Surfactant Tween Research Articles

Essential oil and its nanoemulsion of Eucalyptus cladocalyx: chemical characterization, antioxidant, anti-inflammatory and anticancer activities

ABSTRACT Formulating a nanoemulsion (NE) of essential oil (EO) could enhance its efficiency while requiring lower concentrations. Eucalyptus cladocalyx F. Muell EO was rich in monoterpenes hydrocarbons. NE was prepared and the effect of surfactant (Tween 20, 40 and 80) and shearing time were investigated. The results showed that the best NE was formed using Tween 80 after 25 min of emulsification. Small droplet size (40 nm), low polydispersity index PDI (0.49), and stable zeta potential highlighted the excellent NE stability which was tested under storage conditions for 4 months. The results showed that the antioxidant and anticancer activities of NE were enhanced compared to free EO. Furthermore, NE and EO exhibited high anti-inflammatory effects by inhibiting nitric oxide (NO), Interleukin 6 (IL-6), and tumor necrosis factors alpha (TNF-α) production in liposaccharides (LPS)-induced RAW264.7 cells. In conclusion, a stable Eucalyptus cladocalyx-NE was produced, with improved biological activities.

Antimicrobial and antibiofilm effects of shikonin with tea tree oil nanoemulsion against Candida albicans and Staphylococcus aureus

The current work aims to develop a shikonin and tea tree oil loaded nanoemulsion system stabilized by a mixture of GRAS grade surfactants (Tween 20 and monoolein) and a cosurfactant (Transcutol P). This system was designed to address the poor aqueous solubility and photostability issues of shikonin. The authenticity of shikonin employed in this study was confirmed using nuclear magnetic resonance (NMR) spectroscopy. The optimized nanoemulsion exhibited highly favorable characteristics in terms of zeta potential (−23.8 mV), polydispersity index (0.216) and particle size (22.97 nm). These findings were corroborated by transmission electron microscopy (TEM) micrographs which confirmed the spherical and uniform nature of the nanoemulsion globules. Moreover, attenuated total reflectance (ATR) and X-ray diffraction analysis (XRD) analysis affirmed improved chemical stability and amorphization, respectively. Photodegradation studies were performed by exposing pure shikonin and the developed nanoemulsion to ultraviolet light for 1 h using a UV lamp, followed by high performance liquid chromatography (HPLC) analysis. The results confirmed that the developed nanoemulsion system imparts photoprotection to pure shikonin in the encapsulated system. Furthermore, the research investigated the effect of the nanoemulsion on biofilms formed by Candida albicans and methicillin resistant Staphylococcus aureus (MRSA). Scanning electron microscopy, florescence microscopy and phase contrast microscopy unveiled a remarkable reduction in biofilm area, accompanied by disruptions in the cell wall and abnormalities on the cell surface of the tested microorganisms. In conclusion, the nanoencapsulation of shikonin with tea tree oil as the lipid phase showcased significantly enhanced antimicrobial and antibiofilm potential compared to pure shikonin against resistant strains of Candida albicans and Staphylococcus aureus.

Antioxidant Capacity in Two Different Cultivars of Ripe and Unripe Peaches Utilizing the Cloud-Point Extraction Method

In this study, the objective was to ascertain the optimal extraction method for the recovery of polyphenols from two peach cultivars, namely ‘Andross’ and ‘Everts’, at unripe and ripe stages. Two extraction techniques were explored: conventional extraction and cloud-point extraction (CPE), utilizing various solvents, including water, ethanol, 60% ethanol, and the surfactant Tween 80. Moreover, the conditions of CPE (such as pH, ionic strength, surfactant concentration, etc.) were optimized. To elucidate the antioxidant activity of the extracts, the total polyphenol content (TPC), the ferric-reducing antioxidant power (FRAP) assay, and the DPPH antiradical scavenging were measured. Our findings indicate that CPE is a superior method for polyphenol recovery. Unripe fruits had more antioxidants than ripe ones. Unripe ‘Andross’ fruit has a TPC of 1465.32 mg gallic acid equivalents per kilogram (mg GAE/kg). FRAP and DPPH levels were 7.33 and 5.12 mmol ascorbic acid equivalents (AAE/kg), respectively. With a TPC of 1714.53 mg GAE/kg, the unripe fruit from the ‘Everts’ cultivar has even more antioxidant capacity. Additionally, its FRAP and DPPH values were increased at 8.57 and 6.08 mmol AAE/kg, respectively. These findings underscore the efficacy of CPE as a preferred method for polyphenol extraction while also highlighting the enhanced antioxidant potential of unripe peaches, particularly in the ‘Everts’ cultivar.

