Zeta Potential Values Research Articles

Enhancing solubilization of Nebivolol hydrochloride through tuning pluronic F-127 with ionic Surfactants: An experimental and theoretical investigation

In the present work, the interaction of the antihypertensive drug Nebivolol hydrochloride (NBL) with nonionic surfactant pluronic F-127 (F-127) is investigated in an aqueous medium. Two ionic surfactants, viz., cationic, cetyl trimethyl ammonium bromide (CTAB) and anionic, sodium tetradecyl sulphate (STS) were added to F-127 to improve the physicochemical properties of the single micellar medium. The characterization techniques employed were, FTIR, UV–visible spectroscopy, dynamic light scattering, zeta potential, antioxidant, conductivity, and FESEM studies. The critical micellar concentration (CMC) of CTAB and STS are estimated from the conductivity experiments which is lowered due to the addition of F-127 and NBL. The lowering of CMC is attributed to the solubilization of NBL in the binary micellar mediums. The extent of binding of NBL in F-127, F-127 + CTAB, and F-127 + STS were quantified by determining the binding constant values using the Benesi–Hildebrand (B-H) plot from UV absorbance data. They were, 838.2 M−1 for F-127 1100.7 M−1 for F-127 + CTAB and 1836.5 M−1 for F-127 + STS systems. There was an increase in the size of the micelle due to the encapsulation of the drug in both binary micellar systems. The zeta potential (ZP) values displayed enhanced stability of the drug in binary micellar systems. The radical scavenging activity (RSA %) of NBL was estimated to be 16.5 % in F-127, 24.7 % in F-127 + CTAB, and 44.9 % in F-127 + STS systems. The encapsulation efficiency (EE %) for the above three systems were 14.7 %, 16.4 % and 18.5 %, respectively. The surface parameters and the interactions were verified through molecular docking studies. The results suggest that the properties of F-127 can be improved by tuning with ionic surfactants to solubilize NBL. To our knowledge, this is the first report of NBL solubilization in mixed micellar systems. Similar studies with other drug systems can be applied to get improved results.

Synthesized tin oxide nanoparticles promote apoptosis in human osteosarcoma cells

Complicated protocols have been used to tune the size of tin oxide nanoparticles (SnO2 NPs) in conventional chemical synthesis approaches. In this study, we addressed this issue through the combination of polarity solvent reduction and sonication as a potential strategy for optimizing the size of SnO2 NPs for anticancer applications. Then the anticancer activity and safety of synthesized SnO2 NPs on U-2OS human osteosarcoma cells and normal human osteoblast, NHOst, respectively, were assessed by several assays. SEM and TEM analyses revealed that synthesized SnO2 NPs had a spherical-shaped morphology with an average particle size of about 10 nm. FTIR result showed a broad absorption peak at 649 cm– 1, corresponding to the stretching vibration of the O–Sn–O bond. XRD analysis exhibited eight main peaks, revealing a tetragonal system of rutile-like structure. DLS study showed that synthesized SnO2 NPs had an average hydrodynamic size of 43.93 nm with a zeta potential value of −31.00 mV. Cellular assays displayed that SnO2 NPs mitigate the growth of U-2OS human osteosarcoma cells (IC50: 15.50 µg/mL) with partial cytotoxicity on normal osteoblasts. It was then discovered that SnO2 NPs triggered stress effects by raising the levels of LDH release, ROS, and MDA and lowering those of SOD, CAT activity, and GSH content. Also, it was discovered that SnO2 NPs activated both intrinsic and extrinsic signaling pathways mediated by MMP collapse, elevation of caspase-3, −9, −8 activities and corresponding mRNA, and upregulation of Bax/Bcl-2 mRNA ratio. Overall, this study found that extrinsic and mitochondrial apoptotic pathways can both be activated by synthesized SnO2 NPs to induce apoptosis in human osteosarcoma cells. This finding calls for additional research in the future.

