Protein spot arrays on graphene oxide coatings for efficient single-cell capture.

Biomedical applications such as cell screening or cell-cell interaction studies require placement and adhesion of cells on surfaces with controlled numbers and location. In particular, single-cell arraying and positioning has come into focus as a basis of such applications. An ideal substrate would combine biocompatibility with favorable attributes such as pattern stability and easy processing. Here, we present a simple yet effective approach to single-cell arraying based on a graphene oxide (GO) surface carrying protein (fibronectin) microarrays to define cell adhesion points. These capture NIH-3T3 cells, resulting in cell arrays, which are benchmarked against analogous arrays on silanized glass samples. We reveal significant improvement in cell-capture performance by the GO coating with regards to overall cell adhesion and single-cell feature occupancy. This overall improvement of cell-arraying combined with retained transparency of substrate for microscopy and good biocompatibility makes this graphene-based approach attractive for single-cell experiments.

Adsorption and binding dynamics of graphene-supported phospholipid membranes using the QCM-D technique.

We report on the adsorption dynamics of phospholipid membranes on graphene-coated substrates using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique. We compare the lipid vesicle interaction and membrane formation on gold and silicon dioxide QCM crystal surfaces with their graphene oxide (GO) and reduced (r)GO coated counterparts, and report on the different lipid structures obtained. We establish graphene derivative coatings as support surfaces with tuneable hydrophobicity for the formation of controllable lipid structures. One structure of interest formed is lipid monolayer membranes which were formed on rGO, which are otherwise challenging to produce. We also demonstrate and monitor biotin-avidin binding on such a membrane, which will then serve as a platform for a wide range of biosensing applications. The QCM-D technique could be extended to both fundamental studies and applications of other covalent and non-covalent interactions in 2-dimensional materials.

Ultra-thin graphene-polymer heterostructure membranes.

The fabrication of arrays of ultra-thin conductive membranes remains a major challenge in realising large-scale micro/nano-electromechanical systems (MEMS/NEMS), since processing-stress and stiction issues limit the precision and yield in assembling suspended structures. We present the fabrication and mechanical characterisation of a suspended graphene-polymer heterostructure membrane that aims to tackle the prevailing challenge of constructing high yield membranes with minimal compromise to the mechanical properties of graphene. The fabrication method enables suspended membrane structures that can be multiplexed over wafer-scales with 100% yield. We apply a micro-blister inflation technique to measure the in-plane elastic modulus of pure graphene and of heterostructure membranes with a thickness of 18 nm to 235 nm, which ranges from the 2-dimensional (2d) modulus of bare graphene at 173 ± 55 N m-1 to the bulk elastic modulus of the polymer (Parylene-C) as 3.6 ± 0.5 GPa as a function of film thickness. Different ratios of graphene to polymer thickness yield different deflection mechanisms and adhesion and delamination effects which are consistent with the transition from a membrane to a plate model. This system reveals the ability to precisely tune the mechanical properties of ultra-thin conductive membranes according to their applications.

Lung cancer detection by native fluorescence spectra of body fluids--a preliminary study.

Lung cancer takes a heavy toll every year, since the survival rate is not more than 15%. In this paper, we present results of a novel technique based on the autofluorescence of body fluids like blood plasma, acetone extract of cellular components, sputa and urine of lung cancer patients (N=27). A set of ratio parameters based on the fluorescence peaks of tryptophan and elastin, in plasma and sputum; flavin, NADH (reduced nicotinamide adenine dinucleotide) and porphyrin in urine; porphyrin alone in acetone extract of formed elements, were all evaluated. Similar sets of ratios were obtained for age adjusted normal controls (N=27) and all these ratios were given as inputs to multivariate (principle component and discriminant) analyses, which showed that the two groups could be classified with an accuracy of about 90%. Since the instrumentation involved was an ordinary steady state Xe lamp based spectrofluorometer, the technique is of significant advantage in screening and early detection of lung cancer in high risk population such as heavy smokers.

Phonon-assisted electroluminescence from metallic carbon nanotubes and graphene.

We report on light emission from biased metallic single-wall carbon nanotube (SWNT), multiwall carbon nanotube (MWNT) and few-layer graphene (FLG) devices. SWNT devices were assembled from tubes with different diameters in the range 0.7-1.5 nm. They emit light in the visible spectrum with peaks at 1.4 and 1.8 eV. Similar peaks are observed for MWNT and FLG devices. We propose that this light emission is due to phonon-assisted radiative decay from populated pi* band states at the M point to the Fermi level at the K point. Since for most carbon nanotubes as well as for graphene the energy of unoccupied states at the M point is close to 1.6 eV, the observation of two emission peaks at approximately 1.6 +/- approximately 0.2 eV could indicate radiative decay under emission or absorption of optical phonons, respectively.

