含氮杂冠醚双亲聚合物纳米球的制备及性能

设计、合成了含氮杂冠醚和腺嘌呤的双亲聚合物,聚[N,N-二乙氧基-1,10-二氮杂-18冠-6-5-甲基-腺嘌呤-异酞酸酯](PCASE).SEM观测到在水溶液中该聚合物与5-氟尿嘧啶(5-flu)小分子识别后自发聚集成直径约140～210nm的纳米球,用动态光散射测得水溶液中PCASE/5-flu纳米球的粒径主要集中在120～230nm范围内,FTIR研究了PCASE/5-flu纳米球内聚合物PCASE中腺嘌呤与底物5-氟尿嘧啶的分子识别,结果表明,识别后5-氟尿嘧啶环上C(2)=O伸缩振动峰从1724cm-1位移至1718cm-1,且聚合物中腺嘌呤NH2峰3324cm-1消失,出现了一个新的NH2峰3432cm-1,说明5-氟尿嘧啶环上C(2)=O与聚合物PCASE中腺嘌呤上NH2间形成了氢键.变温红外谱显示,识别后的羰基峰1718cm-1随温度的升高逐渐向高波数回移,并最终稳定在5-氟尿嘧啶环上C(2)=O识别前的1724cm-1处,且识别后产生的新NH2峰3432cm-1随温度的升高逐渐减弱至消失,表明所形成的氢键断裂.     

含核酸碱基的双亲聚合物纳米球的制备及性能

设计并合成了含有核酸碱基腺嘌呤的双亲聚合物, 聚[聚乙二醇600-5-氧-(6-腺嘌呤代己烷基)-异酞酸酯](PPEAHI), 研究了其在水溶液中的自组织行为, SEM观测了该聚合物在水溶液中的聚集形态, 表明PPEAHI在水溶液中自组织成纳米球. 将纳米球水溶液冻干后, 用FTIR研究了PPEAHI聚合物上的腺嘌呤与底物胸腺嘧啶间的相互作用, 结果表明受体与底物的互补基团间形成了氢键, 发生了分子识别, 并用变温红外光谱进一步证实了氢键的形成.     

含冠醚双亲共聚物纳米聚集体的制备及性能

模拟DNA化学结构,设计并合成了双亲共聚物聚（2,2'-（1,10-二氮杂-[18]冠-6-1,10-二基）二乙基5-（（腺嘌呤-9-基）甲基）间苯二甲酸酯）（PDCAI）,利用扫描电镜（SEM）观测了其在水溶液中的自组织形态,采用红外光谱法（FT-IR）研究了其与底物胸腺嘧啶（thymine）的氢键识别,并以变温红外进一步证实和考察了氢键的形成及断裂. 同时,尝试了利用K⁺对PDCAI的自组织形态和氢键识别进行了调控,结果表明：在水溶液中PDCAI自发聚集成条带状聚集体,利用K⁺调控可使其聚集形态转变为棒状、纳米管状或螺旋棒状;在水溶液中底物thymine的C₂=O与PDCAI进行了氢键识别,而通过K⁺调控,氢键识别基变为thymine的C₄=O,说明PDCAI聚集形态的转变导致thymine在与其识别过程中进行识别构象的重组织. PDCAI的研制对研究揭示聚合物自发形成螺旋的分子特征、制备螺旋型聚合物、研制新型药物载体及功能调控具有参考意义.     

取代基对腺嘌呤与胸腺嘧啶氢键复合物体系结合能的影响

优化得到了17个取代胸腺嘧啶与腺嘌呤形成的氢键复合物的结构, 并计算了这些复合物的结合能, 探讨了胸腺嘧啶上不同取代基对结合能的影响. 结果表明, CF₃取代的胸腺嘧啶与腺嘌呤间的结合能大于胸腺嘧啶与腺嘌呤间的结合能, 这可能是屈氟尿苷具有阻止病毒及肿瘤扩散功能的原因所在. SO₃H, CN和NO₂取代的胸腺嘧啶与腺嘌呤间具有更大的结合能, 表明这3个基团取代的胸腺嘧啶也可能具有潜在的抗肿瘤作用. 分子中原子理论与自然键轨道分析表明, 在所有体系中, 氢键N—H…N最强, N—H…O=C次之, C—H…O=C最弱, 轨道作用在氢键作用中占有重要地位.     

取代基对腺嘌呤与胸腺嘧啶氢键复合物体系结合能的影响简

优化得到了17个取代胸腺嘧啶与腺嘌呤形成的氢键复合物的结构,并计算了这些复合物的结合能,探讨了胸腺嘧啶上不同取代基对结合能的影响. 结果表明,CF3取代的胸腺嘧啶与腺嘌呤间的结合能大于胸腺嘧啶与腺嘌呤间的结合能,这可能是屈氟尿苷具有阻止病毒及肿瘤扩散功能的原因所在. SO3H,CN和NO2取代的胸腺嘧啶与腺嘌呤间具有更大的结合能,表明这3个基团取代的胸腺嘧啶也可能具有潜在的抗肿瘤作用. 分子中原子理论与自然键轨道分析表明,在所有体系中,氢键N—H…N最强,N—H…O=C次之,C—H…O=C最弱,轨道作用在氢键作用中占有重要地位.     