Formation of Nigella Sativa L. seed oil nanoemulsion‐based delivery systems by sonication: Factors affecting particle size and stability

AbstractDue to their unique functional properties, nanoemulsions help enrich many hydrophobic compounds in water‐based beverages. In this study, using two nonionic surfactants (Tween 40 and Tween 80), separately, nanoemulsions containing Nigella Sativa L. oil were prepared by ultrasound method and tested to determine their size, polydispersity index, morphology, turbidity, and stability during 60 days of storage. In this study, the type of nonionic surfactants used significantly affected the average droplet diameter in the formed systems. Hence, Tween 40 produced tiny droplets, while using Tween 80 produced larger droplets. The comparison of the mean particle sizes by the Duncan method at a 95% confidence level showed that the effect of different surfactant concentrations (2, 4, 6, and 8 wt%) on the particle size was significant. The results showed that the lowest particle size corresponding to the formulation with 4 wt% Tween 40 and the 15‐min sonication was 59.2 nm, and the particle size distribution was monomodal. The results indicated that in the absence of a cosurfactant (glycerol), both pasteurization and boiling processes increased in particle size. However, adding glycerol before the thermal process improved the thermal stability of the samples. The results of this study revealed that ultrasound could be used to prepare nanoemulsions with microscopic particles in the nanometer size without high concentrations of synthetic surfactants.

Colloid-chemical properties of surfactant–nitric acid–water systems

The behavior of the surfactants Tween 80, SaS and alkyl betaine in aqueous and nitric acid environments as promising additives for nitrate leaching of hard-to-process ore concentrates of non-ferrous metals was studied. The influence of surfactant concentration (0.04–1.28 g/dm3), nitric acid concentration (0.1–10 g/dm3) and temperature (295–343 K) on the surface tension, critical micelle concentration (CMC), pH and optical density of aqueous surfactant solutions and surfactant–HNO3–H2O systems was found. The critical micelle concentration of the surfactants used was estimated. A positive effect of nitric acid on the surface activity of surfactants was discovered, which manifests itself in a decrease in both the CMC and the surface tension at the liquid–gas interface. The values of surface activity and Gibbs energy of surfactant micelle formation in aqueous and nitric acid media were calculated. Associative processes in the solutions and compositions were confirmed by measuring the optical density of the systems under study.

Design of novel aqueous two-phase systems to be coupled in biological remediation processes

The ability of a biodegradable Deep Eutectic Solvent (DES) reline to induce phase segregation in aqueous solutions of polymeric non-ionic surfactants (Tween 20 and Tween 80) has been demonstrated as a preliminary step to be employed for assisting a biological degradation process of a model contaminant. The binodal curves for systems composed of (surfactants + reline + Water) have been determined at several temperatures, and the experimental data have been correlated using well-known equations. The equilibrium data have been analysed in the light of the operating temperature and the hydrophobicity of surfactants. Tie-lines of these systems have been determined, together with useful parameters such as tie-line length and tie-line slopes. Othmer-Tobias and Bancroft equations have been applied to provide an adequate description of the equilibrium data. Finally, the application of this new approach for the remediation of aqueous polluted effluent has proven to be highly efficient, with extraction percentages exceeding 99% for two model persistent contaminants (Acid Black 48 and Crystal Violet). Consequently, this ATPS is proposed as an extra-stage to enhance the remediation percentages achieved through biological methods. Furthermore, the process has been simulated using commercial software.

