Huihua Huang

Modification of pineapple peel fibre with succinic anhydride for Cu2+, Cd2+ and Pb2+ removal from aqueous solutions

Research on chemical modification of pineapple peel fibre with succinic anhydride was carried out to create a novel adsorbent for Cu2+, Cd2+ and Pb2+ removal from aqueous solution. After pretreatment with iso‐propyl alcohol and NaOH, pineapple peel fibre was modified via reaction with succinic anhydride for introduction of carboxylic functional groups. The modified pineapple peel fibre was characterized with Fourier transform infrared (FTIR) spectroscopy and evaluated for its adsorptive ability for Cu2+, Cd2+ and Pb2+ from synthetic metal solutions. The FTIR analysis proved the introduction of carboxylic functional groups in the backbone of the modified pineapple peel fibre. The modified pineapple peel fibre showed higher adsorptive capacity for Cu2+, Cd2+ and Pb2+ compared with raw pineapple peel and pineapple peel fibre pretreated with iso‐propyl alcohol. The adsorption of Cu2+, Cd2+ and Pb2+ on the modified pineapple peel fibre depended on solution pH value, adsorption time and initial metal concentration. The maximum adsorption capacities of the modified fibre were observed at pH 5.4 for Cu2+ (27.68 ± 0.83 mg g−1 or 0.44 mmol g−1), at pH 7.5 for Cd2+ (34.18 ± 1.02 mg g−1 or 0.30 mmol g−1) and at pH 5.6 for Pb2+ (70.29 ± 2.11 mg g−1 or 0.34 mmol g−1) respectively. The adsorption followed the pseudo‐second‐order kinetics model and the experimental data coincided well with the Langmuir model.

Modified pineapple peel cellulose hydrogels embedded with sepia ink for effective removal of methylene blue

Novel composite hydrogels based on pineapple peel cellulose and sepia ink were synthesized by homogeneous acetylation of cellulose in ionic liquid 1-butyl-3-methylimidazolium chloride. The structure and morphology of the prepared hydrogels were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscope, X-ray diffraction, thermogravimetry and differential scanning calorimetry. The effects of acetylation time, acetylation temperature, molar ratio of acetic anhydride/anhydroglucose unit and the additive amount of sepia ink on methylene blue adsorption capacity of the hydrogels embedded with sepia ink were also investigated. Methylene blue adsorption of the hydrogels followed pseudo-second-order kinetic model and sepia ink improved adsorption capacity significantly. The adsorption capacity at equilibrium was increased from 53.72 to 138.25mg/g when the additive amount of sepia ink of the hydrogels was 10%.

Enhanced Swelling and Responsive Properties of Pineapple Peel Carboxymethyl Cellulose-g-poly(acrylic acid-co-acrylamide) Superabsorbent Hydrogel by the Introduction of Carclazyte

The superabsorbent hydrogels were synthesized by grafting acrylic acid and acrylamide onto pineapple peel carboxymethyl cellulose and effect of carclazyte introduction was compared. The structure and morphology of the superabsorbents were investigated by Fourier transform infrared spectroscopy, X-ray diffraction, and field emission scanning electron microscopy. Swelling behaviors of the superabsorbents were investigated in distilled water, 0.9% NaCl solution, various salt and pH solutions, as well as surfactant solutions and simulated physiological fluids. The swelling dynamic mechanism of the superabsorbents was explained well by Fickian diffusion and Schotts pseudo-second-order models. The introduction of carclazyte effectively improved the swelling capacity of the superabsorbents in various solutions as well as its salt- and pH-sensitivity. The prepared superabsorbents also exhibited excellent sensitivities to various surfactant solutions and simulated physiological fluids, showing potential applications in the biomaterials field.

Impacts of some macromolecules on the characteristics of hydrogels prepared from pineapple peel cellulose using ionic liquid

