Radiation synthesis of a water-soluble temperature sensitive polymer, activated copolymer and applications in immobilization of proteins

In this work the radiation polymerization of N-isopropylacrylamide (NIPAAM) in aqueous solutions has been carried out and a water-soluble, temperature sensitive polymer and copolymer were obtained by using γ-rays from Co-60 source at room temperature. We have gained the optimum dose and dose—rate of radiation synthesis of linear polyNIPAAM through determining conversion yield and viscosity. In order to immobilize protein (BSA) and enzyme (HRP) into this water-soluble polymer, we prepared an activated copolymer, poly ( N-isopropylacrylamide-co-N-acryloxysuccinimide). The BSA and HRP has been immobilized onto the activated copolymer. The BSA (HRP) / copolymer conjugates still kept the original thermally sensitive properties of the linear polyNIPAAM. The conjugation yield of BSA to the activated copolymer decreased with increasing of dose. The thermal stability of the immobilized HRP was stable at 0 °C for a long time and has, at least, 4 days stability at room temperature. Immobilized HRP activity was lowered when the temperature was raised above its LCST. This phenomenon was reversible and the immobilized HRP regained activity below its LCST. The optimum pH of the immobilized HRP shifted from ca.5 upward to ca.7.     

酪氨酸为底物的过氧化物酶催化荧光反应

G.G.Guilbault等人曾对过氧化物酶催化H_2O_2氧化高香草酸(HVA)的反应进行过较详尽的研究。利用这个反应可以对有关的氧化还原酶、辅酶、有机底物、无机离子和微量H_2O_2进行分析检测。但是,以高香草酸为底物,价格昂贵,作为通用检测方法不够经济。Guilbault认为酪氨酸有类似的反应,且价格便宜,但未进行详细研究。我们在此基础上,提出     

萝卜雄性不育系花药发育的细胞形态学研究

选用５种萝卜雄性不育系为材料，以相应保持系作对照，进行细胞形态学研究．结果表明，萝卜雄性不育系小孢子败育有两种方式；１．４７５Ａ花药发育受阻于孢原细胞分化期之前，不产生孢原细胞，也不分化形成花粉囊，接近开花期时花药已畸形．２．２６２Ａ、北京白Ａ、春红Ａ、１３４Ａ花药发育受阻于单核花粉期．绒毡层细胞具多种异常变化：①径向异常肥大、高度液泡化并侵入药室；②细胞壁解体，细胞内含物融合形成周原质团；③以上两种异常活动同时具有．随着绒毡层细胞退化解体，小抱子核质解体导致败育，药室瘪缩变形，只留下少数染色很深的细胞残留物质．不育系的维管组织有韧皮部和木质部的分化，但不及保持系发达．     

Gamma radiation induced synthesis of gold nanoparticles in aqueous polyvinyl pyrrolidone solution and its application for hydrogen peroxide estimation

Gold nanoparticles (Au nps) have been synthesized in aqueous solution of polyvinyl pyrrolidone (PVP) by gamma radiolysis from HAuCl₄·3H₂O precursor and in presence of small concentrations of Ag⁺, 2-propanol and acetone. The effect of different experimental parameters, such as concentration of reactant, molecular weight of PVP on nanoparticle formation was studied. TEM image confirmed that spherical Au nps were formed when PVP of molecular weight 360,000 Da was used as capping agent. H₂O₂ is a reactant in the enzyme catalyzed reaction of o-phenylene diamine (o-PDA). The reaction product has a weak absorption in the yellow region of the spectrum. When this product interacts with Au nps, it leads to enhancement of the absorption peak. The nanoparticles synthesized by radiation method were used for estimation of H₂O₂. The absorbance value of this peak at λ_max was observed to change with H₂O₂ concentration, which was monitored for estimation of H₂O₂. The response is linear in the range of 2.5×10⁻⁶ mol dm⁻³ to 2×10⁻⁴ mol dm⁻³ and 1×10⁻⁷ mol dm⁻³ to 3×10⁻⁶ mol dm⁻³ H₂O₂ in two separate sets of experimental parameters with detection limit 1×10⁻⁷ mol dm⁻³.     

