The electrochemical reaction controlled optical response of cholestrol oxidase (COx) conjugated CdSe/ZnS quantum dots.

This paper reports the enhanced performance of cholesterol oxidase (COx) conjugated CdSe/ZnS quantum dots (QDs) by using water-soluble mercaptoacitic acid (MAA) as linker. The functionalized MAA-CdSe/ZnS QDs conjugated in four different dilutions of cholesterol oxidase significantly affected QDs photoluminescence intensities, which affected the process of charge transfer from QDs to MAA. The conjugation of COx to MAA-QDs in increased dilutions resulted in the regain of PL intensities, which were attributed to the passivation of MAA HOMO/LUMO states. The electrochemical impedance spectroscopy and cyclic voltammetry of the conjugated QDs were performed to get study the charge transfer mechanism. The 1:1000 diluted COx conjugated MAA-CdSe/ZnS QDs was found to have the lowest charge transfer resistance of 228 Ω, the highest diffusion (~ 1.39 × 10-13 cm2/s) and charge transfer rates (~ 4.5 × 10-6 s-1) between the electrode and the redox species. The current study demonstrated the sensitivity of electrochemical and optical based detection on the alkaline.

Ellipsometric-based novel DNA biosensor for label-free, real-time detection of Bordetella parapertussis.

Pertussis (or whooping cough) is a contagious disease mainly affecting infants and children and predominantly caused by Bordetella pertussis followed by Bordetella parapertussis. B. parapertussis causes a milder cough but usually symptomatically appears like B. pertussis infection. Thus the epidemiology of illness caused by B. parapertussis is not well understood. In this study, a sensitive and specific method for the rapid diagnosis of B. parapertussis is presented. The covalent immobilization of thiol-terminated DNA oligonucleotides (ss DNA SAM) on a silicon surface by disulfide bond formation is investigated with atomic force microscopy (AFM) and ellipsometry. The measurements indicated an average layer thickness of 5 ± 0.84 nm for 2 µg/µl concentration and 24 h incubation time. This thickness changed to 8.4 ± 0.92 nm for the same concentration (2 µg/µl) by altering the incubation time to 48 h. Ellipsometric data recorded before and after hybridization of B. parapertussis revealed an increase in mean grain area from 91 nm2 to 227 nm2 and a change in the refractive index from 1.489 to 1.648 for 2 µg/µl B. parapertussis, respectively. This change in the refractive index was used to evaluate the amount of adsorbed molecules and their density. The results showed that the density of adsorbed molecules increased from 0.2 to 0.97 g/cm3 after B. parapertussis attachment, respectively. To confirm the hybridization of B. parapertussis to ss DNA SAM, the ds DNA SAM was denatured and the ss DNA SAM surface was reproduced with an average height variation of 6.42 ± 0.75 nm. This showed the stability of the DNA film that can be tuned by varying the concentration and incubation time, thus providing a robust method for the label-free detection of B. parapertussis other than routinely used PCR detection.

Catalyst driven optical properties of the self-assembled ZnS nanostructures.

In this paper, we present the effect of different catalysts (Mn, Au and Sn) on the room temperature photoluminescence and Raman spectra of VLS grown ZnS nanostructures. The catalysts found to self-dope the ZnS nanostructures during its growth were confirmed by XRD and XPS results. The extent of self-doping, which depended on the type and size of catalysts, was observed strongly to have affected the optical properties of ZnS nanostructures, particularly intrinsic defects like S and Zn vacancies. Intense broad bands in the visible due to intrinsic defects, namely Zn and S vacancies were observed, which were quite different for each catalyst as well as for the size of the catalyst. Au and Mn catalyzed ZnS nanostructures also showed creation of catalyst related defects, which were absent in the case of Sn. From the PL spectra, an estimation of the Zn and S vacancies was made for each type of catalyzed ZnS nanostructures. Surface optic (SO) phonon modes of the ZnS nanostructures were also observed to behave differently for the three catalysts. The dielectric continuum model was applied to determine the correlation length and variation in the surface potential modulations in these nanostructures. It was deduced from optical studies that the location of dopant in self-doped ZnS nanostructures strongly affected the luminescence properties. Finally it was concluded that self-doping using a suitable catalyst can be a simple and controllable way to dope ZnS nanostructures with tailored optical characteristics.

Antibacterial effects of silver nanoparticles on the bacterial strains isolated from catheterized urinary tract infection cases.

