Muhammad Ateeq

Green synthesis and molecular recognition ability of patuletin coated gold nanoparticles.

Patuletin isolated from Tagetespatula was used as a capping and reducing agent to synthesize in one pot gold nanoparticles capped with patuletin. Conjugation of gold with patuletin was confirmed by FT-IR and UV-visible spectroscopy and amount of patuletin conjugated to gold nanoparticles was found to be 63.2% by weight. Particle sizes were measured by atomic force microscopy (AFM) and were found to have a mean diameter of about 45 nm. Patuletin-coated gold nanoparticles were found to be highly fluorescent. To examine their potential as chemical sensors, they were contacted with fourteen different drugs. Of these drugs, only one, piroxicam, was found to quench luminescence. Quenching obeyed Beers law in a concentration range of 20-260 µM. Important for molecular recognition applications, fluorescence quenching by piroxicam was not affected by pH variation, elevated temperatures, addition of other drugs and addition of blood plasma to the colloidal suspensions.

Morphological analysis of the antimicrobial action of silver and gold nanoparticles stabilized with ceftriaxone on Escherichia coli using atomic force microscopy

The antibiotic ceftriaxone was conjugated to Ag and Au nanoparticles. The activity of the conjugates against Escherichia coli ATCC 8739 was compared to that of pure ceftriaxone and of unconjugated nanoparticles using atomic force microscopy and more conventional techniques such as the agar well diffusion method. Conjugation to Ag nanoparticles increased the antibacterial activity of ceftriaxone by about 2 times, and conjugation to Au by about 6 times. Conjugation also appeared to improve the kinetics of the antibiotic. Thus, for example, membrane damage was barely evident two hours after contacting a cell culture with pure ceftriaxone. In the same time, Ag conjugates severely damaged membranes and Au conjugates completely disrupted the cell morphology.

Synthesis, characterization and evaluation of lecithin-based nanocarriers for the enhanced pharmacological and oral pharmacokinetic profile of amphotericin B

We report the synthesis, characterization and evaluation of lecithin-drug hybrid nanocarriers (NCs) with enhanced oral bioavailability and anti-parasitic potential for poorly water-soluble drugs. Amphotericin B (AmB), a poor water-soluble drug with poor membrane penetrating ability, was selected as a model drug to demonstrate the potential of the lecithin-drug hybrid NCs. Lec-AmB NCs were prepared by the self-assembly of lecithin into nanoparticles (NPs) at a critical micellar concentration of 4 mg ml-1 and into liposomes at a critical liposomal concentration of 53 mg ml-1 in aqueous systems. The Lec-AmB NPs (200-300 nm) were further coated with polyethylene glycol (MW 600) and Tween 20, whereas the liposomes (70-90 nm) were used as such for this study. The Lec-AmB NCs were evaluated for their ability to boost in vivo oral pharmacokinetic parameters in rabbits and in vitro anti-leishmanial activity against the promastigotes of Leishmania tropica. A reciprocal relationship was observed between the size and drug encapsulation efficiency of the NPs, but no such relationship was observed in the case of the liposomes. More importantly, the oral bioavailability and anti-leishmanial activity of Lec-AmB NPs was enhanced up to 21- and 6.3-fold, and 21- and 2-fold, respectively, in the case of the liposomes. The improvement in the bioavailability and anti-leishmanial activity is very significant compared to the deoxycholate complex of AmB (water soluble, injectable market product: Anfotericina FADA®), and this study, thus shows the promising potential of easy-to-prepare NCs with improved therapeutic efficiency using phosphocholine-based biocompatible surfactants.