Synthesis of nano-crystal PVMo2W9@[Cu6O(TZI)3(H2O)6]4⋅nH2O for catalytically biodiesel preparation

To develop efficient and reusable catalysts for biodiesel production, quaternary heteropolyacid H4PVMo2W9O40 (PVMo2W9) was effectively wrapped inside rht-MOF-1 {rht-MOF-1 = [Cu6O(TZI)3(H2O)6]4⋅nH2O}, affording a crystalline H4PVMo2W9O40@rht-MOF-1 (1) by one-pot hydrothermal method. The identification of the crystal structure of 1 was achieved through the utilization of X-ray crystallography. Nano-size crystals of 1 (n-1) were prepared with the assistance of surfactant Tween 20. Notably, crystal n-1 was of cube shape grown along {100} facets rather than octahedral shape for 1. When n-1 was applied as the catalyst for the esterification reactions, high conversion rates were achieved. E. g. about 97 % conversion for oleic acid to the corresponding monoalkyl esters and about 87 % for rapeseed oil to biodiesel. The catalyst was heterogeneous and recyclable 7 times without obvious attenuation. Further, the correlation between the catalytic activity and structure of n-1 was investigated in terms of the distribution of active sites, various pores in rht-MOF-1, and the accessibility of catalytic sites on the {100} facets.

Natural microbial surfactant containing self-nanoemulsifying formulation with improved performance of paclitaxel therapy: A newer avenue in breast cancer treatment

Due to the presence of a high concentration of surfactants (e.g., Cremophor EL, Tween 80), paclitaxel (PTX) drug delivery systems administered orally and intravenously demonstrate severe toxicity. In the current research work, a unique self-nanoemulsifying drug delivery system (SNEDDS) comprising surfactin, a microbial biosurfactant was used for reducing the formulation toxicity and improving the biopharmaceutical performance. The preformulation study including solubility analysis indicated suitability of corn oil as the natural lipophile. Nanoemulsion boundaries were delineated by aqueous titration of the lipid phase (ethyl oleate: plurol oleique), surfactants (Tween 80 and Surfactin) and cosolvent (Transcutol HP) to identify the optimum compositions on the basis of formulation quality attributes with globule size <250 nm, emulsification time <3 min and in vitro drug release >85% in 60 min. Biocompatibility evaluation of PTX-Surfactin SNEDDS on rat hepatocytes by H2DCF assay to determine the ROS level indicated an insignificant increase in fluorescence intensity, while PTX Tween 80-SNEDDS showed nearly 20% increase in ROS levels compared to the control cells. Furthermore, histopathology examination showed the absence of any signs of inflammation from intestinal segments treated with PTX Surfactin-SNEDDS, while PTX Tween 80-SNEDDS revealed infiltration of cells and the presence of inflammation on the intestinal villous microstructures. The anticancer activity evaluation by in vitro cytotoxicity on MCF-7 cells showed PTX Surfactin-SNEDDS and PTX Tween 80-SNEDDS with IC50 of 2.65 μM and 11.52 μM, respectively, while PTX suspension showed IC50 of 18.5 μM. Moreover, blank Surfactin-SNEDDS showed IC50 of 15.23 μM, while no cytotoxicity was observed for blank Tween 80-SNEDDS. Overall, the study interpreted high suitability of biosurfactant for developing the self-nanoemulsifying formulation of PTX with enhanced bioavailability, biocompatibility and synergistic improvement in the anticancer activity over the formulations containing synthetic surfactant.

Characterization and stability assessment of Ocimum gratissimum leaves extract loaded nanostructured lipid carrier

AbstractIn the last few decades, several nanoparticles technologies of actives delivery systems have emerged in the formulation of personal care products. The purpose of this study is to formulate the nanostructured lipid carrier loaded with Ocimum gratissimum leaves extract (OGNLC) and to characterize the chemical and physical properties of the OGNLC formulation. Ultrasound‐Assisted Extraction (UAE) method are used in this study to obtain O. gratissimum extract with the determination of the TPC, while melt emulsification homogenization conjoined with ultrasonic homogenization method are used to prepare OGNLC samples. Two types of surfactants (Tween 80 and soy lecithin) are incorporated in the formulation to form OGNLC with various compositions (%) to determine the best formulation. The effect of varying compositions of surfactants in OGNLC samples on the mean particle size (MPS), polydispersity index (PDI), zeta potential (ZP) and encapsulation efficiency (EE%) of OGNLC are characterized. The best formulation also was analyzed by FTIR spectroscopy, and the encapsulation efficiency are determined. The stability of OGNLC particle size was also assessed after 30 days of exposure under low and room temperature (4°C, 25°C). An optimal OGNLC consists of 2.0% O. gratissimum extract, 2.0% GMS, 10.0% VCO, and varying surfactant compositions of 2.0% of Tween 80, and 1.0% of soy lecithin by a mean particle size of 155.73 ± 1.53 nm, a PDI value of 0.203 ± 0.007, zeta potential of |−37.2| ± 0.95 mV, and encapsulation efficiency (%) of 95.70% ± 6.256%. The stability assessment of OGNLC showed that the obtained formulation is at least stable for more than 30 days. This study concludes that the composition of surfactants are important factors affecting the size and stability of the OGNLC. This is the first study to report on the synthesis of nanostructured lipid carrier loaded with O. gratissimum.

