proliferation of stem cells on various carbon platforms has been demonstrated, the chemical role of G and GO, if any, in guiding uncommitted stem cells toward differentiated cells is not known. Herein, we report that the strong noncovalent binding abilities of G allow it to act as a preconcentration platform for osteogenic inducers, which accelerate MSCs growing on it toward the osteogenic lineage. The molecular origin of accelerated differentation is investigated by studying the binding abilities of G and GO toward different growth agents. Interestingly, differentiation to adipocytes is greatly suppressed on G because insulin, which is a key regulator for the synthesis of fatty acids, is denatured upon π-π adsorption on G; in contrast, GO does not interfere with adipogenesis due to electrostatic binding with insulin. The different binding interactions and their subsequent influence on stem cell growth and differentiation are ascribed to different degrees of π-π stacking and electrostatic and hydrogen bonding mediated by G and GO.

Age-related changes in the corpus callosum in early-onset bipolar disorder assessed using volumetric and cross-sectional measurements.

Corpus callosum (CC) area abnormalities have been reported in magnetic resonance imaging (MRI) studies of adults and youths with bipolar disorder (BPD), suggesting interhemispheric communication may be abnormal in BPD and may be present early in the course of illness and affect normal neuromaturation of this structure throughout the lifecycle. Neuroimaging scans from 44 youths with DSM-IV BPD and 22 healthy controls (HC) were analyzed using cross-sectional area measurements and a novel method of volumetric parcellation. Univariate analyses of variance were conducted on CC subregions using both volume and traditional area measurements. Youths with BPD had smaller middle and posterior callosal regions, and reduced typical age-related increases in CC size. The cross-sectional area and novel volumetric methodologies resulted in similar findings. Future longitudinal assessments of CC development would track the evolution of callosal abnormalities in youths with BPD and allow exploration of the functional significance of these findings.

Graphene-based SELDI probe with ultrahigh extraction and sensitivity for DNA oligomer.

We demonstrate that graphene can be used as an ultrahigh efficiency preconcentration and detection platform for ssDNA. DNA-adsorbed graphene can be used directly for Surface Enhanced Laser Desorption Ionization-Time of Flight-Mass Spectrometry (SELDI-TOF-MS). The rapid enrichment of biomolecules and direct, label-free detection are potentially useful for analysis in proteomics and genomics.

Room-temperature synthesis of soluble carbon nanotubes by the sonication of graphene oxide nanosheets.

The transformation of two-dimensional graphene oxide (GO) nanosheets into carbon nanotubes was achieved by sonicating GO in 70% nitric acid. Through the use of mass spectrometry to track the evolution of molecular fragments during the acid ultrasonication, it was observed that GO can be readily decomposed into polyaromatic hydrocarbons (PAHs). The cavitation-induced condensation of these PAHs results in their molecular reconstruction to form folded carbon nanostructures. UV-emitting, water-soluble carbon nanoparticles as well as carbon nanotubes that exhibit magnetic properties were fabricated under catalyst-free conditions.

Subcortical differences among youths with attention-deficit/hyperactivity disorder compared to those with bipolar disorder with and without attention-deficit/hyperactivity disorder.

INTRODUCTION: A significant number of children with bipolar disorder (BP) have co-morbid attention-deficit/hyperactivity disorder (ADHD). It is unknown if these children have neuroimaging findings unique to their co-morbid presentation, or if their brain findings are similar to children diagnosed with BP alone. METHOD: Fifty three children with Diagnostic and Statistical Manual of Mental Disorders, 4(th) edition (DSM-IV) BP (23 with ADHD, 30 without), 29 healthy controls (HC), and 23 children with ADHD, similar in sex and age, had magnetic resonance imaging (MRI) scans on a 1.5T GE scanner. Volumetric assessments were performed for basal ganglia and limbic subcortical structures. RESULTS: Youths with ADHD had smaller caudate and putamen volumes compared to both BP groups and they had moderately smaller total amygdala volumes compared to the other three groups. Youths with BP + ADHD had moderately larger nucleus accumbens volumes than HC, and females in both BP groups had smaller hippocampal volumes compared to ADHD and HC. No differences were found between the BP and BP + ADHD groups. CONCLUSION: These data suggest that morphometric subcortical volumes in youths with BP + ADHD are more similar to those in youths with BP. They do not share subcortical neuroanatomic correlates with the ADHD group. These findings suggest that BP + ADHD is a subtype of pediatric BP rather than severe ADHD.

Amygdala volume associated with alcohol abuse relapse and craving.

OBJECTIVE: Amygdala volume has been associated with drug craving in cocaine addicts, and amygdala volume reduction is observed in some alcohol-dependent subjects. This study sought an association in alcohol-dependent subjects between volumes of reward-related brain regions, alcohol craving, and the risk of relapse. METHOD: Besides alcohol craving, the authors assessed amygdala, hippocampus, and ventral striatum volumes in 51 alcohol-dependent subjects and 52 age- and education-matched healthy comparison subjects after detoxification. After imaging and clinical assessment, patients were followed for 6 months and alcohol intake was recorded. RESULTS: Alcohol-dependent subjects showed reduced amygdala, hippocampus, and ventral striatum volumes and reported stronger craving in relation to healthy comparison subjects. However, only amygdala volume and craving differentiated between subsequent relapsers and abstainers. A significant decrease of amygdala volume in alcohol-dependent subjects was associated with increased alcohol craving before imaging and an increased alcohol intake during the 6-month follow-up period. CONCLUSIONS: These findings suggest a relationship between amygdala volume reduction, alcohol craving, and prospective relapse into alcohol consumption.