Aqueous Colloidal Solution Research Articles

Water-Soluble Pristine C60 Fullerenes Inhibit Liver Fibrotic Alteration and Prevent Liver Cirrhosis in Rats.

Liver cirrhosis is an outcome of a wide range of liver chronic diseases. It is attributed to oxidative stress; therefore, antioxidant usage could be a promising treatment of that. So, exploring the impact of effective free radical scavenger pristine C60 fullerenes on liver fibrosis and cirrhosis and their ability to interact with main growth factor receptors involved in liver fibrogenesis was aimed to be discovered. We used N-diethylnitrosamine/carbon tetrachloride-induced simulations of rat liver fibrosis (10 weeks) and cirrhosis (15 weeks). Pristine C60 fullerene aqueous colloid solution (C60FAS) was injected daily at a dose of 0.25 mg/kg throughout the experiment. Liver morphology and functional and redox states were assessed. C60 fullerenes' ability to interact with epidermal, vasoendothelial, platelet-derived, and fibroblast growth factor receptors (EGFR, VEGFR, PDGFR, and FGFR, respectively) was estimated by computational modeling. We observed that C60FAS reduced the severity of fibrosis in fibrotic rats (0.75 vs. 3.0 points according to Ishak score), attenuated the hepatocyte injury, normalized elevated blood serum alkaline phosphatase (ALP) and lactate dehydrogenase (LDH), and mitigated oxidative stress manifestation in liver tissue restoring its redox balance. When applied to cirrhotic animals, C60FAS reduced connective tissue deposition as well (2.4 vs. 5.4 points according to Ishak score), diminished ALP and LDH (by 16% and 61%), and normalized conjugated and nonconjugated bilirubin, restoring the liver function. Altered liver lipid and protein peroxides and glutathione peroxidase activity were also leveled. Within a computer simulation, it was shown that C60 fullerenes can block hinge prohibiting ATP binding for EGFR and FGFR and thus blocking associated signal pathways. This ability in addition to their antioxidant properties may contribute to C60 fullerene's antifibrotic action. Thus, C60FAS may have a substantial therapeutic potential as an inhibitor of liver fibrosis and cirrhosis.

Biomimetic Synthesis of Sub-20 nm Covalent Organic Frameworks in Water.

Covalent organic frameworks (COFs) are commonly synthesized under harsh conditions yielding unprocessable powders. Control in their crystallization process and growth has been limited to studies conducted in hazardous organic solvents. Herein, we report a one-pot synthetic method that yields stable aqueous colloidal solutions of sub-20 nm crystalline imine-based COF particles at room temperature and ambient pressure. Additionally, through the combination of experimental and computational studies, we investigated the mechanisms and forces underlying the formation of such imine-based COF colloids in water. Further, we show that our method can be used to process the colloidal solution into 2D and 3D COF shapes as well as to generate a COF ink that can be directly printed onto surfaces. These findings should open new vistas in COF chemistry, enabling new application areas.

Green synthesis and stabilization of silver nanoparticles using Lysimachia foenum-graecum Hance extract and their antibacterial activity

AbstractThe Lysimachia foenumgraecum Hance extract (LHE) was used for silver nanoparticles (AgNPs) synthesis. In this study, the herbal plant of Lysimachia foenumgraecum Hance (LH) was extracted with deionized water and we are the first to successfully use LHE as reducing and stabilizing agents for the green synthesis of AgNPs. The concentration of LHE used in this study was in the range of 0.003 to 1.0 wt%. Aqueous colloidal solutions of AgNPs reduced and stabilized by LHE show long-term stability due to the steric stabilization effect. This can be confirmed by zeta potential measurements which afforded values approximately of 0 mV, indicating the steric stability of AgNPs colloidal solutions synthesized by LHE. Furthermore, the obtained AgNPs colloidal solutions show superior antibacterial effect to gram-positive bacteria (Staphylococcus aureus) comparing to Chloramphenicol (positive control). AgNPs with LHE 0.003 wt% affords the highest antibacterial effect to S. aureus showing an inhibition zone diameter of 19.08 ± 0.67 mm; which is superior to Chloramphenicol.