Experimental and theoretical insight into the effect of a novel composite dispersant on the properties of coal pitch water slurry

To optimize the utilization efficiency of coal pitch (CP), an innovative composite dispersant was designed and employed in the preparation of coal pitch water slurry (CPWS) by effectively combining modified sodium lignosulfonate (MLS) and amphoteric polycarboxylate (AAD) based on the principle of complementary advantages. The effects of the proportion of MLS to AAD on the characteristics of CPWS were systematically analyzed and assessed by various technical methods, including apparent viscosity, rheological behavior, static stability, adsorption behavior, etc. Results indicated that the CPWSs utilizing distinct composite dispersants belonged to the category of yield pseudoplastic fluids and had a good correlation with the Herschel-Bulkley model. Among them, the CD-2, composite dispersant with a mass ratio of MLS:AAD = 1:1, exhibited superior performance in terms of viscosity reduction and stabilization properties. It demonstrated the maximum adsorption capacity (5.23 mg/g) and adsorption layer thickness (7.22 nm) compared to other dispersants. Meanwhile, it could significantly increase the wettability (with a contact angle of 74.5°) and the absolute Zeta potential value (32.5 mV) of CP. The density functional theory (DFT), molecular dynamics (MD) simulation, and extended Derjaguin-Landua-Verwey-Overbeek (eDLVO) theory were carried out to investigate the interaction mechanism of composite dispersant with CP and the interaction energy among CP particles. The differences in energy levels between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HUMO) of MLS and AAD were significantly smaller than that of H2O. The hydrophobic groups of composite dispersants were efficiently adsorbed onto CP, while the hydrophilic groups adsorbed water molecules, with an adsorption energy reaching −169.36 kcal/mol. The steric hindrance of composite dispersant exerted a crucial influence on the dispersion of CPWS, enabling CP particles to be stabilized in water. The present study offers a novel approach to enhance the characteristics of CPWS and establishes a theoretical foundation for the design of efficient composite dispersants.

Effect of alkali residue and humic acid on aggregate structure of saline‐alkali soil

AbstractHumic acid (HA) and alkali residue (AR) exert an essential impact on soil aggregate structure, but how HA and AR promote the formation of macroaggregates jointly is not clear. The aim of this research was to explore influence of alkali residue and humic acid (AHA) on the structure and stability of soil aggregates, with saline‐alkali soil in North China as an example. The morphology and structure of the soil with AHA added were detected by a scanning electron microscope, Fourier transform infrared spectroscopy, and X‐ray diffraction. Soil aggregate structure was analyzed by mean weight diameter (MWD), geometric mean diameter (GMD), and fractal dimension (D), and the trend of soil colloid forming macroaggregates was evaluated by zeta potential and surface charge. The results showed that under dry and wet sieves, MWD and GMD both surged initially and then decreased with the rise of AHA content, while D had the opposite trend. With the addition of 3%, AHA, MWD, and GMD reached their peak which proves that the proportion of soil macroaggregates was the highest. In the meantime, absolute value of zeta potential was low, which illustrates that the soil colloid system was in an unstable state of condensation and microaggregates tend to transform into macroaggregates. A large number of ions such as Ca2+ and Mg2+ in AHA promoted variable charge of saline‐alkali soil, and the binding frequency of Ca2+ with negatively charged humus and soil colloid particles was increased. AHA holds great promise for improving the aggregate structure of saline‐alkali soil.

Process optimization for green synthesis of silver nanoparticles using Rubus discolor leaves extract and its biological activities against multi-drug resistant bacteria and cancer cells

