Dynamic Light Scattering Method Research Articles

Antibacterial and antibiofilm potentials of vancomycin-loaded niosomal drug delivery system against methicillin-resistant Staphylococcus aureus (MRSA) infections

The threat of methicillin-resistant Staphylococcus aureus (MRSA) is increasing worldwide, making it significantly necessary to discover a novel way of dealing with related infections. The quick spread of MRSA isolates among infected individuals has heightened public health concerns and significantly limited treatment options. Vancomycin (VAN) can be applied to treat severe MRSA infections, and the indiscriminate administration of this antimicrobial agent has caused several concerns in medical settings. Owing to several advantageous characteristics, a niosomal drug delivery system may increase the potential of loaded antimicrobial agents. This work aims to examine the antibacterial and anti-biofilm properties of VAN-niosome against MRSA clinical isolates with emphasis on cytotoxicity and stability studies. Furthermore, we aim to suggest an effective approach against MRSA infections by investigating the inhibitory effect of formulated niosome on the expression of the biofilm-associated gene (icaR). The thin-film hydration approach was used to prepare the niosome (Tween 60, Span 60, and cholesterol), and field emission scanning electron microscopy (FE-SEM), an in vitro drug release, dynamic light scattering (DLS), and entrapment efficiency (EE%) were used to investigate the physicochemical properties. The physical stability of VAN-niosome, including hydrodynamic size, polydispersity index (PDI), and EE%, was analyzed for a 30-day storage time at 4 °C and 25 °C. In addition, the human foreskin fibroblast (HFF) cell line was used to evaluate the cytotoxic effect of synthesized niosome. Moreover, minimum inhibitory and bactericidal concentrations (MICs/MBCs) were applied to assess the antibacterial properties of niosomal VAN formulation. Also, the antibiofilm potential of VAN-niosome was investigated by microtiter plate (MTP) and real-time PCR methods. The FE-SEM result revealed that synthesized VAN-niosome had a spherical morphology. The hydrodynamic size and PDI of VAN-niosome reported by the DLS method were 201.2 nm and 0.301, respectively. Also, the surface zeta charge of the prepared niosome was − 35.4 mV, and the EE% ranged between 58.9 and 62.5%. Moreover, in vitro release study revealed a sustained-release profile for synthesized niosomal formulation. Our study showed that VAN-niosome had acceptable stability during a 30-day storage time. Additionally, the VAN-niosome had stronger antibacterial and anti-biofilm properties against MRSA clinical isolates compared with free VAN. In conclusion, the result of our study demonstrated that niosomal VAN could be promising as a successful drug delivery system due to sustained drug release, negligible toxicity, and high encapsulation capacity. Also, the antibacterial and anti-biofilm studies showed the high capacity of VAN-niosome against MRSA clinical isolates. Furthermore, the results of real-time PCR exhibited that VAN-niosome could be proposed as a powerful strategy against MRSA biofilm via down-regulation of icaR gene expression.

Influence of coating on peroxidase-like activity of magnetic nanoparticles

Chitosan stabilized iron oxide magnetic nanoparticles (Chit-MNPs) were prepared with the theoretical Chit/Fe3O4 weight ratios equal to 0.5, 1, 2, 3 w/w and characterized by different techniques. The effect of various Chit/Fe3O4 weight ratios on the samples’ hydrodynamic diameter, zeta potential, and isoelectric point was studied by the dynamic light-scattering method. Using TEM analysis, the average magnetic core size was found to be ranging from 6 nm to 9 nm. The obtained results are comparable to those from magnetic measurements. The magnetic measurements confirmed successful chitosan coating on MNPs by means of the decrease in saturation magnetizations from 69.2 emu·g−1 for unmodified MNPs to 66.6, 65.9, 65.5 and 65.2 emu·g−1 for Chit-MNPs at different ratios of Chit/MNPs 0.5, 1, 2, and 3. TGA was used to quantify the amount of chitosan adsorbed on MNPs surface – the max. amount was 0.045 mg chitosan/mg MNPs. The peroxidase-like catalytic activity of unmodified MNPs and chitosan Chit-MNPs in present of a substrate such as N,N-diethyl-p-phenylenediamine sulfate salt (DPD) and hydrogen peroxide was studied. The results confirmed the peroxidase-like activity of samples, – they catalytically oxidise substrate DPD by H2O2 to produce a typical colour reaction. The chitosan coating was found to slightly decrease catalytic activity compared to MNPs at pH 7.4. Despite the fact, these findings can be useful for creating sets of MNPs and Chit-MNPs samples possessing predefined peroxidase-like activity and could be applied for chromogenic reactions in the future.

