On the association between poly(vinyl alcohol) and sodium dodecyl sulfate and its effect on liquid–liquid interfacial tension: A mathematical model

Association between poly(vinyl alcohol-co-vinyl acetate) copolymer (PVA) and sodium dodecyl sulfate (SDS) was studied experimentally and theoretically. It was found that, for the ethyl acetate-aqueous phase interface in which PVA was previously adsorbed, the interfacial tension (γ) increases abruptly to a maximum and then exhibits a relatively mild decay with the addition of SDS to the aqueous phase. The theoretical results indicate that vinyl acetate (VAc) segments determine γ. However, for relatively low concentrations of SDS (C_SDS), this latter plays a major role because through its association with the VAc segments it modulates the extent to which PVA is adsorbed at the interface, indirectly determining the value of γ. As C_SDS approaches to the CMC value for SDS, its influence on γ decreases because SDS tends to self-assembly rather than associates with VAc. These model predictions are consistent with experimental findings reported in the literature.     

Efficient loading and entrapment of tamoxifen in human serum albumin based nanoparticulate delivery system by a modified desolvation technique

Herein, the poorly water-soluble drug, Tamoxifen (Tmx), was loaded in the amphipathic matrix of human serum albumin (HSA) nanoparticles by a modified desolvation method. In order to enhance the drug loading (DL) and drug entrapment efficiency (DEE) (<2% and 10%, respectively), ultrasonication of Tmx-HSA mixture was performed prior to desolvation process. Tmx loading and entrapment efficiency were optimized by employment of the response surface methodology (RSM)-central composite design (CCD) of experiments. Under the optimum conditions of 1.59 mg Tmx/ml concentration, 7.76 pH and 5 h incubation of HSA-Tmx, the DL of 6.7% and DEE of 74% are achievable. Particles with the average size of 195 nm, zeta potential of −21 mV and polydispersity index of 0.09 were produced under these conditions. A more sustained Tmx release behavior was observed from polyethylene glycol (PEG) conjugated nanoparticles in comparison to the non-PEGylated ones. The short-term stability investigation showed no alteration in physicochemical properties of nanoparticles at 4 and 37 °C, but small increase in nanoparticles size was observed after three months of storage at room temperature. This is the first report for efficient production of a Tmx delivery system based on HSA nanoparticles.     

胶束增敏荧光法测定复方新诺明中的磺胺甲(噁)唑

根据表面活性剂具有胶束增敏的作用,发现十二烷基硫酸钠(SDS)在pH为3.9的HAc-NaAc缓冲溶液中,对复方新诺明中的磺胺甲唑(SMZ)的荧光有增敏作用,并用荧光光度计实现了灵敏的检测。实验分别对表面活性剂及用量、介质pH值、乙醇用量及放置时间进行了探讨,选择了最佳的实验条件。建立了用增敏荧光光度法测定复方新诺明中的磺胺甲唑含量的新方法。该方法的线性范围为7.0×10-6~4.0×10-5mol/L,检出限为:5.72×10-7mol/L。方法用于复方新诺明中磺胺甲唑含量的测定,结果令人满意。     

Application of high density steam flash-explosion in protein extraction of soybean meal

The high density steam flash-explosion (HDSFE) was used to extract protein from soybean meal. Soybean meal samples were treated at 1.3 MPa and 1.8 MPa for 60 s, 120 s and 180 s, respectively. After HDSFE treatment at 1.8 MPa for 180 s, the extraction yield of protein was increased from 50.50% to 65.66% compared with untreated soybean meal. The emulsification properties and fat-binding capacity of soy protein isolate (SPI) extracted from soybean meal treated by HDSFE were all improved compared with SPI extracted from untreated soybean meal and white flakes. Molecular weight distribution analysis of SPI showed that after HDSFE treatment the peak with molecular weight about 504 kDa and 43.3 kDa disappeared and the peak with molecular weight about 669 kDa increased indicating protein aggregation. Gel electrophoresis showed that high molecular weight aggregates of protein have been formed by covalent bond.     

