Ultrasonic emulsification of parenteral valproic acid-loaded nanoemulsion with response surface methodology and evaluation of its stability

Response surface methodology (RSM) was used to optimize the formulation of a nanoemulsion for central delivery following parenteral administration. A mixture of medium-chain triglyceride (MCT) and safflower seed oil (SSO) was determined as a sole phase from the emulsification properties. Similarly, a natural surfactant (lecithin) and non-ionic surfactant (Tween 80) (ratio 1:2) were used in the formulation. A central composite design (CCD) with three-factor at five-levels was used to optimize the processing method of high energy ultrasonicator. Effects of pre-sonication ultrasonic intensity (A), sonication time (B), and temperature (C) were studied on the preparation of nanoemulsion loaded with valproic acid. Influence of the aforementioned specifically the effects of the ultrasonic processing parameters on droplet size and polydispersity index were investigated. From the analysis, it was found that the interaction between ultrasonic intensity and sonication time was the most influential factor on the droplet size of nanoemulsion formulated. Ultrasonic intensity (A) significantly affects the polydispersity index value. With this optimization method, a favorable droplet size of a nanoemulsion with reasonable polydispersity index was able to be formulated within a short sonication time. A valproic acid loaded nanoemulsion can be obtained with 60% power intensity for 15 min at 60 °C. Droplet size of 43.21 ± 0.11 nm with polydispersity index of 0.211 were produced. The drug content was then increased to 1.5%. Stability study of nanoemulsion containing 1.5% of valproic acid had a good stability as there are no significant changes in physicochemical aspects such as droplet size and polydispersity index. With the characteristisation study of pH, viscosity, transmission electron microscope (TEM) and stability assessment study the formulated nanoemulsion has the potential to penetrate blood–brain barrier in the treatment of epilepsy.     

Ultrasound stimulated production of a fibrinolytic enzyme

The present study is aimed at enhanced production of a fibrinolytic enzyme from Bacillus sphaericus MTCC 3672 under ultrasonic stimulation. Various process parameters viz; irradiation at different growth phases, ultrasonication power, irradiation duration, duty cycle and multiple irradiation were studied for enhancement of fibrinolytic enzyme productivity. The optimum conditions were found as follows, irradiation of ultrasonic waves to fermentation broth at 12 h of growth phase with 25 kHz frequency, 160 W ultrasound power, 20% duty cycle for 5 min. The productivity of fibrinolytic enzyme was increased 1.82-fold from 110 to 201 U/mL compared with the non sonicated control fermentation. Drop in glucose concentration from 0.41% to 0.12% w/v in ultrasonicated batch implies that, ultrasonication increases the cell permeability, improves substrate intake and progresses metabolism of microbial cell. Microscopic images before and after ultrasonic stimulation clearly signifies the impact of duty cycle on decreasing biomass concentration. However, environmental scanning electron micrograph does not show any cell lysis at optimum ultrasonic irradiation. Offshoots of our results will contribute to fulfill the demand of enhancement of microbial therapeutic enzyme productivity, through ultrasonication stimulation.     

Preparation of resveratrol-enriched grape juice from ultrasonication treated grape fruits

Grape (Vitis spp.) is a major source of resveratrol that can be eaten directly or after making jam, jelly, wine and juice. Resveratrol (3,5,4′-trihydroxystilbene) has a profound positive influence on human health, including anti-carcinogenic, anti-cancer, anti-inflammatory, and anti-ageing effects and the ability to lower blood sugar. During industrial production of grape juice, resveratrol is lost because of the use of clarifying agents and filtration; therefore, commercial grape juice contains very low amounts of resveratrol. In this study, we investigated the accumulation of resveratrol in grape juice prepared from three varieties of grape, viz. Campbell Early, Muscat Bailey A (MBA) and Kyoho, following post-harvest ultrasonication cleaning for 5 min and 6 h of incubation in the dark at 25 °C. This process resulted in the amounts of resveratrol increasing by 1.53, 1.15 and 1.24 times in juice prepared from Campbell Early, MBA and Kyoho, respectively, without changing the amounts of total soluble solids. Overall, our results indicate that ultrasonication treatment of post-harvested grape fruits can be an effective method for producing resveratrol-enriched grape juice as well as cleaning grapes thoroughly.     