Improved Characterization of Aqueous Single-Walled Carbon Nanotube Dispersions Using Dynamic Light Scattering and Analytical Centrifuge Methods.

Aqueous dispersions of single-walled carbon nanotubes (SWCNTs) with a surfactant were studied by using a combination of differential sedimentation and dynamic light scattering methods. When applied to elongated particles like SWCNTs, the differential sedimentation method makes it possible to measure their diameters in dispersions, while the dynamic light scattering method allows to measure their lengths. Both methods have logarithmic dependence on the ratio between the length and diameter of the particles, and their simultaneous use improves the accuracy of measuring particles' dimensions. It was shown that sonication of dispersions leads not only to unbundling of agglomerates into individual nanotubes but also to a decrease in their lengths and the appearance of new defects detectable in increasing the D/G ratio in the Raman spectra. Unbundling into individual nanotubes occurs after exposure to 1 kWh/L energy density, and the single nanotube diameter with SDBS is ca. 3.3 nm larger than that of the naked nanotubes. Conductivity of thin SWCNT films made out of individual nanotubes demonstrates a power law dependence with the exponent close to the theoretical one for rigid rods.

Encapsulation Of β-Carotene And Curcumin In Liposome From Soybean Lecithin And L-α-Phosphatidylcholine Using SC-CO2 With The Assistance Of Ultrasonication

The newest method to maintain better bioavailability of antioxidant compounds in the human digestive process is encapsulation using liposomes. The liposomes used were lecithin from soybean seeds and L-α-Phosphatidylcholine. Furthermore, curcumin and β-carotene were encapsulated in soy lecithin liposomes using SC-CO2 with 100% ethanol, aquadest 50% v/v ethanol and 100% aquadest at 50°C, 60°C, and 70°C and pressure 15 MPa, 20 MPa and 25 MPa by ultrasonication for 60 minutes. This research was conducted to obtain liposomes from curcumin and β-carotene encapsulation, analyse the effect of lecithin from soybean seeds on the formation of encapsulation in liposomes, analyse the effect of operating conditions on the encapsulation process on the size of curcumin and β-carotene in liposomes and determine the size characteristics of liposomes. This was analysed using a UV-Vis Spectrophotometer and Particle Size Analyzer (PSA) with the Dynamic Light Scattering method and also using the Scanning Electron Microscope (SEM) method. The results of the PSA test showed that the increase in operating temperature and pressure resulted in an increase in liposome particle size. UV-Vis analysis proved that the content of curcumin and β-carotene in liposomes from L-α-Phosphatidylcholine had better results. It was found that using SC-CO2+Sonicator had higher concentrations of curcumin and β-carotene with the condition that the higher the temperature, the higher the curcumin content. The use of liposomes has increased the stability of encapsulated suspensions and prevented flocculation. SEM analysis proved that the encapsulation of curcumin with L-α-Phosphatidylcholine has the smallest particle size distribution of 2 micro meters so that it can be categorized as multilamellar vesicles (MLV).

Development of Positively Charged Poly-L-Lysine Magnetic Nanoparticles as Potential MRI Contrast Agent.

A colloidal solution of magnetic nanoparticles (MNPs) modified with biocompatible positively charged poly-L-lysine (PLL) with an oleate (OL) layer employed as an initial coating was produced as a potential MRI contrast agent. The effect of various PLL/MNPs' mass ratios on the samples' hydrodynamic diameter, zeta potential, and isoelectric point (IEP) was studied by the dynamic light-scattering method. The optimal mass ratio for MNPs' surface coating was 0.5 (sample PLL0.5-OL-MNPs). The average hydrodynamic particle size in the sample of PLL0.5-OL-MNPs was 124.4 ± 1.4 nm, and in the PLL-unmodified nanoparticles, it was 60.9 ± 0.2 nm, indicating that the OL-MNPs' surface became covered by PLL. Next, the typical characteristics of the superparamagnetic behavior were observed in all samples. In addition, the decrease in saturation magnetizations from 66.9 Am2/kg for MNPs to 35.9 and 31.6 Am2/kg for sample OL-MNPs and PLL0.5-OL-MNPs also confirmed successful PLL adsorption. Moreover, we show that both OL-MNPs and PLL0.5-OL-MNPs exhibit excellent MRI relaxivity properties and a very high r2(*)/r1 ratio, which is very desirable in biomedical applications with required MRI contrast enhancement. The PLL coating itself appears to be the crucial factor in enhancing the relaxivity of MNPs in MRI relaxometry.

