Spectrofluorometric method for detection glycogen using chemically gold nanoparticles: Cyanobacteria as biological model.

There is a need for simple spectrofluorimetric method for detection of glycogen molecule based on binding to nanogold. Here we propose such a quantification method for glycogen using cyanobacteria as a biological model. Biologically, two strains of cyanobacteria were selected based on their previously tested nanogold biosynthetic abilities. Chemically, spherical gold nanoparticles were prepared and tested for binding to the glycogen molecule. Experimental analyses were conducted to determine the morphological and optical properties of the Au-glycogen hydrocolloids. Results: The plasmon band of biosynthesized AuNPs-glycogen was centered at 520-540 nm with size diameter was 41.7 ± 0.2 nm. The vibrational bands of glycogen were observed at 1,000 to 1,200 cm-1. The Au3+/Au0 redox coupling cycle was observed. The luminescence of AuNPs showed more stability by the addition of gradual concentrations of glycogen molecules. The detection (LOD) and quantitation limits (LOQ) were observed to be 0.89 and 2.95 µmol L-1 respectively (R2 = 0.99). The good chemical stability of this colloidal system and the glycogen molecule studied via density functional theory (DFT). The HOMO level of glycogen unit was closed near to LUMO level of Au3+. Conclusion: The associations formed between the gold nanoparticles and glycogen resulted in good chemical stability. This indicates that the quantification method proposed can be stably applied.

Multidrug-Resistant Bacterial Pathogens and Public Health: The Antimicrobial Effect of Cyanobacterial-Biosynthesized Silver Nanoparticles.

BACKGROUND: Cyanobacteria are considered as green nano-factories. Manipulation of the size of biogenic silver nanoparticles is needed to produce particles that suit the different applications such as the use as antibacterial agents. The present study attempts to manipulate the size of biosynthesized silver nanoparticles produced by cyanobacteria and to test the different-sized nanoparticles against pathogenic clinical bacteria. METHODS: Cyanothece-like. coccoid unicellular cyanobacterium was tested for its ability to biosynthesize nanosilver particles of different sizes. A stock solution of silver nitrate was prepared from which three different concentrations were added to cyanobacterial culture. UV-visible spectroscopy and FTIR were conducted to characterize the silver nanoparticles produced in the cell free filtrate. Dynamic Light Scattering (DLS) was performed to determine the size of the nanoparticles produced at each concentration. The antimicrobial bioassays were conducted on broad host methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus sp., was conducted to detect the nanoparticle size that was most efficient as an antimicrobial agent. RESULTS: The UV-Visible spectra showed excellent congruence of the plasmon peak characteristic of nanosilver at 450 nm for all three different concentrations, varying peak heights were recorded according to the concentration used. The FTIR of the three solutions revealed the absence of characteristic functional groups in the solution. All three concentrations showed spectra at 1636 and 2050-2290 nm indicating uniformity of composition. Moreover, DLS analysis revealed that the silver nanoparticles produced with lowest concentration of precursor AgNO3 had smallest size followed by those resulting from the higher precursor concentration. The nanoparticles resulting from highest concentration of precursor AgNO3 were the biggest in size and tending to agglomerate when their size was above 100 nm. The three types of differently-sized silver nanoparticles were used against two bacterial pathogenic strains with broad host range; MRSA-(Methicillin-resistant Staphylococcus aureus) and Streptococcus sp. The three types of nanoparticles showed antimicrobial effects with the smallest nanoparticles being the most efficient in inhibiting bacterial growth. DISCUSSION: Nanosilver particles biosynthesized by Cyanothece-like cyanobacterium can serve as antibacterial agent against pathogens including multi-drug resistant strains. The most appropriate nanoparticle size for efficient antimicrobial activity had to be identified. Hence, size-manipulation experiment was conducted to find the most effective size of nanosilver particles. This size manipulation was achieved by controlling the amount of starting precursor. Excessive precursor material resulted in the agglomeration of the silver nanoparticles to a size greater than 100 nm. Thereby decreasing their ability to penetrate into the inner vicinity of microbial cells and consequently decreasing their antibacterial potency. CONCLUSION: Antibacterial nanosilver particles can be biosynthesized and their size manipulated by green synthesis. The use of biogenic nanosilver particles as small as possible is recommended to obtain effective antibacterial agents.

Ion-Triggered In Situ Gelling Nanoemulgel as a Platform for Nose-to-Brain Delivery of Small Lipophilic Molecules.