Abstract Composite hydrogels were prepared from pineapple peel cellulose with the combinations of polyethylene glycol (PEG), polyvinyl alcohol (PVA), к-carrageenan (CN), or soluble starch (SH) in 1-allyl-3-methylimidazolium chloride solvent. Impacts of these macromolecules on the texture profile analysis (TPA) parameters, equilibrium swelling ratio (ESR), and sodium salicylate (NaSA) load of the prepared hydrogels were studied. The NaSA release kinetics of the composite hydrogels were also compared. The composite hydrogels exhibited differences in Fourier transform infrared spectroscopy (FTIR), TPA parameters, ESR, NaSA load ratio, and release kinetics. CN addition increased the hardness of the hydrogels, while PEG played an opposite role. SH and PVA could decrease hardness, gumminess, and resilience, and SH could increase the springiness and cohesiveness of the hydrogels. Most of the composite hydrogels exhibited the same basic FTIR features as the simple hydrogel. Freeze-dried composite hydrogels exhibited a markedly higher ESR than the oven-dried ones, and additions of PEG, PVA, CN, and SH showed the same effect. Addition of the PEG and PVA combination could lower the ESR of the hydrogels, whereas additions of the PEG and CN combination or PEG and SH combination could markedly increase the ESR of the hydrogels. Addition of PEG, PVA, CN, and SH respectively could increase the NaSA load ratio of the hydrogels. Oven-drying treatment, additions of the PEG and PVA combination or PEG and CN combination were propitious for extending the NaSA fast-release phase of the hydrogels.

Eco-friendly polyvinyl alcohol/carboxymethyl cellulose hydrogels reinforced with graphene oxide and bentonite for enhanced adsorption of methylene blue

Eco-friendly polyvinyl alcohol/carboxymethyl cellulose (isolated from pineapple peel) hydrogels reinforced with graphene oxide and bentonite were prepared as efficient adsorbents for methylene blue (MB). The structure and morphology of the prepared hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). Introducing graphene oxide and bentonite into the hydrogels evidently enhanced the thermal stability, swelling ability and MB adsorption capacity. The effects of initial concentration of MB, pH, contact time and temperature on MB adsorption capacity of the prepared hydrogels were investigated. Adsorption kinetics and equilibrium adsorption isotherm fitted pseudo-second-order kinetic model and Langmuir isotherm model well, respectively. After introducing graphene oxide and bentonite into the hydrogels, the maximum adsorption capacity calculated from the Langmuir isotherm model reached 172.14 mg/g at 30 °C, obviously higher than the hydrogels prepared without these additions (83.33 mg/g). Furthermore, all the prepared hydrogels also displayed good reusability for the efficient removal of MB. Consequently, the prepared hydrogels could be served as eco-friendly, stable, efficient and reusable adsorbents for anionic dyes in wastewater treatment.

Preparation and characterization of cellulose composite hydrogels from tea residue and carbohydrate additives

Composite hydrogels were prepared from tea cellulose in ionic liquid of 1-allyl-3-methylimidazolium chloride and effect of κ-carrageenan, chitosan, guar gum and soluble starch on characteristics of the prepared hydrogels were investigated. The prepared hydrogels were characterized via Fourier transform infrared, thermogravimetry analysis, differential scanning calorimetry. Sodium salicylate was used as the model drug to compare the swelling, drug loading and releasing kinetics of the prepared hydrogels. Thiazolyl blue tetrazolium bromide assay and relative growth rates were adopted to evaluate cell cytotoxicity and biocompatibility of the prepared hydrogels. Chitosan and guar gum could improve thermostability and mechanical characteristics of the composite hydrogels, while κ-carrageenan or soluble starch could improve equilibrium swelling ratio, sodium salicylate loading and releasing. Guar gum and chitosan could increase permeation resistance and were beneficial for release control of the hydrogels. Addition of chitosan, κ-carrageenan, guar gum and soluble starch were proven cell compatibility and non-cytotoxicity.

Changes in resistant starch from two banana cultivars during postharvest storage

Banana resistant starch samples were extracted and isolated from two banana cultivars (Musa AAA group, Cavendish subgroup and Musa ABB group, Pisang Awak subgroup) at seven ripening stages during postharvest storage. The structures of the resistant starch samples were analysed by light microscopy, polarising microscopy, scanning electron microscopy, X-ray diffraction, and infrared spectroscopy. Physicochemical properties (e.g., water-holding capacity, solubility, swelling power, transparency, starch-iodine absorption spectrum, and Brabender microviscoamylograph profile) were determined. The results revealed significant differences in microstructure and physicochemical characteristics among the banana resistant starch samples during different ripening stages. The results of this study provide valuable information for the potential applications of banana resistant starches.

