抗癌药物柔红霉素的光谱电化学研究

采用现场光谱电化学技术,结合循环伏安和红外光谱等手段,研究了柔红霉素的电极过程,并提出了可能的还原机理.结果表明,柔红霉素的还原途径与其浓度存在一定的联系:稀溶液的还原经历一ECE过程--得到两个电子还原为柔红霉氢醌后,发生化学反应脱去7位上的糖基侧链,得到的7-去氧柔红霉醌继续被还原,生成的自由基中间体可发生歧化反应或通过分子间缔合而稳定;当溶液浓度较大时,柔红霉素分子在得到一电子生成半醌自由基中间体后,以其双分子缔合物的形式稳定存在.     

阿霉素的光谱电化学研究

利用循环伏安、紫外可见光谱电化学、荧光光谱电化学、圆二色光谱电化学等方法研究了阿霉素(ADM)在石墨电极上的电化学行为.结果发现,阿霉素在+0.2～+0.7V和-0.2～-0.7V范围内分别出现一对氧化还原峰.正电位下,蒽环上的酚羟基发生单电子氧化,并伴随后续化学反应.负电位范围内,阿霉素经历ECE电极反应过程,即蒽醌经单电子还原生成半醌自由基,半醌可发生不可逆的化学反应,脱去配氧糖基,转变为7-去氧柔毛霉醌(7-deoxyadriamycinone),后者在更负的电位下形成一对可逆的新的氧化还原峰.     

ESR方法检测竹红菌素的半醌负离子自由基

从顺磁共振波谱检测到通过竹红菌素的光诱导还原和基态竹红菌素跟脂肪胺的电子转移两条途径所得到的自由基信号, 并由电化学还原得到同一自由基, 确认它为半醌负离子自由基。竹红菌素溶液中加入芳香胺观察不到ESR信号。它的3,10位上与醌基相邻近的羟基离解以后, 无论在基态还是在激发态都观察不到ESR信号。此外, 还从吸收光谱观察到半醌负离子自由基吸收以及竹红菌素跟脂肪胺之间的相互作用。     

ESR方法检测竹红菌素的半醌负离子自由基

从顺磁共振波谱检测到通过竹红菌素的光诱导还原和基态竹红菌素跟脂肪胺的电子转移两条途径所得到的自由基信号,并由电化学还原得到同一自由基,确认它为半醌负离子自由基。竹红菌素溶液中加入芳香胺观察不到ESR信号。它的3,10位上与醌基相邻近的羟基离解以后,无论在基态还是在激发态都观察不到ESR信号。此外,还从吸收光谱观察到半醌负离子自由基吸收以及竹红菌素跟脂肪胺之间的相互作用。     

天然产物色胺酮及其衍生物合成的研究进展

综述了色胺酮及其衍生物的合成方法。大部分方法都是以吲哚醌和吲哚酮为起始原料,其中吲哚醌和靛红酸酐反应合成色胺酮及其衍生物的方法较为理想。由于色胺酮类化合物具有很好的抗癌、杀菌和消炎等生物活性,新的简捷、低成本合成方法的开发仍然是必要的。     

某些还原性生物分子对竹红菌甲素敏化产生^1O~2的抑制作用

存在还原性的生物分子如甲硫氨酸、尿酸和 还原性谷胱甘肽时,竹红菌甲素经受单电子还原形成甲素的半醌自由基、在去氧溶液中观察到了 甲素半醌负离子自由基的ESR信号.在充氧的溶液中检测到了超氧负离子自由基.还原剂的存在降低了单重态氧的生成并引起超氧负离子自由基的生成.     

某些还原性生物分子对竹红菌甲素敏化产生^1O~2的抑制作用

存在还原性的生物分手如甲硫氨酸、尿酸和还原性谷胱甘肽时,竹红菌甲素经受单电子还原形成甲素的半醌自由基、在去氧溶液中观察到了甲素半醌负离子自由基的ESR信号.在充氧的溶液中检测到了超氧负离子自由基.还原剂的存在降低了单重态氧的生成并引起了超氧负离子自由基的生成.     

抗癌药物马蔺子素伏安行为及极谱催化波研究

采用线性扫描示波极谱法、循环伏安法、紫外光谱法及恒电位电解法等方法分别在水和N,N-二甲基甲酰胺(DMF)两种介质中研究了抗癌药物马蔺子素的伏安行为及其极谱平行催化波产生机理.结果表明,在Na₂B₄O₇-KH₂PO₄(pH=7.7)缓冲溶液中,马蔺子素的醌基首先发生1e-和1H+还原,产生中间体半醌自由基,该自由基再以同样方式进一步还原生成相应氢醌,并伴随有化学反应;在DMF-四乙基溴化铵(TEAB)质子惰性介质中,马蔺子素连续两步单电子还原生成相应氢醌阴离子,无中间体半醌自由基的化学反应发生.上述过程产生马蔺子素可逆还原波.当氧化剂K₂S₂O₈存在时,马蔺子素醌基还原中间体半醌自由基被氧化,使原醌基再生,产生了马蔺子素的极谱平行催化波.测得S₂O₈^2-氧化马蔺子素半醌自由基的表观一级速率常数k_f=3.3×10⁶L·mol^-1·s^-1.     

