Ultrasonic-assisted Method Research Articles

Ultrasonic-assisted hydrothermal synthesis of RhCu alloy nanospheres for electrocatalytic urea production.

Herein, the electronic structure of RhCu nanospheres was optimized and the size of the nanoparticles was reduced by an ultrasonic-assisted hydrothermal method. The performance of electrocatalytic urea synthesis was improved with an enhanced faradaic efficiency and urea yield rate of 34.82 ± 2.47% and 26.81 ± 0.62 mmol g-1 h-1, respectively. This work opens a novel insight into synthesizing an electrocatalyst by ultrasonic treatment for urea production.

Two-dimensional TiO nanosheets with photothermal effects for wound sterilization.

To combat multidrug-resistant bacteria, researchers have poured into the development and design of antimicrobial agents. Here, low-cost two-dimensional (2D) antibacterial material titanium monoxide nanosheets (TiO NSs) were prepared by an ultrasonic-assisted liquid-phase exfoliation method. When cultured with bacteria, TiO NSs showed intrinsic antimicrobial capacity, possibly due to membrane damage caused by the sharp edges of TiO NSs. Under near-infrared (NIR) laser irradiation, TiO NSs showed high photothermal conversion efficiency (PTCE) and sterilization efficiency. By combining these two antibacterial mechanisms, TiO NSs exhibited a strong killing effect on Gram-negative Escherichia coli (E. coli) and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA). Especially after treatment with TiO NSs (150 μg mL-1) +near-infrared (NIR) light irradiation, both bacteria were completely killed. In vivo experiments on wound repair of bacterial infection further confirmed its antibacterial effect. In addition, TiO NSs had no obvious toxicity or side effects, so as a kind of broad-spectrum 2D antibacterial nanoagent, TiO NSs have broad application prospects in the field of pathogen infection.

Leaching mechanism of strategic metals from superalloy scrap under ultrasonic cavitation

To improve the recovery efficiency of strategic metals from superalloy scrap, an ultrasonic-assisted leaching method was proposed. During the ultrasonic-assisted leaching process, at 60 min, the leaching rates of Re, Ni, Co, Al, Cr, and W are 92.3%, 95.2%, 98.5%, 98.7%, 97.5%, and 27.2%, respectively, which are far superior to those in the normal leaching process at 120 min. The improvement in leaching efficiency can be attributed to the physical and chemical coupling effects of ultrasonic cavitation. The physical effect can prevent the formation of the impeded dissolution layer and encourage contact between solution and superalloy scrap, which improves the leaching rates of strategic metals. The chemical effect can promote the production of hydroxyl radicals in the HCl−H2O2 system, which can enhance the potential of the leaching system, resulting in stimulation of the chemical oxidation process of Re to ReO4−.

Synthesis and enhanced photocatalytic application of porous nanocomposites of (r)GO/TiO2 embedded HCP (hyper crosslinked polymer).

Nanocomposites (r)GO/TiO2/hyper crosslinked polymer (HCP) were prepared using ultrasonic-assisted method, and identified by (SEM), (EDS), (TEM), and (XRD) techniques. This study was performed to examine the effect of various operating parameters on photocatalytic degradation of Rhodamine B (Rh.B) over (r)GO/TiO2 embedded HCP followed by an optimization study using response surface methodology (RSM) based on Box-Behnken design (BBD). The photocatalytic activity of rGO/TiO2/polycalix[4]resorcinarene ((r)GTP) was evaluated using the cationic dye Rhodamine B as a pollutant model under solar light (intensity = 850W/m2) between 10 and 12 am, June, Ahvaz, Iran. Response Surface Methodology was adopted for the optimization of degradation parameters viz pH, dye concentration, and nanocomposites dosage and contact time. The optimum values for the maximum Rhodamine B (Rh B) degradation of rGO/TiO2/polycalix (rGTP) and GTP were obtained, in which the degradation of rGTP was 100% and the degradation efficiency of GO/TiO2/polycalix (GTP) was 70%. ANOVA analysis results demonstrated that irradiation time and nanocomposite mass were the most significant parameters. It was found that rGO/TiO2/polycalix[4]resorcinarene (rGTP) nanocomposite displayed the best degradation yield for the dye. The results showed that the rGTP nanocomposite displayed good EIS and CV properties besides being eco-friendly and reusable. It could also show a high capacity for the elimination of the dye in the industrial wastewaters.