Prognostic impact of baseline circulating extracellular vesicles (BCEVs) in the setting of patients with advanced non-small cell lung cancer (ANSCLC) eligible for first line treatment with osimertinib.

e14553 Background: In the liquid biopsy era, the interrogation of extracellular vesicles (EVs) content might be complementary for cancer prognostication and response assessment. In this explorative study, we aimed to describe whether the serial characterization of BCEVs plasma tumor-derived EVs could longitudinally reflect response and resistance to available first-line treatments, investigating the potential to predict clinical outcomes in patients with advanced NSCLC (aNSCLC). Methods: From 2020/02 to 2022/05, 27 treatment-naïve patients with aNSCLC (stageIIIB/IV), eligible for first-line treatment with an EGFRTKI (Osimertinib) or ICIs (e.g. Pembrolizumab ± platinum‐based chemotherapy) based on the predictive molecular pathology, were enrolled. Blood samples (∼5 mL) were collected into K2EDTA tubes early in the morning with fasting condition. We isolated EVs from 2 ml of plasma using exo-Easy Maxi Kit (Qiagen-USA). EVs’s size and distribution was determine by use of Dynamic Light Scattering method (DLS). Besides a Bradford assay (cfEV) for the indirect quantification of EV amount based on EVs proteins content was performed. According to the radiologic response, EV analyses were evaluated in patients with available plasma samples from baseline (T0) to the first radiologic evaluation of disease within 12 weeks (T1). Results: From 2020/02 to 2022/05, 27treatment-naïve patients with aNSCLC (stageIIIB/IV), eligible for first-line treatment with an EGFRTKI (Osimertinib) or ICIs (e.g. Pembrolizumab ± platinum‐based chemotherapy) based on the predictive molecular pathology, were enrolled. Blood samples (∼5 mL) were collected into K2EDTA tubes early in the morning with fasting condition. We isolated EVs from 2 ml of plasma using exo-Easy Maxi Kit (Qiagen-USA). EVs’s size and distribution was determine by use of Dynamic Light Scattering method (DLS). Besides a Bradford assay (cfEV) for the indirect quantification of EV amount based on EVs proteins content was performed. According to the radiologic response, EV analyses were evaluated in patients with available plasma samples from baseline (T0) to the first radiologic evaluation of disease within 12 weeks (T1). Conclusions: This real-world study confirmed the in vivo feasibility of isolating and characterizing BCEVs via DLS and Bradford assay from the plasma of patients with ANSCLC. The quantitative changes of the plasma EVs correlated with survival in the real-time monitoring of such first-line patients, mostly in the oncogene-addicted population receiving osimertinib.

DETERMINATION OF FERROFLUID MAGNETISATION CURVEBASED ON THE MEASUREMENT OF PARTICLE DISTRIBUTIONOBTAINED BY THE DLS METHOD

Ferrofluid is a colloid with particles of about 10nm that show magnetic properties. These fluids are used in avariety of applications. Their application is affected by the type of carrier base liquid, the magnetic propertiesof the particle's material, and their size and shape. In practical applications, the magnetisation curve andthe initial magnetic susceptibility are the most important characteristics of any ferrofluid. There are manymethods for determining magnetic characteristics, e.g., using magnetometers. The magnetisation curve canalso be determined on the particle distribution obtained using a transmission electron microscope (TEM).However, the cost of these devices and tests is relatively high. This paper describes a method for determiningthe magnetisation curve based on particle size measurements using the dynamic light scattering (DLS)method. Also, it is necessary to know the saturation magnetisation of the ferrofluid. The obtained magneticcharacteristics were compared with magnetisation curves described in other publications. The purpose ofthis paper is to present the method and determine the influence of various particle distribution parameterson ferrofluid characteristics. The advantage of the method is that a small volume of ferrofluid is requiredin measurements using the DLS method. The measurement can be performed quickly, and the result can beused to estimate the magnetic properties of ferrofluids quickly. These characteristics can be used in analyses(mathematical or numerical calculations) of different devices such as magnetic seals, magnetic couplings,magnetic dampers, etc.

