反相高效液相色谱法测定3种中成药中的葛根素

 建立了测定小儿清感灵片、步长新脑心通胶囊和感冒清热颗粒 3种中成药中葛根素含量的反相高效液相色谱方法。采用APEXODS色谱柱 ,以醋酸铵缓冲液 (10 0mmol/L ,pH 5 0 ) 甲醇 (体积比为 75∶2 5 )的混合溶液为流动相 ,检测波长为 2 5 0nm ,流速为 0 8mL/min。葛根素在 2mg/L～ 2 0mg/L时其色谱峰面积与质量浓度的线性关系良好 (r =0 9999) ;上述 3种中成药中的葛根素含量分别为 3 48mg/g ,1 0 8mg/ g及 1 5 2mg/ g(蔗糖型 ) ;其加样回收率分别为 99 0 % ,93 4%和 97 5 %。该法简便、快速、专属性强 ,可以作为多种中药制剂中葛根素含量的测定方法。     

SciFinder-guided rational design of fluorescent carbon dots for ratiometric monitoring intracellular pH fluctuations under heat shock

Intracellular pH plays a significant role in various biological processes, including cell proliferation, apoptosis, metabolism, enzyme activity and homeostasis. In this work, a novel design strategy for the preparation of pH responsive carbon dots (CDs-pH) for ratiometric intracellular imaging was reported. By using SciFinder database, fluorescent CDs-pH with the required pK_a value of 6.84 were rationally designed, which is vital important for precise sensing of intracellular pH. As a result, the synthesized CDs-pH demonstrated robust ability to test pH fluctuations within the physiological range of 5.4-7.4. The CDs-pH was further utilized for fluorescent ratiometric imaging of pH in living HeLa cells, effectively avoided the influence of autofluorescence from native cellular species. Moreover, real-time monitoring of intracellular pH fluctuation under heat shock was successfully realized. This SciFinder-guided design strategy is simple and flexible, which has a great potential to be used for the development of other types of CDs for various applications.     

用峰鉴别技术反相高效液相色谱法测定火锅汤料中微量吗啡

本文报道了以峰鉴别技术为定性依据的测定火锅汤料中微量吗啡的反相高效液相色谱法。本法采用改良的Ｓｔａｓ－ｏｔｔｏ法分离提取复杂样品中的微量吗啡。由于采用峰鉴别技术，增加了定性参数，大大提高了定性方法的准确性。本法简便、快速。最低检出浓度为０．０４ｍｇ／Ｌ。在数十例样品分析中，与其它仪器分析结果比照，非常符合。     

Optimization of on-chip elongation for fabricating double-stranded DNA microarrays

The sequence-specific recognitions between DNA and proteins are playing important roles in many biological functions. The double-stranded DNA microarrays (dsDNA microarrays) can be used to study the sequence-specific recognitions between DNAs and proteins in highly parallel way. In this paper, two different elongation processes in forming dsDNA from the immobilized oligonucleotides have been compared in order to optimize the fabrication of dsDNA microarrays: (1) elongation from the hairpins formed by the self-hybridized oligonucleatides spotted on a glass; (2) elongation from the complementary primers hybridized on the spotted oligonucleatides. The results suggested that the dsDNA probes density produced by the hybridized-primer extension was about four times lower than those by the self-hybridized hairpins. Meanwhile, in order to reduce the cost of dsDNA microarrays, we have replaced the Klenow DNA polymerase with Taq DNA polymerase, and optimized the reaction conditions of on-chip elongation. Our experiements showed that the elongation temperature of 50 °C and the Mg²⁺ concentration of 2.5 mM are the optimized conditions in elongation with Taq DNA polymerase. A dsDNA microarray has been successfully constructed with the above method to detect NF-kB protein.     

SINGLE AND BINARY ADSORPTION PERFORMANCE OF SALICYLIC ACID AND 5-SULFOSALICYLIC ACID ONTO HYPERCROSSLINKED POLYMERIC ADSORBENTS

Single and binary adsorption behaviors of salicylic acid and 5-sulfosalicylic acid onto hypercrosslinked polymeric adsorbents, i.e. NDA-101 and NDA-99 were investigated. The Freundlich model can successfully describe all the adsorption isotherms tested, which indicates a favorable and exothermic adsorption process. The adsorption of salicylic acid relies on π-π interaction, while the electrostatic interaction further influences the adsorption of 5-sulfosalicylic acid onto NDA-99. The adsorptive capacity of salicylic acid on NDA-99 decreases but increases on NDA-101 with 5-sulfosalicylic acid as the background component in a binary solute system. The amount of 5-sulfosalicylic acid adsorbed was decreased with the increase in initial concentration of salicylic acid on both adsorbents. The competition for the adsorption sites is considered to be predominant in the solid-to-liquid interaction process. The adsorption selectivity of salicylic acid onto NDA-101 is higher than onto NDA-99 by more than an order of magnitude. Thus, combination technique involving NDA-101 followed by NDA-99 can be effectively applied to separate and recover salicylic acid and 5-sulfosalicylic acid from wastewater.     

Preparation of multisubstituted allenes from allylsilanes

[reaction: see text] A three-step route of converting allylsilanes to functionalized allenes was developed. Thermal decomposition of 1,1-dibromo-2-(silylmethyl)cyclopropanes, which were quantitatively prepared by treatment of allylsilane derivatives with CHBr3/KO(t)Bu, afforded substituted 2-bromo-1,3-butadienes with elimination of bromosilanes. The Pd-catalyzed reaction of the bromodienes with soft nucleophiles gave the allene derivatives. Previously inaccessible tri- and tetrasubstituted allenes can be prepared by this method as well.     

Effect of Pluronic F127 on the pore structure of macrocellular biodegradable polylactide foams

Thermally induced phase separation technique was utilized to fabricate biodegradable poly(l ‐lactic acid) (PLLA) macrocellular foams which were capable of being applied in tissue engineering. The block copolymer Pluronic F127 composed of (polyethyleneoxide)‐(polypropyleneoxide)‐(polyethyleneoxide) [(PEO)‐(PPO)‐(PEO)] was used as a porogen. Water/dioxane mixtures with different volume ratios were used as solvents. The addition of Pluronic F127 could induce an appearance of large pores (50–200 μm) besides small pores (10–20 μm) or a change from a solid–liquid phase separation to a liquid–liquid phase separation. The role of Pluronic F127 depends on the water/dioxane ratios in the PLLA/dioxane/water system. The X‐ray diffraction patterns and porosity measurement results showed that Pluronic F127 was crystallized and existed on the pore wall. The effect of Pluronic F127 on changing pore structure is attributed to the occurrence of the interaction of the lipophilic PPO blocks in Pluronic F127 with PLLA clews, consequently, this results in PLLA aggregation and early phase separation on cooling. Copyright © 2004 John Wiley & Sons, Ltd.     

Microwave-assisted deformylation of N-aryl formamide by KF on basic Al2O3

The formyl group was successfully removed from N-aryl formamide by KF on a solid support of basic Al₂O₃ in 4-20 min with microwave irradiation. The conditions mimic base-catalyzed hydrolysis of formamide and are compatible with carbamates and t-butyl esters, but not methyl, ethyl, and benzyl esters.