Urinary tract infections (UTI) are among the most common type of nosocomial infections. Patients with indwelling urinary catheters are at the highest risk of getting infected. The antibacterial effects of silver compounds have been known to man kind for ancient times. It has recently been found that silver nanoparticles possess significant antibacterial potential. Surface modifications of urinary catheters with Ag-NPs may prevent the risk of contamination and the associated infections. In this study we have studied the antibacterial effects of Ag-NPS on bacterial isolates from UTI cases. Our results suggest possible utility of Ag-NPs as coating agent.

Iron status of Hindu brahmin, Jain and Muslim communities in Surat, Gujarat.

AIM OF THE STUDY: To determine iron status of healthy, unrelated Brahmin, Jain and Muslim participants having different dietary habits. METHODOLOGY: Control participants other than above three communities, consumed vegetarian or non-vegetarian diet. Brahmin and Jain were strictly vegetarian but Jain did not consume roots or tubers. Muslims consumed non-vegetarian food. Standard techniques were used to measure hematological parameters, serum iron, total iron bindings capacity (TIBC), serum ferritin, transferrin and transferrin saturation. For statistical evaluation mean, standard deviation, pair t test, χ2 and ANOVA (F test) were employed. RESULTS: Study includes 565 male and 198 female children and adults. Among them 205 were children and remaining adults. All four categories i.e. control, Brahmin, Jain and Muslims showed higher incidence of anemia and iron deficiency in females compared to males. Mean values of hematological parameters did not vary significantly in four groups. Serum iron, TIBC, transferrin and ferritin levels indicated iron deficiency anemia more frequently in Jains and less frequently in Muslims (p<0.05). Iron status of Brahmin was comparable with controls (p<0.01). Majority of the participants had serum ferritin concentration >15 ng/mL. Except one male Jain child none of the participants had serum ferritin concentration <12 ng/mL. Jain subjects more frequently had serum iron concentration <60 µg/dL. CONCLUSION: Jain participants had higher incidence of iron deficiency anemia. Vegetarian diet consumed by Gujarati Hindu Brahmin community provided them with a sufficient iron to maintain their iron profile like Muslims consuming non-vegetarian diet.

Effects of aspirin and indomethacin on ventricular arrhythmias--comparative study.

The effects of aspirin and indomethacin on the ventricular arrhythmias produced by ligation (ischaemia) and unligation (reperfusion) of the circumflex branch of the left coronary vessel were evaluated in fifty male rabbits weighing 1.5-2 kg. Pretreatment of animals with aspirin (50 mg/kg i/v) suppressed all arrhythmias during ischaemia. Low dose of aspirin (12.5 mg/kg i/v) produced no mortality. Indomethacin (2.5 mg/kg) was unable to control ischaemia and reperfusion-induced ventricular arrhythmias. However, higher doses of indomethacin (50 mg/kg) suppressed ischaemia-induced arrhythmias to some extent but the mortality rate was increased (37%). Fragment of ventricular fibrillation was zero during ischaemia after treatment with aspirin and indomethacin but reperfusion-induced ventricular fibrillation was not controlled by any of these drugs. Aspirin (12.5 mg/kg, 50 mg/kg) and indomethacin (2.5 mg/kg) significantly suppressed ischaemia--induced tachyarrhythmias while reperfusion induced tachyarrhythmias were suppressed only by aspirin. There was no significant effect on the mean arterial pressure after these drug treatments.

The effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on the spontaneously beating isolated auricles of the rabbit heart.

The effects of NSAIDs (aspirin and indomethacin) on the isolated auricles of the rabbit heart were studied by observing the effects of these drugs on automaticity, excitability and contractility of the auricles. Aspirin (25,50,100 uM) produced concentration dependent depression in the automaticity of the SA node while indomethacin (10 uM, 25 uM) has stimulant effects and 50 uM produced depressant action. Only low concentration of indomethacin (10 uM) produced significant effect. Aspirin (25,50,100 uM) and indomethacin (50 uM) have significant depressant effects on the excitability of the auricles. Aspirin (100 uM) has suppressant effects (p < 0.05) on the normal contractility while the adrenaline stimulated contractility is not suppressed by aspirin and indomethacin significantly. The results obtained in this study with aspirin and indomethacin on chronotropicity and inotropicity of the rabbit atria have been discussed in the light of experimental work done by the workers regarding conventional antiarrhythmic drugs.

Stability of aspirin in solid mixtures.

It has been shown that the degradation of aspirin in mixtures may be monitored by thermal analytical techniques. The methodology employed differential scanning calorimetry and thermal gravimetric analysis by standard techniques providing simple and rapid analysis for screening the stability of aspirin in mixtures. The degradation was found to depend on the nature of the additive but, in particular, the presence of acidic or basic groups within its structure.