A novel ultrasonication method in the preparation of zirconium impregnated cellulose for effective fluoride adsorption

In the present work, we propose for the first time a novel ultrasound assisted methodology involving the impregnation of zirconium in a cellulose matrix. Fluoride from aqueous solution interacts with the cellulose hydroxyl groups and the cationic zirconium hydroxide. Ultrasonication ensures a green and quick alternative to the conventional time intensive method of preparation. The effectiveness of this process was confirmed by comprehensive characterization of zirconium impregnated cellulose (ZrIC) adsorbent using Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectrometry (EDX) and X-ray diffraction (XRD) studies. The study of various adsorption isotherm models, kinetics and thermodynamics of the interaction validated the method.     

Dissolution and reconstitution of casein micelle containing dairy powders by high shear using ultrasonic and physical methods

The effect of shear on the solubilization of a range of dairy powders was investigated. The rate of solubilization of low solubility milk protein concentrate and micellar casein powders was examined during ultrasonication, high pressure homogenization and high-shear rotor–stator mixing and compared to low-shear overhead stirring. The high shear techniques were able to greatly accelerate the solubilization of these powders by physically breaking apart the powder agglomerates and accelerating the release of individual casein micelles into solution. This was achieved without affecting the structure of the solubilized proteins. The effect of high shear on the re-establishment of the mineral balance between the casein micelles and the serum was examined by monitoring the pH of the reconstituted skim milk powder after prior exposure to ultrasonication. Only minor differences in the re-equilibration of the pH were observed after sonication for up to 3 min, suggesting that the localized high shear forces exerted by sonication did not significantly affect the mass transfer of minerals from within the casein micelles.     

Use of aqueous ozone rinsing to improve the disinfection efficacy and shorten the processing time of ultrasound-assisted washing of fresh produce

In minimal processing industry, chlorine is widely used in the disinfection process and ultrasound (US) increases the disinfection efficacy of chlorine and reduces the cross-contamination incidence during washing. Tap water (TW), which has no disinfection effect, is generally used to rinse off sanitizer residues on the surface of disinfected fresh-cut vegetables. In this study, aqueous ozone (AO), a low-cost and residue-free sanitizer, was used to replace TW rinsing in combination with US (28 kHz)–chlorine (free chlorine [FC] at 10 ppm, a concentration recommended for industrial use) for the disinfection of fresh-cut lettuce as a model. US–chlorine (40 s) + 2.0 ppm AO (60 s) treatment resulted in browning spots on lettuce surface at the end of storage. In contrast, US–chlorine (40 s) + 1.0 ppm AO (60 s) did not lead to deterioration of the sensory quality (sensory crispness, color, and flavor) and a change in total color difference, and the activities of browning-related enzymes were significantly lower. Moreover, US–chlorine (40 s) + 1.0 ppm of AO (60 s) treatment led to significantly lower counts of Escherichia coli O157:H7, Salmonella Typhimurium, aerobic mesophilic (AMC), and molds and yeasts (M&Y) on days 0–7 than US–chlorine (60 s) + TW (60 s) and single 1.0 ppm AO (120 s) treatments, suggesting that AO provided an additional disinfection effect over TW, while reducing the overall processing time by 20 s. Cell membrane permeability analysis (alkaline phosphatase, protein, nucleotide, and adenosine triphosphate leakage) showed that the combination with 1.0 ppm AO caused more severe cell membrane damage in E. coli O157:H7 and S. Typhimurium, explaining the higher disinfection efficacy. 16S rRNA sequencing revealed that following US–chlorine (40 s) + 1.0 ppm of AO (60 s) treatment, Massilia and Acinetobacter had higher relative abundances (RAs) on day 7 than after US–chlorine (60 s) + TW (60 s) treatment, whereas the RAs of Escherichia–Shigella was significantly lower, indicating that the former treatment has a superior capacity in maintaining a stable microbial composition. This explains from an ecological point of view why US–chlorine (40 s) + 1.0 ppm of AO (60 s) led to the lowest AMC and M&Y counts during storage. The study results provide evidence that AO has potential as an alternative to TW rinsing to increase the disinfection efficacy of US–chlorine.     