Multi-drug resistant (MDR) bacteria are considered a serious public health threat. Also, increasing rate of resistance to anticancer drugs, as well as their toxicity, is another point of concern. Therefore, the new antibacterial and anticancer agents are always needed. The synthesizing silver nanoparticles (AgNPs) using medicinal plants, is an effective approach for developing novel antibacterial and anticancer agents. Rubus discolor, a native species of the Caucasus region, produces leaves that are typically discarded as a by-product of raspberry production. The present study has focused on optimizing the green synthesis of AgNPs using R. discolor leaves extract through response surface methodology. The optimal values for AgNPs synthesis were an AgNO3 concentration of 7.11 mM, a time of 17.83 h, a temperature of 56.51 °C, and an extract percentage of 29.22. The production of AgNPs was confirmed using UV–visible spectroscopy (λmax at 456.01 nm). TEM analysis revealed well-dispersed AgNPs (an average size of 37 nm). The XRD analysis confirmed the crystalline structure. The EDX detected a strong peak at 3 keV corresponded to Ag. The zeta potential value (− 44.2 mV) indicated the stability of nanoparticles. FT-IR spectra showed the presence of various functional groups from plant compounds, which play an important role in the capping and bio-reduction processes. The AgNPs revealed impressive antibacterial activities against MDR Escherichia coli and Pseudomonas aeruginosa (MIC ranging from 0.93 to 3.75 mg ml−1). The phytochemical analysis indicated the presence of phenolics, tannins, and flavonoids on the surface of AgNPs. They also showed significant cytotoxic effects on A431, MCF-7, and HepG2 cells (IC50 values ranging from 11 to 49.1 µg ml−l).

Synergistic Effects of High-Intensity Ultrasound Combined with L-Lysine for the Treatment of Porcine Myofibrillar Protein Regarding Solubility and Flavour Adsorption Capacity.

This study aimed to investigate the synergistic effects of high-intensity ultrasound (0, 5, 10, 15, and 20 min) in combination with L-lysine (15 mM) on improving the solubility and flavour adsorption capacity of myofibrillar proteins (MPs) in low-ion-strength media. The results revealed that the ultrasound treatment for 20 min or the addition of L-lysine (15 mM) significantly improved protein solubility (p < 0.05), with L-lysine (15 mM) showing a more pronounced effect (p < 0.05). The combination of ultrasound treatment and L-lysine further increased solubility, and the MPs treated with ultrasound at 20 min exhibited the best dispersion stability in water, which corresponded to the lowest turbidity, highest absolute zeta potential value, and thermal stability (p < 0.05). Based on the reactive and total sulfhydryl contents, Fourier transform infrared spectroscopy, and fluorescence spectroscopy analysis, the ultrasound treatment combined with L-lysine (15 mM) promoted the unfolding and depolymerization of MPs, resulting in a larger exposure of SH groups on the surface, aromatic amino acids in a polar environment, and a transition of protein conformation from α-helix to β-turn. Moreover, the combined treatment also increased the hydrophobic bonding sites, hydrogen-bonding sites, and electrostatic effects, thereby enhancing the adsorption capacity of MPs to bind kenone compounds. The findings from this study provide a theoretical basis for the production and flavour improvement of low-salt MP beverages and the utilisation of meat protein.

Unique properties of titanium dioxide quantum dots assisted regulation of growth and biochemical parameters of Hibiscus sabdariffa plants

Owing to the uniqueness of quantum dots (QDs) as a potential nanomaterial for agricultural application, hence in the present study, titanium dioxide quantum dots (TiO2 QDs) were successfully synthesized via sol-gel technique and the physico-chemical properties of the prepared TiO2 QDs were analyzed. Based on the results, the TiO2 QDs showed the presence of anatase phase of TiO2. TEM examination revealed spherical QDs morphology with an average size of 7.69 ± 1.22 nm. The large zeta potential value (-20.9 ± 2.3 mV) indicate greater stability of the prepared TiO2 QDs in aqueous solutions. Moreover, in this work, the application of TiO2 QDs on Hibiscus sabdariffa plants was conducted, where H. sabdariffa plants were foliar sprayed twice a week in the early morning with different concentrations of TiO2 QDs (0, 2, 5, 10, 15 and 30 ppm) to evaluate their influence on these plants in terms of morphological indexes and biochemical parameters. The results exhibited an increasing impact of the different used concentrations of TiO2 QDs on morphological indexes, such as fresh weight, dry weight, shoot length, root length, and leaf number, and physio-biochemical parameters like chlorophyll a, chlorophyll b, carotenoid contents, total pigments and total phenolic contents. Remarkably, the most prominent result was recorded at 15 ppm TiO2 QDs where plant height, total protein and enzymatic antioxidants like catalase and peroxidase were noted to increase by 47.6, 20.5, 29.5 and 38.3%, respectively compared to control. Therefore, foliar spraying with TiO2 QDs positively serves as an effective strategy for inducing optimistic effects in H. sabdariffa plants.