Threaded Polycrystals Na2SO4/Cd0.1Zn0.9S: Cu, Аg on the Surface of the New Material Si/(nano SiС)

Abstract—The results of growing polycrystalline (PC) films (FL) of luminophore (LP) based on a solid solution of Cd0.1Zn0.9S: Cu, Аg, sodium salt compounds (Nа2SO4, Na6Cd7S10 = 3Na2S · 7CdS) in an aqueous colloidal solution containing zinc acetate, cadmium nitrate and sodium sulfide compounds on the surface of a new material, a hybrid Si substrate (nano-SiС), under normal physical conditions are presented. The grown PCs were investigated by methods: electron microscopy in the modes of using secondary and reflected electrons, by the method of energy dispersive X-ray spectroscopy (Energy-dispersive X-ray Spectroscope, EDXS). The surface of the substrate was also studied by the Raman method after removing the grown PCs from its surface. a study of morphology showed that PCs are represented by micro-formations: threadlike, needle-shaped and oval in shape and with different crystalline structures. Using the EDXS method, the elemental composition of micro formations was determined. In all forms of pc, Zn, Cd, S and Na are present. It was found that filamentary PCs are represented by the composition Cd0.1Zn0.9S and needle-shaped and oval ones by Cd0.23Zn0.77S. It was shown that the growth form, the location of filamentary PCs on the film surface are determined by the internal structure of the substrate. A mechanism for the formation of filamentary pc composite structure Na2SO4/Si/Cd0.1Zn0.9S by the “solution–solid–solid” growth mechanism is proposed. Raman spectroscopy found that a PC film grown in an aqueous colloidal solution containing LP, sodium compounds on a substrate of a new material improves the luminescent properties of the Si/nano SiC substrate in the infrared region of the spectrum.

Genotoxicity evaluation of multiwalled carbon nanotubes: in vivo studies in mice

The toxicity of carbon nanoparticles in recent years has attracted much attention due to their active use in industry, medicine and agriculture, which brings not only obvious benefits, but also potential danger to the environment and human health. Getting into the natural environment, bioaccumulating and bioconcentrating in them, carbon nanotubes pose a real threat to mammals, since due to their high migration ability they can penetrate the food chain of animals and humans. Therefore, the aim of this study was to study the genotoxicity of carbon nanotubes in in vivo experiments on laboratory mice. For this, based on the method of single cell alkaline gel electrophoresis assay, studies were conducted to determine the effect of aqueous colloidal solutions of multiwalled carbon nanotubes on genotoxicity towards various tissues in laboratory mice. During these acute and subacute in vivo experiments we have established that orally introduced multiwalled carbon nanotubes colloids damage deoxyribonucleic acid in various organs. In particular, 0.5 mg of multiwalled carbon nanotubes administered daily for 21 days have a prominent genotoxic effect. Thus, the obtained results have illustrated that multiwalled carbon nanotubes can potentially affect the genetic material in mammals, orally administered nanotubes increase the rate of nuclear deoxyribonucleic acid destruction.

C60 fullerenes increase the intensity of rotational movements in non-anesthetized hemiparkinsonic rats

The effect of C60 fullerene aqueous colloid solution (C60FAS) on the intensity of long‑lasting (persisting for one hour) rotational movements in non‑anesthetized rats was investigated. For this purpose, an experimental hemiparkinsonic animal model was used in the study. Rotational movements in hemiparkinsonic animals were initiated by the intraperitoneal administration of the dopamine receptor agonist apomorphine. It was shown that a preliminary injection of C60FAS (a substance with powerful antioxidant properties) in hemiparkinsonic rats induced distinct changes in animal motor behavior. It was revealed that fullerene‑pretreated animals, in comparison with non‑pretreated or vehicle‑pretreated rats, rotated for 1 h at an approximately identical speed until the end of the experiment, whereas the rotation speed of control rats gradually decreased to 20-30% of the initial value. One can assume that the observed changes in the movement dynamics of the hemiparkinsonic rats after C60FAS pretreatment presumably can be induced by the influence of C60FAS on the dopaminergic system, although the isolated potentiation of the action of apomorphine C60FAS cannot be excluded. Nevertheless, earlier data on the action of C60FAS on muscle dynamics has suggested that C60FAS can activate a protective action of the antioxidant system in response to long‑lasting muscular activity and that the antioxidant system in turn may directly decrease fatigue‑relate d changes during long‑lasting muscular activity.

