基于稳定剂和微胶囊化联用技术制备姜黄素纳米颗粒

以光稳定性为指标,筛选稳定剂Zn2+的最适作用浓度;以包埋率为指标,分析水相与醇相体积比、壁材比（阿拉伯胶与玉米醇溶蛋白质量比）、芯壁比（姜黄素与玉米醇溶蛋白-阿拉伯胶质量比）对姜黄素纳米颗粒制备的影响,在单因素试验基础上进行L9（34）正交试验优化,采用多指标综合平衡法确定姜黄素纳米颗粒制备最优工艺;同时分析微胶囊化对姜黄素溶液光稳定性的改善效果。结果表明：加入0.3 g/L的Zn2+有助于改善姜黄素溶液的光稳定性;姜黄素纳米颗粒最优制备工艺为水相与醇相体积比3∶1,壁材比8∶10（质量比）,芯壁比7∶100（质量比）,此时姜黄素纳米颗粒包埋率为95.844%,载药量为62 mg/g,粒径为0.994 μm。姜黄素纳米颗粒的光解反应比未包埋的姜黄素的光解反应要慢,微胶囊技术提高了姜黄素溶液对光稳定性。     

氧化锌纳米颗粒对玉米储藏过程中霉菌区系及其品质的影响

目的 探索氧化锌纳米颗粒对玉米储藏过程中霉菌区系及其品质的影响。方法 将玉米分成3份,经过不同浓度氧化锌纳米颗粒悬浮液的处理,以不添加氧化锌纳米颗粒作为对照,置于30℃下模拟储藏35 d,对不同处理组的玉米霉菌区系和储藏品质变化进行监测与分析。结果 储藏35 d后,处理组霉菌量为4.0×10⁴ CFU/mL,而对照组霉菌量为1.4×10⁶ CFU/mL,表明氧化锌纳米颗粒有效抑制了玉米储藏过程中霉菌的生长繁殖。玉米在整个储藏过程中优势霉菌主要为黄曲霉、黑曲霉、温特曲霉、桔青霉和查氏青霉等青霉属和曲霉属。随着储藏时间的增加,玉米中脂肪酸值、电导率、丙二醛显著上升,过氧化物酶活力显著下降,水分也呈下降趋势。揭示了低浓度氧化锌纳米颗粒对细胞膜有一定的保护作用,而高浓度氧化锌纳米颗粒会对细胞膜系统造成破坏。结论 氧化锌纳米颗粒可以显著抑制玉米储藏过程中霉菌的生长繁殖,同时低浓度添加更有利于玉米的储藏。     

人参皂苷Rh2-壳聚糖纳米粒子制备及对A549细胞的抑制作用

人参皂苷Rh2是一种具有抑制肿瘤生长功效的生物活性物质。本实验采用离子交联的方法制备壳聚糖纳米粒子包载人参皂苷Rh2,以解决Rh2的水溶性差、生物相容度低的问题。以纳米粒子的粒径、Zeta-电位为评价指标,对制备条件（m（壳聚糖）∶m（三聚磷酸钠）、壳聚糖分子质量以及Rh2投药量）进行探究,筛选纳米粒子最佳成球条件;通过透射电子显微镜、原子力显微镜对纳米粒子形态进行观察,采用X射线衍射考察晶型变化;最后通过体外实验探究载药纳米粒子对人非小细胞肺癌A549细胞增殖的影响以及细胞对其的摄取行为。结果表明,最优条件（m（壳聚糖）∶m（Rh2）∶m（三聚磷酸钠）为8∶1.5∶2、壳聚糖分子质量为50 kDa）下制备得到的载药纳米粒子粒径和Zeta-电位分别为（222.70±17.34）nm和（46.50±2.57）mV,载药量和包封率分别为7.89%和49.54%,载药纳米粒子分布均一、性能稳定,适用于药物递送。细胞实验结果显示载药纳米粒子能够被A549细胞摄取,较游离药物抑制A549细胞的增殖作用增强。研究表明离子交联法制备而成的壳聚糖纳米粒子是一种具有应用前景的Rh2递送载体。     

