Safe nanotechnologies for increasing the effectiveness of environmentally friendly natural agrochemicals

Natural compounds and living organisms continue to play a limited role in crop protection, and few of them have reached the market, despite their attractiveness and the efforts made in research. Very often these products have negative characteristics compared to synthetic compounds, e.g., higher costs of production, lower effectiveness, lack of persistence, and inability to reach and penetrate the target plant. Conversely, nanotechnologies are having an enormous impact on all human activities, including agriculture, even if the production of some nanomaterials is not environmentally friendly or could have adverse effects on agriculture and the environment. Thus, certain nanomaterials could facilitate the development of formulated natural pesticides, making them more effective and more environmentally friendly. Nanoformulations can improve efficacy, reduce effective doses, and increase shelf‐life and persistence. Such controlled‐release products can improve delivery to the target pest. This review considers certain available nanomaterials and nanotechnologies for use in agriculture, discussing their properties and the feasibility of their use in sustainable crop protection, in particular, in improving the effectiveness of natural bio‐based agrochemicals. © 2019 Society of Chemical Industry     

纳米复合相变蓄冷材料的制备及蓄冷特性分析

针对生鲜冷链物流领域冷藏运输温度要求,该研究通过差示扫描量热仪（Differential Scanning Calorimeter, DSC）对甘氨酸、山梨醇、甘露醇、氯化钾进行筛选,经优化后配置出主储能为0.6mol/L甘氨酸+0.1mol/L山梨醇（命名为TA2）,以此体系为基液添加纳米二氧化钛和纳米氧化铝,并添加高吸水性树脂（Super Absorbent Polymer, SAP）对防泄漏现象进行优化,探究添加纳米粒子后复合相变蓄冷材料的相变潜热和热循环稳定性。将该复合材料应用于自制保温箱,以水晶梨为试验对象进行了蓄冷箱保冷特性试验,对比蓄冷保温箱载货与空载情况下箱内各点的温度变化,综合考虑蓄冷保温箱内蓄冷剂侧面布置和顶层布置加侧面布置这两种摆放方式对保冷性能的影响。结果显示,添加质量分数为0.5%的纳米二氧化钛粒子可使基液的导热系数达到最大值,经优化的最终材料为TA2+0.5%TiO2+0.25%SAP,相变潜热为294.57 J/g,Onset温度为-5.8 ℃,经过200次循环试验,复合材料热性能稳定。蓄冷剂以侧布加顶布的摆放方式下的大部分箱内空间可在0～5 ℃保持480 min,温度场更均匀,利于保持生鲜产品新鲜度。研究结果可为相变材料在生鲜冷链物流中的研制及应用提供参考。     

Chitosan-Based Carbon Dots with Applied Aspects: New Frontiers of International Interest in a Material of Marine Origin

Carbon dots (CDs) have attracted significant research attention worldwide due to their unique properties and advantageous attributes, such as superior optical properties, biocompatibility, easy surface functionalization, and more. Moreover, biomass-derived CDs have attracted much attention because of their additional advantages related to more environmentally friendly and lower-cost synthesis. In this respect, chitosan has been recently explored for the preparation of CDs, which in comparison to other natural precursors exhibited additional advantages. Beyond the benefits related to the eco-friendly and abundant nature of chitosan, using it as a nanomaterial precursor offers additional benefits in terms of structure, morphology, and dopant elements. Furthermore, the high content of nitrogen in chitosan allows it to be used as a single carbon and nitrogen precursor for the preparation of N-doped CDs, significantly improving their fluorescent properties and, therefore, their performances. This review addresses the most recent advances in chitosan-based CDs with a special focus on synthesis methods, enhanced properties, and their applications in different fields, including biomedicine, the environment, and food packaging. Finally, this work also addresses the key challenges to be overcome to propose future perspectives and research to unlock their great potential for practical applications.     