MORPHOLOGICAL ASSESSMENT OF WOUND HEALING AFTER CRYODESTRUCTION OF SKIN USING AN AQUEOUS COLLOIDAL SOLUTION OF C60 FULLERENES

The aim is to assess the morphological state of a cold skin wound in an experiment, using an aqueous colloidal solution of C60 fullerenes. Materials and methods: An experimental study was conducted in 30 six-month-old male rats divided into three groups, 10 individuals in each group: group I included rats that did not undergo any manipulations; group II was represented by rats which underwent a cold wound simulation on the lateral thigh surface; group III was represented by rats who had a simulated cold wound followed by introduction of an aqueous colloidal solution of C60 fullerenes at a dose of 0.1 mg/kg for 5 days into the abdominal cavity, starting from the cryodamage day. Animals of all groups were removed from the experiment on days 7, 14 and 21. The material for the morphological study was skin with underlying soft tissues. The resulting sample was studied, using histological, histochemical, morphometric and statistical research methods. Results: C60 fullerenes stimulate proliferative activity in the epidermis, located in the wound marginal regions or covering the regenerate surface, which leads to an increase in epithelial layer thickness by 2.6, 2.6, 2.5 times on 7, 14 and 21 days; promotes faster cleansing of the wound from necrotic tissue, reducing the thickness of the zone of primary necrosis on days 7, 14 and 21 by 1.3 times by increasing the demarcation zone on days 7, 14 and 21 by 1.4, 1.4 and 2, 2 times; reduces the thickness of the secondary necrosis area on 7, 14 and 21 days by 1.4, 1.5 and 1.3 times; accelerates filling of the wound defect with granulation tissue, the layer thickness of which increases by 2.3, 2.2 and 1.4 times on the 7th, 14th and 21st days, respectively; reduces the severity of hemodynamic disorders and cell infiltration in the wound defect adjacent tissues of the dermis, hypodermis with the underlying muscle tissue. Conclusions: A comprehensive morphological study of the experimental material indicates that the injection into the abdominal cavity of an aqueous colloidal solution of C60 fullerenes activates reparative processes in the skin cold wounds, which go through all the classical stages.

Гістологічні особливості волокон литкового м’язу щурів при ішемії та використані С60 фулеренів в ролі антиоксидантів

Мета роботи – провести аналіз гістологічних змін у литковому м’язі за умов експериментальної ішемії різної тривалості, за умови внутрішньочеревного введення С60 фулеренів в ролі антиоксиданта. Експеримент реалізовано на щурах інбредної лінії Wistar масою 140–160 г. Виділено такі групи тварин: контрольна, тварини з ішемією (1, 2 та 3 год), тварини з ішемію (1, 2 та 3 год) та за умови внутрішньочеревного введення С60 фулеренів. Гістологічну обробку тканини проводили за загальноприйнятою методикою, фарбувалили за методом Ван-Гізон. Проаналізовано морфологічні особливості ішемізованих м’язових волокон musculus gastrocnemius різної тривалості та терапевтичного впливу водного колоїдного розчину С60 фулеренів на ступінь вираженості патоморфологічних змін у такому м’язі. Встановлено, що литковий м’яз є стійким до ішемічних пошкоджень легкого ступеня за умов внутрішньочеревного введення С60 фулеренів, які є потужними антиоксидантами та здатні ефективно поглинати вільні радикали. Проте, дослідження показали, що зі збільшенням тривалості ішемічного ушкодження захисна дія фулеренів пропорційно зменшується до тривалості дії ішемії. Зокрема, простежується початкова тенденція до руйнації м’язових волокон, порушення цілісності мембрани, спостерігається заміщення м’язевої тканини сполучною, розрив саркомерів, встрата поперечної посмугованості, відсутність ядер, гіперемія капілярного русла, а також відмічаються некротично-деструктивні зміни, які відбуваються за рахунок надлишку не інактивованих супероксид- і гідроксид-радикалів. Таким чином, проведене лабораторне дослідження може слугувати підґрунтям для розробки лікарських препаратів проти м’язових патологій, а також сприятиме розробці комплексної методики лікування ранніх етапів ішемічного пошкодження скелетних м’язів людини.