Agglomeration effect of nanoparticles on foam stability of nonionic surface-active liquid: experimental and density functional theory studies

Innovative applications of foam are the need of time which fundamentally depends on the stability of the foam. In the present research work, the static foam behavior of the nonionic surfactant Tween-20 in the presence and absence of Titanium dioxide nanoparticles (TiO2-NPs) was investigated. The role of TiO2-NPs on foaming power based on foam height and foamability was studied at different temperatures. At 29 ± 1 0C, maximum foam height for Tween 20 (5% surfactant solution in distilled water) without and with TiO2-NPs was increased from 45.60 to 60.30 cm exhibiting 32.25% increase. In view of studying foam stability, axial dye displacement rate (ADDR) test was performed without and with nanoparticles where TiO2-NPs resist liquid drainage. TiO2 -NPs and Tween-20 form intermolecular hydrogen bonding which helps to enhance the foam stability as revealed by the density functional theory (DFT) studies. However, TiO2 -NPs have tendency to agglomerate if zeta potential value is low that severely affect the foaming power and foamability.

SARS-CoV-2 Protein Nanoparticle Vaccines Formed In Situ From Lyophilized Lipids.

The receptor binding domain (RBD) of the SARS-CoV-2 Spike (S) glycoprotein is an appealing immunogen, but associated vaccine approaches must overcome the hapten-like nature of the compact protein and adapt to emerging variants with evolving RBD sequences. Here, a vaccine manufacturing methodology is proposed comprising a sterile-filtered freeze-dried lipid cake formulation that can be reconstituted with liquid proteins to instantaneously form liposome-displayed protein nanoparticles. Mannitol is used as a bulking agent and a small amount of Tween-80 surfactant is required to achieve reconstituted submicron particles that do not precipitate prior to usage. The lipid particles include an E. coli-derived monophosphoryl lipid A (EcML) for immunogenicity, and cobalt porphyrin-phospholipid (CoPoP) for antigen display. Reconstitution of the lipid cake with aqueous protein results in rapid conversion of the RBD into intact liposome-bound format prior to injection. Protein particles can readily be formed with sequent-divergent RBD proteins derived from the ancestral or Omicron strains. Immunization of miceelicits antibodies that neutralize respective viral strains. When K18-hACE2 transgenic mice are immunized and challenged with ancestral SARS-CoV-2 or the Omicron BA.5 variant, both liquid liposomes displaying the RBD and rapid reconstituted particles protect mice from infection, as measured by the viral load in the lungs and nasal turbinates.

Preparation of nanoformulation of 5-fluorouracil to improve anticancer efficacy: integrated spectroscopic, docking, and MD simulation approaches

Nanoformulations (NFs) can be used as a novel drug delivery system to treat all cancer types. One of the major drawbacks of conventional anticancer drugs is that they have poor specificity and higher toxicity towards normal cells. 5-fluorouracil (5-FU) is a well-studied anticancer drug that has a significant role in various cancers, specifically colorectal cancer therapy. This study was performed to determine the functional groups, particle size, surface charge, heterogeneity, and stability of the NF. The NFs of 5-FU were prepared through the ultrasonication technique by increasing the surfactant (Tween-80) concentrations. Among all three NFs, nanoformulated 5-FU (n5-FU) showed the most effective particle size (10.72 nm) with a zeta potential of (-4.57 mV). The cytotoxicity and apoptosis profiles confirmed that n5-FU enhanced the anticancer effect of the pure drug in HCT-116 cells, as evident from MTT assay, fluorescence microscopy, and FACS analysis. In HCT-116 cells, the IC50 values of pure and n5-FU were obtained as 41.3 μM and 18.8 μM, respectively, indicating that n5-FU was more effective against the cancer cell line. The cellular uptake study was performed to check the intake of NF in cancer cells. However, the microtubule-affinity regulating kinase-4 (MARK-4), a cancer-target protein, was purified to study the inhibition and interaction studies. The inhibition assay confirmed the inhibitory potential of 5-FU against MARK-4 protein. the multi-spectroscopic, molecular docking and MD simulation studies were performed to analyse the conformational changes, binding studies, intermolecular interactions, and stability of MARK-4 protein upon binding 5-FU. This demonstrates that NF can enhance the effectiveness of anticancer drugs. Communicated by Ramaswamy H. Sarma

