Multimodal Sensing Strategy Using pH Dependent Fluorescence Switchable System

Biomolecules assisted preparation of fluorescent gold nanoparticles (FL-Au NPs) has been reported in this work using glucose oxidase enzyme as both reducing and stabilizing agent and demonstrated their application through multimodal sensing strategy for selective detection of cysteine (Cys). Three different methods namely fluorescence turn OFF-ON strategy, naked eye detection and electrochemical methods are used for Cys detection by employing FL-Au NPs as a common probe. In case of fluorescence turn-OFF method a strong interaction between Au NPs and thiol results in quenching of fluorescence due to replacement of glucose oxidase by Cys at neutral pH. Second mode is based on fluorescence switch-ON strategy where initial fluorescence is significantly quenched by either excess acid or base and further addition of Cys results in appearance of rosy-red and green fluorescence respectively. Visual colour change and fluorescence emission arises due to etching of Au atoms on the surface by thiol leading to formation of Au nanoclusters. Finally, electrochemical sensing of Cys is also carried out using cyclic voltammetry in 0.1 M PBS solution. These findings provide a suitable platform for Cys detection over a wide range of pH and concentration levels and hence the sensitivity can also be tuned accordingly.

DYKE-DAVIDOFF-MASSON SYNDROME PRESENTING WITH RECURRENT SEIZURES

Dyke-Davidoff-Masson syndrome (DDMS) is cerebral hemiatrophy occurring following brain insult resulting from infarct, trauma or infection in utero or soon after birth. Clinical features of this syndrome include variable degree of contralateral hemiparesis, facial asymmetry, seizures and mental retardation. Recurrent seizures is the most debilitating and poor prognostic indicator of this disease. Neuroimaging plays pivotal role in establishing the diagnosis of DDMS syndrome. CT/MR imaging shows unilateral cerebral parenchymal atrophy, prominent sulcal spaces, ipsilateral ventriculomegaly, cerebellar atrophy, falcine and superior Sagittal sinus shift to affected side. Bone windowing in CT scan shows decreased skull volume on affected side calvarial thickening, elevation of sphenoid wing and petrous temporal bone, expanded sinuses and mastoids. Here we describe 34 years old female who had hemiparesis, seizures and facial asymmetry since childhood and imaging evaluation established diagnosis of congenital type of DDMS.

Simple and facile preparation of silver–polydopamine (Ag–PDA) core–shell nanoparticles for selective electrochemical detection of cysteine

A simple one-step method for the preparation of silver–polydopamine (Ag–PDA) core–shell nanoparticles is proposed and its application for non-enzymatic electrochemical detection of cysteine is demonstrated.

Facile and simultaneous synthesis of graphene quantum dots and reduced graphene oxide for bio-imaging and supercapacitor applications

A simple and facile method for the simultaneous preparation of graphene quantum dots (GQDs) having different emission colours, viz., yellow, green and blue, and reduced graphene oxide (RGO) utilized respectively for bio-imaging and supercapacitor applications is demonstrated.

Glucose oxidase stabilized fluorescent gold nanoparticles as an ideal sensor matrix for dual mode sensing of glucose

A simple, facile and green route for the preparation of glucose oxidase stabilized simple Au NPs and fluorescent Au NPs for the dual mode bio-sensing application of glucose using colourimetric and electrochemical methods is demonstrated.

Nickel-oxide multiwall carbon-nanotube/reduced graphene oxide a ternary composite for enzyme-free glucose sensing

We report a solvent-free method of preparation for a NiO–carbon nanotube/graphene ternary composite using nickel formate as a green precursor via a thermal decomposition method.

NEONATAL STROKE DUE TO VARICELLA ARTERIOPATHY

Varicella zoster is one of the common infective etiological factors known to produce arteriopathy of cerebral vasculature. Varicella zoster infection spreads transaxonally first to the adventitia and later transmurally to intima. Primary infection or reactivation of varicella zoster, both are associated with involvement of cerebral vessels of large as well as of small calibre varicella zoster associated arteriopathy was reported up to 12 months after the infection. Recurrence of strokes are seen post varicella infection. Hence the identification of varicella zoster as an etiological agent of ischemic stroke in neonatal age group patients is necessary and requires follow-up. Other neurologic sequelae following varicella infection are aneurysm formation leading to subarachnoid and cerebral haemorrhage, carotid dissection and rarely peripheral arterial disease. Due to lack of adequate epidemiological, neuroimaging and laboratory data, guidelines for treatment of varicella ateriopathy are not clear.

Gold nanoparticles-immobilized, hierarchically ordered, porous TiO2 nanotubes for biosensing of glutathione

Glutathione (GSH) is vital for several functions of our human body such as neutralization of free radicals and reactive oxygen compounds, maintaining the active forms of vitamin C and E, regulation of nitric oxide cycle, iron metabolism, etc. It is also an endogenous antioxidant in most of the biological reactions. Given the importance of GSH, a simple strategy is proposed in this work to develop a biosensor for quantitative detection of GSH. This particular biosensor comprises of gold nanoparticles (Au NPs)-immobilized, hierarchically ordered titanium dioxide (TiO₂) porous nanotubes. Hexagonally arranged, honeycomb-like nanoporous tubular TiO₂ electrodes are prepared by using a simple electrochemical anodization process by applying a constant potential of 30 V for 24 hours using ethylene glycol consisting of ammonium fluoride as an electrolytic medium. Structural morphology and crystalline nature of such TiO₂ nanotubes are analyzed using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). Interestingly, nanocomposites of TiO₂ with Au NPs is prepared in an effort to alter the intrinsic properties of TiO₂, especially tuning of its band gap. Au NPs are prepared by a well-known Brust and Schiffrin method and are immobilized onto TiO₂ electrodes which act as a perfect electrochemical sensing platform for GSH detection. Structural characterization and analysis of these modified electrodes are performed using FESEM, XRD, and UV-visible spectroscopic studies. GSH binding events on Au NPs-immobilized porous TiO₂ electrodes are monitored by electrochemical techniques, namely, cyclic voltammetry (CV) and chronoamperometry (CA). Several parameters such as sensitivity, selectivity, stability, limit of detection, etc are investigated. In addition, Au NPs dispersed in aqueous medium are also explored for naked-eye detection of GSH using UV-visible spectroscopy in order to compare the performance of the proposed sensor. Our studies clearly indicate that these materials could potentially be used for GSH sensing applications.

