Exploring the influence of ultrasound on the antibacterial emulsification stability of lysozyme-oregano essential oil

A lysozyme-oregano essential oil (Lys-OEO) antibacterial emulsion was developed via ultrasonic treatment. Based on the general emulsion materials of ovalbumin (OVA) and inulin (IN), the addition of Lys and OEO successfully inhibited the growth of E. coli and S. aureus, two representatives of which were Gram-negative and Gram-positive bacteria respectively. The emulsion system in this study was designed to compensate for the limitation that Lys could only act on Gram-positive bacteria, and the stability of the emulsion was improved using ultrasonic treatment. The optimal amounts among OVA, Lys and OEO were found to be the mass ratio of 1:1 (Lys to OVA) and 20% (w/w) OEO. The ultrasonic treatment at the power of 200, 400, 600, and 800 W and time length of 10 min improved the stability of emulsion, in which the surface tension was below 6.04 mN/m and the Turbiscan stability index (TSI) did not exceed 10. The multiple light scattering showed that sonicated emulsions were less prone to delamination; salt stability and pH stability of emulsions were improved, CLSM image showed emulsion as oil-in-water type. In the meantime, the particles of the emulsions were found to become smaller and more uniform with ultrasonic treatment. The best dispersion and stability of the emulsion were both achieved at 600 W with a zeta potential of 7.7 mV, the smallest particle size and the most uniform particle distribution.     

The influence of ultrasound on the capacity of lead accumulators

An increase of 12%–40% in the capacity of lead accumulators is obtained by the action of ultrasound. Simultaneously, the number of discharge cycles is increased. These achievements are important when considering the problem of energy. A few causes of the results obtained are explained.     

Preliminary investigations on the antibacterial activity of zinc oxide nanostructures

We have fabricated electroactive multilayer thin films containing ferritin protein cages. The multilayer thin films were prepared on a solid substrate by the alternate electrostatic adsorption of (apo)ferritin and poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) (NIPAAm-co-CIPAAm) in pH 3.5 acetate buffer solution. The assembly process was monitored using a quartz crystal microbalance. The (apo)ferritin/poly(NIPAAm-co-CIPAAm) multilayer thin films were then cross-linked using a water-soluble carbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide. The cross-linked films were stable under a variety of conditions. The surface morphology and thickness of the multilayer thin films were characterized by atomic force microscopy, and the ferritin iron cores were observed by scanning electron microscopy to confirm the assembly mechanism. Cyclic voltammetry measurements showed different electrochemical properties for the cross-linked ferritin and apoferritin multilayer thin films, and the effect of stability of the multilayer film on its electrochemical properties was also examined. Our method for constructing multilayer films containing protein cages is expected to be useful in building more complex functional inorganic nanostructures.     

The influence of immersion and contact ultrasound treatment on selected properties of the apple tissue

Ultrasound (US) treatment is considered to be one of the most promising non-thermal technology used in the food processing. The food-related applications of this technique are linked to the analytical and technological purposes. The ultrasound waves in the food can cause the formation of micro-channels due to the systematic and alternating compression and decompression of the material (so called “sponge effect”). Additionally, in liquids the ultrasound application can cause the cavitation which can modify the food properties as well. Hence, due to its mechanism, the ultrasound treatment can also improve the extraction of pigments, aromas or antioxidants from the food matrices.     

MWCNT-oxazolidinone conjugates with antibacterial activity

Journal of Nanoparticle Research - The electronic and optical properties of the iron-doped bismuth nanoclusters having less than 15 atoms are presented here. This doping is especially interesting...     