Monitoring the growth dynamics of colloidal gold-silver core-shell nanoparticles using in situ second harmonic generation and extinction spectroscopy.

The growth dynamics of gold-silver core-shell (Au@Ag) nanoparticles are studied using in situ time-dependent second harmonic generation (SHG) and extinction spectroscopy to investigate the nanoparticle shell formation. The silver shell is grown by reduction of silver cations onto a 14 nm gold core using ascorbic acid in colloidal aqueous solution under varying reaction concentrations producing Au@Ag nanoparticles of final sizes ranging from 51 to 78 nm in diameter. The in situ extinction spectra show a rapid increase in intensity on the timescale of 5-6 s with blue shifting and narrowing of the plasmonic peak during the silver shell formation. The in situ SHG signals show an abrupt rise at early times of the reaction, followed by a time-dependent biexponential decrease, where the faster SHG lifetime corresponds to the timescale of the shell growth, and where the slower SHG lifetime is attributed to changes in the nanoparticle surface charge density. A large enhancement in the SHG signal at early stages of the reaction is caused by plasmonic hot spots due to the nanoparticle surface morphology, which becomes smoother as the reaction proceeds. The final extinction spectra are compared to finite-difference time-domain (FDTD) calculations, showing general agreement with experiment, where the plasmon peak red shifts and increases in spectral width as the silver shell thickness increases. These in situ SHG and extinction spectroscopy results, combined with FDTD calculations, help characterize the complicated processes involved in colloidal nanoparticle shell formation in real time for developing potential plasmon-enhanced nanomaterial applications.

Kinetic determination of sedimentation for GMZ bentonite colloids in aqueous solution: Effect of pH, temperature and electrolyte concentration

Bentonite colloids are readily generated by eroding the compacted bentonite blocks with flowing groundwater and facilitate the transport of radionuclides due to their high mobility. The geological fate of colloids is highly relevant to the aggregation and sedimentation of colloids in porous media. In the present work, the week-scale stability of bentonite colloids concerning sedimentation was determined by photon correlation spectroscopy (PCS) as a function of pH, temperature, and electrolyte concentration. The related mechanisms governing colloidal stability were elucidated by employing the DLVO model. The results showed that the alkaline condition was favorable for bentonite colloidal stability, while high temperature and high salinity destabilized colloids due to the decrease in repulsive potential energy. Ca2+ contributed more significantly to colloid sedimentation than Na+ because of the favorable replacement in the Stern layer. The critical coagulation concentration (CCC) values calculated theoretically from DLVO theory were applicable to predict the stability of bentonite colloids. Knowledge from the present work provides deep insight into the stability of bentonite colloids and has potential implication for understanding the detailed physico-chemical processes governing colloid migration under various subsurface environments.

Characterization of radiolytically synthesized feroxyhyte and oxidized magnetite nanoparticles