叶面喷施铁基纳米材料对大豆生长的影响及机制研究

为探究叶面喷施铁基纳米材料(NMs)对作物生长的影响及其潜在机制,利用水培试验探究了两种铁基NMs(γ-Fe2O3 NMs和Fe3O4 NMs)和Fe-EDTA对大豆生长的影响.先通过叶面喷施不同浓度(0、1、10、50 mg·L-1)的铁基NMs,确定最佳施用浓度(10 mg·L-1),再在最佳施用浓度下,比较两种NMs与Fe-EDTA对大豆生长和蔗糖转运的作用效果及机制.结果 表明,叶面喷施不同浓度铁基NMs对大豆地上部和地下部干质量、根长、根尖数、根体积均有促进作用,且效果随着浓度的升高呈现先增加后降低的趋势.10 mg·L-1为铁基NMs促进大豆生长的最佳浓度,且不同处理组的促生效果表现为γ-Fe2O3 NMs>Fe3O4 NMs>螯合铁肥(相同含铁量的Fe-EDTA).铁基NMs的缓释性及高表面活性使其比Fe-EDTA具有更高的生物可利用性,γ-Fe2O3 NMs处理的大豆根、茎、叶中铁含量是等量Fe-EDTA处理的1.29、1.09、1.24倍;10 mg·L-1γ-Fe2O3 NMs、Fe3O4 NMs、Fe-EDTA处理下,大豆净光合速率与对照组相比分别增加了62.7％、41.5％、30.7％,铁基NMs对大豆叶片蒸腾速率、气孔导度和胞间二氧化碳浓度的促进效果也明显高于Fe-EDTA;铁基NMs通过调控蔗糖转运相关基因(GmSWEET 15、GmSUT 2)的表达量,促进光合产物向根部的运输,增加大豆根冠比,促进根部养分(S、P、Ca、Mn、Cu)吸收.研究表明,叶面喷施纳米铁肥能够促进作物生长、蔗糖转运及养分吸收,且相对于传统铁肥其促进效果更为显著(P<0.05),这为铁基纳米肥在农业生产中的应用提供了理论依据.     

纳米材料在植物遗传转化中的应用

植物细胞壁是植物遗传转化过程中外源生物分子传递的主要限制因素.传统植物遗传转化方法需要外力辅助或生物介导.基于纳米材料构建的核酸载体无需外力即可转染,并具有生物相容性好、保护外源核酸免受破坏和转染效率高等突出优点,为植物遗传工程技术提供了新的途径.本文在阐述植物遗传转化瓶颈、常用遗传转化技术的缺陷、纳米材料在植物遗传转...     

金属纳米材料的植物生物效应及其多组学研究进展

金属纳米材料(MNMs)在农业领域中的广泛应用,已经引起国内外学者对其生态风险的关注。传统毒理学研究方法与组学技术(转录组学、代谢组学和蛋白质组学)相结合,逐渐成为当前纳米生态毒理学研究领域的主要手段。本文首先从植物生长效应、亚细胞及生理生化水平等不同层次,分别评述了MNMs植物效应的传统毒理学研究的主要发现;其次,阐述了转录组学、蛋白质组学以及代谢组学等多组学技术在MNMs植物毒理学领域中应用的最新研究进展,旨在进一步揭示MNMs植物效应潜在的分子机制;最后分析了该领域的研究现状、尚待解决的问题和未来发展方向,并提出今后的研究思路。     

叶面喷施两种典型纳米材料对苋菜积累多环芳烃的影响

为探究叶面喷施硅、锌等是否能够减少作物对土壤有机污染物的吸收机理,选择纳米二氧化硅、纳米氧化锌以及对应的盐作为叶面喷施材料,考察了它们对苋菜生长和吸收累积多环芳烃(PAHs)的影响。结果表明:材料喷施未对植物叶绿素产生显著影响,但均增加了植物干质量。在S1处理中(低浓度污染处理),硅酸钠处理干质量增加了42%;在S2处理中(高浓度污染处理),硅酸钠、纳米二氧化硅、硫酸锌处理干质量分别增加了50.2%、64.0%和77.7%。在S1处理中,与对照(CK)相比,喷施硅酸钠、纳米二氧化硅、硫酸锌和纳米氧化锌处理的苋菜中荧蒽浓度分别降低了46.5%、35.3%、27.4%和25.8%,纳米二氧化硅处理使苋菜中芘的浓度降低了25.6%;在S2处理中,各处理未发生显著变化。研究表明,在一定的条件下,纳米氧化锌和纳米二氧化硅的喷施降低了苋菜对PAHs的累积。     