Mycobacteriophage D29 Lysin B exhibits promising anti-mycobacterial activity against drug-resistant Mycobacterium tuberculosis.

The emergence of antibiotic resistance in Mycobacterium tuberculosis has been the culprit behind the inefficient treatment of tuberculosis (TB). Mycobacteriophages being rapid and specific in their activity against mycobacteria including M. tuberculosis are an emerging alternative solution to the antibiotic resistance problem. D29 mycobacteriophage is known as an efficient lytic phage. Its lytic cassette encodes for two lytic proteins, Lysin A (LysA) and Lysin B (LysB), and a holin protein responsible for the translocation of the former two. LysB is a mycolyl-arabinogalactan esterase, which has shown a promising lytic effect on M. tuberculosis. In this study, we explored the lytic efficiency of D29 mycobacteriophage LysB protein on drug-resistant strains of M. tuberculosis. We demonstrate that LysB effectively lyses multi-drug-resistant M. tuberculosis both alone and along with anti-TB drugs. We also report that the surfactant Tween-80, although not vital, potentiates LysB activity. We are able to demonstrate that LysB can eliminate M. tuberculosis residing in mouse macrophages. Thus, by combining our in vitro and ex vivo data, we are able to claim that LysB is a potential phage-derived therapeutic which should undergo pre-clinical and clinical trials. IMPORTANCE To combat the rapidly emerging drug-resistant M. tuberculosis, it is now essential to look for alternative therapeutics. Mycobacteriophages can be considered as efficient therapeutics due to their natural ability to infect and kill mycobacteria including M. tuberculosis. Here, we have exploited the mycolyl-arabinogalactan esterase property of LysB encoded from mycobacteriophage D29. This study is novel in terms of targeting a multi-drug-resistant pathogenic strain of M. tuberculosis with LysB and also examining the combination of anti-TB drugs and LysB. All the experiments include external administration of LysB. Therefore, the remarkable lytic activity of LysB overcomes the difficulty to enter the complex cell envelope of mycobacteria. Targeting the intracellularly located M. tuberculosis by LysB and non-toxicity to macrophages take the process of the development of LysB as a drug one step ahead, and also, the interaction studies with rifampicin and isoniazid will help to form a new treatment regimen against tuberculosis.

Emulsion Stability and CO2 Removal Performance of MDEA-AMP Blends with Tween-80 Surfactants

Carbon dioxide (CO2) is a corrosive and inflammable gas found in natural gas. The most widely technique used for CO2 separation in the natural gas industry is via amine absorption method. However, due to the corrosive nature of amines, researchers actively looking for an alternative method to separate CO2. Therefore, the emulsion liquid membrane (ELM) was developed to address this issue. In spite of that, it still remains as challenge to find suitable formulation to produce stable emulsion with good CO2 removal performance. In this study, the amine blend emulsion containing Methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) with Tween80 (Polysorbate-80) were prepared. An aqueous phase was formed by blending of MDEA and AMP in sodium hydroxide (NaOH) solution. The organic phase composed of kerosene and Tween-80 used as surfactant. The effect of varying concentrations of Tween-80 on the emulsion stability and CO2 absorption capacity of ELM were investigated in this study. The emulsion was prepared by mixing the aqueous and organic phases for 5 minutes at a speed of 10,000 rpm until it become homogenous. The CO2 absorption capacity was conducted in a rotating disc contactor column with a 2-bar pressure of CO2 gas supply. This study demonstrated that, by blending of 8% v/v MDEA and 4% v/v AMP with 10% v/v Tween-80, 56.89% of CO2 removal could be achieved while maintaining an emulsion stability of 95%.