Electrochemical detection of epinephrine using a biomimic made up of hemin modified molecularly imprinted microspheres

Electrochemical detection of epinephrine, an important neurotransmitter in mammalian central nervous system, is demonstrated in this study using a simple bio-mimic prepared by hemin modified microspheres of a molecularly imprinted polymer.

Detection of the neurotransmitter dopamine by a glassy carbon electrode modified with self-assembled perovskite LaFeO3 microspheres made up of nanospheres

Glassy carbon electrode modified with LaFeO₃ microspheres made up of nanospheres and having high electrocatalytic ability to detect the neurotransmitter dopamine.

Liquid crystal (LC) monolayer on Indium Tin Oxide (ITO): structural and electrochemical characterization

Superior quality, stable monolayers of LC compounds on ITO substrates are found to be very effective in orienting bulk LC samples.

Contribution of regulatory T cells to alleviation of experimental allergic asthma after specific immunotherapy

BACKGROUND

Allergen-specific immunotherapy (SIT) has been used since 1911, yet its mechanism of action remains to be elucidated. There is evidence indicating that CD4(+)FOXP3(+) regulatory T cells (Treg cells) are induced during SIT in allergic patients. However, the contribution of these cells to SIT has not been evaluated in vivo.

OBJECTIVE

To evaluate the in vivo contribution of (i) CD4(+) CD25(+) T cells during SIT and of (ii) SIT-generated inducible FOXP3(+) Treg cells during allergen exposure to SIT-mediated suppression of asthmatic manifestations.

METHODS

We used a mouse model of SIT based on the classical OVA-driven experimental asthma. Treg cells were quantified by flow cytometry 24 and 96 h post SIT treatment. We depleted CD4(+) CD25(+) T cells prior to SIT, and CD4(+)FOXP3(+) T cells prior to allergen challenges to study their contribution to the suppression of allergic manifestations by SIT treatment.

RESULTS

Our data show that depletion of CD4(+)CD25(+) T cells at the time of SIT treatment reverses the suppression of airway hyperresponsiveness (AHR), but not of airway eosinophilia and specific IgE levels in serum. Interestingly, the number of CD4(+)CD25(+)FOXP3(+) T cells is transiently increased after SIT in the spleen and blood, suggesting the generation of inducible and presumably allergen-specific Treg cells during treatment. Depletion of CD4(+)FOXP3(+) Treg cells after SIT treatment partially reverses the SIT-induced suppression of airway eosinophilia, but not of AHR and serum levels of specific IgE.

CONCLUSION AND CLINICAL RELEVANCE

We conclude that SIT-mediated tolerance induction towards AHR requires CD4(+)CD25(+) T cells at the time of allergen injections. In addition, SIT generates CD4(+)CD25(+)FOXP3(+) T cells that contribute to the suppression of airway eosinophilia upon allergen challenges. Therefore, enhancing Treg cell number or their activity during and after SIT could be of clinical relevance to improve the therapeutic effects of SIT.

Analysis on structural, SHG efficiency, optical and mechanical properties of KDP single crystals influenced by Glycine doping

Good quality single crystals of potassium dihydrogen orthophosphate (KDP) were grown with different doping concentration of Glycine by conventional solution technique in aqueous solution. X-ray diffraction study has been carried out in order to see the effect of dopant on the structural parameters of KDP. There is no additional phase was observed which was further confirmed by Raman spectroscopic analysis. The second harmonic generation efficiency was measured by using Kurtz powder technique. The relative second harmonic generation (SHG) efficiency of the grown crystals was found to be increased with doping concentration up to 2.5 mol%. Optical transmission study also revealed the same behaviour with enhancement up to 2.5 mol% concentration and later decreased but still higher than pure KDP. The mechanical strength was found to increase with increasing the doping concentration.

A validated stability-indicating LC method for the separation of enantiomer and potential impurities of Linezolid using polar organic mode

Although a number of methods are available for evaluating Linezolid and its possible impurities, a common method for separation if its potential impurities, degradants and enantiomer in a single method with good efficiency remain unavailable. With the objective of developing an advanced method with shorter runtimes, a simple, precise, accurate stability-indicating LC method was developed for the determination of purity of Linezolid drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. This method is capable of separating all the related substances of Linezolid along with the chiral impurity. This method can also be used for the estimation of assay of Linezolid in drug substance as well as in drug product. The method was developed using Chiralpak IA (250 mm×4.6 mm, 5 μm) column. A mixture of acetonitrile, ethanol, n-butyl amine and trifluoro acetic acid in 96:4:0.10:0.16 (v/v/v/v) ratio was used as a mobile phase. The eluted compounds were monitored at 254 nm. Linezolid was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection, limit of quantification, precision, linearity, accuracy, robustness and system suitability.