负载辣椒素的巯基改性壳聚糖-玉米醇溶蛋白纳米颗粒制备与稳定性分析

针对辣椒素的口服局限性，采用巯基化改性制备巯基壳聚糖，与玉米醇溶蛋白复合包埋辣椒素，得到纳米颗粒递送体系。根据粒径、载药量等指标确定制备工艺，通过荧光光谱、傅里叶变换红外光谱、透射电镜等验证其包埋效果，并评价其稳定性和消化释放特性。结果显示，在巯基壳聚糖-玉米醇溶蛋白-辣椒素比例为10∶10∶1，纳米颗粒粒径为（76.05±1.06）nm，载药量为（36.85±1.22）μg/mg，通过氢键和疏水相互作用形成，形状为规则球形。此外，纳米颗粒具有较好的pH值稳定性和离子强度稳定性，在体外模拟消化过程中能够有效延缓辣椒素的释放，消化4 h后释放率仅为（40.08±4.28）%，可进一步用于辣椒素的口服递送研究。     

涂覆聚苯乙烯/银复合材料对用废纸生产的卡纸强度和抗菌性能的影响

在无毒、环境友好的生物质材料（稻草粉末）存在的条件下,利用新方法制备了可作为抗菌剂的银纳米颗粒。采用透射电子显微镜（TEM）、X射线衍射（XRD）仪和紫外光谱对银纳米颗粒进行分析。同时,将制备的银纳米颗粒与聚苯乙烯配制成涂布液对以旧报纸为原料制备的卡纸进行涂布,探讨了涂覆聚苯乙烯/银复合材料的卡纸的强度性能、抗菌能力和水蒸气渗透性的变化。     

硒化猴头菇多糖的制备、结构表征及抗增殖活性

以猴头菇纯化多糖（Hericium erinaceus polysaccharide,HEPS）（总糖含量＞92%）为研究对象,在含有VC和亚硒酸钠的氧化还原体系中,制备得到猴头菇多糖纳米硒复合物（HEPS-Se）。通过原子吸收分光光谱仪、傅里叶变换红外光谱仪、X射线衍射仪、扫描电子显微镜、EDX元素分析仪、X射线光电子能谱、纳米粒度仪等对其结构进行表征;同时研究HEPS-Se对人肺癌细胞A549、人前列腺癌细胞DU145的抗增殖作用。结果表明：所制备的HEPS-Se为形貌规则、均一的球体,其元素组成比例为C∶O∶Se∶Pt＝32.92∶24.74∶30.46∶11.87;其中Se元素的含量高达481.79 μg/g。傅里叶变换红外光谱表明HEPS主要通过—OH、—C＝O等基团与纳米硒结合。与HEPS相比,HEPS-Se的粒径显著降低,电位绝对值提高了69.12%。同时,体外抗增殖活性结果表明,HEPS-Se能显著抑制人前列腺癌细胞DU145、人肺癌细胞A549的增值活性,并呈现明显的剂量效应。本研究为有机硒补充剂的开发提供良好的理论依据。     

多羧基纤维素纳米晶的制备与性能研究

采用乙二胺四乙酸二酐（EDTAD）酯化法制备表面羧基含量及羟基取代度可控的多羧基化纤维素纳米晶（ECNC）,并通过改变酯化条件,优化实验结果;通过傅里叶变换红外光谱（FT IR）、透射电子显微镜（TEM）、电导滴定、X射线衍射（XRD）、元素分析、Zeta电位等对ECNC进行分析。结果表明,ECNC保持了CNC的形貌和结晶结构完整性,并且在水和磷酸盐（PBS）缓冲溶液中的分散性较CNC显著提高;同时,通过改变酯化反应条件可控制ECNC表面羧基含量及羟基取代度。该ECNC颗粒有望用于高性能复合纳米材料的制备及功能化纳米复合颗粒的制备中。     