Ultrasound improves the thermal stability and binding capacity of ovomucin by promoting the dissociation of insoluble ovomucin aggregates

Ovomucin (OVM) is a natural glycoprotein with various biological activities but poor solubility. This study aimed to enhance the solubility of OVM by using an ultrasonic-assisted method. The effect of ultrasound (US) on the structure, thermal stability and biological functions of OVM aggregates was evaluated. It was found that insoluble OVM aggregates were dissociated and the solubility increased significantly to 90.0 % after US under 400 W for 45 min. US also improved the onset temperature (To) and denaturation temperature (Td) of OVM. More importantly, the cholesterol binding capacity of both OVM and its digestion products were significantly improved after US (p < 0.05). The gastrointestinal digestion products of US-OVM also showed higher α-amylase and α-glucosidase inhibition than native OVM aggregates. US-induced dissociation of OVM aggregates and the conversion of β-sheet and β-turn to random coil, resulting in the exposure of hydrophobic binding sites may be an important reason for the enhanced stability and adsorption capacity. These findings suggested that US was an effective method for preparing soluble OVM and improved its adsorption capacity, which can further facilitate the application of OVM in the food industry.

Solving the Bonding Problem of the Ni Thin Coating with the Ultrasonic Assisted Electrochemical Potential Activation Method.

Electroplating nanocrystallite Ni coating can improve the mechanical properties of the metal structure surface, which is widely used in fabricating metal MEMS devices. Because of the large internal compressive stress caused by the oxidation layer of the substrate surface, the Ni coating easily falls off from the substrate surface. To solve this bonding problem, the ultrasonic assisted electrochemical potential activation method was applied. The ultrasonic experiments have been carried out. The bonding strength was measured by the indentation method. The substrate surface oxygen element was tested by the X-ray photoelectron spectroscopy (XPS) method. The dislocation was observed by the TEM method. The compressive stress was tested by the XRD method. The coating surface roughness Ra was investigated by the contact profilometer method. The results indicated that the ultrasonic activation method can remove the oxygen content of the substrate surface and reduce the dislocation density of the electroplating Ni coating. Then, the compressive stress of the electroplated Ni coating has been reduced and the bonding strength has been improved. From the viewpoint of the compressive stress caused by the oxygen element of the substrate surface, mechanisms of the ultrasonic activation method to improve the bonding strength were researched originally. This work may contribute to enhancing the interfacial bonding strength of metal MEMS devices.

Two-Dimensional FePS3 Nanosheets as an Integrative Sonosensitizer/Nanocatalyst for Efficient Nanodynamic Tumor Therapy.

As the emerging modalities for tumor therapy, sonodynamic therapy (SDT) and chemodynamic therapy (CDT) can generate reactive oxygen species (ROS), typically inducing tumor cell apoptosis. However, the construction of more efficient sonosensitizers integrated with excellent Fenton/Fenton-like catalytic activity to improve the synergistic therapeutic effect of SDT and CDT is still highly challenging. In this study, 2D semiconductor FePS3 nanosheets (NSs), as one of the metal phosphorus trichalcogenides for both sonosensitizer and Fenton catalyst, are successfully synthesized via an ultrasonic-assisted liquid phase exfoliation method from bulk FePS3 and further modified with lipoic acid-polyethylene glycol (LA-PEG) to obtain FePS3 -PEG NSs with desirable biocompatibility. The in vitro and in vivo results demonstrate that the engineered FePS3 -PEG NSs induce the combinatorial SDT/CDT effect attributing to the enhanced ROS generation and significant glutathione depletion, which can conduct highly efficient and safe tumor inhibition and prolong the life span of tumor-bearing mice. This work provides the paradigm of semiconductor FePS3 NSs as the integrative sonosensitizer/Fenton nanocatalyst for dual nanodynamic tumor therapy, paving the new way for exploring other 2D metal phosphorus trichalcogenides in biomedicine.

