螺旋霉素分子印迹磁性纳米吸附剂的合成及应用

制备了一种以螺旋霉素为模板分子的分子印迹磁性纳米吸附剂。以磁性纳米Fe₃O₄为内核,经丙烯酸表面修饰后再以螺旋霉素为模板分子、甲基丙烯酸为功能单体、乙二醇二甲基丙烯酸酯为交联剂,通过表面自由基聚合反应制备得到。该吸附剂对螺旋霉素、交沙霉素、替米考星和酒石酸泰乐菌素4种大环内酯类抗生素表现出良好的富集效果（富集倍数分别为310、118、758和72）,其选择性明显优于常规C₁₈吸附剂。该吸附剂可重复使用至少6次。结合高效液相色谱-紫外检测器建立了上述4种抗生素的分析方法。方法检出限为0.53~2.75 μg/L,定量限为1.78~9.16 μg/L;在50、100和150 μg/L低中高3个添加水平下,方法回收率在80.78%~123.02%之间,相对标准偏差<15.8%（n=5）。该方法被应用于分析蜂蜜中的上述4种抗生素。     

胺基修饰的高度交联聚苯乙烯树脂对间苯二酚吸附行为研究

研究了AH系列胺基修饰的超高交联树脂对水溶液中间苯二酚的静态吸附行为特征,结果表明,它们对间苯二酚的吸附容量明显高于母体交联树脂NDA-100和大孔弱碱性阴离子交换树脂D301.AH系列树脂与吸附质分子之间不仅有范德华作用力,还存在着氢键等作用力.该类树脂对间苯二酚的吸附为自发的放热过程,属于以物理作用为主兼有弱化学作用的吸附过程.吸附速率符合准一级动力学方程,表观吸附速率常数随树脂胺基含量的升高而降低.     

汽油活性炭基脱硫吸附剂的制备与评价

以250℃温度下浓硫酸改性后的活性炭为载体,采用浸渍法制备了以MnO₂为活性组分的活性炭基的汽油脱硫吸附剂MnO₂/AC,考察了吸附剂的制备条件及脱硫条件对脱硫效果的影响。研究结果表明,适宜的吸附剂制备条件为,以Mn(NO₃)₂为活性组分前驱物,Mn(NO)₂浸渍液浓度0.15mol/L、常温下浸渍24h、焙烧温度350℃、焙烧时间2h。该吸附剂在静态吸附温度120℃、吸附时间2h、剂油质量比0.10的条件下可使原料油硫的质量分数从628.6×10^-6降至221.5×10^-6,脱硫率达到64.8%;在动态吸附温度60℃、空速1.76h^-1的条件下,初始流出汽油硫的质量分数降至21.8×10^-6,初始脱硫率达到96.5%。     

聚(丙烯酸-co-丙烯酰胺)/蒙脱土/腐殖酸钠复合物对Pb2+的吸附性能

用制备的聚(丙烯酸-co-丙烯酰胺)/蒙脱土/腐殖酸钠复合吸附剂,研究了溶液pH值、吸附时间和Pb2+溶液初始浓度等因素对重金属Pb2+的吸附性能,探讨了复合吸附剂对Pb2+的吸附机理。结果表明,在pH值为6.0、吸附时间2 h、Pb2+溶液初始浓度0.01 mol/L和吸附剂用量0.10 g的条件下,复合吸附剂对Pb2+的吸附量达到364.05 mg/g,平衡所需的时间为15 min。与蒙脱土相比,复合吸附剂具有更高的吸附容量和更快的吸附速率。     

Use of expanded bed adsorption to purify flavonoids from Ginkgo biloba L.