短直链淀粉纳米颗粒的制备及其表征

本文以蜡质玉米淀粉为原料,酶解脱支不同时间制备短直链淀粉,在4℃下自组装形成淀粉纳米颗粒。采用透射电子显微镜(TEM)、动态光散射(DLS)、红外光谱仪(FTIR)、X射线衍射仪(XRD)、差示扫描量热仪(DSC)和高效凝胶排阻色谱(HPSEC)等对其结构和形貌进行表征。透射电子显微镜(TEM)和动态光散射(DLS)结果显示,淀粉纳米颗粒呈球形或椭球形,粒径在30~150nm之间,并随酶解时间的增加而增大;X射线衍射仪(XRD)结果表明,所有的淀粉纳米颗粒都表现出典型的B型晶体结构,相对结晶度在40%以上。与其他酶解时间制备的短直链相比,酶解6 h制备的短直链分子量分布范围最窄,形成的纳米颗粒峰值糊化温度最高(89.03℃),焓值最大(13.92 J/g),本文研究了不同酶解时间对淀粉纳米颗粒性质的影响,为酶解回生法制备淀粉纳米颗粒的研究和应用提供一定的理论基础。     

玉米醇溶蛋白-阿拉伯胶纳米颗粒的制备及性质表征

以玉米醇溶蛋白(zein)和阿拉伯胶(arabic gum,AG)为原料,通过反溶剂法制备纳米颗粒,形成核壳结构的zein-AG运载体系。通过研究zein储备液质量浓度、体系中乙醇与水体积比(醇水比)、pH值、盐离子浓度对纳米颗粒稳定性影响,制备高效负载生育酚的zein-AG纳米颗粒。实验结果表明,zein储备液质量浓度为50g/L,醇水比为1∶50,zein与AG的质量比为1∶1.5时,形成粒径为122.6 nm,多分散指数(PDI)为0.17,电位为-32.8 m V的稳定纳米颗粒;在pH=3~9内zein-AG纳米颗粒粒径在120~140 nm;pH=3时zein-AG纳米颗粒电位较低为-17.8 m V,但pH=4~9时电位在-25~-40 m V,PDI在0.3以下,非常稳定;盐离子浓度不超过20mmol/L时,纳米颗粒粒径均为纳米级,超过20 mmol/L时纳米颗粒发生严重絮凝,证明zein和AG为静电相互作用力结合,有一定的电荷屏蔽作用。当纳米颗粒与生育酚质量比为1∶5时,包封率达到86.9%以上,且粒径、PDI、电位均在稳定范围内。复合AG的zein纳米颗粒的稳定性、耐盐耐酸碱性、对生育酚负载率均有显著提高。     

抗菌性载银纳米微晶纤维素的制备及表征

以纳米微晶纤维素（NCC）为载体、聚乙烯吡咯烷酮（PVP）为分散剂,利用葡萄糖还原硝酸银以制备纳米银颗粒,得到载银纳米微晶纤维素溶液。利用紫外可见分光光度计、透射电子显微镜、X射线衍射仪对载银纳米微晶纤维素溶液进行表征。结果表明,由此体系制备的载银纳米微晶纤维素中纳米银颗粒平均粒径为10～20 nm,为晶体结构,且分散均匀。利用抑菌圈法对载银纳米微晶纤维素的抗菌性能进行检测,发现其对大肠杆菌、金黄色葡萄球菌等均有较好的抑制作用。     

Genotypic differences in zinc efficiency of Chinese maize evaluated in a pot experiment

BACKGROUND: Zinc (Zn) deficiency, a major problem limiting crop production worldwide, is common on calcareous soils of China. Using such a Zn‐deficient soil supplied adequately with plant mineral nutrients, with or without Zn, 30 Chinese maize genotypes were grown for 30 days in a greenhouse pot experiment and assessed for Zn efficiency (ZE), measured as relative biomass under Zn‐limiting compared with non‐limiting conditions. RESULTS: Substantial variation in tolerance to low Zn nutritional status was observed within the maize genotypes. Tolerant genotypes did not show Zn deficiency symptoms at the studied early seedling growth, and there was a well‐defined relationship between shoot dry matter and the ZE trait. ZE values ranged on average from 45 to 100% for shoot dry weight. Under low available soil Zn conditions, shoot and root dry weights, shoot Zn concentration and content, leaf superoxide dismutase (SOD) activity, leaf area and plant height were all correlated with ZE. Shoot Zn and phosphorus (P) concentrations were negatively correlated. CONCLUSION: Three genotypes (L55 × 178, L114 × 178 and Zhongnong 99) were identified as highly Zn‐efficient and three (L53 × 178, L105 × 178 and L99 × 178) as very low in ZE. This selection allows further work to evaluate ZE based on grain yield and grain Zn concentration, including field experiments likely to benefit farmers producing maize on Chinese soils low in available Zn. Copyright © 2012 Society of Chemical Industry     