超声对细胞膜通透性的影响及应用

适当参数的超声，使细胞膜发生可以修复的损伤，使细胞膜的通透性提高，从而使细胞内的物流释放到细胞外，细胞外的物质进入细胞内，这一现象可以用于释放代谢产物或中间产物，基因转导，强化化学方法治疗肿瘤等方面。     

Effects of ultrasound on the catalytic activity of matrix-bound glucoamylase

The effect of ultrasonic waves on the activity of glucoamylase bound to a porous polystyrene matrix is investigated in this Paper. The immobilized enzyme was sonated in a flow cuvette at frequencies between 1 and 11 MHz and sound intensities up to 5 kW m-2. The effect was measured as a function of the type and concentration of the substrate, carrier particle size, flow rate of the substrate solution and ultrasonic frequency. The activity increase is discussed in terms of a possible ultrasonic mechanism.     

固体隔声层对超声波传播的影响实验研究

介绍了一种可用于实验教学的测量固体隔声层对超声波传播发生影响的实验装置,并进行了实际测量,理论和实验结果相符较好。     

Dense coating of surface mounted CuBTC Metal-Organic Framework nanostructures on silk fibers, prepared by layer-by-layer method under ultrasound irradiation with antibacterial activity

The growth of Cu₃(BTC)₂ (BTC = 1,3,5-benzenetricarboxylate), also known as CuBTC and HKUST-1, Metal-Organic Framework (MOF) nanostructures on silk fibers were achieved by layer-by-layer technique in alternating bath of Cu(OAc)₂·2H₂O and H₃BTC solutions under ultrasound irradiation. The effect of pH, reaction time, ultrasound irradiation and sequential dipping steps in growth of the CuBTC Metal-Organic Framework nanostructures has been studied. These systems depicted a decrease in the size accompanying a decrease in the sequential dipping steps. In addition, dense coating of silk fibers with CuBTC MOF results in decrease the emission intensity of silk fibers. The silk fibers containing CuBTC Metal-Organic Framework exhibited high antibacterial activity against Escherichia coli and Staphylococcus aureus. The samples were characterized with powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) spectra and scanning electron microscopy (SEM). XRD analyses indicated that the prepared CuBTC MOF nanostructures on silk fibers were crystalline.     

The influence of porosity on ultrasound attenuation in carbon fiber reinforced plastic composites using the laser-ultrasound spectroscopy

Wideband acoustic spectroscopy with a laser ultrasound source for quantitative analysis of the effect of porosity on the attenuation coefficient of longitudinal acoustic waves in carbon fiber reinforced plastic (CFRP) composite materials was experimentally implemented. The samples under study had different bulk-porosity levels (up to 10%), which were determined using X-ray computer tomography. A resonance ultrasound attenuation peak associated with the one-dimensional periodicity of the layered composite structure was observed for all samples. The absolute value of the resonance-peak maximum and its width depend on the local concentration of microscopic isolated pores and extended delaminations in the sample structure. The obtained empirical relationships between these parameters of the frequency dependence of the ultrasound attenuation coefficient and the type of inhomogeneities and their volume concentration can be used for rapid evaluation of the structural quality of CFRP composites.     

Effect of ultrasound on the activity of alliinase from fresh garlic

Alliinase is a homodimeric glycoprotein found most often in genus Allium plants. In this study, alliinase was purified from fresh garlic by using ammonium sulfate precipitation and gel filtration on a Sephacryl S-200 column. Homogeneity of the purified protein with a molecular weight of 54,000 Da was confirmed by SDS-PAGE. The effect of ultrasound on the alliinase activity was further studied. The optimal parameters for stimulating the alliinase activity were as follows: ultrasonic intensity, 0.5 W/cm(2) and ultrasonic frequency, 40 kHz. Under the optimal conditions, ultrasonic irradiation did not affect the enzyme's optimal temperature and pH, and improved its thermal stability. The low frequency and mild intensity ultrasound could increase the alliinase activity about 47.1%. Under ultrasound, the alliinase activity was inhibited by exogenous pyridoxal 5'-phosphate (PLP) and K(+), and obviously enhanced by Fe(2+). However, PLP and both of the metal ions showed opposite effects in the absence of ultrasound. Ultrasound could retard or slow down the inhibitory effect of l-cysteine on the alliinase activity. These results indicated that the activity of alliinase from fresh garlic might be enhanced by the low frequency and mild intensity ultrasound.     