GARLIC EXTRACT PHYTOSOME: PREPARATION AND PHYSICAL STABILITY

Objective: Allicin is one of the components contained in garlic extract (Allium sativum L) and can easily be decomposed. To improve the chemical stability of allicin, a garlic extract was formulated in a phytosome system. Phytosomes, which are colloidal systems, are susceptible to ostwald ripening, which can result in an increase in particle size distribution. Changes in the size distribution indicate that the system is physically unstable. The aimed of the study was to test the physical stability of the garlic extract phytosome stored at three different temperatures for four weeks.&#x0D; Methods: Garlic extract phytosomes (GEP) were prepared by the thin layer hydration method using garlic extract and lecithin at the same concentration of 4.5%. Furthermore, the phytosomes were stored at 4 °C, 25 °C, and 40 °C for four weeks. Every week, a physical evaluation was carried out (organoleptic, pH, density, particle size, polydispersity index, and zeta potential). The data obtained were analysed statistically using the Friedman test.&#x0D; Results: The phytosome’s organoleptic result showed separation at 4 °C and 40 °C, starting from the second week. The average particle size of phytosomes was 214.3 nm, the zeta potential value was -29.08 mV, and the polydispersity value was 0.46. The results of statistical analysis showed that the Asymp. Sig&lt;0.05 indicated that the particle size, zeta potential, polydispersity index, pH values, and density were significantly different at each week and storage temperature.&#x0D; Conclusion: Conclusion based on study indicated a decrease in the physical stability of phytosomes, especially those stored at extreme temperatures (4 °C and 40 °C).

Biochemical Analysis and Characterization of Silver Nanoparticles Synthesized by the Endophytic Fungus Plectosphaerella oligotrophica S8A26 Associated with Anaphalis contorta

Endophytic fungi associated with medicinal plants produce compounds that have vast biological activities. Anaphalis contorta is a highly therapeutic plant that has been used in traditional medicine by various communities. In the present study, the endophytic fungus Plectosphaerella oligotrophica S8A26 was isolated from the stem part of A. contorta and assessed for its plant growth promotion abilities, and showed positive results for phosphate solubilization and ammonia production. The secondary metabolites were analyzed for the presence of seven biochemicals, which indicate the presence of flavonoids, phenols, saponins, and steroids. The total flavonoid content and total phenolic content were recorded to be 25.67 µg of QE/mg of EE and 5.06 µg of GAE/mg of EE, respectively. The isolate was allowed to synthesize silver nanoparticles and characterized using X-ray diffraction, Energy Dispersive X-ray, Particle size distribution, and Zeta potential. XRD analysis has shown the AgNPs are crystalline with an average size of 24.81 nm. EDX study reveals silver as the main component with 48.63%. Particle size distribution indicates that the majority of the particles occur in the size range of 65–70 nm. Zeta potential value of −31.8 mV shows that the AgNPs are stable. Studies like the biological activities of the endophyte as well as AgNPs, secondary metabolite profiling, and the isolation of bioactive compounds would constitute important future research.

ZnO nanomaterials with enhanced antimicrobial activity obtained by Eichhornia crassipes aqueous extract‐mediated synthesis

