Shahnaz Qadri

Removal and recovery of acridine orange from solutions by use of magnetic nanoparticles.

Here we report a separation of a cationic dye, acridine orange (AO), by use of magnetic nanoparticles (gamma-Fe(2)O(3)). The particles were showed to capture 98% of the dye within the first 20 min of contact time. The maximum sorption capacity of the magnetic nanoparticles (MNPs) for AO was 59mg/g. The sorption isotherms fit well with the Freundlich model. The sorption kinetics fits well the pseudo-second-order rate equation model. 60-90% dye recovery was achieved by rotary evaporating the dye bearing nanoparticles in acetone. The nanoparticles were recycled for additional dye removal.

Oxyradical-induced GFP damage and loss of fluorescence.

Small amounts of highly reactive oxygen species (oxyradicals) are normal by-products of cellular metabolism. However, under certain conditions large amounts of oxyradicals are generated inside cells which may cause extensive cellular damage. Not surprisingly, a large number of disease states have been linked to oxidative stress, including cancer, diabetes, Parkinsons disease, Alzheimers disease, and heart disease. Previously, we had shown that fluorescence spectroscopy could be used to study the pH-dependence of GFP denaturation with various agents. In this report, we show that GFP readily loses its auto-fluorescence upon exposure to oxyradicals as measured by fluorescence spectroscopy. We further show that oxyradical scavengers can prevent this loss of GFP fluorescence, thus oxyradical-induced loss of GFP fluorescence could be used to screen for antioxidants. We have evaluated various parameters which could affect the sensitivity of this GFP-based oxyradical scavenging assay, such as concentration H(2)O(2) used to produce oxyradicals, pH of the buffer, as well as UV intensity. Surprisingly we found that pH had a very dramatic effect on oxyradical-induced GFP damage. GFP was found to be most susceptible to oxyradical-induced damage at pH 6.5, and least susceptible at pH 8.5. This is the first demonstration that GFP loses its fluorescence upon exposure to oxyradicals. Furthermore, the data presented here suggest that GFP could be used to develop assays to screen for antioxidants or radical scavengers.

PEG coating reduces NMR relaxivity of Mn0.5Zn0.5Gd0.02Fe1.98O4 hyperthermia nanoparticles

To investigate both T1 and T2 MR relaxation enhancement of Gd substituted Zn‐Mn ferrite magnetic nanoparticles. Both uncoated and polyethylene glycol (PEG) coated particles were used.

Acute systemic exposure to silver-based nanoparticles induces hepatotoxicity and NLRP3-dependent inflammation

Abstract Nanoparticles (NPs) are increasingly being commercialized for use in biomedicine. NP toxicity following acute or chronic exposure has been described, but mechanistic insight into this process remains incomplete. Recent evidence from in vitro studies suggested a role for NLRP3 in NP cytotoxicity. In this study, we investigated the effect of systemic administration of composite inorganic NP, consisting of Ag:Cu:B (dose range 1–20 mg/kg), on the early acute (4–24 h post-exposure) and late phase response (96 h post-exposure) in normal and NLRP3-deficient mice. Our findings indicate that systemic exposure (≥2 mg/kg) was associated with acute liver injury due to preferential accumulation of NP in this organ and resulted in elevated AST, ALT and LDH levels. Moreover, within 24 h of NP administration, there was a dose-dependent increase in intraperitoneal neutrophil recruitment and upregulation in gene expression of several proinflammatory mediators, including TNF-α, IL-1β and S100A9. Histological analysis of liver tissue revealed evidence of dose-dependent hepatocyte necrosis, increase in sinusoidal Kupffer cells, lobular granulomas and foci of abscess formation which were most pronounced at 24 h following NP administration. NP deposition in the liver led to a significant upregulation in gene expression of S100A9, an endogenous danger signal recognition molecule of phagocytes, IL-1β and IL-6. The extent of proinflammatory cytokine activation and hepatotoxicity was significantly attenuated in mice deficient in the NLRP3 inflammasome, demonstrating the critical role of this innate immune system recognition receptor in the response to NP.