Silymarin coated gold nanoparticles ameliorates CCl4-induced hepatic injury and cirrhosis through down regulation of hepatic stellate cells and attenuation of Kupffer cells

Silymarin coated gold nanoparticles with a mean size of 20 nm were synthesized and functionalized in one pot using silymarin as a reducing and stabilizing agent. Conjugation of gold with silymarin was confirmed with FT-IR and UV-visible techniques. The aim of this study was to investigate the hepatoprotective and antifibrotic potential of Silymarin coated gold nanoparticles. For this purpose oxidative liver damage was induced in Wistar rats by intraperitoneal injection of CCl4 dissolved in olive oil (1u2006:u20061 v/v, 1 ml kg−1). Silymarin coated gold nanoparticles were administered intragastrically once per day for 14 weeks in a dose of 30 mg kg−1 of body weight. Hepatoprotective and antifibrotic activities of silymarin coated gold nanoparticles were assessed in terms of reduction in serum enzymes (ALT, AST, ALP), through histopathology and immunohistochemistry techniques. It also reduced the CCl4-induced damaged area as well as fibrotic area to 0% as assessed by histopathology. The Alpha SMA and Kupffer cells were also reduced in number around the portal traid area by the silymarin coated gold nanoparticles. These hepatoprotective and antifibrotic effects were better than the positive control silymarin. Our results suggest the therapeutic effect of silymarin coated gold nanoparticles in CCl4-induced liver injury and cirrhosis by promoting extracellular matrix degradation, hepatic stellate cells inactivation with strong enhancement of hepatic regenerative capacity. Silymarin coated gold nanoparticles could be administered for up to 14 weeks without inducing side effects or alterations of the histological structure of kidneys, heart, pancreas and lungs.

Hepatoprotective and urease inhibitory activities of garlic conjugated gold nanoparticles

A robust synthetic method is reported for the synthesis of highly stable, poly disperse and spherical gold nanoparticles conjugated to an aqueous garlic extract (G-AuNPs). An ionic solution of gold was mixed and stirred with a dilute aqueous garlic extract at room temperature for 4 hours. The G-AuNPs were characterized by UV-Visible spectroscopy. The morphology and size of the G-AuNPs were determined by atomic force microscopy. FTIR spectroscopy revealed that secondary metabolites present in the garlic extract worked as capping agents around the gold nanoparticles. The G-AuNPs were quite stable even at higher temperature or with salt concentrations up to 10 mM or with various pH ranging from 4 to 11. Two different model systems were tested for evaluating the biological roles of G-AuNPs. They showed excellent hepatoprotective activity in a CCl4-induced acute hepatic injury model which was better than the positive control, silymarin. They also showed urease inhibitory activity with an IC50 value of 180.61 ± 1.06 μg mL−1. Therefore, the G-AuNPs can be useful in the treatment of diseases caused by injury or inflammation.

Atomic force microscopic imaging of Acanthamoeba castellanii and Balamuthia mandrillaris trophozoites and cysts

Light microscopy and electron microscopy have been successfully used in the study of microbes, as well as free‐living protists. Unlike light microscopy, which enables us to observe living organisms or the electron microscope which provides a two‐dimensional image, atomic force microscopy provides a three‐dimensional surface profile. Here, we observed two free‐living amoebae, Acanthamoeba castellanii and Balamuthia mandrillaris under the phase contrast inverted microscope, transmission electron microscope and atomic force microscope. Although light microscopy was of lower magnification, it revealed functional biology of live amoebae such as motility and osmoregulation using contractile vacuoles of the trophozoite stage, but it is of limited value in defining the cyst stage. In contrast, transmission electron microscopy showed significantly greater magnification and resolution to reveal the ultra‐structural features of trophozoites and cysts including intracellular organelles and cyst wall characteristics but it only produced a snapshot in time of a dead amoeba cell. Atomic force microscopy produced three‐dimensional images providing detailed topographic description of shape and surface, phase imaging measuring boundary stiffness, and amplitude measurements including width, height and length of A. castellanii and B. mandrillaris trophozoites and cysts. These results demonstrate the importance of the application of various microscopic methods in the biological and structural characterization of the whole cell, ultra‐structural features, as well as surface components and cytoskeleton of protist pathogens.

