查找使用阿拉丁产品的科研文献

Application of natural deep eutectic solvents for extraction and determination of phenolics in Cajanus cajan leaves by ultra performance liquid chromatography

Zuofu Wei,Xiaolin Qi,Tingting Li,Meng Luo,Wei Wang,Yuangang Zu,Yujie Fu

In this study, novel and green natural deep eutectic solvents (NADESs) as extraction media, are presented for the extraction and determination of phenolics in Cajanus cajan leaves by ultra performance liquid chromatography. Fourteen different NADES systems were investigated for the extraction of phenolics with diverse polarity in C. cajan leaves. Experiments with different extraction solvents and multivariate data analysis demonstrated that the NADES composed of choline chloride and maltose possessed excellent extractability for both polar and weak polar compounds compared to conventional solvents. The influential parameters of microwave-assisted extraction procedure with NADES were examined and optimized. The optimized conditions were as follows: extraction solvent 20% of water in choline chloride/maltose (1/2), extraction temperature 60   °C, liquid/solid ratio 30:1   mL/g and irradiation time 12   min. Moreover, a fast and sensitive UPLC method was firstly developed for the comprehensive analysis of fourteen phenolics in C. cajan leaves. This method was performed within 40   min, and exhibited satisfactory linearity, precision and recovery. These results indicate that the proposed method represents an excellent alternative for the extraction and quantification of phenolics in plant materials.

Improved LFIAs for highly sensitive detection of BNP at point-of-care

Yan Gong,Jie Hu,Jane Ru Choi,Minli You,Yamin Zheng,Bo Xu,Ting Wen,Feng Xu

Phosphoric acid doped polybenzimidazole as an heterogeneous catalyst for selective and efficient dehydration of saccharides to 5-hydroxymethylfurfural

Miaomiao Han,Xiao Liu,Guangcheng Huang,Yadong Liu,Shengxiang Ji

5-Hydroxymethylfurfural (HMF) is considered as a valuable platform chemical for fuels and chemical intermediates. Tremendous efforts have been made on the development of catalysts for the dehydration of saccharides to HMF with high conversion and selectivity. Here we reported a new solid acid, phosphoric acid doped polybenzimidazole (PA–PBI), for the dehydration of fructose to HMF with high selectivity (∼94%) at high fructose concentration (50 wt%) in a water–methyl isobutyl ketone (MIBK) biphasic system. PA–PBI was directly obtained by the one-pot polycondensation reaction and was very stable under harsh reaction conditions due to the strong acid–base interaction between PA and imidazole in PBI. PA–PBI was recycled to catalyze the dehydration of fructose four times without the loss of activity and could also catalyze a variety of disaccharides and polysaccharides to produce HMF. The high selectivity and the ease of recycling make PA–PBI a superior catalyst for the dehydration of saccharides to HMF.

Comprehensive Evaluation of Deep Eutectic Solvents in Extraction of Bioactive Natural Products

Li Duan,Li-Li Dou,Long Guo,Ping Li,E-Hu Liu

Deep eutectic solvents (DESs) are emerging as green and sustainable solvents for efficient extraction of bioactive compounds or drugs. This work aimed to comprehensively evaluate the potential and effectiveness of DESs for extraction of different types of natural compounds from biomass. Five Chinese herbal medicines including Berberidis Radix, Epimedii Folium, Notoginseng Radix et Rhizoma, Rhei Rhizoma et Radix, and Salviae Miltiorrhizae Radix et Rhizoma were selected to assess the efficiency of DESs on extraction of alkaloids, flavonoids, saponins, anthraquinones, and phenolic acids, respectively. Totally 43 types of choline chloride-, betaine-, and l-proline-based DESs with different polarity, viscosity, composition, and solubilization abilities were tailored to test their extraction efficiency, and the operation conditions were statistically optimized using response surface methodology to produce the most efficient process. In this work, DES solvents were first introduced to extract alkaloids and anthraquinones. The results indicated that most prepared DESs proved to be efficient solvents for extraction of alkaloids, but lower extractability for anthraquinones. The extraction capacity of DES may be correlated with their physical–chemical properties, including H-bonding interactions, polarity, viscosity, and pH. This study demonstrated that DESs were suitable green extraction solvents for selectively and efficiently extracting bioactive compounds from biomaterials.