Ultrasound induced cleaning of polymeric nanofiltration membranes

Cleaning of the flat sheet nanofiltration membranes, using backflushing, chemical cleaning, and ultrasonication operated individually as well as in combination with chemicals, has been studied in the present work. Identical hydrophilic polyamide membranes were fouled individually using an aqueous solution containing a single dye, an aqueous solution containing a mixture of dyes, and a synthetically prepared petroleum refinery effluent. Effect of different parameters such as the concentration of cleaning solution, contact time, frequency, and power of ultrasound on the efficacy of membrane cleaning has been studied. Optimal cleaning was achieved under sonication conditions of frequency of 24 kHz and power dissipation of 135 W. It was demonstrated that application of sonication under optimum conditions without chemical agents, gave about 85% water flux recovery. In the case of combined chemical and ultrasonic treatment, it was clearly observed that the use of chemical agent increased the efficacy of ultrasonic cleaning. The hybrid method recovered the initial water flux to almost 90% based on the use of 1.0 M aqueous NaOH and 4 min of sonication. Overall, the use of aqueous NaOH in combination with sonication showed a better efficiency for cleaning than the individual processes thus demonstrating a new avenue for membrane cleaning.     

Application of high-frequency ultrasound standing waves for the recovery of lipids from high-fat dairy effluent

Effect of high-frequency ultrasonication was examined on wastewater of a cheese manufacturing plant. Tests were carried out at two frequencies (500 kHz and 1 MHz) and two temperatures (22 and 40 °C). Samples were subjected to different energy densities; 7.5, 30.2, 60.5 and 121.0 J/mL at 500 kHz and 7.9, 31.7, 63.4 and 126.8 J/mL at 1 MHz to observe the creaming and recovery of lipid. These energy densities correspond to 30, 120, 240 and 480 s of sonication. Sonication was performed using a single plate transducer and reflector system at 40 W to create standing wave to coalesce and flocculate lipid globules. Recovery was higher at 40 °C after 480 s of sonication at both frequencies (77% at 500 kHz and 75% at 1 MHz). The lowest recovery of 47% was observed at 500 kHz and 22 °C at all applied energy densities. Changes in particle size and turbidity in the bottom aliquot indicated that high-frequency ultrasound caused coagulation and aggregation and settling of colloidal particles. Increase in particle size was observed to be highest at 1 MHz, 40 °C and 480 s of sonication. These results confirm that high-frequency ultrasound standing wave technology can be used to recover lipid from high-lipid dairy wastewater including that from cheese manufacturing.     

Effect of ultrasonication on the flotation of fine graphite particles: Nanobubbles or not?

It has been reported that nanobubbles can be produced by ultrasonication. However, it remains unclear whether part of the contribution of ultrasonication on flotation performance can be attributed to the generation of nanobubbles. In this work, we systematically studied this point of ultrasonication by combining a series of techniques including flotation testing, AFM (atomic force microscope) measurement, and settling testing. AFM imaging showed that no surface nanobubbles were found at the HOPG-water interface before and after subjection to ultrasonication. Further, surface nanobubbles were generated with solution exchange before ultrasonciation and then they were subjected to ultrasonication. It was found that ultrasonication did not destroy the pre-existing surface nanobubbles at the HOPG (highly oriented pyrolytic graphite) -water interface. Settling tests and flotation tests indicate that ultrasonication has a negligible influence on the interaction between graphite particles and thus flotation performance. Nanobubbles were not one of the outcomes for ultrasonication.     

Graphite oxide: an efficient reagent for oxidation of alcohols under sonication

Graphite oxide (GO) was used as an effective oxidizing agent for the synthesis of aldehydes and ketones from various alcohols under ultrasonic irradiation. Under optimized conditions, quantitative yields of the products were obtained. Compared to other reagents used for the same chemical transformation, GO displays several advantages, including low cost, ease of synthesis, and high stability to ambient conditions.