Iron(III) chloride deaerated alkaline aqueous colloidal solutions in the presence of 2-propanol and DEAE-dextran (diethylaminoethyl-dextran hydrochloride) were γ-irradiated with doses of 36 and 130 kGy. The dose rates were ~7 and ~31 kGy h−1. The extremely stable aqueous suspension of substoichiometric Fe2.83O4 magnetite nanoparticles ~4.7 nm in size were formed at a dose rate of ~7 kGy h−1 and at a dose of 36 kGy. At a dose of 130 kGy the anisotropic δ-FeOOH magnetic discs with a diameter of ~256 nm and thickness of ~40 nm were formed. Each disc has a substructure consisting of approximately eighteen laterally stacked thin nanodiscs of about 2.2 nm in thickness. At a higher dose rate of ~31 kGy h−1and at a dose of 36 kGy, XRD revealed the presence of highly substoichiometric Fe2.75O4 magnetite, whereas TEM analysis revealed the presence of ~4.3 nm magnetite nanoparticles along with rod-shaped γ-Fe2O3 nanoparticles. The values of isomer shift in Mössbauer spectra of about 0.33 mm s−1 showed that all Fe(II) in substoichiometric magnetites oxidized to Fe(III) one month after synthesis. At high dose and dose rate, the rolled rod-like δ-FeOOH magnetic nanoparticles were formed having the diffraction patterns with streaks, which are characteristic of tubular structures. The magnetic measurements showed exceptional intrinsic room-temperature magnetic properties of both δ-FeOOH nanostructures with the Curie temperature above 300 K. In order to ascertain the formation of Fe(II) intermediate products prior to their oxidation, γ-irradiated samples were isolated by admixing glycerol. The amounts of Fe(II) in glycerol-isolated solid samples were determined using Mössbauer spectroscopy. Carbonate Green Rust I [GR(CO32−)] and Fe(OH)2 intermediate phases were confirmed by XRD and Mössbauer spectroscopy. The amounts of Fe2+ in the acidified solutions containing dissolved γ-irradiation ferrous products were determined using the potassium permanganate titration. The amounts of Fe2+ were 68.9% and 96.1% at doses of 36 and 130 kGy, respectively. Thus, at a dose of 130 kGy the radiolytically generated Fe(OH)2, after coming in contact with oxygen and CO2 from the air, topotactically oxidized to GR(CO32−) and further to δ-FeOOH without any structural changes. The lower dose rate (~7 kGy h−1) favored the δ-FeOOH nanodisc morphology, whereas the higher dose rate (~31 kGy h−1) favored the formation of tubular rod-like δ-FeOOH nanoparticles.

Effects of silver nanoparticles and zirconium trisulphide nanoplates on the adaptation of woody species microclones to ex vitro conditions

The transfer of microclones to nonsterile conditions is one of the critical stages of micropropagation. Nanoparticles and nanomaterials can significantly improve effectiveness of this technique if used as substances increasing adaptive capabilities of the propagated plants. We have studied the impact of silver nanoparticles and zirconium trisulphide nanoplates on the adaptation of microclones of white poplar × aspen hybrid, hairy birch, crack willow, red oak and scots pine upon transfer to ex vitro conditions. The performed study has revealed that foliage application of colloidal aqueous solutions of zirconium trisulphide and silver nanoparticles at 3 μg/l concentration to in vitro microclones was more effective than the reference growth regulator. The best results were observed in the experiments with red oak microclones, where the number of surviving and adapted plants increased by 50-60 %. Increase in biomorphological parameters was accompanied by improvement of photosynthetic activity. The results indicate high potential of zirconium trisulphide nanoplates and silver nanoparticles for protecting woody species microclones during their transfer to non-sterile conditions of glasshouse.

Antioxidant Properties of Amino Acid Derivatives of Fullerene C60

A comparative study of the relative antioxidant activity (RAA) of fullerene С60 and its amino acid derivatives is performed via amperometry and fluorimetry. The sizes of nanoparticles in the corresponding colloidal solutions are determined via dynamic light scattering (photon correlation spectroscopy) to study the effect the steric factors of the investigated compounds have on the magnitude of the RAA. Data are subjected to statistical correlation regression analysis using results obtained for the RAA dependence of fullerene С60 and salt forms of its acid derivatives on the corresponding sizes of nanoparticles in colloidal aqueous solutions. A close negative (inverse) correlation is identified between the size of nanoparticles in a solution and their antioxidant properties, with a pronounced synergic effect related to the influence of both chemical structure of the studied compounds and their structural organization in colloid solution. It is found that the structure of a substituent in a molecule of amino acid derivative of fullerene С60 also influences the size of the forming nanoparticles. At the same time, reductive properties of amino acid derivatives of fullerene С60 are generally determined by the electron effects of substituents.