Lipase-Catalyzed Incorporation of Different Fatty Acids into Tripalmitin-Enriched Triacylglycerols: Effect of Reaction Parameters

Tripalmitin-enriched triacylglycerols were concentrated from palm stearin by acetone fractionation and as the substrate reacted with a mixture of equimolar quantities of fatty acids (C8:0-C18:3). The incorporation degree and acyl migration level of the fatty acids and acylglycerols composition were investigated, providing helpful information for the production of human milk fat substitutes. Higher incorporation degrees of the fatty acids were obtained with lipase PS IM, Lipozyme TL IM, and Lipozyme RM IM followed by porcine pancreatic lipase and Novozym 435-catalyzed acidolysis. During reactions catalyzed by Lipozyme TL IM, Lipozyme RM IM, and lipase PS IM, incorporation degrees of C12:0, C14:0, C18:1, and C18:2 were higher than those of other fatty acids at operated variables (molar ratio, temperature, and time), and the triacylglycerols content reached the highest (82.09%) via Lipozyme RM IM-catalyzed acidolysis. On the basis of significantly different levels of acyl migration to the sn-2 position, lipases were in the order of lipase PS IM < Lipozyme TL IM < Lipozyme RM IM.

Pineapple peel carboxymethyl cellulose/polyvinyl alcohol/mesoporous silica SBA-15 hydrogel composites for papain immobilization

Hydrogel composites based on pineapple peel carboxymethyl cellulose, polyvinyl alcohol and mesoporous silica SBA-15 were synthesized by an eco-friendly method of repeated freeze-thaw cycles for the application of papain immobilization. The experiment was optimized to obtain an efficient papain immobilization carrier. Simultaneously the immobilization conditions, including enzyme concentration, pH, crosslinker concentration and cross-linking time were optimized. The immobilized papain had maximum activity at low reaction temperature of 40°C and showed pH-sensitivity by exhibiting a rapid decrease of activity within a narrow range from pH 7.0 to pH 7.5. Compared with the free papain, the immobilized papain revealed enhanced pH, thermal and storage stability. After 2h incubation at 80°C, the immobilized papain retained 56% of its initial activity while the free papain only retained 16%. After 10days of storage, 79% of the initial activity was retained for the immobilized papain while only 27% for the free papain.

Green tea polyphenols induce cell death in breast cancer MCF-7 cells through induction of cell cycle arrest and mitochondrial-mediated apoptosis*

In order to study the molecular mechanisms of green tea polyphenols (GTPs) in treatment or prevention of breast cancer, the cytotoxic effects of GTPs on five human cell lines (MCF-7, A549, Hela, PC3, and HepG2 cells) were determined and the antitumor mechanisms of GTPs in MCF-7 cells were analyzed. The results showed that GTPs exhibited a broad spectrum of inhibition against the detected cancer cell lines, particularly the MCF-7 cells. Studies on the mechanisms revealed that the main modes of cell death induced by GTPs were cell cycle arrest and mitochondrialmediated apoptosis. Flow cytometric analysis showed that GTPs mediated cell cycle arrest at both G1/M and G2/M transitions. GTP dose dependently led to apoptosis of MCF-7 cells via the mitochondrial pathways, as evidenced by induction of chromatin condensation, reduction of mitochondrial membrane potential (ΔΨm), improvement in the generation of reactive oxygen species (ROS), induction of DNA fragmentation, and activations of caspase-3 and caspase-9 in the present paper.摘要目的评估茶多酚对人乳腺癌细胞MCF-7 凋亡的影响, 并探讨了其作用机制。创新点全面考察了茶多酚对抗乳腺癌的分子机制,为茶 多酚作为抗肿瘤辅助药物提供理论依据。方法首先选取不同组织来源的五种人肿瘤细胞(人肝 癌细胞HepG2、人肺癌细胞A549、人前列腺癌 细胞PC3、人宫颈癌细胞Hela、人乳腺癌细胞 MCF-7)作为体外模型,以MTT 法检测茶多酚 对其增殖抑制作用。然后,选用最敏感细胞 MCF-7 为研究对象,采用流式细胞术检测茶多酚 对细胞周期分布的影响,用Hoechst 3328 染色法 观察茶多酚对细胞核形态的影响,用JC-1 染色法 观察茶多酚对细胞线粒体跨膜电位的影响,用双 氯荧光素(DCFH-DA)染色法观察茶多酚对细 胞活性氧(ROS)水平的影响,用凝胶电泳DNA 片段测定法(DNA ladder)观察茶多酚处理后细 胞DNA 断裂情况,用蛋白质印迹法(Western blot)检测茶多酚对细胞凋亡关键蛋白caspase-3 和caspase-9 表达的影响,全面探讨了茶多酚体外 抗肿瘤机制。结论实验结果显示,茶多酚能够通过诱导细胞周期阻 滞和线粒体凋亡抑制MCF-7 细胞增殖。茶多酚诱 导线粒体凋亡的途径是使线粒体跨膜电位下降, 促使MCF-7 细胞内ROS 生成,促使细胞DNA 断裂和促进细胞内caspase-3 和caspase-9 的活化。