超声波对菠萝果蛋白酶活性和光谱的影响

以菠萝果为材料，用盐析法制备菠萝果蛋白酶粗酶，进一步经SephadexG-50和DEAE-纤维素柱层析纯化，其SDS—PAGE呈单一的电泳带，并获得了菠萝果蛋白酶结晶。一定参数的超声作用可以使酶活力提高，经光谱分析，超声处理后酶的吸收光谱不改变，而荧光发射峰由336nm红移到339nm，紫外差示光谱在一定的波长也呈现出明显的正峰和负峰。本文讨论了超声波影响菠萝果蛋白酶活性的机理。     

Novel heterocyclic 1,3,4-oxadiazole derivatives of fluoroquinolones as a potent antibacterial agent: Synthesis and computational molecular modeling

Design and synthesis of novel series of 1,3,4-oxadiazoles containing FQs derivatives and screened their antibacterial, antimycobacterial properties. The synthesized compounds were characterized by different spectral techniques like IR, ¹H NMR, ¹³C NMR, mass and elemental analysis. The results of the antimicrobial activity and compounds 6d, 6b, 6e, 6f and 6a demonstrated potent antibacterial activities with zone of inhibition of 42, 36, 37, 34 and 30 mm against S. aureus, E. faecalis, S. pneumoniae, E. coli and K. pneumoniae, respectively. 1,3,4-Oxadiazole derivatives 6a, 6b, 6 g were showed excellent antimycobacterial activity against M. smegmatis H₃₇Rv with MICs 22.35, 16.20, 20.28 µg/mL, respectively. FQs 6d and 6b exhibited highest hydrogen bonding interactions with Asp83 (3.11 A?), Ser80 (2.15 A?) Asp27 (σ-σ), Arg87 (Π-Π), Arg87 (Π-Π), Ser80 (σ-σ), Ala84 (σ-σ) and binding energies ΔG?=????6.41, ??6.97 kcal/mol with active site of topoisomerase-IV from S. pneumoniae [4KPE]. We performed a computational investigation of compounds 6a–j for their absorption, distribution, metabolism and excretion (ADME) properties by using the Molinspiration, Molsoft toolkits. The ligands 6f, 6d and 6b reveal the highest pharmacokinetic properties and possess maximum drug-likeness model score 1.59, 1.46 and 1.23, respectively.

Graphic abstract

     

Influence of ultrasound to the activity of tyrosinase

The influence of ultrasound to the activity of tyrosinase was investigated. According to the analyses of ultraviolet–visible spectrometry and Fourier transform infrared spectroscopy, both monophenolase and diphenolase activities of tyrosinase treated by ultrasound were higher than that of control, with the decrease of lag time and the increase of activity. No oxytyrosinase was observed and β-sheet conformation was predominant in the tyrosinase under ultrasound treatment. Moreover, with the observation of atomic force microscopy, the large molecular groups of tyrosinase were broken into small ones under the treatment of ultrasound. The present result suggested the activity of tyrosinase could be activated under the tested ultrasound treatment, mainly due to the increased likelihood of the combination of substrate and enzyme, or the possible change and exposure of the active site in tyrosinase.     