A new length detection-micro fluidic device using an autocatalytic reaction

A new length detection-micro fluidic device was developed using a sodium sulfite/hydrogen peroxide autocatalytic reaction system as a model reaction, and sub-ppm levels of horse radish peroxidase were determined with this device. Sodium sulfite solution containing bromo thymol blue as an indicator and hydrogen peroxide solution were pumped into a T-shaped mixer with the help of a microliter syringe pump and then mixed. The blue solution had changed to yellow beyond the midpoint of the fine pathway (micro channel). Furthermore, when horse radish peroxidase (PO_x) was pumped, a part of the blue solution in the micro channel (blue band) was shortened. Therefore, it was possible to determine the PO_x concentration by via the length of the blue band. The relationship between the blue band length (y, mm) and the common logarithm of the PO_x concentration (x, M) gave a straight line in the concentration range of 0.05–1 ppm. The equation for the straight line was as follows: y = −3.78 log(x) + 16.4. The correlation coefficient was γ = 0.995, the relative standard deviation was 5.7% (n = 10), and the detection limits of the PO_x concentration was 0.029 ppm. Correspondence: Shukuro Igarashi, Department of Biomolecular Functional Engineering, Faculty of Engineering, Ibaraki University, Nakanarusawa 4-12-1, Hitachi, Ibaraki 316-8511, Japan     

红外光谱法研究花色苷色素的酯化修饰

花色苷是一类广泛存在于植物中的水溶性色素。这类色素不仅色泽鲜艳,色调自然,而且安全性高,具有保健功能。然而,天然的花色苷色素存在稳定性差的缺陷,从而严重阻碍了其在食品工业中的广泛应用。为了改善花色苷色素的稳定性,采用分子修饰的方法,通过丁二酸酐酯化修饰花色苷色素,从而在保证色素色泽的前提下显著提高了花色苷色素的稳定性。由于花色苷的成分复杂,分析其酯化前后结构变化的步骤既繁琐又困难。利用红外光谱技术的宏观指纹特性对萝卜红色素的酯化修饰前后的结构进行分析。结果表明, 花色苷分子结构中糖环上的羟基与丁二酸酐发生酯化反应,形成了相应的酯类化合物,这可能是花色苷色素提高稳定性的根本原因。     

萝卜中重金属元素的测定分析

用原子吸收分光光度法测定了河南豫北地区的三种萝卜中重金属元素。结果显示,该地区萝卜中铅含量较高,镉和汞含量极微。     

顶空固相微萃取气相色谱法测定萝卜中有机氯农药及类似物

建立了顶空固相微萃取气相色谱法测定萝卜中有机氯农药及类似物的分析方法。用水稀释萝卜汁后,用顶空固相微萃取法萃取样品中有机氯农药及类似物,用气相色谱电子捕获检测器进行检测。方法的相关系数r≥0.991,实际样品中被测成分的检出限最大为3.36μg/kg。14种有机氯农药测定结果的相对标准偏差不大于12.8%(n=5);3个浓度水平的加标回收率范围为67.2%~115%。方法可用于测定萝卜中有机氯农药及类似物。     

The Effect of Catch Crops on the 15N Nitrogen Percolation and Leaching During the Early Winter Period

Abstract

Lysimeter experiments with application of ¹⁵N in growth chambers were used to investigate to what extent the growth of oil radish can prevent by temporary biological N conservation the nitrogen percolation and leaching during late autumn and early winter periods. It could be shown that the oil radish plants incorporated 47% of the applied ¹⁵N and thus reduced substantially the ¹⁵N percolation to the deeper soil layers (60–100 cm) and the ¹⁵N leaching losses. Before giving final recommendations, the fate of the ¹⁵N contained in the oil radish must be examined in the late winter and early spring periods, after freezing of the plants.     

Physical features of ultrasound assisted enzymatic degradation of recalcitrant organic pollutants

This work has attempted to provide answer to the interaction of sonolysis and enzymatic treatment on degradation of recalcitrant dyes in a combined treatment. The model system comprises of two dyes, acid red and malachite green as model pollutants, along with horseradish peroxidase as a model enzyme and ultrasound of 20 kHz frequency. A dual approach of coupling experimental results with simulations of cavitation bubble dynamics has been adopted. Utilization of oxidation potential of horseradish peroxidase has been found to be a function of convection level in the medium. Cavitation phenomenon is found to have an adverse effect on enzyme action due to generation of high amplitude shock waves, which denature the enzyme. Degradation of dye at high static pressure increases due to absence of cavitation and high energy interaction (or collisions) between enzyme and dye molecules, which are beneficial towards enzymatic oxidation of the latter. High intensity convection generated by ultrasound also obviates need for an external shielding agent such as PEG that prevents attachment of the phenoxy radicals to enzyme that blocks the active sites of the enzyme.