AbstractBACKGROUNDZinc oxide nanoparticles (ZnO NPs) were obtained through precipitation synthesis, using aqueous water hyacinth leaf extract (Eichhornia crassipes) under alkaline conditions. The effect of the extract on the physicochemical and antimicrobial properties of the ZnO was evaluated starting from concentrated extract (labeled as E100) and performing two dilutions of this concentrated extract at 50% and 25% in water (E50, and E25).RESULTSThe FTIR spectra revealed strong peaks at ≈3440 cm−1, corresponding to vibrations from OH stretching, and medium‐intense peaks at 1384 and 1327 cm−1, assigned to CC, COOH and COC vibrations, which are related to the presence of the extract; a weak band at 884 cm−1 and a broad band in the region below 600 cm−1 indicate the presence of ZnO. The hydrodynamic size of the ZnOE100, ZnOE50 and ZnOE25 samples were 202, 244 and 313 nm, respectively. No significant variations on the Eg value were observed. Field emission scanning electron microscopy images showed that the ZnO NPs have triangular‐like shapes and agglomeration of the NPs synthesized for the ZnOE25 sample. The minimum inhibitory concentration (MIC) of the ZnO NPs showed no significant effects related to the concentration the plant extract used.CONCLUSIONSVariations in particle size and zeta potential can be introduced in ZnO by varying the content of the extract; the presence of organic groups from the extract, along with a positive zeta potential value, can promote the bactericide effect of ZnO nanomaterials prepared by bio‐assisted synthesis. © 2024 Society of Chemical Industry (SCI).

Microgels from egg white as novel stabilizers of Pickering emulsion

Common preparation of microgels is complex. In this study, we aimed to find a convenient method to prepare microgels without high energy input. We prepared egg white microgel (EWM) by ultrasonic-microwave synergistic treatment (US-MW) and evaluate the ability of EWM to stabilize emulsions. The cavitation effect of ultrasound (US) could avoid excessive aggregation of protein caused by microwave (MW) and achieved the regulation of EWM particle size. Compared with EWM prepared by MW and water bath treatment, EWM treated by US-MW had small particle size (233.23 ± 6.49 nm), high absolute value of zeta potential (−25.27 ± 0.74 mV), high hydrophobicity (505.87 ± 5.22) and large contact angle (78.92°), which made it easier to be adsorbed on water-oil interface with higher emulsification, showing great potential in preparation of Pickering emulsions. Emulsions with EWM concentration >1.5% had good stability and EWM showed great ability to stabilize high volume fraction of oil phase (φ = 0.85). Confocal laser scanning microscopy images showed that EWM was adsorbed on the surface of oil droplets, formed physical barrier to stabilize emulsions. Rheological results showed the emulsions (EWM concentration >1.5% and φ > 0.75) had high apparent viscosity and modulus. This study provided a basis for simple preparation of EWM with high emulsifying capacity, and the EWM could effectively stabilize Pickering emulsions which could be further applied in active substance delivery and fat replacement.

Sustainable Finished Leather Preservation

Part 1 of the current paper described the green synthesis of myrobalan capped copper nanoparticles for the preservation of the finished leather. In Part II of the current study, Copper Nanoparticles (CuNPs) were synthesized using green synthesis with wattle (tannin) extract as a reducing agent. Green synthesis is the preferred approach for the synthesis of metal nanoparticles due to its eco-friendly and cost-effectiveness for the preservation of finished leather. To improve the antibacterial qualities of leather with different types of finishes, the resin finished leather was coated with synthesized wattle copper nanoparticles (W-CuNPs). The chemical constituents of wattle induce the reduction of Cu2+ ions to CuNPs with the capping process and also remain as a stabilizing agent for the capping process. The formation of W-CuNPs was confirmed by UV-Spectroscopy at an absorbance of 467 nm. The identified functional groups such as -OH, C=C, and C-N were analyzed by Fourier transform infrared spectrum (FT-IR) which are responsible for the reduction and stabilization of copper nanoparticles. The spherical shape of the nanoparticles was ascertained by Scanning Electron Microscope (SEM), whereas Energy dispersive X-ray (EDX) studies confirmed the presence of copper with 65%. The average particle size of W-CuNPs was found to be 96 nm. The zeta potential value of -24 mv affirmed the stability of the W-CuNPs. The maximum zone of inhibition was 12 mm against Gram-positive (Bacillus subtilis) and 11 mm against Gram-negative (Serratia marcescens) bacteria on W-CuNPs coated finished leather, which exhibits strong antimicrobial activity. Hence, CuNPs synthesized by wattle extract have the potential to preserve the finished leather and its products as an antibacterial agent.