Determination of Infusion Filter Efficiency applying Dynamic Light Scattering

Abstract Filter membranes (pore size 0.2 μm) are frequently used to perform a sterile filtration. To characterize the pore size of filter membranes, a method to determine the particle retention of nanoparticles was defined. The Dynamic Light Scattering method was first analysed and calibrated to correlate the particle concentration with absolute intensity of scattered light. Afterwards, standard particle suspensions with particle sizes of 0.150 μm and 0.239 μm were lead through an infusion filter and the particle retention of the filter was evaluated by the determination of the original and the filtrated particle concentration. The test filter retained 91% of the smaller and 98% of the larger particles. Evaluating the particle retention with Dynamic Light Scattering could be a time saving method with lesser effort compared to existing methods.

Investigation of C60/NMP and C60/NMP/xylene solutions by absorption spectroscopy and dynamic light scattering

The behavior of intermolecular interactions in fresh and aged solutions of fullerene C60 in neat N-methyl-2-pyrrolidone (NMP), as well as in NMP/xylene mixed solvents, were studied by the methods of ultraviolet-visible spectroscopy and dynamic light scattering (DLS). It has been experimentally shown that the aging of the C60/NMP solution leads to the disappearance of the characteristic maximum of molecular absorption at ∼330 nm with smoothing, as well as to an increase in the optical absorption intensity. The latter depend on the formation of “C60- NMP”complexes, as well as on the transition of fullerene molecules to the nanocluster state. Increasing the xylene content in the C60/NMP leads to significant changes in charge transfer between solute and solvent (“C60-NMP”, “C60-C60”) at a fixed concentration of fullerene. The latter leads to the reorganization of nanoparticles, which proceeds with the destruction of molecular complexes. In this case, using the DLS method, it was found that the geometric dimensions of the synthesized C60 nanoclusters decrease.

An experimental study on the use of iron oxide magnetic nanoparticles synthesized through watermelon rind extracts for industrial applications

In this study, an easy and eco-friendly way for the synthesis of magnetic nanoparticles was investigated and mainly focused on its use on magnetic particle inspection (MPI) as a fluorescent magnetic particle. For this purpose, iron oxide magnetic nanoparticles (Fe3O4 MNPs) were prepared via rapid and green route using watermelon rinds extract (WRE). The synthesized WRE@Fe3O4 MNPs have been characterized by Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Dynamic light scattering (DLS). From the SEM images of the WRE@Fe3O4 MNPs, it has been shown that particle size was ranging from 50 nm to 100 nm. EDS spectrum indeed confirmed the presence of significant amounts of Fe and O. The average particle size was found to be 554.8 nm by DLS method. The magnetic property of WRE@Fe3O4 MNPs was analyzed by Vibrating sample magnetometer (VSM). The analysis of synthesized nanoparticles showed an amount of 24.35 emu/g for magnetic saturation. All of the results, the green synthesized WRE@Fe3O4 MNPs demonstrated good potential for identifying cracks in the test block during MPI testing. Thus, the cracks between 1.29 and 1.55 mm in the test block were successfully identified.

Self-assembly of C60 fullerene molecules in the hexane–xylene solvent system

The behavior of self-assembly of C60 molecules in solutions of C60/hexane/xylene were studied by the methods of refractometry, ultraviolet–visible spectroscopy and dynamic light scattering (DLS). It was experimentally shown that with a slight increase in either the concentration of fullerene C60 or the volume fraction of xylene in a C60/hexane/xylene solution, the refractive index of the medium increases. Increasing the xylene content of the C60/hexane/xylene system leads to significant changes in charge transfer between solute and solvent, which, in particular, exhibit both a positive solvatochromic effect and a hypochromic effect in a strong absorption band at ∼328.8 nm. It was established by the DLS method that with an increase in the concentration of C60 in the C60/hexane solution from 20 to 30 mg/dm3, the maximum radius of the synthesized nanoclusters in solutions changed from ∼6.25 nm to ∼17.2 nm, and also with an increase in the mole fraction of xylene in the C60/hexane/xylene system, the cluster size gradually decreases.