Phase change material for efficient removal of crystal violet dye.

Hazardous dye removal and recovery from wastewater requires efficient capturing material. We report a phase change material (PCM) with phase change temperature of 16 degrees C giving up to 98% removal of crystal violet in few minutes. The PCM was found to collect 54 times of its weight soluble dye. The dye adsorption kinetics obeys a second order pseudo rate. Upon cooling the PCM to below 16 degrees C it gels and enabled solid removal of the captured dye.

Magnetothermal genetic deep brain stimulation of motor behaviors in awake, freely moving mice

Establishing how neurocircuit activation causes particular behaviors requires modulating the activity of specific neurons. Here, we demonstrate that magnetothermal genetic stimulation provides tetherless deep brain activation sufficient to evoke motor behavior in awake mice. The approach uses alternating magnetic fields to heat superparamagnetic nanoparticles on the neuronal membrane. Neurons, heat-sensitized by expressing TRPV1 are activated with magnetic field application. Magnetothermal genetic stimulation in the motor cortex evoked ambulation, deep brain stimulation in the striatum caused rotation around the body-axis, and stimulation near the ridge between ventral and dorsal striatum caused freezing-of-gait. The duration of the behavior correlated tightly with field application. This approach provides genetically and spatially targetable, repeatable and temporarily precise activation of deep-brain circuits without the need for surgical implantation of any device.

Self-Controlled Hyperthermia Characteristics of ZnGdFe Nanoparticles

We report self-controlled heating temperature rising characteristics of gadolinium-substituted zinc iron ferrite magnetic nanoparticles. ZnGdFe2O 3 nanoparticles were synthesized chemically by a co-precipitation process for application as hyperthermia inducing agents. The structure, morphology and magnetic properties of the nanoparticles were characterized using scanning electron microscope, X-ray diffractometer, and superconducting quantum interference device. The magnetic properties investigated included Curie temperature Tc, saturation magnetization Ms, remanent magnetization Mr, coercive field Hc, and hysteresis. It was observed from the study of the synthesized ZnGd ferrite nanoparticles that addition of Gd resulted in an increase in nanoparticles systems overall Curie temperature as well as its pyromagnetic coefficient.

NMR relaxation in systems with magnetic nanoparticles: A temperature study

To measure and model nuclear magnetic resonance (NMR) relaxation enhancement due to the presence of gadolinium (Gd)‐substituted Zn‐Mn ferrite magnetic nanoparticles (MNP) at different temperatures.

Metallic nanoparticles to eradicate bacterial bone infection

Treatment of osteomyelitis by conventional antibiotics has proven to be challenging due to limited accessibility to this unique location. Inorganic routes against bacterial infection have been reported for external and topical applications, however in vivo application of these antimicrobials has not been fully explored. Targeted delivery of metallic nanoparticles with inherent antimicrobial activity represents an alternative means of overcoming the challenges posed by multidrug-resistant bacteria and may potentially reduce overall morbidity. In this study we utilized silver-copper-boron composite nanoparticles in an attempt to eradicate S. aureus bone infection in mice. Our results demonstrate effective response when nanoparticles were administered via i.v. or i.m. route (1mg/kg dose) where 99% of bacteria were eliminated in an induced osteomyelitis mouse model. The 1mg/kg dose was neither toxic nor produced any adverse immune response, hence it is believed that metallic nanoparticles present an alternative to antibiotics for the treatment of bone infection.

Nanoparticles rapidly assess specific IgE in plasma.

Allergy is the sixth leading cause of chronic disease in the world. This study demonstrates the feasibility of detecting allergy indicators in human plasma, noninvasively, at the point of care and with a comparable efficiency and reduced turnaround time compared with the gold standard. Peanut allergy was utilized as a model due to its widespread occurrence among the US population and fatality if not treated. The detection procedure utilized magnetic nanoparticles that were coated with an allergen layer (peanut protein extract). Peanut immunoglobulin E (IgE) was detected in concentrations close to the minimum detection range of CAP assay. The results were obtained in minutes compared with the CAP assay which requires more than 3 h.