Impact of opening hermetic storage bags on grain quality,fungal growth and aflatoxin accumulation

Purdue Improved Crop Storage (PICS) bags are used by farmers in Sub-Saharan Africa for pest management of stored grains and products, including maize. These bags hermetically seal the products, preventing exchange with external moisture and gases. Biological respiration within the bags create an environment that is unsuitable for insect development and fungal growth. This study was conducted to determine the impact of routine opening of the storage bags for maize consumption on fungal growth and aflatoxin contamination. Maize with moisture contents (MC) high enough to support fungal growth (15%, 16%, 18% and 20%) was stored in PICS bags, which were opened weekly and exposed to humid conditions (85% RH) for 30 min over a period of 8 weeks and 24 weeks. Monitors indicated that oxygen defused into the open bags but did not reach equilibrium with the bottom layers of grain during the 30-min exposure period. Fungal colony forming units obtained from the grain surface increased 3-fold (at 15% MC) to 10,000-fold (at 20% MC) after 8 weeks. At both 8 weeks and 24 weeks, aflatoxin was detected in at least one bag at each grain moisture, suggesting that aflatoxin contamination spread from a planted source of A. flavus-colonized grain to non-inoculated grain. The results indicate that repeatedly breaking the hermetic seal of the PICS bags will increase fungal growth and the risk of aflatoxin contamination, especially in maize stored at high moisture content. This work also further demonstrates that maize should be properly dried prior to storage in PICS bags.     

Comparative effects of hermetic and traditional storage devices on maize grain: Mycotoxin development,insect infestation and grain quality

A large-scale study was conducted to assess which of the five most accessible hermetic storage devices on the Kenyan market fulfill the needs of smallholder farmers by positively impacting three major areas of concern: insect infestation, grain quality, and mycotoxin (aflatoxin and fumonisin) contamination. Efficacy of two hermetic silos (plastic and metal) and three hermetic bags (PICS, GrainPro's GrainSafe™, and Super Grain) was directly compared to current maize storage in polypropylene (PP) bags under local environmental conditions using representative storage volumes during a 6-month storage period. Impact of maize grain stored at typical (∼15%) and recommended (<13.5%) moisture levels and potential efficacy losses through frequent interruption of the underlying hermetic principals was assessed. Hermetic storage significantly reduced the increase in aflatoxin compared to PP bags regardless of the moisture level of the grain. An <5% per month aflatoxin increase was achieved by three of the five devices tested: Metal silo, PICS and GrainSafe™ bag. A strong correlation between grain moisture, storage time and aflatoxin development was found in PP bags, but not in any of the hermetic devices. The same result was not obtained for fumonisin development in stored maize. The rate of Fumonisin increase was similar in all tested devices, including the polypropylene bags, and conditions. The periodic opening of the hermetic devices had no significant effect on the efficacy of the hermetic devices but the repeated disturbance of the PP bags led to a significant increase in aflatoxin levels. The maize weevil Sitophilus spp. was most commonly found with a total incidence of 72%. Grain storage under hermetic conditions reduced insect infestation, grain weight loss and discoloration. However, maize storage above recommended moisture levels led to a distinct odor development in all hermetic devices but not the PP bags. Hence, proper grain drying is a prerequisite for maize storage in airtight conditions.     