Influence of Activators and Inhibitors on the Collagenase with Collagen Interaction Monitored by Dynamic Light Scattering in Solutions

Real–time digestion of type I collagen molecules by bacterial collagenase from Clostridium histolyticum has been monitored using Dynamic Light Scattering method. Time dependencies for translation diffusion coefficient (Dt) and hydrodynamic radius (RH) on were obtained for pure “collagen + collagenase” Tris–HCl buffer solution at different temperatures and for solutions with added CaCl2, ZnCl2 and MgCl2 and EDTA. It was shown that digestion of type I collagen molecules by bacterial collagenase is the first-order reaction. Reaction rate coefficients were calculated.

Structure and refractive index of fibrin protofibril aggregates according to laser phase microscopy accompanied by DLS and AFM.

The structures, sizes, and refractive indices (RI) of protein aggregates formed in a fibrinogen-thrombin system are examined using laser phase microscopy (LPM) accompanied by dynamic light scattering (DLS) and atomic force microscopy (AFM) measurements. Fibrin aggregates found in pure fibrinogen and fibrinogen with thrombin solutions by the DLS method, after drying the sample, form complex structures of different shapes and sizes on a glass surface. The LPM reveals submicron-sized dimeric structures in the pure fibrinogen solution, elongated micron-length structures, and rectangular structures in the fibrinogen-thrombin sample. AFM measurements show that the elongated structures form branched fibers, which in turn assembly into rectangular structures. All sizes obtained by LPM and AFM are consistent with DLS measurements. The refractive indices of all the structures, estimated by optical thickness, vary from 1.53 to 1.62, which indicates that they are fibrinogen derivatives. Effective visualization of the structure and determination of the optical properties for fibrin gel indicate that laser phase microscopy is capable of tissue imaging and characterization.

Palladium supported aminobenzamide modified silica coated superparamagnetic iron oxide as an applicable nanocatalyst for Heck cross-coupling reaction

An applicable palladium-based nanocatalyst was constructed through the immobilization of palladium onto 2-aminobenzamide functionalized silica coated superparamagnetic iron oxide magnetic nanoparticles. The nanocatalyst (named as Pd@ABA@SPIONs@SiO2) was characterized by several characterization methods, including scanning electron microscope (SEM), transmission electron microscopy (TEM), vibrating-sample magnetometry (VSM), energy-dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma (ICP), and X-ray photoelectron spectroscopy (XPS) analyses. Microscopy results showed that the nanoparticles are spherical in shape with 20–25 nm size. The size of the nanoparticles was confirmed by the DLS method. The superparamagnetic nature of the catalyst was confirmed by the VSM method. The successful functionalization of SPIONs@SiO2 was confirmed by FT-IR spectroscopy. The presence of palladium in the structure of the nanocatalyst was illustrated by XRD and EDS analysis. Also using XPS technique, the oxidation state of palladium in Pd@ABA@SPIONs@SiO2 was determined zero before and after the catalyst was applied in Mizoroki-Heck reaction. Several aryl halides and alkenes were reacted in the presence of the nanocatalyst and formed the corresponding products in high isolated yields. The nanocatalyst showed very good reusability and did not decrease its activity after 10 sequential runs. Density functional theory (DFT) calculation was performed to provide a mechanism for the reaction and confirmed the role of the palladium catalyst in the reaction function.

Measurement of the Translational Diffusion Coefficient and Hydrodynamic Radius of Proteins by Dynamic Light Scattering.

Diffusion is a fundamental process in biological systems that governs the molecular collisions driving biochemical reactions and membrane and transport. Measurement of the diffusion coefficient and application of the Stokes-Einstein equation produces the hydrodynamic radius, which is a commonly used gauge of particle size. Additionally, measurement of the diffusion coefficient and the sedimentation coefficient, and application of the Svedberg equation, yields the molecular weight, which is particularly useful in the characterization of very large macromolecules. Dynamic light scattering (DLS) is the most common method to measure the diffusion coefficient of macromolecules. We describe a procedure to perform DLS measurements on monomeric bovine serum albumin (BSA) purified by size-exclusion chromatography using the Zetasizer Nano S particle size analyzer. We compare several analytical methods in existing software programs to estimate the diffusion coefficient of BSA (extrapolated to water at 20°C at infinite dilution, ) and describe a statistical method to obtain 95% confidence limits of the precision of the estimates. We compare estimates to literature values obtained by diffusiometry, sedimentation velocity analytical ultracentrifugation, and other DLS instruments. The method of cumulant analysis in the program SEDFIT (www.analyticalultracentrifugation.com) produced the most precise estimate, 6.06 ± 0.07 F (1 F = 10-7 cm2 s-1), which was within the range of estimates obtained by diffusiometry or sedimentation velocity. This protocol is useful for DLS method validation and quality control.