二乙二醇二甲基丙烯酸酯交联的胸腺嘧啶分子印迹聚合物纤维素支撑膜对核酸碱基分子选择性研究

使用光度分析法探讨了功能单体9-乙烯腺嘌呤和模板分子胸腺嘧啶在甲醇中的结合作用。在此基础上，以二乙二醇二甲基丙烯酸酯为交联剂，纤维素膜为支持体，制备了分子印迹聚合物膜。通过扫描电镜观察并比较了分子印迹聚合物膜、非分子印迹聚合物膜和纤维素载体膜通道的差异，以胸腺嘧啶、尿嘧啶、胞嘧啶、鸟嘌呤和腺嘌呤为底物，评价了印迹聚合物膜的渗透选择性。结果表明分子印迹膜对模板分子胸腺嘧啶及结构类似物尿嘧啶呈现高的选择性，与用乙二醇二甲基丙烯酸酯为交联剂制备的分子印迹膜比较，也呈现高的扩散速率和选择性，因此该膜对生物样品DNA完全水解产物胸腺嘧啶和RNA水解产物尿嘧啶的识别展现了良好的应用前景。     

超细纳米Pd粒子与聚乙烯吡咯烷酮的相互作用

在微量聚乙烯吡咯烷酮(PVP)存在下, 利用超声还原氯化钯水溶液, 制备出超细纳米Pd颗粒, 用高分辨透射电镜、红外光谱、紫外-可见光谱和X射线光电子能谱等技术对其表面形貌及结构进行了表征. 结果表明, 纳米Pd粒子的粒径均一, 大约为3 nm. 纳米Pd/PVP复合粉末的羰基红外吸收峰比PVP的羰基吸收峰红移9 cm^-1; 且当超声反应50 min时, PVP紫外吸收波峰蓝移16 nm, 表明了纳米Pd与PVP之间存在一定的相互作用力. XPS结果证明, 纳米Pd与PVP的羰基基团通过配位作用使超细纳米Pd粒子得以稳定分散存在.     

Cu2+对腺嘧啶-胸腺嘧啶碱基对阴离子质子转移的影响

采用B3LYP/DZP++方法研究了腺嘌呤-胸腺嘧啶(A-T)碱基对阴离子(AT)-的单质子转移机理以及金属离子Cu2+对(AT)-碱基对质子转移的影响.(AT)-碱基对的单质子转移路径是由胸腺嘧啶N25位上的质子H26沿分子间的氢键N25-H26…N10转移到腺嘌呤的N10位.金属Cu2+可通过络合作用分别吸附在(AT)-碱基对O24、O28、N4、N13上,从而影响(AT)-碱基对中质子转移过程.Cu2+络合作用在胸腺嘧啶(T)的O24、O28上时,发生了从胸腺嘧啶到腺嘌呤方向上的单质子转移反应;而作用在腺嘌呤(A)的N4、N13上时,得到了双质子转移的稳定产物.     

含腺嘌呤双亲化合物的合成与膜内的分子识别

设计并合成了含腺嘌呤碱基的双亲化合物N⁶-十四酰基-9-[8-(1-三甲胺基)辛基]溴化腺嘌呤;用目标化合物和卵磷脂制备混合脂质体受体.分别研究了受体与抗癌药物氟脲嘧啶底物在混合脂质体亲脂区通过互补氢键进行的分子识别.研究结果表明,底物氟脲嘧啶在263 nm处的吸收峰随时间的延长而逐渐减弱,这种减色作用归因于脂质体内的腺嘌呤与氟脲嘧啶在脂质体内的亲脂区形成的氢键.     

Fe掺杂CuS纳米颗粒的合成及其在光热/化学动力学联合治疗中的应用

以乙酰丙酮铜和硫粉为铜源和硫源,在油酸(OA)-油胺(OM)-十八烯(ODE)体系中合成了近红外吸收的硫化铜(CuS)纳米颗粒,并通过改变硫元素活化状态的方式调节其吸收峰到适合光热治疗的1 064 nm附近。通过阳离子交换法进一步制备了Fe、Mn等元素掺杂的CuS纳米颗粒,并保持其吸收峰位置几乎不变。使用微乳法进行聚乙二醇(PEG)化修饰后,这些纳米颗粒在水溶液中表现出良好的分散性和稳定性。分别测试了CuS纳米颗粒在Fe³⁺掺杂前后的光热性能及羟基自由基(·OH)生成能力。结果表明,PEG修饰后Fe³⁺掺杂的CuS纳米颗粒(CuS∶Fe-PEG)在1 064 nm处的质量消光系数为37.5 L·g^-1·cm^-1,光热转换效率可达43.7%。虽然光热性能略低于未掺杂的CuS-PEG,但其·OH生成能力有大幅提升。细胞实验也表明,在弱酸性条件下,CuS∶Fe-PEG具有更好的肿瘤细胞抑制能力,在1 064 nm激光照射下能够有效杀死肿瘤细胞,可用于光热/化学动力学联合治疗。     