Outstanding energy storage performance in Co[sbnd]Fe bimetallic metal-organic framework spindles via decorating with reduced graphene oxide nanosheets

Reduced graphene oxides (rGOs; 3 and 5 wt%) decorated on CoFe bimetallic metal-organic framework (CoFe-MOF) have been synthesized by the ultrasonic-assisted solvothermal method. XRD patterns did not show any significant amendment in crystalline structure of MIL-88A and 3 % rGO@CoFe-MOF revealed better crystallinity than other samples. TEM and FESEM images clearly demonstrated that the rGO nanosheets are coated on the CoFe-MOF spindles. BET and BJH analyzes showed that the 3 % rGO@CoFe-MOF composite had the highest specific surface area (149 m2 g−1) and mean pore size (1.79 nm) compared to the other samples. The MOF and rGO decorated on MOF samples were deposited on Ni foam (NF) and their electrochemical performance as binder-free electrodes was evaluated in 3 M KOH electrolyte. The 3 % rGO@CoFe-MOF/NF electrode exhibits outstanding specific capacitance of 2069.1 F g−1 at a current density of 0.5 A g−1 and good cycling stability with 91.3 % capacitance retention at a high current density of 10 A g−1 after 5000 cycles. The assembled 3 % rGO@CoFe-MOF//activated carbon asymmetric supercapacitor device delivers a maximum energy density of 75.8 Wh kg−1 at a power density of 700 W kg−1. The results exhibit that the 3 % rGO@CoFe-MOF can be a propitious electrode material in energy storage devices.

Structural characteristic of polysaccharide isolated from Nostoc commune, and their potential as radical scavenging and antidiabetic activities

In this paper, Nostoc commune crude polysaccharide was extracted by heating and Ultrasonic-assisted methods separately, homogeneous polysaccharide HNCP3 and UNCP4 were obtained after purified by DEAE-52 cellulose column chromatography and Sephacryl G-100 gel column chromatography. The structures of HNCP3 and UNCP4 were characterized by molecular weight determination, infrared spectroscopy, DSC detection, sodium periodate oxidation, smith degradation reaction and methylation analysis. The conformation of the solution was studied by SEM and AFM. The results showed that the Ultrasonic-assisted extraction had effects on the molecular weight, monosaccharide composition, molar ratio and configuration of Nostoc commune. The main chain of HNCP3 and UNCP4 was → 6)-D-Glcp(1→ and → 2, 6)-D-Glcp, but UNCP4 contained 1, 2, 6-galactose and 2, 3-Me2-D-Ara branches, while HNCP3 did not. The results of the monosaccharides composition of indicated that mannose was presented in both HNCP3 and UNCP4. SEM and AFM showed that the structure of UNCP4 was helical, and the solution conformations of HNCP3 and UNCP4 were different in different solution environments. Studies on DPPH radicals, superoxide anions, and hydroxyl radicals scavenging abilities showed that UNCP4 had higher antioxidant activity, while studies on the antidiabetic activities showed that the hypoglycemic effect of UNCP4 was stronger than that of HNCP3. Therefore, Ultrasonic-assisted extraction (UAE) increases the bioactivity of Nostoc commune polysaccharide (NCP) as well as the extraction rate.

Effects of ultrasonic-assisted nickel pretreatment method on electroless copper plating over graphene

In this paper, copper deposited graphene was fabricated through electroless plating. A novel and facile pretreatment method is introduced based on ultrasonic treatment with nickel nano-particles as the catalytic core. This method abandons the sensitization and activation process in the traditional pretreatment that reduces the time and economic cost dramatically. The static contact angle was determined by an Olympus BX51M optical microscope. The surface morphology and plating composition were characterized via scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), the infrared radiation (IR) transmittance spectra of the copper plated graphene were measured by Fourier transform infrared spectroscopy (FTIR), the layer structure was measured by Raman spectrum, the phase identification was identified by X-ray diffraction (XRD), the thermogravimetric analysis (TGA) (Q5000 TA instruments, USA) was carried out to detect the thermal characteristics. The electrical resistivity of copper-plated graphene was performed in an especially designed apparatus. The results show that the surface of graphene is coarsened, and the size is reduced after ultrasonic treatment, which can facilitate the nucleation and fine particle distribution of metal. The electroless plated efficiency of copper of the nickel pretreatment copper-plated graphene is 64.27 wt%, higher than that of generic copper-plated graphene at 58.62 wt%. The resistivity decreases rapidly from 1.69 × 10–2 Ω cm of the original Gr to 0.79 × 10–2 Ω cm of Cu/Ni@Gr due to the large number of fine copper particles scattered around the graphene.