The development of a new electrochemical sensor based on Cu2O@C core–shell and polyalizarin/nafion polymers for determination of bisphenol A at two area potentials

In this paper, employing a hydrothermal method, we synthesized Cu2O nanoparticles and Cu2O@C core–shell. The scanning electron microscope (SEM), X -Ray diffraction (XRD), dynamic light scattering (DLS) and zeta potential techniques were used for characterized of the Cu2O nanoparticles and Cu2O@C core–shell. The zeta potential values were obtained to be -11.16 mV and -0.88 mV for Cu2O and Cu2O@C, respectively. The average hydrodynamic size of diameter for Cu2O and Cu2O@C was obtained as 48-62 nm and 200-250 nm by DLS method. Polyalizarin yellowe R (PAYR) and Nafion (Nf) conductive polymers with Cu2O@C core–shell immobilizing on glassy carbon electrode (PAYR/Cu2O@C /Nf/GCE), they were applyed for fabrication of an original electrochemical sensor to detect and determine bisphenol A. Cyclic voltammetry (CV) and impedimetric techniques were employed to confirm the proposed sensor construction. Furthermore, the electrocatalytic-based oxidation behavior which electrode showed was studyed by cyclic voltammetry and differential puls voltammetry (DPV) methods. The results showed that, PAYR/Cu2O@C/Nf composite has a great electrocatalytic features for detecting and determining bisphenol A at 0.12V(OX1) and 0.63V(OX2). For OX1 peak, linear range (1 – 1400 µM), limit of detection (260 nM) and sensitivity (0.0009 µA/µM) were obtained. Moreover, considering the peak of OX2, linear range (1 – 1400 µM), limit of detection (240 nM) and sensitivity (0.0009 µA/µM) were calculated. PAYR/Cu2O@C/Nf/GCE presented considerable advantages for instance high sensitivity, used for real samples, simple preparation, low detection of limit, and specially the oxidation of bisphenol A at two applied potentials that it reported for the first time.

Preparation and Some Physicochemical Properties of Water–Surfactant–Halohydrocarbon Microemulsions Suitable for the Creation of Combined Fire Extinguishing Agents

The research findings related to synthesis and study of water–sodium dodecyl sulfate–1-pentanol–triethanolamine–2-iodoheptafluoropropane and water–sodium dodecyl sulfate–1-pentanol–triethanolamine–1,2-dibromotetrafluoroethane microemulsions at the standard temperature were summarized. Use of microemulsions provides a promising means of combining with water chemically active inhibitors such as halohydrocarbons, which are water-immiscible under ambient conditions. This affords fire extinguishing agents integrating different flame suppression mechanisms: chemical inhibition of the combustion reaction and flame cooling. The electrical conductivities and heat capacities of the microemulsions synthesized were determined and used for analyzing the structural changes caused in them by changes in their composition. Using the dynamic light scattering method, the size of the microdroplets of the microemulsions was determined, and their size distribution was examined. Based on the data obtained, the fire extinguishing performance of the microemulsions (cooling capacity, possible applications, and mechanism of action) was described. Laboratory tests of the fire extinguishing efficiency of the microemulsions were carried out.

An experimental study on characterization and properties of eco-friendly nanolubricant containing polyaniline (PANI) nanotubes blended in RBD palm olein oil