Thermal decomposition kinetics and mechanism of poly(ethylene 2,5-furan dicarboxylate) Nanocomposites for food packaging applications

Poly(ethylene 2,5-furan dicarboxylate) (PEF) based nanocomposites containing different nanoparticles like Ag, TiO2, ZnO, ZrO2 Ce-Bioglass, have been synthesized via in-situ polymerization techniques targeting food packaging applications. Zeta potential measurements showed an increase in the negative zeta potential value due to an increase in the surface charge density of the nanocomposites. Thermogravimetric analysis results proved that, except PEF-ZnO nanocomposite, all the other nanocomposites exhibited good resistance to thermal degradation without serious mass loss until 330 °C. Thermal decomposition kinetic analysis and the dependence of activation energy on the degree of conversion (α), indicated that the presence of ZnO nanoparticles influences, the degradation mechanism of PEF. In contrast, the presence of Ce-Bioglass nanoparticles leads to a slower degradation process, contributing to the enhanced resistance to thermal degradation of the PEF-Bioglass nanocomposite. The thermal degradation mechanism of PEF nanocomposites analyzed by pyrolysis‒gas chromatography/mass spectrometry (Py-GC/MS) indicated that the primary thermal degradation mechanism for the studied nanocomposites was β-hydrogen bond scission, while to a lesser extent, α-hydrogen bond scission products were noted in PEF-TiO2 and PEF-ZrO2 nanocomposites.

Bio‐fabrication of Zinc oxide nanoparticles using Strobilanthes cordifolia: Characterization and evaluation of antioxidant, anti‐cholinergic, anti‐inflammatory and wound healing activities

AbstractStrobilanthes cordifolia has emerged as a promising material in traditional medicine. In this study, we have made an attempt to synthesize zinc oxide nanoparticles derived from S. cordifolia leaf. The team employed a wide range of techniques including UV, FT‐IR, XRD, FE‐SEM with EDAX, HR‐TEM with SAED, DLS, Zeta potential, BET and PZC analysis to thoroughly examine the properties of the NPs. FTIR analysis provided evidence of various functional groups within the NPs. XRD analysis demonstrated the crystal nature and phase purity of the NPs. SEM analysis showcased the spherical shape of the particles, while TEM revealed their rod‐like shape with sizes averaging at approximately 10 nm. DLS analysis indicated the average particle size, and the high zeta potential value confirmed the stability and BET analysis deciphered the specific surface area of the biosynthesized NPs. The NPs confirmed strong antioxidant properties with DPPH, ABTS, and hydroxyl radicals. Enzyme studies confirmed good anti‐cholinergic activity and anti‐inflammatory efficacy, highlighting their potential therapeutic benefits. The NPs demonstrated promising wound healing properties. Overall, this research study sheds light on the medicinal aspects of zinc oxide nanoparticles from S. cordifolia leaf extract and it offers exciting prospects for future exploration and development in this field.

Propolis-loaded liposomes: characterization and evaluation of the in vitro bioaccessibility of phenolic compounds.

Propolis has low water solubility, poor stability, and limited bioaccessibility of phenolic constituents when subjected to in vitro digestion. To overcome these drawbacks, the liposomal encapsulation method can be employed. Soybean phosphatidylcholine lecithin mixed with Tween 80 (T80) and ammonium phosphatides (AMP) was used to produce propolis extract (PE)-loaded liposomes. The mean particle size, zeta potential, encapsulation efficiency values, and transmission electron microscopy analysis were used to characterize liposomes. Individual phenolics were determined for digested and nondigested propolis-loaded liposomes and propolis extract. Tween 80 incorporation reduced the size of unloaded liposomes, whereas AMP inclusion yielded larger liposomes. In both formulations, PE loading significantly increased the size and reduced the zeta potential values and homogeneity of the size distribution. In free PE, the most bioaccessible polyphenols were phenolic acids (3.20 to 5.63 %), and flavonoids such as caffeic acid phenethyl ester, galangin, pinobanksin, and pinocembrin (0.03 to 2.12 %) were the least bioaccessible. Both liposomal propolis provided significantly higher bioaccessibility of phenolic compounds. The liposomes with T80 and AMP in their compositions recovered 52.43 and 185.90 % of the total amount of phenolic compounds in the nondigested samples, respectively. The liposomes containing AMP not only exhibited high solubility for PE but also provided protection to the phenolic compounds during in vitro digestion. Liposomal encapsulation could be a promising approach to improving the solubility and stability of PE in digestive fluids, making it suitable for the delivery of propolis in oral formulations.