Effect of ultrasonic-assisted extraction method on the oil yield and fatty acid profile of Thraustochytrium multirudimentale and Rhodotorula mucilaginosa

This study aims to examine the effect of ultrasonic-assisted extraction method on the yield of oil and the profile of fatty acid from microalga and yeast. The microalga cultivated was identified genetically as Thraustochytrium multirudimentale MAST-1 and the yeast as Rhodotorula mucilaginosa KAST-1. The oils were extracted from dried biomass by solvents using modified Bligh and Dyer (BD) method. Before the extraction, the material underwent ultrasonication, water bath immersion, and centrifugation for biomass separation from the solvent. Extracted oils were further analyzed for compositions of fatty acid using Gas Chromatography-Mass Spectrometry (GC-MS). An increase in the length of ultrasonication in the Bligh and Dyer method yielded a higher amount of oil. The cell walls disruption using ultrasonication for 60 minutes produced the highest oil yield. The BD’s extraction method was the best for yeast R. mucilaginosa KAST-1 with a yield of 46.3% oil, while the microalga T. multirudimentale MAST-1 gave only 20.6% oil. The fatty acids identified in the microalga oil were palmitic, stearic, oleic, elaidic and pentadecylic acid, while in yeast oil were palmitoleic, palmitic, pentadecylic, margaric, linoleic, elaidic, stearic and erucic acid. Linoleic acid as one of polyunsaturated fatty acid (PUFA) was detected in yeast oil.

Microstructure and shear strength on ultrasonic-assisted soldered the Si/Cu joint using Sn-3.5Ag solder

The thermal stress, resulting from the big difference of CTE between Si and Cu, could reduce the strength of joints. In this study, Silicon and Cu were soldered by a two-step process (pre-metallization and brazing), which could alleviate the stress. Firstly, a Al-Si metallization layer (consisting α-Al matrix and Si phase) was prepared on the surface of monocrystalline Si by using Al metal powder at 900 ℃. Then the joint of pre-metallized Si and Cu was successfully achieved by ultrasonic-assisted soldering method with Sn-3.5Ag filler at 250 ℃ in air. The effects of ultrasonic time on microstructure and shear strength of the Si/Cu joints were investigated in details. It was found that the oxide layer was broken and gradually dissolved with the ultrasonic action, which was attributed to the high velocity (3055 m/s), high pressure (2.32×108 Pa), and the high temperature (5700 K) generated by the cavitation bubble collapse. Besides, the Ag2Al compounds and Si phases at the solder/metallization layer interface were observed. And the Cu6Sn5+Cu3Sn compounds were detected forming at the solder/Cu interface. As the ultrasonic vibration duration time increased, Ag2Al compounds attached to the Al-Si layer gradually increased, and ultimately entered into the filler. Attentionly, the maximum strength of Si/Cu joint was 32.4 MPa with the ultrasonic time of 6 s, and the fracture occurred inside the monocrystalline Si. The results show that ultrasonic action affects the distribution of Ag2Al compound and Si phase, which has an important influence on the joint strength.

Ultrasonic-Assisted Method for the Preparation of Carbon Nanotube-Graphene/Polydimethylsiloxane Composites with Integrated Thermal Conductivity, Electromagnetic Interference Shielding, and Mechanical Performances

Due to the rapid development of the miniaturization and portability of electronic devices, the demand for polymer composites with high thermal conductivity and mechanical flexibility has significantly increased. A carbon nanotube (CNT)-graphene (Gr)/polydimethylsiloxane (PDMS) composite with excellent thermal conductivity and mechanical flexibility is prepared by ultrasonic-assisted forced infiltration (UAFI). When the mass ratio of CNT and Gr reaches 3:1, the thermal conductivity of the CNT-Gr(3:1)/PDMS composite is 4.641 W/(m·K), which is 1619% higher than that of a pure PDMS matrix. In addition, the CNT-Gr(3:1)/PDMS composite also has excellent mechanical properties. The tensile strength and elongation at break of CNT-Gr(3:1)/PDMS composites are 3.29 MPa and 29.40%, respectively. The CNT-Gr/PDMS composite also shows good performance in terms of electromagnetic shielding and thermal stability. The PDMS composites have great potential in the thermal management of electronic devices.