Polyaniline nanotubes (PANI NTs) blended in refined, bleached and deodorized palm olein (RBDL) nanolubricants were prepared via a two-step method. Initially, the synthesized PANI NTs were characterized to investigate the morphology and elemental composition of the obtained PANI NTs. The obtained image from transmission electron microscopy clearly showed the presence of flake-like structure of PANI NTs. The presence of these PANI NTs was further affirmed with energy-dispersive X-ray analysis, which shows the presence of high carbon atoms (the main element for PANI NTs). The formulated surfactant-free nanolubricants were stabilized using ultrasonication with volume concentrations of 0.01, 0.03, 0.05, 0.1, 0.3 and 0.5%. The dispersion behavior of nanolubricants was investigated using visual sedimentation capturing, UV–Vis spectrophotometer and dynamic light scattering (DLS) method. The sedimentation observation of the nanolubricants over the duration of almost 1 month showed there was no sedimentation of the nanoparticles. UV–Vis spectra indicated that all the prepared PANI/RBDL nanolubricants followed Beer–Lambert law. The value of absorbance was found to be slightly decreased, with respect to the duration of time after sample preparation. The dispersion stability analysis supported by DLS method revealed that the amount of particles agglomeration increased after 1 month of preparation. The chemico-physical properties of prepared PANI/RBDL nanolubricants were further investigated by analyzing the chemical bonding using Fourier-transform infrared spectroscopy (FTIR). Additionally, this study intends to investigate the influence of PANI NTs toward the life cycle of base oil via thermogravimetric (TG) analysis. FTIR analysis showed that nanolubricants were chemically stable as there were only physical interactions between PANI additives and RBDL base oil, while the degradation behavior in TG curve demonstrated that the nanolubricants could withstand higher temperature as the volume concentration of nano-additives increased. Rheology and thermal conductivity properties of PANI/RBDL nanolubricants were performed by using rheometer and thermal properties analyzer, respectively. Viscosity measurement revealed that PANI/RBDL nanolubricants exhibited Newtonian behavior. Also, viscosity was found to have been increased with a volume concentration of PANI NTs but decreases with the increase in temperature. From the thermal conductivity measurement, it is proven that the PANI NTs dispersed in the RBDL palm base oil support the thermal properties enhancement. The 0.5% PANI/RBDL nanolubricants had achieved the highest thermal conductivity of 0.4301 W m−1 K −1 at 80 °C with enhancement percentage of 25.76% when compared to conventional base oil at a similar temperature.

Influence of UV radiation on TiO2 nanoparticles antibacterial behaviour

Purpose: The influence of UV radiation on the antibacterial properties of titanium oxide nanoparticles was examined using yeast Saccharomyces cerevisiae strain for this purpose. Design/methodology/approach: Nanopowders were made with sol-gel method. Surface morphology studies of the obtained materials were made using Zeiss's Supra 35 scanning electron microscope. In order to confirm the chemical composition of observed nanopowders, qualitative tests were performed by means of spectroscopy of scattered X-ray energy using the Energy Dispersive Spectrometer (EDS). The DLS (Dynamic Light Scattering) method was used to analyse the particle size distribution using the AntonPaar Litesizer 500 nanoparticle size analyser. Changes in particle size distribution at elevated temperatures were also observed. The antibacterial properties of titanium oxide nanoparticles were examined by subjecting the yeast sample to irradiation with an UV lamp. Findings: Samples containing yeast Saccharomyces cerevisiae were irradiated with and without the addition of TiO2 nanoparticles. A faster decrease in the colony count was observed compared to irradiated exposures without the addition of a suspension. Practical implications: Presented materials can be used in the production of antibacterial coatings for surfaces occurring in public spaces such as schools, hospitals, public toilets for the simple and effective elimination of bacteria and fungi as a result of exposures. Originality/value: The antibacterial properties of titanium oxide nanoparticles under UV radiation were confirmed.

Preparation, characterization and application of a surfactant-free microemulsion containing 1-octen-3-ol, ethanol, and water

The ternary diagram of a surfactant-free microemulsion (SFME) containing 1-octen-3-ol as oil phase and ethanol as the “double solvent” was constructed. Three phase regions of O/W, B.C. and W/O were identified by conductivity measurement and UV–vis spectroscopy. With an increase in 1-octen-3-ol content, the magnitude of change in surface tension of the SFME is comparatively larger in both W/O and O/W regions, but smaller in B.C. region. This change pattern reflects the difference in the microstructures in each phase region of the SFME system. The autocorrelation function of the dynamic light scattering (DLS) was determined, and a double exponential decay phenomenon was observed. The microstructures of the O/W, B.C. and W/O SFMEs were ascertained by the use of DLS method. The microstructures of the SFME were observed from negative staining TEM measurements. It was found that the O/W and W/O SFMEs contain spherical droplets, whereas the B.C. system is a bicontinuous structure.The surfactant-free solubilization of riboflavin in the W/O SFME was measured by UV–vis spectrophotometry. The W/O SFME has good solubilization ability for riboflavin, similar to that of traditional microemulsion systems. The surfactant-free solubilization of curcumin in the O/W SFME was also determined. The solubilized amount of curcumin reached a maximum of 17.65 mg/ml, an increase of approximately 10,000 fold compared to its water solution. The solubilized curcumin has higher light stability and thermal stability in SFME than those in its water solution.