On the Effect of pH, Temperature, and Surfactant Structure on Bovine Serum Albumin–Cationic/Anionic/Nonionic Surfactants Interactions in Cacodylate Buffer–Fluorescence Quenching Studies Supported by UV Spectrophotometry and CD Spectroscopy

Due to the fact that surfactant molecules are known to alter the structure (and consequently the function) of a protein, protein–surfactant interactions are very important in the biological, pharmaceutical, and cosmetic industries. Although there are numerous studies on the interactions of albumins with surfactants, the investigations are often performed at fixed environmental conditions and limited to separate surface-active agents and consequently do not present an appropriate comparison between their different types and structures. In the present paper, the interactions between selected cationic, anionic, and nonionic surfactants, namely hexadecylpyridinium chloride (CPC), hexadecyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyethylene glycol sorbitan monolaurate, monopalmitate, and monooleate (TWEEN 20, TWEEN 40, and TWEEN 80, respectively) with bovine serum albumin (BSA) were studied qualitatively and quantitatively in an aqueous solution (10 mM cacodylate buffer; pH 5.0 and 7.0) by steady-state fluorescence spectroscopy supported by UV spectrophotometry and CD spectroscopy. Since in the case of all studied systems, the fluorescence intensity of BSA decreased regularly and significantly under the action of the surfactants added, the fluorescence quenching mechanism was analyzed thoroughly with the use of the Stern–Volmer equation (and its modification) and attributed to the formation of BSA–surfactant complexes. The binding efficiency and mode of interactions were evaluated among others by the determination, comparison, and discussion of the values of binding (association) constants of the newly formed complexes and the corresponding thermodynamic parameters (ΔG, ΔH, ΔS). Furthermore, the influence of the structure of the chosen surfactants (charge of hydrophilic head and length of hydrophobic chain) as well as different environmental conditions (pH, temperature) on the binding mode and the strength of the interaction has been investigated and elucidated.

Improved Bioavailability of Ebastine through Development of Transfersomal Oral Films

The main objective of this research work was the development and evaluation of transfersomes integrated oral films for the bioavailability enhancement of Ebastine (EBT) to treat allergic rhinitis. The flexible transfersomes, consisting of drug (EBT), lipid (Phosphatidylcholine) and edge activator (EA) Polyoxyethylene sorbitan monooleate or Sorbitan monolaurate, were prepared with the conventional thin film hydration method. The developed transfersomes were further integrated into oral films using the solvent casting method. Transfersomes were evaluated for their size distribution, surface charge, entrapment efficiency (EE%) and relative deformability, whereas the formulated oral films were characterized for weight, thickness, pH, folding endurance, tensile strength, % of elongation, degree of crystallinity, water content, content uniformity, in vitro drug release and ex vivo permeation, as well as in vivo pharmacokinetic and pharmacodynamics profile. The mean hydrodynamic diameter of transfersomes was detected to be 75.87 ± 0.55 nm with an average PDI and zeta potential of 0.089 ± 0.01 and 33.5 ± 0.39 mV, respectively. The highest deformability of transfersomes of 18.52 mg/s was observed in the VS-3 formulation. The average entrapment efficiency of the transfersomes was about 95.15 ± 1.4%. Transfersomal oral films were found smooth with an average weight, thickness and tensile strength of 174.72 ± 2.3 mg, 0.313 ± 0.03 mm and 36.4 ± 1.1 MPa, respectively. The folding endurance, pH and elongation were found 132 ± 1, 6.8 ± 0.2 and 10.03 ± 0.4%, respectively. The ex vivo permeability of EBT from formulation ETF-5 was found to be approximately 2.86 folds higher than the pure drug and 1.81 folds higher than plain film (i.e., without loaded transfersomes). The relative oral bioavailability of ETF-5 was 2.95- and 1.7-fold higher than that of EBT-suspension and plain film, respectively. In addition, ETF-5 suppressed the wheal and flare completely within 24 h. Based on the physicochemical considerations, as well as in vitro and in vivo characterizations, it is concluded that the highly flexible transfersomal oral films (TOFs) effectively improved the bioavailability and antihistamine activity of EBT.