Background: Intranasal route offers a direct nose-to-brain delivery via olfactory and trigeminal nerves and minimizes the systemic exposure of the drug. Although reliable and non-invasive, intranasal administration of lipophilic neuroprotective agents for brain targeting is still challenging. Literature focuses on naturally-derived compounds as a promising therapeutics for chronic brain diseases. Naringin, a natural flavonoid obtained from citrus fruits possesses neuroprotective effects. By regulating multiple crucial cellular signaling pathways, naringin acts on several therapeutic targets that make it suitable for the treatment of neurodegenerative diseases like Alzheimer's disease and making it a suitable candidate for nasal administration. However, the hydrophobicity of naringin is the primary challenge to formulate it in an aqueous system for nasal administration. Method: We designed a lipid-based nanoemulsifying drug delivery system of naringin using Acrysol K140 as an oil, Tween 80 as a surfactant and Transcutol HP as a cosolvent, to improve solubility and harness the benefits of nanosizing like improved cellular penetration. Intranasal instillations of therapeutic agents have limited efficacy due to drug washout and inadequate adherence to the nasal mucosa. Therefore, we reconstituted the naringin self-emulsifying system in a smart, biodegradable, ion-triggered in situ gelling hydrogel and optimized for desirable gel characteristics. The naringin-loaded composition was optimized and characterized for various physicochemical and rheological properties. Results: The formulation showed a mean droplet size 152.03 ± 4.6 nm with a polydispersity index <0.23. Ex vivo transmucosal permeation kinetics of the developed formulation through sheep nasal mucosa showed sustained diffusion and enhanced steady-state flux and permeability coefficient. Scanning and transmission electron microscopy revealed the spherical shape of emulsion droplets and entrapment of droplets in a gel structure. The formulation showed excellent biocompatibility as analyzed from the viability of L929 fibroblast cells and nasal mucosa histopathology after treatment. In vivo biodistribution studies revealed significantly higher drug transport and brain targeting efficiency. Conclusion: In situ gelling system with nanoemulsified naringin demonstrated a safe nasal delivery providing a new dimension to the treatment of chronic neurodegenerative diseases using small hydrophobic phytoconstituents with minimization of dose and related systemic adverse effects.

Cyanobacteria as Nanogold Factories II: Chemical Reactivity and anti-Myocardial Infraction Properties of Customized Gold Nanoparticles Biosynthesized by Cyanothece sp.

Cyanothece sp., a coccoid, unicellular, nitrogen-fixing and hydrogen-producing cyanobacterium, has been used in this study to biosynthesize customized gold nanoparticles under certain chemical conditions. The produced gold nanoparticles had a characteristic absorption band at 525-535 nm. Two types of gold nanoparticle, the purple and blue, were formed according to the chemical environment in which the cyanobacterium was grown. Dynamic light scattering was implemented to estimate the size of the purple and blue nanoparticles, which ranged from 80 ± 30 nm and 129 ± 40 nm in diameter, respectively. The highest scattering of laser light was recorded for the blue gold nanoparticles, which was possibly due to their larger size and higher concentration. The appearance of anodic and cathodic peaks in cyclic voltammetric scans of the blue gold nanoparticles reflected the oxidation into gold oxide, followed by the subsequent reduction into the nano metal state. The two produced forms of gold nanoparticles were used to treat isoproterenol-induced myocardial infarction in experimental rats. Both forms of nanoparticles ameliorated myocardial infarction injury, with a slight difference in their curative activity with the purple being more effective. Mechanisms that might explain the curative effect of these nanoparticles on the myocardial infarction were proposed. The morphological, physiological, and biochemical attributes of the Cyanothece sp. cyanobacterium were fundamental for the successful production of "tailored" nanoparticles, and complemented the chemical conditions for the differential biosynthesis process. The present research represents a novel approach to manipulate cyanobacterial cells towards the production of different-sized gold nanoparticles whose curative impacts vary accordingly. This is the first report on that type of manipulated gold nanoparticles biosynthesis which will hopefully open doors for further investigations and biotechnological applications.

Cyanobacteria as Nanogold Factories: Chemical and Anti-Myocardial Infarction Properties of Gold Nanoparticles Synthesized by Lyngbya majuscula.

To the best of our knowledge, cyanobacterial strains from the Arabian Gulf have never been investigated with respect to their potential for nanoparticle production. Lyngbya majuscula was isolated from the AlOqair area, Al-Ahsa Government, Eastern Province, Kingdom of Saudi Arabia. The cyanobacterium was initially incubated with 1500 mg/mL of HAuCl4 for two days. The blue-green strain turned purple, which indicated the intracellular formation of gold nanoparticles. Prolonged incubation for over two months triggered the extracellular production of nanogold particles. UV-visible spectroscopy measurements indicated the presence of a resonance plasmon band at ~535 nm, whereas electron microscopy scanning indicated the presence of gold nanoparticles with an average diameter of 41.7 ± 0.2 nm. The antioxidant and anti-myocardial infarction activities of the cyanobacterial extract, the gold nanoparticle solution, and a combination of both were investigated in animal models. Isoproterenol (100 mg/kg, SC (sub cutaneous)) was injected into experimental rats for three days to induce a state of myocardial infarction; then the animals were given cyanobacterial extract (200 mg/kg/day, IP (intra peritoneal)), gold nanoparticles (200 mg/kg/day, IP), ora mixture of both for 14 days. Cardiac biomarkers, electrocardiogram (ECG), blood pressure, and antioxidant enzymes were determined as indicators of myocardial infarction. The results showed that isoproterenol elevates ST and QT segments and increases heart rate and serum activities of creatine phosphokinase (CPK), creatine kinase-myocardial bound (CP-MB), and cardiac troponin T (cTnT). It also reduces heart tissue content of glutathione peroxidase (GRx) and superoxide dismutase (SOD), and the arterial pressure indices of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP). Gold nanoparticles alone or in combination with cyanobacterial extract produced an inhibitory effect on isoproterenol-induced changes in serum cardiac injury markers, ECG, arterial pressure indices, and antioxidant capabilities of the heart.