Effect of Slurry Ice on the Functional Properties of Proteins Related to Quality Loss during Skipjack Tuna (Katsuwonus pelamis) Chilled Storage

The effect of slurry ice on the quality of Skipjack tuna (Katsuwonus pelamis) during chilling storage was investigated and compared to flake ice. Slurry ice‐treated samples showed significantly higher springiness and chewiness variables than the blank and flake ice‐treated samples (P < 0.05). The growth of microorganisms in tuna muscle treated with slurry ice was also down significantly (P < 0.05), and the total aerobic counts didn't reach higher scores than 5.0 log CFU/g during the whole chilling storage. Additionally, the myofibrillar protein, Ca²⁺‐ATPase activity, and total sulfydryl (SH) content in muscle treated with slurry ice were all significantly higher than the blank and flake‐iced samples (P < 0.05). This was probably due to the faster cooling, subzero final‐temperature, and larger heat exchange derived from slurry ice. Standard error of mean and sodium dodecyl sulfate–polyacrylamide gel electrophoresis results also confirmed that slurry ice treatment could effectively retard the degradation of myofibrillar proteins and showed a positive effect on the stability of tissue structures.     

Metabolic profile and biological activities of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco: Studies on the essential oil and polar extracts

We investigated the metabolic profile and biological activities of the essential oil and polar extracts of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco collected in south Portugal. Gas chromatography–mass spectrometry (GC–MS) analysis revealed that oxygen-containing monoterpenes was the principal group of compounds identified in the essential oil. Camphor (40.6%) and fenchone (38.0%) were found as the major constituents. High-performance liquid chromatography with diode array detection (HPLC–DAD) analysis allowed the identification of hydroxycinnamic acids (3-O-caffeoylquinic, 4-O-caffeoylquinic, 5-O-caffeoylquinic and rosmarinic acids) and flavones (luteolin and apigenin) in the polar extracts, with rosmarinic acid being the main compound in most of them. The bioactive compounds from L. pedunculata polar extracts were the most efficient free-radical scavengers, Fe²⁺ chelators and inhibitors of malondialdehyde production, while the essential oil was the most active against acetylcholinesterase. Our results reveal that the subspecies of L. pedunculata studied is a potential source of active metabolites with a positive effect on human health.     

超声波辅助SDS反胶束前萃花生蛋白研究

采用SDS(十二烷基磺酸钠)/异辛烷―正辛醇反胶束体系萃取花生蛋白,并采用超声波辅助萃取,主要研究全脂花生粉加入量、缓冲溶液pH值、萃取时间、萃取温度、超声波功率、KCl浓度、SDS浓度、Wo对蛋白萃取率影响。设计正交实验优化萃取工艺,结果表明,最优前萃工艺条件为:花生粉加入量0.015 g/mL、缓冲溶液pH值9、萃取时间40 min、萃取温度35℃、超声波功率270 W、KCl浓度0.25 mol/L、SDS浓度0.07 g/mL、Wo为24;在此条件下,花生蛋白萃取率为89.62%±1.15%。     

Ni(Ⅱ)-5-Cl-PADAB-SDS体系条件实验

研究发现：在阴离子表面活性剂十二烷基硫酸钠（ＳＤＳ）存在下,以混酸－氢氧化钠缓冲液控制酸度,利用镍与４－（５－氯－２－吡啶偶氮）－１,３－二胺基苯（５－Ｃｌ－ＰＡＤＡＢ）生成紫红色络合物的吸收光谱,可直接光度法测镍。该体系稳定性好,摩尔吸光系数为１．２２×１０５Ｌ·ｍｏｌ－１·ｃｍ－１,镍量在０～１５μｇ·２５ｍＬ－１范围内符合比耳定律     

Reversible Cluster Aggregation and Growth Model for Graphene Suspensions

We present a reversible cluster aggregation model for 2‐D macromolecules represented by line segments in 2‐D; and, we use it to describe the aggregation process of functionalized graphene particles in an aqueous SDS surfactant solution. The model produces clusters with similar sizes and structures as a function of SDS concentration in agreement with experiments and predicts the existence of a critical surfactant concentration (C_crit) beyond which thermodynamically stable graphene suspensions form. Around C_crit, particles form dense clusters rapidly and sediment. At C ? C_crit, a contiguous ramified network of graphene gel forms which also densifies, but at a slower rate, and sediments with time. The deaggregation–reaggregation mechanism of our model captures the restructuring of the large aggregates towards a graphite‐like structure for the low SDS concentrations. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5462–5473, 2017