Cu-Graphene water-based hybrid nanofluids: synthesis, stability, thermophysical characterization, and figure of merit analysis

Hybrid nanofluids are emerging as an alternative to conventional heat transfer fluids and nanofluids for improving the thermal efficiency of heat exchanging devices synergistically due to their outstanding thermophysical properties associated because of the dispersion of different types of nanoparticles as compared to mono nanofluids. This will help in optimizing fluid characteristics in different flow regimes for several applications. However, enhancing the thermal energy efficiency of heat exchangers is challenging owing to the deprived stability of hybrid nanofluids at greater volume concentrations. This work concentrated on the synthesizing, thermophysical depiction, and thermal performance estimation of stable water-based Cu-graphene hybrid nanofluids using very low volume concentrations of Cu and graphene hybrid nanostructures. Cu-graphene hybrid nanofluid was successfully synthesized by dispersing the synthesized Cu and graphene nanostructures (keeping the Cu concentration constant at 0.04 vol % and varying the graphene concentration from 0.01 to 0.1 vol %) in water. Hybrid nanofluids display excellent stability against aggregation for up to 7 weeks, as proven by higher zeta potential values. Thermophysical characteristics of the prepared hybrid nanofluids were effectively measured. The thermal conductivity of Cu-graphene hybrid nanofluids shows exceptional enrichment (~ 35%) at minimal concentrations of hybrid nanostructures. Viscosity of the water-based hybrid nanofluids shows remarkable enhancement as compared to water and represents the increasing trend in viscosity of the base fluid with respect to the increase in concentration of hybrid nanostructures. The thermal and rheological properties of hybrid nanofluids are effectively validated with existing theoretical models. In addition, the specific heat and pumping power of Cu-graphene hybrid nanofluids with respect to the volume concentration of hybrid nanostructures are calculated using the existing theoretical equations. A figure of merit (FOM) analysis was conducted for the synthesized hybrid nanofluids to gauge thermal efficiency and evaluate the applicability of these hybrid nanofluids under laminar and turbulent flow conditions.

Impact of spheroidal graphite morphology on the functionalization of graphene oxide surface

This study conducted a comparative analysis of graphene oxide (GO) surfaces generated using the modified Hummers method at low temperature, employing spheroidal, flake, and micronized graphite with d50 values of approximately 49 µm, 330 µm and 7 µm, respectively. The characterization of the resulting GOs involved TGA, HRTEM, AFM, as well as UV–vis, FTIR, XPS and Raman spectroscopy. Spheroidal graphite produced GO sheets with a thickness of only 1 nm, displaying a zeta potential of −41 mV after 3 h of intercalation and oxidation reaction. In contrast, flake and micronized graphite also yielded 1-nm-thick GO sheets but exhibited a wider size distribution, with zeta potential values of −32 mV and −35 mV, respectively. Moreover, the GO surface derived from spheroidal graphite showed an increased presence of epoxy groups and a reduced concentration of oxidative debris compared to GOs from other graphite types. The curvature of graphite crystals within spheroidal graphite had a more pronounced impact on graphite oxidation than on graphene layer exfoliation. This research highlights the significance of considering graphite sheet curvature as a crucial variable in GO production, providing insights into the novel and noteworthy role that graphite sheet curvature can play in GO materials.

Effects of pH and salt concentration on freeze-thaw fractionation of soymilk protein.