Strategies to reduce mycotoxin levels in maize during storage: a review

Maize (Zea mays L.) is one of the main cereals as a source of food, forage and processed products for industry. World production is around 790 million tonnes of maize because as a staple food it provides more than one-third of the calories and proteins in some countries. Stored maize is a man-made ecosystem in which quality and nutritive changes occur because of interactions between physical, chemical and biological factors. Fungal spoilage and mycotoxin contamination are of major concern. Aspergillus and Fusarium species can infect maize pre-harvest, and mycotoxin contamination can increase if storage conditions are poorly managed. Prevention strategies to reduce the impact of mycotoxin in maize food and feed chains are based on using a hazard analysis critical control point systems (HACCP) approach. To reduce or prevent production of mycotoxins, drying should take place soon after harvest and as rapidly as feasible. The critical water content for safe storage corresponds to a water activity (a _w) of about 0.7. Problems in maintaining an adequately low a _w often occur in the tropics where high ambient humidity make the control of commodity moisture difficult. Damage grain is more prone to fungal invasion and, therefore, mycotoxin contamination. It is important to avoid damage before and during drying, and during storage. Drying maize on the cob before shelling is a very good practice. In storage, many insect species attack grain and the moisture that can accumulate from their activities provides ideal conditions for fungal activity. To avoid moisture and fungal contamination, it is essential that the numbers of insects in stored maize should be kept to a minimum. It is possible to control fungal growth in stored commodities by controlled atmospheres, preservatives or natural inhibitors. Studies using antioxidants, essential oils under different conditions of a _w, and temperature and controlled atmospheres have been evaluated as possible strategies for the reduction of fungal growth and mycotoxin (aflatoxins and fumonisins) in stored maize, but the cost of these treatments is likely to remain prohibitive for large-scale use.     

Production of the mycotoxin, zearalenone, by Fusarium graminearum growing on stored grain. I. Grain storage at reduced temperatures

The limiting conditions of grain moisture content (m.c.) and storage temperature for growth of Fusarium and production of the mycotoxin, zearalenone, were defined in maize, wheat, barley and oat culture. Grain moisture content was the major influence on establishment of the fungus, but storage temperature directly affected the rate of zearalenone synthesis. All the grains tested were susceptible to invasion by Fusarium above 18% m.c. (calculated on a wet-weight basis), even when stored at 7 ºC. In the range 15 to 18% m.c. the grain was increasingly at risk as the storage temperature was raised. Maximum zearalenone yields (500 to 2000 μg/g grain) were obtained in cultures stored at 12 and 18 ºC, even though mycelial growth had been reduced. At 25 ºC, where there was rapid mycelial growth and almost total utilisation of grain after two months' storage, toxin yields were seldom higher than 100 μg/g grain.     

Maize: A Paramount Staple Crop in the Context of Global Nutrition

Abstract: The maize plant (Zea mays), characterized by an erect green stalk, is one of the 3 great grain crops of the world. Its kernels, like other seeds, are storage organs that contain essential components for plant growth and reproduction. Many of these kernel constituents, including starch, protein, and some micronutrients, are also required for human health. For this reason, and others, maize has become highly integrated into global agriculture, human diet, and cultural traditions. The nutritional quality and integrity of maize kernels are influenced by many factors including genetic background, environment, and kernel processing. Cooking procedures, including nixtamalization and fermentation, can increase accessibility of micronutrients such as niacin. However, man cannot live on maize alone. For one‐third of the world's population, namely in sub‐Saharan Africa, Southeast Asia, and Latin America, humans subsist on maize as a staple food but malnutrition pervades. Strategies to further improve kernel macronutrient and micronutrient quality and quantities are under intense investigation. The 2 most common routes to enhance grain nutritional value are exogenous and endogenous fortification. Although exogenous fortification, such as addition of multivitamin premixes to maize flour, has been successful, endogenous fortification, also known as “biofortification,” may provide a more sustainable and practical solution for chronically undernourished communities. Recent accomplishments, such as low‐phytate, high‐lysine, and multivitamin maize varieties, have been created using novel genetic and agronomic approaches. Investigational studies related to biofortified maize are currently underway to determine nutrient absorption and efficacy related to human health improvement.     