Construction of [C4MIM]BF4 based in situ alkaline aqueous biphasic systems by NaOH for efficient extraction saponins from Xanthoceras sorbifolium Bunge leaves

In this study, a novel method for extraction saponins from Xanthoceras sorbifolium Bunge leaves (XLs) was developed using ultrasonic-assisted ionic liquid combined with in situ alkaline aqueous biphasic systems (UAE-IL-AABS). UAE-IL was firstly used to extract saponins from XLs, followed by removal of the phenolic impurities using in situ IL-AABS. A Box-Behnken Design (BBD) was used to analyze the [C4MIM]BF4 concentration, time, liquid/solid ratio, and power on the saponins yield. Under the optimal conditions with [C4MIM]BF4 concentration 2.3 M, time 19.9 min, liquid/solid ratio 24.9:1 (mL/g), and power 165 W, the saponins yield was 8.17%, which was 11.01% higher than ultrasonic assisted ethanol extraction method. The major compounds in UAE-IL were also identified using UPLC-MS/MS. Moreover, the optimized conditions of IL-AABS with recovery rate of saponins was 96.70%. Finally, a low extraction time, and favorable impurities removal efficiency and recyclability suggested UAE-IL-AABS is greener for production in the food, medicine, and chemical industry.

Extraction of raspberry ketone from red raspberry and its intervention in the non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by diffused hepatocyte bullous fat in the liver, which is not caused by alcohol or drugs like amiodarone and tamoxifen. Presently, no drug is approved for NAFLD treatment. Therefore, it’s important to extract effective components from natural plants to alleviate NAFLD. In this study, we extracted and purified raspberry ketone, a natural phenolic compound from red raspberry (Rubus ideaus L.) by an ultrasonic-assisted ethanol extraction method. The structure of red raspberry ketone (RRK) was determined using Fourier-transform infrared spectroscopy and the purity of RRK was found as 80.06 ± 1.19%. After 28 days of intragastric administration of RRK, the bodyweight of NAFLD model rats decreased significantly (p < 0.05). Besides, the levels of low-density lipoprotein cholesterol, total cholesterol, and total triglyceride (TG) decreased and the content of high-density lipoprotein cholesterol in serum increased drastically. Moreover, the level of liver damage indicators (aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase) and the levels of glucose, insulin, free-fatty acid, tumor necrotic factor-α in the liver decreased distinctly. The levels of TG and malondialdehyde in the liver decreased, whereas the levels of superoxide dismutase, total glutathione, and glutathione peroxidase drastically increased. We also found that RRK reduced the uneven size of liver cells and blurred boundaries of hepatic lobules, and alleviated hepatic steatosis and inflammation caused by NAFLD. We inferred that RRK could relieve NAFLD progression by regulating glucose and lipid metabolism and alleviating oxidative stress in vivo. This study sheds new light on the use of RRK as a functional food for NAFLD prevention.

Steam reforming of ethanol for hydrogen production by low-temperature steam reforming using modified Ni-Sn/CeO2 catalyst

This study focuses on the development of Ni-Sn bimetallic catalysts supported on ZrO2 modified CeO2 and their application for low temperature steam reforming of ethanol (LTSRE) at different temperature 200–400 °C. The catalyst powders are prepared by an ultrasonic-assisted solution combustion synthesis method. The ethanol conversion and selectivity of H2, CO2, CO, and CH4 has been studied with feed composition H2O:EtOH = 12: 1 mol ratio, feed flow rate 0.1 cc/min, and reaction time 20 hrs. Fresh and spent catalysts are characterized using XRD, FTIR, Raman, FESEM, XPS, and TGA-DTA. ZrO2 changes the support chemistry and enhances the activity and stability of the catalyst. At 400 °C, 100 % ethanol (EtOH) conversion, 69 % H2 selectivity with least coke deposition is observed for the catalyst with 5 wt% metal (Ni:Sn = 14:1) loading on Ce:Zr 1:2 mol ratio (NiSn5/CZ12) support.

The synthesis and characterization of Ni-M-Tb/Al2O3 (M: Mg, Ca, Sr and Ba) nanocatalysts prepared by different types of doping using the ultrasonic-assisted method to enhance CO2 methanation

In the present study, Ni-M-Tb/Al2O3 (M: Mg, Ca, Sr and Ba) nanostructured catalysts with different ratios of the alkali metals were synthesized by the ultrasonic-assisted one-pot method. The catalytic performance was investigated in terms of CO2 conversion, CH4 selectivity, and stability via the H2-TPR analysis. The structural properties were delineated using XRD, SEM, TEM and BET equation. The results showed that the 2Ni-5Mg-5Tb/Al2O3 catalyst with a maximum CO2 conversion of 75.37% and CH4 selectivity of 100%, at the operating temperature of 400 °C in the molar ratio of H2:CO2:3.5 for 100 h, had the best performance. This could benefit from the particular electronic structure of Tb in combination with Mg and Ni, reducing agglomeration, as demonstrated by the SEM and BET results. Based on the current findings, novel catalysts with high conversion efficiency of CO2 to CH4 might be achieved by tuning a decent combination of alkaline and rear earth elements as the promoters of Ni-based catalysts.