Three techniques (liquid–liquid extraction, packed bed adsorption and expanded bed adsorption) have been compared for the purification of flavonoids from the leaves of Ginkgo biloba L. A crude Ginkgo extract was obtained by refluxing with ethanol for 3 h. The yield of flavonoids achieved by this crude extraction was about 19% (w/w) and the purity of flavonoids in the concentrated extract was between 1.9 and 2.3% (w/w). The crude extract was then dissolved in deionized water and centrifuged where necessary to prepare clarified feedstock for further purification. For the method using liquid–liquid extraction with ethyl acetate, the purity, concentration ratio and yield of flavonoids were 25.4–31.0%, 16–18 and >98%, respectively. For the method using packed bed adsorption, Amberlite XAD7HP was selected as the adsorbent and clarified extract was used as the feedstock. The dynamic adsorption breakthrough curves and elution profiles were measured. For a feedstock containing flavonoids at a concentration of 0.25 mg/mL, the appropriate loading volume to reach a 5% breakthrough point during the adsorption stage was estimated to be 550–600 mL for a packed bed of volume 53 mL and a flow rate of 183 cm/h. The results from the elution stage indicated that the majority of impurities were eluted by ethanol concentrations of 40% (v/v) or below and efficient separation of flavonoids from the impurities could be achieved by elution of the flavonoids with 50–80% ethanol reaching an average purity of ∼25%. The recovery yield of flavonoids using the packed bed purification method was about 60% of the flavonoids present in the clarified feedstock (corresponding to around 30% for the total flavonoids in the unclarified crude extract). For the method using expanded bed adsorption also conducted with Amberlite XAD7HP as the adsorbent, the optimal operation conditions scouted during the packed bed experiments were used but unclarified crude extract could be loaded directly into the column. For an expanded bed with a settled bed height of 30 cm, the loss of flavonoids in the column flow-through was about 30%. The two-step elution protocol again proved to be effective in separating the adsorbed impurities and flavonoids. More than 96% of the bound impurities were completely removed by 40% ethanol in the first elution stage and less than 4% remained in the final product eluted by 90% ethanol in the second elution stage. Also, ∼74% of the adsorbed flavonoids on column (corresponding to 51% of the total flavonoids in the unclarified feedstock) were recovered in the product. In addition to higher recovery yield, the average process time to obtain the same amount of product was decreased in the expanded bed adsorption (EBA) process. The results suggest that the adoption of EBA procedures can greatly simplify the process flow sheet and in addition reduce the cost and time to purify flavonoids from Ginkgo biloba. These results clearly demonstrate the potential for the use of EBA to purify pharmaceuticals from plant sources.     

Factors affecting the reactivity of thiol-functionalized mesoporous silica adsorbents toward mercury(II)

Numerous mercaptopropyl-functionalized silica spheres have been prepared by either post-synthesis grafting of MCM-41 and MCM-48 or self-assembly co-condensation of mercaptopropyltrimethoxysilane (MPTMS) or mercaptopropyltriethoxysilane (MPTES) and tetraethoxysilane (TEOS) precursors in hydroalcoholic medium in the presence of a cationic surfactant as templating agent and ammonia as catalyst. These materials of approximately the same particle size and morphology featured different functionalization levels, various degrees of structural order, and variable distribution of thiol groups in the mesopores. Their reactivity in solution has been studied using Hg(II) as model analyte. Total accessibility (on a 1:1 S:Hg stoichiometry basis) was demonstrated and quantified for well-ordered materials whereas less open and less organized structures with high degrees of functionalization were subject to less-than-complete loadings. Capacities measured at pH 2 were lower than at pH 4 because of distinct mercury-binding mechanisms. Kinetics associated to the uptake process were studied by in situ electrochemical monitoring of Hg(II) consumption from aqueous suspensions containing the various adsorbents. They indicate only little difference between materials of the MCM-41 and MCM-48 series at similar functionalization levels, fast mass transport in well-ordered mesostructures in comparison to the poorly or non-ordered ones (except at pH 2 where charge formation induced some restriction in materials characterized by long-range structural order), and even faster processes in the wormlike frameworks (characterized by shorter range structural order). Hg(II) binding to thiol-functionalized materials obtained by post-synthesis grafting was found to occur more rapidly in the early beginning of the uptake process as a result of a higher concentration of binding sites at the pore entrance in comparison to the more homogeneous distribution of these groups in the mesochannels of materials obtained by co-condensation.     

Validation of mercury determination by solid sampling Zeeman atomic absorption spectrometry and a specially designed furnace

Certified reference materials (CRMs) of different origin were used to validate the direct determination of total mercury by solid sampling Zeeman atomic absorption spectrometry (SS-ZAAS) and a specially designed furnace. The temperature program provides only for one step. Atomisation of mercury and pyrolysis of the matrix is performed at a constant temperature in the range of 900–1000 °C. Calibration points achieved by CRMs and aqueous solutions are covered by one calibration line, indicating the absence of matrix effects. Relatively high amounts of chlorine, known for causing problems in mercury determination do not influence analytical results. The excellent accuracy of the method results in a very good agreement with the certified values. The precision of SS-ZAAS measurements in a range from 0.5 to 50 ng Hg does not exceed 3% R.S.D. A limit of quantification of 0.008 μg g⁻¹ Hg was achieved.     