Formulation, Optimization and In-vitro Evaluation of Chitosan-lipid nanoparticles for Antibacterial activity against Salmonella typhimurium

Salmonella infections are difficult to treat due to the poor permeability of antibiotics into intracellular compartments and the cell walls of microorganisms with less selectivity, which results in the development of drug resistance. Chitosan is a biocompatible, naturally occurring polymer with shown antibacterial activity against a wide range of pathogenic microorganisms. In the present work, chitosan-based polymer lipid nanoparticles (PLNs) were designed to enhance the antibacterial activity against Salmonella typhimurium. PLNs were optimized by 32 full factorial design with two independent variables viz., polymer-lipid ratio (X1) ranging from 0.8 to 1.2 and surfactants (X2) Tween80:Poloxamer188 (2:1) with a concentration of 1% to 2%. Formulations were prepared by melt emulsification with a homogenization process. The influence of independent variables was checked on particle size (Y1), Polydispersity Index (Y2) and Zeta potential (Y3). The optimized batch had particle size of 234.3±4.2nm, a PDI of 0.291±0.01, and a Zeta potential of 28.9±3.4mV. FTIR analysis reveals the polymer's compatibility with lipid and additives. Analysis of DSC and XRD confirmed the existence of amorphous PLNs. The FESEM findings suggest that PLNs have a nearly spherical shape with a smooth surface morphology. Furthermore, the formulation was tested for in-vitro antibacterial activity against Salmonella typhimurium. From the results of an antibacterial study, it was found that the zone of inhibition, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of PLNs were 24mm, 15.12µg/ml, and 31.25µg/ml, respectively, which was better than the results of pure chitosan (18mm, 62.5µg/ml, and 125µg/ml).

QbD-driven development of phospholipid-embedded lipidic nanocarriers of raloxifene: extensive in vitro and in vivo evaluation studies.

Raloxifene (RLX) is popularly indicated in treatment of osteoporosis and prevention of breast cancer. Owing to its poor aqueous solubility, high pre-systemic metabolism, intestinal glucuronidation, and P-glycoprotein (P-gp) efflux, however, it demonstrates low (< 2%) and inconsistent oral bioavailability. The current work, Quality by Design (QbD)-driven development of phospholipid-embedded nanostructured lipidic carriers (NLCs) of RLX, accordingly, was undertaken to potentiate its lymphatic uptake, augment oral bioavailability, and possibly reduce drug dosage. Factor screening and failure mode effect analysis (FMEA) studies were performed to delineate high-risk factors using solid lipid (glyceryl monostearate), liquid lipid (vitamin E), and surfactant (Tween 80). Response surface optimization studies were performed employing the Box-Behnken design. Mathematical and graphical methods were adopted to embark upon the selection of optimized NLCs with various critical quality attributes (CQAs) of mean particle size as 186nm, zeta potential of - 23.6mV, entrapment efficiency of 80.09%, and cumulative drug release at 12h of 83.87%. The DSC and FTIR studies, conducted on optimized NLCs, indicated successful entrapment of drug into the lipid matrix. In vitro drug release studies demonstrated Fickian diffusion mechanism. In vivo pharmacokinetic studies in rats construed significant improvement in AUC0-72h (4.48-folds) and in Cmax (5.11-folds), unequivocally indicating markedly superior (p < 0.001) oral bioavailability of RLX-NLCs vis-à-vis marketed tablet formulation. Subsequently, level "A" in vitro/in vivo correlation (IVIVC) was also successfully attempted between the percentages of in vitro drug dissolved and of in vivo drug absorbed at the matching time points. In vitro cytotoxicity and cellular uptake studies also corroborated higher efficacy and successful localization of coumarin-6-loaded NLCs into MG-63 cells through microfluidic channels.