Greatly enhanced luminescence efficiency of CdS nanoparticles in aqueous solution

A simple shell-creating technique for the synthesis of CdS nanoparticles covered by ZnS is presented, which also contributes to the understanding of their low quantum yield and luminescence intensity in water, which is usually below 0.01%. The CdS nanoparticles with about 0.8 nm thick ZnS shell were synthesized in a colloidal aqueous solution and stabilized by EDTA. The CdS carrier lifetime and the quantum efficiency is greatly increased. For the latter, values up to 2.7% were achieved. A mechanism for the CdS nanoparticle luminescence in the aqueous solution is proposed, which is based on radiative recombination of charge carriers with structural defects. It was found that the synthesis of CdS in air leads to the inclusion of oxygen atoms in the structure of nanoparticles, which strongly effects the luminescence spectrum. These results show that most of the CdS luminescence centers are localized inside the nanoparticle.

Reversibly compressible and freestanding monolithic carbon spherogels

We present a versatile strategy to tailor the nanostructure of monolithic carbon aerogels. By use of an aqueous colloidal solution of polystyrene in the sol-gel processing of resorcinol-formaldehyde gels, we can prepare, after supercritical drying and successive carbonization, freestanding monolithic carbon aerogels, solely composed of interconnected and uniformly sized hollow spheres, which we name carbon spherogels. Each sphere is enclosed by a microporous carbon wall whose thickness can be adjusted by the polystyrene concentration, which affects the pore texture as well as the mechanical properties of the aerogel monolith. In this study, we used monodisperse polystyrene spheres of approximately 250 nm diameter, which result in an inner diameter of the final hollow carbon spheres of approximately 200 ± 5 nm due to shrinkage during the carbonization process. The excellent homogeneity of the samples, as well as uniform sphere geometries, are confirmed by small- and angle X-ray scattering. The presence of macropores between the hollow spheres creates a monolithic network with the benefit of being reversibly compressible up to 10% linear strain without destruction. Electrochemical tests demonstrate the applicability of ground and CO2 activated carbon spherogels as electrode materials.

Luminescence properties of YVO4:Yb,Er nanoparticles dispersed in water

We have synthesized YVO4: Yb, Er nanoparticles in the size range of 100-500 nm, which form aqueous colloidal solutions and are luminescent when excited by femtosecond light pulses at a wavelength of 263 nm. It was established that the luminescence occurs due to the emission of Er3+ ions in characteristic spectral lines at 525 nm and 550 nm. However, an effective quenching channel for metastable levels of Er3+ ions is evident, so that the characteristic luminescence line of Er3+ ions in the 660 nm region is absent. We associate this quenching channel with a large concentration of lattice defects with possible localization of high-frequency quenchers.

In vitro and in vivo toxicity of pristine C60 fullerene aqueous colloid solution

Toxicity of the C60 fullerene aqueous colloid solution in vitro and in vivo experiments was studied. C60 fullerene in the concentration range of 3.6–144 µg/mL demonstrated low toxicity against human embryonic kidney (HEK293) cells with 383.4 μg/mL IC50 value. The acute toxicity of C60 fullerene in a dose progression (75, 150, 300, 600, 1200 and 1800 mg/kg) was investigated at 14th day after single intraperitoneal (i.p.) administration into mice. No toxic effect of С60 fullerene in the dose range of 75–150 mg/kg was observed; the calculated LD50 value was 721 mg/kg. The toxic effect of C60 fullerene was observed at a concentration of 300 mg/kg and higher, it was accompanied with mice behavior disturbance, hematotoxicity and pathomorphological changes in spleen, hepatic and kidney tissues. In mice treated with 600 mg/kg of C60 fullerene indices of inflammatory process were detected, whereas at 1200 mg/kg dose leukopoies and thrombocytopoies were found to be suppressed. Thus, C60 fullerene aqueous colloid solution in a dose range of 75–150 mg/kg is nontoxic and could be used for biomedical purposes.