超声波对木瓜蛋白酶催化活性影响的机理研究

木瓜蛋白酶经适当参数的超声波处理后酶活力提高。超声处理后酶的米氏常数Km变小,最大反应速率Vm也减小。超声处理后酶的紫外吸收光谱不变,荧光发射光谱也不改变,而差示光谱出现明显的正峰和负峰。研究结果表明,超声波处理后,木瓜蛋白酶的构型没有改变,而构象发生了变化。本文讨论了超声波影响木瓜蛋白酶活性的可能机理。     

Bioactive compounds and antibacterial activities in crystallized honey liquefied with ultrasound

The effect of ultrasound on the crystal size, phenols, flavonoids, Maillard products and antibacterial activity of crystallized honeys was studied. Three multifloral honeys (M), one monofloral (MO) and one honeydew (HD) honey were used. Ultrasound was performed at 42 kHz for different times (0, 5, 10 and 15 min). The antibacterial activities were tested against Salmonella typhimurium, Bacillus subtilis, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus and Escherichia coli. In all honeys, the parameters analyzed had significant differences ((P < 0.05)). After 15 min of ultrasound the HD had increments of 44 mg of gallic acid/100 g of honey in phenols, and some M showed increase in flavonoids (5.64 mg of quercitin /100 g of honey) and improvement in inhibition against Salmonella typhimurium was 13.1%. In some honeys the correlation between phenols or flavonoids and antibacterial activity were significant ((P < 0.05)). No correlation was found between Maillard products and antibacterial activity. The ultrasound treatment effect on the crystal size, phenols, flavonoid, Maillard products, and antibacterial activity of crystallized honeys were different in each honey.     

Investigation into the antibacterial activity of monodisperse BSA-conjugated zinc oxide nanoparticles

The antibacterial behavior of bovine serum albumin conjugated zinc oxide nanoparticles against Escherichia coli was investigated. The zinc oxide nanoparticles were synthesized by using bovine serum albumin as the structure directing agent. And the morphology and crystal phase of the zinc oxide nanoparticles were determined by transmission electron microscopy, X-ray diffractograms and Fourier transform infrared spectrograph techniques. The synthesized zinc oxide nanoparticles showed high antibacterial activity when compared with plain zinc oxide. And the antibacterial activity was assessed by measuring the growth inhibition and testing the zone of inhibition. Furthermore, the plausible mechanism of antibacterial behavior was attributed to the generation of reactive oxygen species by zinc oxide nanoparticles.     

Synergistic antibacterial and antibiofilm effects of ultrasound and MEL-A against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is drug-resistant and biofilm-forming pathogenic bacteria with severe morbidity and mortality, and has been continuously detected in food products in recent years. Mannosylerythritol lipids (MELs) are novel biosurfactants and perform antibacterial property against gram-positive bacteria. Ultrasound has been applied into food sterilization as non-thermal techniques and has advantage of maintaining food nutrition and flavor over heat pasteurization. In this work, the synergistic treatment of ultrasound and MEL-A was used to combat planktonic cells and biofilm of MRSA. As a result, the combined treatment has exhibited remarkable antibacterial effect proved by enumeration of viable microbes. Furthermore, flow cytometry, scanning electron microscopy and transmission electron microscopy revealed ultrasound has enhanced the inhibitory effect of MEL-A through exacerbating cell membrane damage. On the other hand, the collaborating working modes to eradicate MRSA biofilm were disturbing cell adhesion to surface by MEL-A and destructing mature biofilm mechanically by ultrasound, reaching to over 90% of clearance rate. The findings of this study illustrated the synergistic antimicrobial mechanism of ultrasound and MEL-A treatments, and offered theoretical basis for their potential applications in food preservation.     

Effect of liquid-phase properties on ultrasound intensity and cavitational activity

The intensity of ultrasound is attenuated due to various properties of the liquid, such as viscosity, density, etc. In this paper, a simple method is proposed to measure the combined attenuation and cavitational activity of ultrasound intensity in various organic liquids using standard KI decomposition reaction. A modified experimental attenuation coefficient is proposed and its dependence on liquid viscosity reasonably matches the theoretical predictions made by Stokes [G.G. Stokes, Trans. Camb. Philos. Soc. 8 (1849) 287]. Exploratory work to determine the effect of other liquid properties on cavitational activity is carried out. Correlations are proposed to explain the dependence of the attenuated cavitational activity on various properties of a liquid.