Ultrasonic-assisted synthesis of Ni based-layered double hydroxide doped carbon nanotube and its highly efficient in water oxidation reaction

Among the developed electrocatalysts, NiCr-layered double hydroxides (NiCr-LDH) are one of the most effective electrocatalytic materials for water oxidation. However, applications of such a kind of materials are practically limited due to their poor electric conductivity. In this work, the single-walled carbon nanotube (SWCNT) was doped to NiCr-LDH, and the LDH-based nanocomposites were synthesized using the one-step ultrasonic-assisted method. Physicochemical properties of the NiCr-LDH/SWCNT composites were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), field emission−scanning electron microscopy (FE−SEM), and linear sweep voltammetry (LSV). The NiCr-LDH/SWCNT composites were used as effective nanomaterials for oxygen evolution reaction (OER) at a near neutral medium. The LSV results confirm that the overpotential of the NiCr-LDH/SWCNT-0.006 sample decreased to about 120 mV at pH = 9.5, as compared with that of the NiCr-LDH or NiCr-LDH-SWCNT-0.006 (prepared by the two-step method) sample. The high oxygen evolution activity of NiCr-LDH/SWCNT-0.006 was associated with the co-presence of the homogeneously dispersed NiCr-LDH, good electrochemical activity, and high electrical conductivity. In addition, the as-prepared optimized NiCr-LDH/SWCNT electrocatalyst was highly stable for the OER reaction.

Optimization of ultrasonic-assisted polysaccharide extraction from Hyperici Perforati Herba using response surface methodology and assessment of its antioxidant activity

This study performed a comprehensive investigation of Hyperici Perforati Herba polysaccharide (HPHP) regarding the development and optimization of extraction methods, elucidation of structure and characteristics, and determination of antioxidant activities. An ultrasonic-assisted extraction method, which offered advantages in terms of the extraction yield and energy efficiency, was developed by response surface analysis. The following optimum conditions were determined: a crushing degree at 65 mesh, ultrasonic time at 50 min and temperature of 43 °C. Through enzyme-mediated deproteination via the Sevag method, activated carbon depigmentation, and DEAE-52 and Sephadex G-100 column elution, three HPHPs were obtained, and their monosaccharides mainly included mannose, galactose, glucose and arabinose. The molar weights were 8.347, 1.199 and 22.426 kDa, respectively. The HPHP structures were an amorphous aggregate of spherical-like shapes with a rough surface of pores and crevices, which presented characteristic Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectra of polysaccharides. Their main glucosidic linkage is the α-type configuration. Moreover, HPHPs exhibited strong scavenging activity for DPPH·, ABTS·+, OH· and O2·− radicals; good ferric reducing power; and effective protection against oxidative damage in human cells. Overall, the results of this work underpinned a fundamental understanding of HPHPs, thus providing a potential antioxidant for further research and development.

Optimization of ultrasonic assisted membrane strategy for saponins from Gynostemma Pentaphyllum with response surface methodology.

Gynostemma pentaphyllum saponin has a variety of biological properties. Classic separation methods of saponin, such as resin absorption and preparative chromatography are limited by environmental pollution and high cost. In the study, ultrasonic assisted membrane separation was firstly used to purify saponin from Gynostemma pentaphyllum. Total proteins, polysaccharides, saponin, gypenoside A and rutin were selected as indexes to optimize the pretreatment and purification parameters by response surface methodology. The fitted models were significant (p < 0.05) and the optimal conditions were: (1) removing protein and polysaccharides by MWCO 10,000Da, ultrasonic power 400W and pH 7.8; (2) separation flavonoids from saponin by MWCO 1000Da, ultrasonic power 300W and pH 7.9. The difficulty in separating saponin from flavonoids was solved by releasing flavonoids from micelles with ultrasonic assisted membrane method. The saponin content in Gynostemma pentaphyllum extracts reached 82.81%, which was more than four times of that obtained with resin adsorption method. The protective effect of saponins on SH-SY5Y cells injury induced by H2O2 was better than that of Gynostemma pentaphyllum extracts. The study suggested that ultrasonic assisted membrane method would be widely applied in the preparation of food materials.