Trichloroacetic Acid Removal by a Reductive Spherical Cellulose Adsorbent

A novel spherical cellulose adsorbent with amide and sulphinate groups was used for a first reduction of trichloroacetic acid(TCAA) and a subsequent adsorption of generated species, haloacetic acids. The removal mechanism involved TCAA reduction by sulphinate groups and the adsorption of the haloacetic acids through electrostatic interaction with amide group. Investigation of product formation and subsequent disappearance reveals that the reduction reactions proceed via sequential hydrogenolysis, and transform to acetate ultimately. Adsorption of haloacetic acids was ascertained by low chloride mass balances(89.3%) and carbon mass balances(75.1%) in solution. The pseudo-first-order rate constant for TCAA degradation was (0.93±0.12) h^-1. Batch experiments were conducted to investigate the effect of pH value on the reduction and adsorption process. The results show that the reduction of TCAA by sulphinate groups requires higher pH values while the electrostatic attraction of haloacetic acids by amino group is favorable in more acidic media.     

Harnessing the Anti-Nociceptive Potential of NK2 and NK3 Ligands in the Design of New Multifunctional μ/δ-Opioid Agonist–Neurokinin Antagonist Peptidomimetics

Opioid agonists are well-established analgesics, widely prescribed for acute but also chronic pain. However, their efficiency comes with the price of drastically impacting side effects that are inherently linked to their prolonged use. To answer these liabilities, designed multiple ligands (DMLs) offer a promising strategy by co-targeting opioid and non-opioid signaling pathways involved in nociception. Despite being intimately linked to the Substance P (SP)/neurokinin 1 (NK1) system, which is broadly examined for pain treatment, the neurokinin receptors NK2 and NK3 have so far been neglected in such DMLs. Herein, a series of newly designed opioid agonist-NK2 or -NK3 antagonists is reported. A selection of reported peptidic, pseudo-peptidic, and non-peptide neurokinin NK2 and NK3 ligands were covalently linked to the peptidic μ-opioid selective pharmacophore Dmt-DALDA (H-Dmt-d-Arg-Phe-Lys-NH₂) and the dual μ/δ opioid agonist H-Dmt-d-Arg-Aba-βAla-NH₂ (KGOP01). Opioid binding assays unequivocally demonstrated that only hybrids SBL-OPNK-5, SBL-OPNK-7 and SBL-OPNK-9, bearing the KGOP01 scaffold, conserved nanomolar range μ-opioid receptor (MOR) affinity, and slightly reduced affinity for the δ-opioid receptor (DOR). Moreover, NK binding experiments proved that compounds SBL-OPNK-5, SBL-OPNK-7, and SBL-OPNK-9 exhibited (sub)nanomolar binding affinity for NK2 and NK3, opening promising opportunities for the design of next-generation opioid hybrids.     

Adsorption properties of hydrazine on pristine and Si-doped Al12N12 nano-cage

The interaction of hydrazine (N₂H₄) molecule with pristine and Si-doped aluminum nitride (Al₁₂N₁₂) nano-cage was investigated using the density functional theory calculations. The adsorption energy of N₂H₄ on pristine Al₁₂N₁₂ in different configurations was about –1.67 and –1.64 eV with slight changes in its electronic structure. The results showed that the pristine nano-cage can be used as a chemical adsorbent for toxic hydrazine in nature. Compared with very low sensitivity between N₂H₄ and Al₁₂N₁₂ nano-cage, N₂H₄ molecule exhibits high sensitivity toward Si-doped Al₁₂N₁₂ nano-cage so that the energy gap of the Si-doped Al₁₂N₁₂ nano-cage is changed by about 31.86% and 37.61% for different configurations in the Si_Al model and by about 26.10% in the Si_N model after the adsorption process. On the other hand, in comparison with the Si_Al model, the adsorption energy of N₂H₄ on the Si_N model is less than that on the Si_Al model to hinder the recovery of the nano-cage. As a result, the Si_N Al₁₂N₁₁ is anticipated to be a potential novel sensor for detecting the presence of N₂H₄ molecule.