Atomic Force Microscopy for Microbial Cell Surfaces

Binnig et al. invented atomic force microscope (AFM) in 1986. It is a scanning tool for nanostructure investigations. It is now considered to be one of the landmarks of modern sciences, for citations of the first article increase more than 13,500 times [1]. The AFM has come up as a new addition to macroscopic and microscopic techniques since it has benefits in sample preparation and the ability of high-resolution imaging in both liquid and air environment if compared to standard light microscopy techniques. This sophisticated instrument has successfully been used in all branches of science like material science [2], food science [3], nanofabrication [4], and microbiology, for nearly two decades after its invention [5]. The microbiology field has been revolutionized by AFM. It has enriched the realm of sample preparation and microbial surface analysis in particular during the last two decades [6].

N-(2-hydroxyphenyl)acetamide and its gold nanoparticle conjugation prevent glycerol-induced acute kidney injury by attenuating inflammation and oxidative injury in mice

The protective activity of N-(2-hydroxyphenyl)acetamide (NA-2) and NA-2-coated gold nanoparticles (NA-2-AuNPs) in glycerol-treated model of acute kidney injury (AKI) in mice was investigated. NA-2 (50xa0mg/kg) and NA-2-AuNPs (30xa0mg/kg) were given to the animals for four days followed by 24-h water deprivation and injection of 50% glycerol (10xa0ml/kg im). The animals were sacrificed on the next day. Blood and kidneys were collected for biochemical investigations (urea and creatinine), histological studies (hematoxylin and eosin; and periodic acid-Schiff staining), immunohistochemistry (actin and cyclooxygenase-2, Cox-2), and real-time RT-PCR (inducible nitric oxide synthase, iNOS; nuclear factor-κB p50, NFκB; hemeoxygenase-1, HO-1; and kidney injury molecule-1, Kim-1). NA-2 protected renal tubular necrosis and inflammation, though the result of NA-2-AuNPs was better than compound alone and it also exhibited the activity at far less dose. The test compound and its gold nano-formulation decreased the levels of serum urea and creatinine level in the treated animals. Both NA-2 and NA-2-AuNPs also conserved actin cytoskeleton, and lowered COX-2 protein expression. Moreover, the mRNA expressions of iNOS and NFkB p50 were down-regulated, and HO-1 and Kim-1 genes were up-regulated. We conclude that NA-2 and NA-2-AuNPs ameliorates kidney inflammation and injury in glycerol-induced AKI animal model via anti-oxidant and anti-inflammatory mechanisms which make it a suitable candidate for further studies. We believe that these findings will contribute in the understanding of the mechanism of action of paracetamol-like drugs and can be considered for clinical research for the prevention of AKI.

Characterizing kidney structures in health and diseases using eosin fluorescence from hematoxylin and eosin stained sections

For a long time, hematoxylin and eosin (H&E) staining has been widely used for the diagnosis of many diseases by assessing the histopathological changes in tissue sections. Eosin, one of the staining dyes in the H&E stain, is fluorescent in the fluorescein isothiocyanate (FITC) and Texas Red (TxR) fluorescent channels. In this study, the use of eosin fluorescence to visualize and quantify histopathological changes was elucidated in a glycerol-induced model of acute kidney injury (AKI) in mice. AKI was induced in BALB/c mice by intramuscularly injecting 10 mL/kg of 50% glycerol after 24 h of water deprivation and, after another 24 h, the kidneys were dissected out. After H&E staining, kidney tissue sections were examined under a fluorescent microscope using a double-channel filter cube (FITC and TxR). The H&E fluorescence pattern of normal kidney structures was characterized as the fluorescence patterns varied between different parts of the kidney and could be used for the structural identification of different parts of the kidney. Interestingly, in the injured kidney sections, a striking increase in the red fluorescence was noticed only in the damaged areas. In the damaged kidney sections, casts deposited inside tubules showed bright yellow fluorescence, whereas fibers showed strong green fluorescence. In vitro experiments were also performed in order to understand possible mechanisms underlying this phenomenon. It was concluded that eosin fluorescence can be used to quantify the degree of damage to kidney tissue which, in turn, may help in assessing the kidney-protective effects of unknown compounds and plant extracts.