Improved corrosion resistance of permanganate-phosphate conversion coat on steel surface by surfactants

In the present work, we studied the effect of the presence of different concentrations of each of Triton-X-100 and Tween-80 surfactants in the bath of permanganate-phosphate conversion coating (PPC) on the corrosion resistance and the microstructure of the prepared coats. The coats were investigated using a scanning electron microscope (SEM), an energy dispersive X-ray spectrometer (EDX), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization techniques. The SEM results show that, on addition of the surfactants to the PPC bath, the porosity of the coat decreases and the coating layer becomes more compact. EIS results indicated that the presence of 0.01 M Triton-X-100 or 0.01 M Tween-80 in the coating solution caused an increase in the protection efficiency of the coat up to 93.7% and 84.1%, respectively. The potentiodynamic polarization results indicated that the two surfactants mainly act as anodic inhibitors due to the adsorption of their molecules at the anodic sites of the surface of steel and retard its oxidation reaction. The EDX and XPS results confirmed the results of the other techniques. A mechanism for the role of the surfactants in the coating process was proposed using the results of XPS and the other techniques.

Multielement analysis of single red blood cells by single cell - inductively coupled plasma tandem mass spectrometry

A method for the analysis of essential metals (Fe, Cu, Mg, and Zn) and non-metals (P, S) in single red blood cells was developed by single cell (SC)-ICP-MS. The use of a triple quadrupole configuration (MS/MS) enabled an effective elimination of polyatomic interferences, which affect the accuracy of ICP-MS analysis using a single quadrupole mass analyzer. Fixation with glutaraldehyde for at least 90 days was developed to improve the quantification of elements in a single red blood cell. The experimental conditions were optimized while special attention was paid to the residence time of analytes in the plasma. Addition of a surfactant (0.05% (v/v) Tween80®) improved quantification of elements in fixed red blood cells. The detection limits obtained by SC-ICP-MS/MS were lower than for ICP-MS, especially for S and P (3 fg and 1.7 fg. cell-1 instead of 163 and 6.3 fg. cell-1, respectively).

Melatonin delivered in solid lipid nanoparticles ameliorated its neuroprotective effects in cerebral ischemia

The current study explores the potential of melatonin (MLT)-loaded solid lipid nanoparticles (MLT-SLNs) for better neuroprotective effects in ischemic stroke. MLT-SLNs were prepared using lipid matrix of palmityl alcohol with a mixture of surfactants (Tween 40, Span 40, Myrj 52) for stabilizing the lipid matrix. MLT-SLNs were tested for physical and chemical properties, thermal and polymorphic changes, in vitro drug release and in vivo neuroprotective studies in rats using permanent middle cerebral artery occlusion (p-MCAO) model. The optimized MLT-SLNs showed particle size of ∼159 nm, zeta potential of −29.6 mV and high entrapment efficiency ∼92%. Thermal and polymorphic studies showed conversion of crystalline MLT to amorphous form after its entrapment in lipid matrix. MLT-SLNs displayed a sustained release pattern compared to MLT dispersion. MLT-SLNs significantly enhanced the neuroprotective profile of MLT ascertained by reduced brain infarction, recovered behavioral responses, low expression of inflammatory markers and improved oxidation protection in rats. MLT-SLNs also showed reduced hepatotoxicity compared to p-MCAO. From these outcomes, it is evidenced that MLT-SLNs have improved neuroprotection as compared to MLT dispersion and thereby present a promising approach to deliver MLT to the brain for better therapeutic outcomes in ischemic stroke.

ATR FTIR spectroscopy of protein and surfactant adsorption to the oil-water interface

An oil-infused polyelectrolyte multilayer (PEM) immersed in aqueous solution is a valid mimic for an oil-water interface, that can be used to probe adsorption of surfactants (including co-/competitive adsorption) using attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR). A PEM has been formed on an ATR internal reflection element, dried and then re-solvated with oil, then exposed to a flowing solution of protein, and subsequently a solution of surfactant. The PEM had undergone prior characterization with atomic force microscopy (AFM). The experiment was replicated using profile analysis tensiometry (PAT). The PEM displays a high degree of solvation with oil; it retains most of this oil in the presence of flowing aqueous solution. FTIR spectra confirmed adsorption of a dairy protein (β-lactoglobulin) to the medium chain triglyceride (MCT)-water interface, and the response of the adsorbed protein layer to a common food formulation surfactant (Tween 60) in the aqueous phase above the interface. The protein is observed to adsorb strongly and irreversibly to the MCT oil-water interface, and the Tween 60 molecules are seen to co-adsorb rather than displace the protein. This observation is supported by measurements of sequential co-adsorption undertaken with PAT.