微环境影响下的乙酰基香豆素与吲哚的固相光反应

本文研究了乙酰基香豆素及其衍生物与吲哚的混晶在微环境影响下的固相光反应，并用固体紫外光谱、固体荧光光谱和X-射线粉末衍射技术考察了混晶的特征。实验结果表明，3-乙酰基香豆素及其7-乙酰氧基、7-苯甲酰氧基、5,6-苯并和6-溴衍生物与吲哚的固相光反应分别得到1:2缩合产物1～5，而6-硝基衍生物与吲哚的固相光反应却得到开环脱羰加成产物6。通过IR、MS、^1H NMR和元素分析结果确定了这六个新产物的结构。固体光谱的测试结果表明，取代乙酰基香豆素与吲哚间混晶的形成，分子间存在相互作用，使分子所处的微环境条件发生了变化。     

脯氨酸和羟脯氨酸层析斑点的显色定量测定法

脯氨酸及羟脯氨酸层析斑点的显色定量至今无理想的方法,通常是用茚三酮或吲哚醌溶液显色,前者呈黄色,敏度低,很少用于定量分析,而后者虽显特异蓝色。但极不稳定,也难以作定量分析。Jepson等曾对羟脯氨酸先用茚三酮或吲哚醌溶液显色,再用Ehrlich试剂显色,呈特异紫色,但未见定量分析报导,Hrabetova等,曾用吲哚醌醋酸锌异丙醇液显色测定脯氨酸;Heathcote等用镉—茚三酮液显色测定各氨基酸层析斑点,此二种氨基酸斑点呈黄色,须在350毫微米波长比色定量,且稳定性欠佳。     

21世纪电化学的若干发展趋势

本文简要回顾 2 0世纪后五十年电化学在理论、实验技术、新现象发现和应用等领域的重要进展 ,提出了 2 1世纪前期电化学的若干发展趋势 ,强调应重视电化学新体系的研究 ,以迎接 2 1世纪能源、材料、生命、信息和环境对电化学技术的挑战     

The review of advances in interfacial electrochemistry in Estonia: electrochemical double layer and adsorption studies for the development of electrochemical devices

The electrochemistry nowadays has many faces and challenges. Although the focus has shifted from fundamental electrochemistry to applied electrochemistry, one needs to acknowledge that it is impossible to develop and design novel green energy transition devices without a comprehensive understanding of the electrochemical processes at the electrode and electrolyte interface that define the performance mechanisms. The review gives an overview of the systematic research in the field of electrochemistry in Estonia which reflects on the excellent collaboration between fundamental and applied electrochemistry.

     

凝并和成核机理下颗粒尺度分布的Monte Carlo求解

颗粒的凝并和成核现象影响其尺度分布,现有的MonteCarlo方法描述颗粒尺度分布的时间演变过程存在若干困难.提出了一种新的多重MonteCarlo(MMC)算法,基于时间驱动,利用加权的虚拟颗粒的思想,在模拟过程中保持虚拟颗粒总数不变和计算区域体积不变.利用该算法对“常凝并核,一阶成核”的情况下颗粒尺度分布的时间演变过程进行了数值求解,所得结果与数值解相符,表明MMC算法具有高且稳定的计算精度.另外,MMC算法由于跟踪比实际颗粒数目少得多的虚拟颗粒而具有较低的计算代价.     

Study on the Interaction of Mitomycin C with ct-DNA by Pd-Porphin Room Temperature Phosphorescence Probe

Study of the interaction of drugs with calf thymus DNA (ct-DNA) in molecular level1-4 is helpful to understand the fundamental aspects of activation of anticancer drugs and provide the valuable information for designing and developing new antitumor agents. Mitomycin C (MMC) is an anticancer drugs being widely used in clinic with high activity and effectiveness for many cancers. DNA has been proved to be the main target molecule of MMC in the body. The activated MMC can hinder the rep…     

Amifostine protection against mitomycin-induced chromosomal breakage in fanconi anaemia lymphocytes