Enhancement of Flow Boiling at Very High Initial Surface Temperature by Using Various Additives

For the simultaneous attainment of enhancement and uniformity in temperature distribution in case of quenching performed in transition and nucleate boiling regimes, the heat treatment is performed by adopting thin coolant flow boiling methodology which depicts high replacement rate of vapour and low coolant consumption rate in comparison with the other cooling methodology such as jet and spray cooling.Furthermore, the simultaneous flow over the entire plate reduces the intensity of non-uniformity in cooling. The analysis of experimental results in case of thin film flow boiling clearly indicates significant improvement in initial heat flux (IHF) and critical heat flux (CHF) in comparison with low mass flux jet and spray coolings. Comparative study also ensures that better enhancement and uniformity in cooling are achieved in the current case in comparison with low mass flux spray and jet coolings. Furthermore, the calculation indicates very low coolant consumption characteristic in comparison with the others. The abovementioned parameters (CHF and IHF) alter due to the change in surface tension, viscosity, specific heat and thermal conductivity of the coolant and therefore, the role of above-mentioned coolant properties in case of thin film boiling is monitored. For this,various additives such as Sodium Dodecyl Sulphate (SDS), Polyethylene Glycol (PEG), Polyoxyethylene 20 Sorbitan Monolaurate (Tween 20) and Ethanol were used. In the present work, the analysis discloses that for the better Nusselt number the optimum Reynolds number is 1953 and Ohensorge number and Prandtl number are 0.0032 and 5.85, respectively.

Increased resistance of a methicillin-resistant Staphylococcus aureus Δagr mutant with modified control in fatty acid metabolism

Methicillin-resistant Staphylococcus aureus (MRSA) strains are distinct from general Staphylococcus strains with respect to the composition of the membrane, ability to form a thicker biofilm, and, importantly, ability to modify the target of antibiotics to evade their activity. The agr gene is an accessory global regulator of gram-positive bacteria that governs virulence or resistant mechanisms and therefore an important target for the control of resistant strains. However, the mechanism by which agr impacts resistance to β-lactam antibiotics remains unclear. In the present study, we found the Δagr mutant strain having higher resistance to high concentrations of b-lactam antibiotics such as oxacillin and ampicillin. To determine the influence of variation in the microenvironment of cells between the parental and mutant strains, fatty acid analysis of the supernatant, total lipids, and phospholipid fatty acids were compared. The Δagr mutant strain tended to produce fewer fatty acids and retained lower amounts of C16, C18 fatty acids in the supernatant. Phospholipid analysis showed a dramatic increase in the hydrophobic longer-chain fatty acids in the membrane. To target membrane, we applied several surfactants and found that sorbitan monolaurate (Span20) had a synergistic effect with oxacillin by decreasing biofilm formation and growth. These findings indicate that agr deletion allows for MRSA to resist antibiotics via several changes including constant expression of mecA, fatty acid metabolism, and biofilm thickening.

KEEFEKTIFAN EKSTRAK TEPUNG DAUN MIMBA (Azadirachta indica A. JUSS) DENGAN PENAMBAHAN BEBERAPA JENIS SURFAKTAN TERHADAP ULAT GRAYAK (Spodoptera litura FAB.) PADA TANAMAN KEDELAI (Glycine max L. MERRILL)

Neem leaves powder extract is a bioinsecticide which can be used to control the pest. The active compound of neem leaves powder extract is easy to be disentangled by the ultraviolet, so that the effectiveness of application itis low in the field. The alternative to solve this problem can be used the addition surfactant to the neem leaves powder extract. The purpose of this research was to determine the influence and the kind of surfactant which is best to increase the effectiveness of neem leaves powder extract to Spodoptera litura pest on a soybean plant. The research was using a completely randomized design (CRD) with four treatments and five replications so there were 20 unit experiments. The treatment has used some kind of surfactant with the different active compound; linear alkylbenzene sulphonate (LAS), alkyl poly glycol ether (APE), alkylphenol ethoxylate (AE) and polyoxyethylene sorbitan monolaurate (PSM). The results showed the addition of synthetic surfactant with the active compound APE, AE and PSM can increase the effectiveness of neem leave powder extract80 g/lof water to the early death, lethal time 50 and total mortality of S. litura. The intensity attack of S. litura showed APE tends to be better to increase the effectivity of neem leaves powder extract than AE and PSM.