تحضیرمتراكبات Au/Ag النانویة بواسطة التبخر الانفجاري للیزرالنبضي في الماء واستخدامها في السيطرة على فعالية انزيم AIP في دم الانسان

تم الحصول على محاليل مائيه غرويه عالقه لمتراكبات الفضة والذهب النانوية بأستخدام طريقة التبخر الانفجاري لقطع معدنية فائقة النقاوة من الذهب والفضة المغموره في ماء لاأيوني ثنائي التقطير وبأستخدام طولين موجيين 1064nm,532nmمن ليزر الياك النبضي بطاقة 100-900mj)). طيف الامتصاص لرنين البلازموني تم الحصول علية بأستخدام مطياف الاشعة المرئية-فوق البنفسجية دعمت النتائج باستخدام تقنية الاشعة السينية والمجهر الالكتروني النافذ. اظهرت اطياف الامتصاص الاشعة المرئية-فوق البنفسجية قمة حادة لكل معدن (400nm)للفضة (525nm) للذهب واظهرت الفحوصات تولد جسيمات نانوية تراوحت قياسها من (5-45nm) للفضة و(8-55nm)للذهب و(10-170nm)للمتراكب فضة- ذهب وبشكل عام بينت الفحوصات بأن الجسيمات النانوية اخذت الشكل الكروي وهيئة بلورية تدعى المكعب مركزي الوجة يعرف ب .(fcc). ان هذا العمل يمثل دراسة تأثير عدد نبضات الليزرعلى خواص سبائك الذهب والفضة النانوية وكذلك دراسة التأثير البايولوجي لهذه السبائك على فعالية انزيم الالكالاين فوسفاتيزفي دم الانسان.

Fabrication and characterization of resveratrol loaded zein-propylene glycol alginate-rhamnolipid composite nanoparticles: Physicochemical stability, formation mechanism and in vitro digestion

In this study, resveratrol loaded zein-propylene glycol alginate-rhamnolipid composite nanoparticles were fabricated to overcome the limitations of resveratrol such as water insolubility and chemical instability. Effect of rhamnolipid level on properties of the composite nanoparticles was characterized systematically. Incorporation of rhamnolipid was proved to modulate the encapsulation efficiency, physicochemical stability as well as digestion behavior of composite nanoparticles in simulated gastrointestinal tract. Fluorescence spectrum and circular dichroism analyses revealed that resveratrol and rhamnolipid altered the micro-environment and secondary structure of the protein in different solvents (colloidal dispersions or aqueous ethanol solutions). Fourier transform infrared spectroscopy (FTIR) confirmed that hydrogen bonds, hydrophobic effects and electrostatic interactions contributed to the formation of resveratrol loaded composite nanoparticles. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) patterns manifested that the amorphous nature of resveratrol encapsulated. Observation of zein-propylene glycol alginate-rhamnolipid composite nanoparticles by field emission scanning electron microscopy (FE-SEM) confirmed the globular nanoparticles and their potential to be an effective vehicle of resveratrol to be supplemented to food systems.

Comprehensive characterization of magnetite-based colloid for biomedical applications

An aqueous colloidal solution of dextran-coated magnetite nanoparticles was studied by nonlinear second-harmonic magnetic response (M2), transmission electron microscopy (TEM), dynamic light scattering (DLS) and electron magnetic resonance (EMR). Nanoparticles were found to aggregate. A set of magnetic parameters of the aggregates, such as the mean magnetic moment, the magnetization damping constant, the longitudinal relaxation time, the field and energy of magnetic anisotropy, and others were evaluated from M2 measurements with the data processing formalism based on the Gilbert–Landau–Lifshitz (GLL) equation for the stochastic dynamics of superparamagnetic (SP) particles. Combined with TEM and DLS, the M2 technique additionally enabled the differentiation between magnetic and nonmagnetic components of the colloid. To achieve full numerical consistency between the parameters obtained from the M2 and TEM data, magnetic correlations of nanoparticles inside the aggregates were taken into account and their correlation radius was evaluated. The observed crossover in the magnetic field dependence of the EMR signal occurring due to the break of the dipole–dipole (d–d) coupling between nanoparticles in the aggregates was described using the M2 and TEM data.