Assessing Purdue Improved Crop Storage (PICS) bags to mitigate fungal growth and aflatoxin contamination

Storing maize in regions of the world without sufficient drying and storage capacity is challenging due to the potential risk of aflatoxin contamination produced by Aspergillus flavus. This study sought to determine if storage of maize in Purdue Improved Crop Storage (PICS) bags prevents mold growth and aflatoxin accumulation. PICS bags are a three-layer, hermitic bag-system that forms a barrier against the influx of oxygen and the escape of carbon dioxide. Maize conditioned at 12, 15, 18, and 21% grain moisture was inoculated with 50 g of maize kernels infected with fluorescent-marked strain of A. flavus. The grain was stored in either PICS or woven bags at 26 °C, and percent oxygen/carbon dioxide levels, fungal growth, aflatoxin, moisture content, and kernel germination were assessed after 1 and 2 months incubation. Maize stored in woven bags was found to equilibrate with the ambient moisture environment over both storage periods, while PICS bags retained their original moisture levels. Aspergillus flavus growth and aflatoxin accumulation were not observed in maize stored in any PICS bags. No aflatoxin B1 was detected in woven bags containing low-moisture maize (12 and 15%), but detectable levels of aflatoxin were observed in high moisture maize (18 and 21%). The percentage of oxygen and carbon dioxide within PICS bags were dependent on initial grain moisture. Higher carbon dioxide levels were observed in the bags stored for 1 month than for 2 months. High initial moisture and carbon dioxide levels correlated with low kernel germination, with the 18 and 21% treatment groups having no seeds germinate. The results of the study demonstrate that storage of maize in PICS bags is a viable management tool for preventing aflatoxin accumulation in storage.     

Xylem- and phloem-based transport of CuO nanoparticles in maize (Zea mays L.)

This work reports on the toxicity of CuO nanoparticles (NPs) to maize (Zea mays L.) and their transport and redistribution in the plant. CuO NPs (100 mg L(-1)) had no effect on germination, but inhibited the growth of maize seedlings; in comparison the dissolved Cu(2+) ions and CuO bulk particles had no obvious effect on maize growth. CuO NPs were present in xylem sap as examined by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS), showing that CuO NPs were transported from roots to shoots via xylem. Split-root experiments and high-resolution TEM observation further showed that CuO NPs could translocate from shoots back to roots via phloem. During this translocation, CuO NPs could be reduced from Cu (II) to Cu (I). To our knowledge, this is the first report of root-shoot-root redistribution of CuO NPs within maize. The current study provides direct evidence for the bioaccumulation and biotransformation of CuO NPs (20-40 nm) in maize, which has significant implications on the potential risk of NPs and food safety.     

Comparison of improved and local maize varieties in the Republic of Benin with emphasis on susceptibility to Sitophilus zeamais Motschulsky

Experiments were conducted to verify differences in agronomic traits and susceptibility to the maize weevil, Sitophilus zeamais, in the field and in traditional maize storage systems between two international improved varieties, which have not been readily accepted by farmers in the Republic of Benin, one partially improved local variety and a local variety obtained from farmers. Factors responsible for differences in susceptibility and suitable screening methods for resistance to the maize weevil were also studied. In the first part of this study the varieties were compared in the field, during field drying and when stored using traditional techniques. The international improved varieties had significantly higher grain yield (60%) but had significantly poorer husk cover. The percentage of damaged ears following field drying, and the numbers of storage pests and grain weight loss after one month of storage were significantly higher in the international improved varieties presumably as a result of poorer husk cover.

In the second part of this study the varieties were compared in a factorial arrangement of three storage forms (undehusked, dehusked and shelled grain) and two infestation methods (free and no-choice). Due to their superior husk cover quality, Benin varieties were significantly more resistant to weevils when infested in the traditional, undehusked storage form than international improved varieties. The smaller-grain, flinty, Benin varieties showed a significantly smaller number of F₁ generation weevils. A significant lengthening of the median development period (MDP) of weevils was observed when maize was stored as dehusked ears compared to shelled grain, particularly on the international improved varieties. No improved vs Benin variety comparisons interacted with free vs no-choice comparisons except for index of susceptibility in the undehusked storage form. Free choice infestations resulted in increased experimental error for number of F₁ weevils, presumably due to a clumped distribution of female weevils during oviposition. When the target farmer's storage system is undehusked ears, it is suggested to use no-choice infestation of undehusked ears as a screening method for elite candidate varieties. An assessment of husk quality and no-choice infestation of shelled grain and/or dehusked maize ears is suggested as more appropriate for preliminary screening of diverse germplasm.