三种纳米材料对水稻幼苗生长及根际土壤肥力的影响

为探讨纳米材料在土壤环境中的生态效应,采用盆栽试验将三种外源纳米材料（nSiO₂、nTiO₂、nZnO）分别添加到水稻土中,研究三种浓度的纳米材料对盆栽水稻幼苗生长及土壤肥力的影响。结果表明：0.5 mg·g^-1 nZnO处理后水稻幼苗鲜质量、干质量和株高增加,但1、2 mg·g^-1 nZnO处理后水稻鲜质量、干质量和株高降低;2 mg·g^-1 nSiO₂处理后水稻干质量和株高显著降低。0.5、2 mg·g^-1 nSiO₂处理后的水稻N含量显著降低,三种浓度nZnO处理后的水稻P含量显著增加,而K含量显著降低。1、2 mg·g^-1nTiO₂处理对水稻生长、主要营养元素（N、P、K）含量以及土壤有效氮、有效磷、有效钾含量的影响均不显著。经三种浓度nSiO₂和nTiO₂处理后的土壤pH和有机质含量均降低,1、2 mg·g^-1 nSiO₂处理后土壤有效氮和有效磷含量显著增加,三种浓度的nZnO处理后土壤有效磷和有效钾含量降低。经三种纳米材料处理后土壤酸性磷酸酶和过氧化氢酶活性分别被显著抑制和显著促进,不同浓度的nZnO处理土壤蔗糖酶和脲酶活性均被显著抑制。总体而言,三种纳米材料中nZnO对植物的生长、养分吸收和土壤酶活性的影响最大。     

Anti-lung cancer efficacy of magnetic nanoscale carrier with camptothecin

AIM: To study the preparation, drug release, cell absorption and anti-lung cancer efficacy of magnetic nanoscale carrier with camptothecin (MNC-Camp). METHODS: The drug release ability of MNC-Camp was detected by ultraviolet spectrophotometric method. Absorption of magnetic nanoparticles by A549 cells was measured by pullulan staining method. The growth inhibition ability of Camp and MNC-Camp on the A549 cells and white blood cells was analyzed by MTT assay. The metastasis ability of A549 cells treated with Camp and MNC-Cmap was evaluated by cell invasion method. The activity of apoptosis protein caspase-3 was detected by ELISA. RESULTS: A549 cells had a good absorption ability on MNC, and the drug release of MNC-Camp increased with time increasing. Compared with MNC group, Camp and MNC-Camp induced the apoptosis of A549 cells, and the half inhibition concentration (IC₅₀) were (35.14±3.21) and (7.16±2.54) mg/L, respectively.Camp and MNC-Camp also decreased the A549 cell transfer number and increased the activity of apoptosis protein caspase-3. All the effects of MNC-Camp were obviously significant than those of free Camp (P<0.05). CONCLUSION: MNC-Camp has a better inhibitory effect on the growth of A549 cells than free Camp, and finally plays an important role in anti-lung cancer effect.     

Preparation and Characterization of Ferrofluid Stabilized with Biocompatible Chitosan and Dextran Sulfate Hybrid Biopolymer as a Potential Magnetic Resonance Imaging (MRI) T2 Contrast Agent

Chitosan is the deacetylated form of chitin and used in numerous applications. Because it is a good dispersant for metal and/or oxide nanoparticle synthesis, chitosan and its derivatives have been utilized as coating agents for magnetic nanoparticles synthesis, including superparamagnetic iron oxide nanoparticles (SPIONs). Herein, we demonstrate the water-soluble SPIONs encapsulated with a hybrid polymer composed of polyelectrolyte complexes (PECs) from chitosan, the positively charged polymer, and dextran sulfate, the negatively charged polymer. The as-prepared hybrid ferrofluid, in which iron chloride salts (Fe³⁺ and Fe²⁺) were directly coprecipitated inside the hybrid polymeric matrices, was physic-chemically characterized. Its features include the z-average diameter of 114.3 nm, polydispersity index of 0.174, zeta potential of −41.5 mV and iron concentration of 8.44 mg Fe/mL. Moreover, based on the polymer chain persistence lengths, the anionic surface of the nanoparticles as well as the high R2/R1 ratio of 13.5, we depict the morphology of SPIONs as a cluster because chitosan chains are chemisorbed onto the anionic magnetite surfaces by tangling of the dextran sulfate. Finally, the cellular uptake and biocompatibility assays indicate that the hybrid polymer encapsulating the SPIONs exhibited great potential as a magnetic resonance imaging T2 contrast agent for cell tracking.