Synthesis of bacterial cellulose and bacterial cellulose nanocrystals for their applications in the stabilization of olive oil pickering emulsion

Huiqiong Yan,Xiuqiong Chen,Huangwang Song,Jiacheng Li,Yuhong Feng,Zaifeng Shi,Xianghui Wang,Qiang Lin

Although bacterial cellulose (BC) and bacterial cellulose nanocrystals (BCNs) have considered to be edible, non-toxic, biocompatible and biodegradable, there is still the dearth of reports of BC and BCNs as the emulsifiers of Pickering emulsions with respect to the applications in foods , cosmetics and medicines. In this work, BC with ultrafine network architecture and 8–40 nm crystalline microfibrils in diameter was produced by Acetobacter xylinum , and then it was hydrolyzed by sulfuric acid followed by the oxidation of hydrogen peroxide to prepare BCNs. The physicochemical properties of BC and BCNs were contrastively evaluated by FT-IR, XRD, TGA and dynamic light scattering (DLS). The emulsifying performances of BC and BCNs in the stabilization of olive oil Pickering emulsion were further evaluated by optical microscope (OM) and fluorescent microscope (FM). Experimental results showed that the sulfuric acid hydrolysis of BC induced the removal of the amorphous components and the cleavage of the crystalline microfibrils, making BCNs possess the initiating decomposition temperature of 350 °C, the crystallinity index (CrI) of 89.6%, average size of 259.6 nm with PDI of 0.26 and zeta potential at about −34.8 mV, which exhibited high thermal stability and good emulsifying performance in comparison with BC. Furthermore, the effects of pH and ionic strength on emulsion stability were also investigated. In comparison to BC, BCNs were more sensitive in response to the change of pH and ionic strength.

High permselectivity hyperbranched polyester/polyamide ultrathin films with nanoscale heterogeneity

Xin Kong,Ze-Lin Qiu,Chun-Er Lin,You-Zhi Song,Bao-Ku Zhu,Li-Ping Zhu,Xiu-Zhen Wei

Membranes with both high permeability and selectivity are desirable for practical separation. In this work, three hyperbranched polyesters (HPEs) with different numbers of hydroxyl-terminated groups and molecular structures were, respectively, incorporated into a polyamide film formed by the interfacial reaction between the mixtures of HPE/piperazine (PIP) and trimesoyl chloride (TMC) on PVC hollow fiber substrates to endow the corresponding thin film composite (TFC) membranes with different permselectivity performances. The successful incorporation of HPEs into the cross-linked polyamide matrix and their gradient distribution in the corresponding selective layer were confirmed by ATR-FTIR and XPS analyses. Moreover, the permeation experiments for the fabricated TFC membranes revealed that HPEs most likely existed within the network or/and aggregate pores of the polyamide matrix due to their nanometer sizes and flexible molecular structures. Both the changes in the pore structures and the increase in the hydrophilicity of the polyamide matrix with the introduction of abundant hydroxyl groups pending in the HPE molecules led to the permeate flux of the TFC membrane increasing significantly. Importantly, nearly spherical H40 HPEs with intramolecular cavities could act as a molecular sieve to endow the selective layer with a high rejection capability. Meanwhile, the H40/PIP selective layer with a more negatively charged surface exhibited a higher rejection for SO42− ions while maintaining a low rejection for Cl− ions. These findings encourage further exploration of a new alternative material with such structures like HPE by interfacial polymerization to construct an ultrathin barrier film with high permselectivity performance.

Adsorption separation of raffinose from sucrose by activated carbon: Equilibrium, kinetics and dynamic breakthrough

Zongbi Bao,Shuran Duan,Zhiguo Zhang,Huabin Xing,Baogen Su,Qiwei Yang,Yiwen Yang,Qilong Ren

Separation of oligosaccharides with a varied number of monosaccharides is an important issue in food chemistry. Raffinose, a functional oligosaccharide, has attracted increasing attentions due to its strong proliferative effect on bacteria. Industrially, cottonseed meal is an important resource for producing raffinose; however, raffinose extracted from the cottonseed meal contains a significant amount of sucrose that debases raffinose’s quality. In this work, an adsorptive separation of raffinose and sucrose on activated carbon was reported. Adsorption isotherms, adsorption kinetics and dynamic column adsorption–desorption were investigated. The activated carbon chosen has a significantly higher adsorption capacity of raffinose (0.60~0.65 g/g) than sucrose (0.35~0.40 g/g) at the equilibrium concentration studied (~35 g/L) and temperature from 293 K to 333 K. Adsorption isotherms and kinetics were fitted by the Freundlich isotherm model and the pseudo-second-order model, respectively. The effect of flow-rate and initial feed concentration on dynamic adsorption were investigated; meanwhile, the separation performance was further confirmed from dynamic desorption using aqueous ethanol of 20% as eluant. Remarkably, raffinose with purity over 90% and recovery of 79.2% could be obtained by the adsorption–desorption cycle using an aqueous feed solution containing 20 g/L of raffinose and 6 g/L of sucrose.

Synthesis of Molecularly Imprinted Polymer via Visible Light Activated RAFT Polymerization in Aqueous Media at Room Temperature for Highly Selective Electrochemical Assay of Glucose

Qiankun Zhu,Xiaoming Li,Yonghua Xiao,Yan Xiong,Suiping Wang,Changli Xu,Jun Zhang,Xuewen Wu

The mild environment where most proteins and antibodies in living systems are prepared has inspired fascination among chemists. Herein, a new, rapid, low-cost, and environment-friendly method is proposed to synthesize molecularly imprinted polymers (MIPs) via visible light activated reversible addition–fragmentation chain transfer polymerization in aqueous media at room temperature for highly selective electrochemical assay of glucose. The MIPs with microsphere morphology, the better hydraulic distribution, large surface area, uniform large pore sizes, and high pore volume exhibit a significant adsorption efficiency compared with nonimprinted polymers for glucose. In addition, the MIP sensor recognizing the glucose significantly exceeds that of the other saccharide analogs, possesses regenerative ability, and presents high sensitivity by applying for the detection of glucose in human urine samples.