Functionalization of carbon nanotubes using phenosafranin.

Spectroscopic analysis and atomic force microscopy (AFM) phase imaging studies show self-assembly of phenosafranin (PSF) to multiwalled carbon nanotubes (MWNTs). The shift in absorption spectra is associated with charge transfer of valence electrons from PSF to electron accepting sites on the MWNTs. The Raman-active disorder modes are used to fingerprint PSF attachment to MWNTs via defect states. AFM phase imaging was used to obtain a molecular topographic visual confirmation of PSF attached to the MWNT.

Treatment of Parkinson's disease.

Inspite of extensive research the ideal drug therapy for idiopathic Parkinson's disease (PD) and its optimal timing remain uncertain. Levodopa still is the mainstay of therapy for PD. Little evidence exists to incriminate early institution of levodopa therapy in development of motor fluctuations and dyskinesias in PD. These complications are probably a consequence of disease progression, and resultant inability to synthesise and store dopamine, and buffer the variability in dopamine availability. Therefore, withholding levodopa therapy until late stage of the disease is not warranted. Dopa agonists provide only a short-term benefit. The neuroprotective effect of selegeline remains to be established. There is not enough evidence to justify the current practice of initiating treatment for PD patients with expensive polypharmacy. Research into the development of inexpensive levodopa containing preparations needs to be encouraged.

Multimodality evoked potentials in aortoarteritis.

Brainstem auditory evoked potentials (BAEPs) have been used to detect early and even asymptomatic brain ischemia. There is a need to detect subclinical brain and/or spinal cord ischemia in patients with aortoarteritis so that ischemic deficits can be prevented by early intervention. We studied multimodality (Visual evoked potentials--VEPs, Somatosensory evoked potentials--SEPs and BAEPs) evoked potentials (EPs) in 10 neurologically asymptomatic subjects with aortoarteritis. EP latencies were normal in all the patients studied. The possible value of EP latencies in detection of early brain and/or spinal cord ischemia in patients with aortoarteritis is discussed.

Treatment of Parkinson's disease.

Inspite of extensive research the ideal drug therapy for idiopathic Parkinson's disease (PD) and its optimal timing remain uncertain. Levodopa still is the mainstay of therapy for PD. Little evidence exists to incriminate early institution of levodopa therapy in the development of motor fluctuations and dyskinesias in PD. These complications are probably a consequence of disease progression, and resultant inability to synthesize and store dopamine, and buffer the variability in dopamine availability. Therefore, withholding levodopa therapy until late stage of the disease is not warranted. Dopa agonists provide only a short-term benefit. The neuroprotective effect of selegiline remains to be established. There is not enough evidence to justify the current practice of initiating treatment for PD patients with expensive polypharmacy. Research into the development of inexpensive levodopa containing preparations needs to be encouraged.

Neurological intensive care in India.

BACKGROUND: Intensive care units need to be optimally utilized especially in developing countries such as India where they are rare and artificial ventilators are available for a limited number of patients. Data concerning the outcome of diverse neurological emergencies are required to enable physicians to make decisions and to advise families of patients on issues such as the institution of artificial ventilation and the use of pressor agents. METHODS: We analysed 271 patients admitted over a 24-month period to our 5-bed neurological intensive care unit, and related the outcome to the occurrence of coma (Group I, n=100), respiratory failure without coma (Group II, n=32) and no respiratory failure or coma (Group III, n=139). Patients with pre-terminal coma alone were included in Group III. RESULTS: Whereas the three groups were similar with regard to age, sex and social class, mortality was entirely different (overall mortality 44%, Group I 86%, Group II 56% , Group III 12%). Only one comatose patient made a good recovery. Among patients requiring ventilatory support, the highest mortality was recorded in comatose patients (62/65; 95%) and the lowest in those with the Guillain-Barré syndrome (6/15; 40%). CONCLUSIONS: We suggest that artificial ventilation be used only in those comatose patients where the underlying cause is potentially reversible such as status epilepticus and that a multicentre study be conducted in the Third World on the prognosis of coma and the use of intensive care units.