The two major storage proteins of soymilk are the globulins 7S and 11S. Freeze-thaw fractionation is a simple method for separating these proteins in raw soymilk. In this study, we assessed the freeze-thaw fractionation ability of raw soymilk under various pH (4.3-11.6) conditions and added salt (sodium chloride) concentrations (0.00-0.67 mol L-1). We successfully achieved fractionation within a pH range of 5.8-6.7 and when the salt concentration was 0.22 mol L-1 or lower. Analysis of particle size distribution and microscopic examination of soymilk revealed no direct correlation between particle size and freeze-thaw fractionation ability. Interestingly, it was confirmed that the ranges of zeta potential values associated with successful freeze-thaw fractionation in raw soymilk remained consistent across different pH and salt concentration conditions. These ranges were between -23 and -28 mV at pH levels ranging from 5.8 to 6.7 and between -18 and -29 mV at added salt concentrations ranging from 0 to 0.22 mol L-1. The pH and salt concentration in raw soymilk markedly influence the freeze-thaw fractionation process. We confirmed that the range of zeta potential values where fractionation was possible remained consistent under various pH and salt concentration conditions. These findings suggest that the zeta potential value might serve as an indicator for evaluating the freeze-thaw fractionation ability of raw soymilk. © 2024 Society of Chemical Industry.

Encapsulation and characterization of soy protein-based ω-3 medium- and long- chain triacylglycerols microencapsulated with diverse homogenization techniques for improving oxidation stability

Recently, MLCTs have attracted considerable attention as a potential alternative to traditional oils due to their suppressive effect on fat accumulation and insulin sensitivity. In this study, the microcapsules of MLCTs with superior performance were fabricated through different homogenization processes to overcome the limitations of ω-3 medium- and long- chain triacylglycerols (MLCTs), including poor stability and prone oxidation. Additionally, the impact of various homogenization techniques, namely, high-pressure, ultrasound, and cavitation jet, on the particle structure, encapsulation efficiency, and oxidation stability of microcapsules (MLCTs) was investigated. The MLCTs microcapsules fabricated through high-pressure homogenization had a smaller particle size of 295.12 nm, lower PDI of 0.24, and a higher zeta-potential absolute value of 32.65, which significantly improved their dispersion and encapsulation efficiency, reaching 94.56 % after the spray-drying process. Furthermore, the low moisture content and superior storage stability of MLCTs microcapsules have the potential to serve as carriers of liposoluble actives.

Nanometal Surface Energy Transfer (NSET) from Biologically Active Heterocyclic Ligands to Silver Nanoparticles Induces Enhanced Antimicrobial Activity against Gram-positive Bacteria

Herein we report the formation of a nanometal surface energy transfer (NSET) pair between a donor biologically active heterocyclic luminescent ligand such as 3-(1,3-Dioxoisoindolin-2-yl)-N, N-dimethylpropan-1-ammonium perchlorate (S4PNL; λem-408nm) and an acceptor silver nanoparticle (Ag NP; λabs-406nm). When the S4PNL ligand interacts with Ag NPs, the quenching in their luminescence intensity at 408nm is noticed, with a Stern-Volmer constant of 0.8×104 M-1. The present donor-acceptor pair displays a binding constant of 2.8×104 M-1 and binding sites of 1.12. The current work shows the energy transfer from a molecular dipole (S4PNL) to a nanometal surface (Ag NP) and thus follows the nanometal surface energy transfer (NSET) ruler with an energy transfer efficiency of 80.0%, 50% energy transfer efficiency distance (d0) of 4.9nm, donor-acceptor distance of 3.4nm. The alteration in the zeta potential value of S4PNL upon interaction with AgNP clearly demonstrates the strong electrostatic interaction between donor and acceptor. Importantly, the current NSET pair shows enhanced antimicrobial activity against gram-positive bacteria such as Bacillus cereus (B. cereus) in comparison to their parent components i.e. S4PNL ligand and Ag NP. The NSET pair shows maximum inhibition against B. cereus (9202.21±463.26 CFU/ml.) at 10% while minimum inhibition is observed at 0.01% of it (39,887.19±242.67 CFU/ml.).