Direct conversion of carbohydrates to diol by the combination of niobic acid and a hydrophobic ruthenium catalyst

Ying Duan,Jun Zhang,Dongmi Li,Dongsheng Deng,Lu-Fang Ma,Yanliang Yang

Tetrahydro-2,5-furandimethanol (THFDM) was obtained directly from a wide variety of carbohydrates by the combination of niobic acid and a hydrophobic ruthenium catalyst. Fructose, glucose, and polysaccharides consisting of fructose or glucose could be converted to THFDM in one-step. The selectivity to THFDM was kept around 60% while the glucose conversion varied from 9% to 49%. The as-synthesized niobic acid was characterized by TEM, N2 adsorption/desorption, XRD, NH3-TPD and FT-IR spectra of adsorpted pyridine. The niobic acid was proved to have medium and strong acid sites with a high Brönsted/Lewis ratio, which played a great role for keeping high THFDM selectivity using glucose as a substrate.

Size-dependent cellular uptake mechanism and cytotoxicity toward calcium oxalate on Vero cells

Sun Xin-Yuan,Gan Qiong-Zhi,Ouyang Jian-Ming

Urinary crystals with various sizes are present in healthy individuals and patients with kidney stone; however, the cellular uptake mechanism of calcium oxalate of various sizes has not been elucidated. This study aims to compare the internalization of nano-/micron-sized (50 nm, 100 nm, and 1 μm) calcium oxalate monohydrate (COM) and dihydrate (COD) crystals in African green monkey renal epithelial (Vero) cells. The internalization and adhesion of COM and COD crystals to Vero cells were enhanced with decreasing crystal size. Cell death rate was positively related to the amount of adhered and internalized crystals and exhibited higher correlation with internalization than that with adhesion. Vero cells mainly internalized nano-sized COM and COD crystals through clathrin-mediated pathways as well as micron-sized crystals through macropinocytosis. The internalized COM and COD crystals were distributed in the lysosomes and destroyed lysosomal integrity to some extent. The results of this study indicated that the size of crystal affected cellular uptake mechanism, and may provide an enlightenment for finding potential inhibitors of crystal uptake, thereby decreasing cell injury and the occurrence of kidney stones.

Efficient one-pot synthesis of n-butyl levulinate from carbohydrates catalyzed by Fe2(SO4)3

Ran An,Guizhuan Xu,Chun Chang,Jing Bai,Shuqi Fang

Butyl levulinate (BL) is a promising new candidate as diesel fuel and fuel additive. In this study, an efficient process for a one-pot synthesis of BL from biomass-derived carbohydrates in butanol medium with the catalysis of metal sulfates was developed. The catalytic activity of a series of metal sulfates for the synthesis of BL from fructose was investigated. Among various metal sulfates, ferric sulfate Fe 2 (SO 4 ) 3 was found to be the most efficient catalyst, which gave a remarkably high BL yield of 62.8   mol% under the conditions of 463   K, 3   h, a catalyst dosage of 5.0   g/L, and fructose concentration of 25   g/L. Different carbohydrates including glucose, cellulose , inulin and sucrose were also used for one-pot synthesis of BL with the catalysis of Fe 2 (SO 4 ) 3 , showing the yields of 39.6, 30.5, 56.6 and 50.1   mol%, respectively. In addition, the recycling and reuse of Fe 2 (SO 4 ) 3 was studied by characterizing them using powder X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS). A plausible reaction pathway for the one-pot synthesis of BL from fructose was proposed. This study provides a facile and feasible way for the synthesis of BL from biomass.

Involvement of ROS in nanosilver-caused suppression of aflatoxin production from Aspergillus flavus

Jing Zhao,Ling Wang,Dan Xu,Zhisong Lu

Silver nanoparticles (AgNPs) have been extensively studied as antimicrobial materials, but their capability of suppressing aflatoxin production has not been investigated. In this work, AgNPs with an average size of 4.5 nm were synthesized to inhibit the growth of Aspergillus flavus (A. flavus). Based on the anti-fungal assay, the concentration of 5 μg mL−1 was chosen to study the direct inhibiting effects of AgNPs on aflatoxin production. Results show that AgNP treatment could significantly decrease secretion of aflatoxin B1 from A. flavus. Real-time measurements of O2− with an electrochemical sensor reveal that the AgNPs could trigger the release of O2− from fungal mycelia. A mechanism involving O2− release is proposed to explain AgNP-caused depression of aflatoxin production from A. flavus. This is the first attempt to study AgNP-induced inhibition on aflatoxin generation and its possible mechanisms.