Spectrofluorimetric method for atenolol determination based on gold nanoparticles.

A simple and sensitive spectrofluorimetric method for determination of atenolol (ATE) using gold nanoparticles (AuNPs) was developed. The method is based on the quenching effect of atenolol on photoluminescence of AuNPs at λem = 705 nm. Variables affecting luminescence of gold nanoparticles such as the solvent, pH value and surfactant were studied and optimized. The method was preliminarily validated according to ICH guidelines. A linear correlation was recorded within the range of 1.0-10 mg mL-1 ATE with the coefficient of determination R2 of 0.999. The limit of detection and limit of quantitation for atenolol were found to be 0.87 and 2.64 mg mL-1, resp. Good recoveries in the range of 98.7-100.0 % were obtained for spiked samples. The proposed method was applied successfully to assaying atenolol in pharmaceuticals formulations.

Novel chitosan-ZnO based nanocomposites as luminescent tags for cellulosic materials.

Novel chitosan-ZnO composites have been synthesized as luminescent taggants for cellulosic materials. The synthesized chitosan-ZnO nanospheres (CS-ZnO NS), chitosan-ZnO-oleic acid quantum dots (CS-ZnO-oleic QD) and chitosan-ZnO-oleic acid:Eu(3+) doped nanorods (CS-ZnO-oleic:Eu(3+) NR) were characterized by X-ray diffraction, photoluminescence spectroscopy, FTIR spectroscopy and transmission electron microscopy. The prepared luminescent CS-ZnO composites were used in printing paste and applied to different types of papers and textiles by using screen printing technique. The colorimetric values of the printed CS-ZnO-oleic acid and CS-ZnO-oleic:Eu(3+) showed that printing caused slightly change in color values. Scanning electron microscopy images and color values of the printed surface showed that CS-ZnO-oleic QD and highly luminescence CS-ZnO-olic:Eu(3+) NR are suitable for use as a printed security feature.

Highly selective recognition on enatioselective of R(+) and S(-)-1,1-Bi(2-naphthol) using of Eu(dap)3 complex as photo probe.

The chiral recognition phenomenon was observed in enantioselective and excited-state energy transfer processes. Based on bimolecular luminescence quenching kinetics for a system containing chiral molecules, the quenching efficiency was evaluated by Stern-Volmer equation for a system containing a chiral R(+) and S(-) resolved quencher species. The utility of this methodology is confirmed by examining the enantio-selective excited-state quenching between Eu(dpa)(3) complex (where dpa = pyridine-2,6-dicarboxylate) acting as the energy donor to R(+)-1,1-Bi(2-Naphthol) and S(-)-1,1-Bi(2-naphthol) as the energy acceptor was studied in solution. The results of this study confirm the utility of luminescence measurements as a probe of chiral discriminatory behavior.

Screening the bio-safety of wheat produced from pretreated grains to enhance tolerance against drought using physiological and spectroscopic methods.

Drought is a serious abiotic stress, causes worldwide intensive reduction in crop growth and productivity. Plants in contrast to other organisms, do not enjoy the luxury of being able to change their environment or seeking shelters. In this investigation, wheat grains were pre-soaked for 12h in salicylic acid (SA) and/or thiourea (ThU) prior they were left to grow in dry land (40% field water capacity) until harvest. The bio-safety of the harvested wheat was deduced using technical physiological and spectral methods. The pretreatment using SA up to ( approximately 1.5mmol) viewed homologous protein profile and less flag leaf proline in comparison to the non-stressed wheat. In addition, SA-pretreatment has maintained 70% of the emission intensity of yielded grain. The spectra of FTIR were more or less similar in yielded grain and flag leaf in SA-pretreatment. On the other hand, ThU pretreatment induced varied protein profile, higher proline than normal, reduced the fluorescence emission intensity by 52%, and induced varied FTIR spectra. Pretreatment of SA not only has enhanced wheat productivity but also increased yield and straw productions even above the non-treated-non-stressed wheat plant. In contrast to ThU SA was considered safe for drought-stress alleviation in crop plant agriculture.

Photophysical properties of clozapine and determination of its concentration by using Eu(III)-dipicolinic acid complex as photo probe.

Clozapine drug is photo-stable under irradiation of light for a long time, so we can store it in difficult and hot conditions. In addition the activity of clozapine is inhibited of the absorption spectra in the presence of glucose and enhanced in the presence of iron(III). We succeeded in detecting the concentration of clozapine in the range 1-60x10(-9)M using Eu(III)-dipicolinic acid complex as photo probe type and using Stern-Völmer equation to determine the Stern-Völmer constant, critical radius and the mechanism of quenching of luminescence of Eu(III)-dipicolinic acid complex is found to be of dipolar-dipolar interaction.