Fanconi anaemia (FA) is a rare genetic chromosomal instability syndrome caused by impairment of DNA repair and reactive oxygen species (ROS) imbalance. This disease is also related to bone marrow failure and cancer. Treatment of these complications with radiation and alkylating agents may enhance chromosomal breakage. We have evaluated the effect of amifostine (AMF) on basal and mitomycin C (MMC)-induced chromosomal breakage in FA blood cells using the micronucleus assay. The basal micronuclei count was higher among FA patients than healthy subjects. Pre-treatment with AMF significantly inhibited micronucleation induced by MMC in healthy subjects (23.4 +/- 4.0 - MMC vs 12.3 2.9 - AMF --> MMC) MN/1000CB, p < 0.01, one way ANOVA) as well as in FA patients (80.0 +/- 5.8 - MMC vs 40.1 +/- 5.8 - AMF --> MMC) MN/1000CB, p < 0.01, ANOVA). Release of ROS by peripheral blood mononuclear cells treated with AMF -> MMC and measured by chemoluminometry showed that AMF-protection was statistically higher among FA patients than in healthy individuals. Based on these results we suggest that AMF prevents chromosomal breakage induced by MMC, probably by its antioxidant effect.     

Synthesis and antitumor activities of mitomycin C (1----3)-beta-D-glucan conjugate.

The conjugate of mitomycin C (MMC) with linear (1----3)-beta-D-glucan from Alcaligenes faecalis var. myxogenes IFO 13140 was synthesized and its antitumor activities investigated. The conjugate (MMC-carboxymethylated linear (1----3)-beta-D-glucan (CMPS)) was obtained by treatment of CMPS with MMC in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. In vitro cytotoxicity of MMC-CMPS against L1210 leukemia cells was similar to that of MMC. In i.p.-i.p. system in vivo against P388 leukemia in mice, the maximum increase of MMC-CMPS conjugate in life span (ILSmax) was higher than that of MMC but the therapeutic index was reduced. However, the antitumor activity of MMC-CMPS conjugate against subcutaneously implanted sarcoma 180 solid tumor in mice by i.p. administration was similar to that of MMC at a dose of 1.5 mg eq MMC/kg/d x 7 and the reduction of the number of leukocytes caused by MMC was suppressed by attaching MMC to CMPS. In addition, on assay using serum of sarcoma 180 solid tumor-bearing mice with injection of MMC-CMPS conjugate, a drastic loss of tumor cells and an increase in polymorphonuclear leukocytes (PMN) were observed. This result suggested that MMC-CMPS conjugate induced tumor-regressing factor similar to CMPS.     

Recent advances in nanocollision electrochemistry

Ensemble averaging measurements obscure the link between the electrochemical performance and the specific properties of an individual because of the interplay of inhomogeneity and heterogeneity. Nanocollision electrochemistry has attracted increasing interest because of its extremely high sensitivity, revealing the intrinsic properties of individual entities that are masked in the traditional ensemble measurements. In this perspective review, we summarized the recent developments in nanocollision-based single entity electrochemistry and photoelectrochemistry, the combined nanocollision electrochemistry with the other complementary techniques, as well as accurate data process. In closing, future challenges, opportunities, and destinations related to nanocollison electrochemistry were discussed.     

Optical-facilitated single-entity electrochemistry

Single-entity electrochemistry focusing on the study of transient electrochemical process at the confined interface, has become a promising field that addresses questions from multi-disciplines such as cellular biology, material chemistry, organic chemistry, etc. It offers the fruitful information hidden in bulk electrochemical measurements. As the optical techniques improve in spatial and temporal resolution, the combination of electrochemistry with optical microspectroscopy provides more comprehensive information of single-entity electrochemistry. Herein, we review recent progress made in optical–electrochemical measurements covering three aspects from the precise localization and temperature measurements of single compartments, to the in-situ tracking of dynamic behaviors of single nanoparticles in electrochemical process, and to the monitoring confinement-controlled electrochemistry at the single molecule/ion level. The review demonstrates how these optical methods are innovatively integrated with single-entity sensing. It also reveals how these optical–electrochemical combinations push single-entity electrochemistry forward.     

金属应变电化学研究进展

从宏观应变电化学现象，到微观层次的局部裂纹环境测量与模拟、裂纹扩展预测模型化、再钝化法确立裂纹扩展速率以及应变电化学过程控制等方面，综述了金属应变电化学的发展历程和主要的研究进展。     

Switching “on and off” faradaic electrochemistry at an otherwise passivated electrode using gold-coated magnetic nanoparticles

Herein we combined the use of self-assembled monolayer (SAM) modified electrodes and gold coated magnetic nanoparticles (Au@MNPs) to modulate faradaic electrochemistry when nanoparticles are absorbed on and removed from, a passivated electrode using an external magnetic field. Substantial faradaic electrochemistry of potassium ferricyanide in solution is first prevented by modifying gold electrodes with 11-mercaptoundecanoic acid to form a passivating SAM. Restoration of the faradaic electrochemistry is then achieved by introducing Au@MNPs which are brought to the surface using an external magnetic field. The faradaic electrochemistry can again be suppressed by removing Au@MNPs from the SAM using another external magnetic field.