Molecular Recognition Based on Hydrogen-bonding in the Coliposomes of Phosphatidylcholine and Amphiphiles Using Nucleobases

IntroductionMolecular recognition is an essential phenomenonin living systems, as observed in the formation of com-plementary hydrogen bonds in DNA[1]. It is interestingto know whether more primitive structures containingthe same bases as thatof DNAor RNA…     

A “plug and play” polymer through biocomplementary hydrogen bonding

This article describes a DNA‐like polymer that exhibits the ability to self‐assemble through hydrogen bonding. We synthesized poly[1‐(4‐vinylbenzyl)thymine] (PVBT) and 9‐hexadecyladenine (A‐C16) through an atom transfer radical polymerization (ATRP) and alkylation, respectively. Biocomplementary PVBT/A‐C16 hierarchical supramolecular complexes formed in dilute DMSO solution through nucleobase recognition, that is, hydrogen bonding interactions between the thymine (T) groups of PVBT and the adenine (A) group of A‐C16; evidence for this molecular recognition was also gained from dynamic light scattering studies. ¹H NMR titration studies in CDCl₃ showed that T–A complexes formed rapidly on the NMR time scale with high association constants (up to 534 M^?1). Moreover, FTIR spectroscopic, differential scanning calorimetry, wide‐angle X‐ray diffraction, and small‐angle X‐ray scattering analyses provided further details into the nature of the self‐assembly of these systems. In the bulk state, these complexes self‐assemble into well‐ordered lamellar structures; the changing d‐spacing distance (ranging from 4.98 to 2.32 nm) at different A‐C16 loadings reveals that the molecular structures of the PVBT/A‐C16 complexes are readily tailored. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6416–6424, 2008     

Self-assembly and molecular recognition of adenine- and thymine-functionalized nucleolipids in the mixed monolayers and thymine-functionalized nucleolipids on aqueous melamine at the air-water interface

Self-assembly and molecular recognition of the monolayers composed of an equimolar mixture of adenine- and thymine-functionalized nucleolipids at the air-water interface have been investigated in detail using surface pressure-molecular area isotherms and in situ infrared reflection absorption spectroscopy (IRRAS). Prior to molecular recognition, the adenine moieties in the monolayer were almost oriented on an end-on mode through π-stacking and hydrogen bonding interactions, and the C-C-C planes of the alkyl chains were preferentially oriented perpendicular to the water surface, while the thymine moieties in the monolayer were involved in hydrogen bonding almost with a flat-on orientation. On aqueous subphases containing complementary bases, no significant molecular recognition was observed for the monolayers of individual nucleolipids. In the monolayer of equimolar mixture, molecular recognition occurred between the adenine and thymine moieties through hydrogen bonding probably with the development of cyclic structures of adenine-thymine-adenine-thymine quartets. Although molecular recognition between the monolayer of thymine-functionalized nucleolipids and aqueous melamine took place through triple hydrogen bonds, no melamine binding to the monolayer of equimolar mixture was observed, which reflects the formation of the quartets in the mixed monolayers at the air-water interface. FTIR and small-angle X-ray diffraction (XRD) results of the corresponding Langmuir-Blodgett films support the hydrogen bonding recognition and molecular orientation.     

Interaction of adenine and thymine with aqueous sugar solutions

The solubility of the nucleic acid bases, adenine and thymine, in aqueous erythritol, xylose, glucose, and sucrose solutions has been studied. The solubility of adenine increases linearly with glucose and sucrose concentration, whereas with the other reagents a nonlinear increase is observed. Below 1.5M reagent concentration, the solubility of adenine increases in the order erythritol < robose, xylose < glucose < sucrose. The solubility of thymine in these solutions, on the other hand, decreases, increases, or does not change depending upon the reagent. The effect of temperature on the solubility of adenine and thymine in sugar solution indicates that the transfer of these molecules from water to sugar solution is exothermic.Presented in part at the VIIth All-India Symposium in Biophysics held at Visva Bharati University during October 1976.     

Biocomplementary interaction behavior in DNA‐like and RNA‐like polymers

A series of nucleobased polymers and copolymers were synthesized through atom transfer radical polymerization (ATRP). Biocomplementary DNA‐ and RNA‐like supramolecular complexes are formed in dilute DMSO solution through nucleobase recognition. ¹H NMR titration studies of these complexes in CDCl₃ indicated that thymine‐adenine (T‐A) and uracil‐adenine (U‐A) complexes form rapidly on the NMR time scale with high association constants (up to 534 and 671 M^–1, respectively) and result in significant T_g increase. WAXD and differential scanning calorimetry analyzes in the bulk state indicate the presence of highly physical cross‐linked structures and provide further details into the nature of the self‐assembly of these systems. Furthermore, this study is of discussion on the difference in the hydrogen bond strength between T‐A and U‐A base pairs within polymer systems, indicating that the strength of hydrogen bonds in RNA U‐A pairs is stronger than that in DNA T‐A base pairs. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6388–6395, 2009     

Functional monomers and polymers 159 synthesis and photochemical reactions of polymers containing thymine photodimer units in the main chain

Polyamides containing thymine photodimer units in the main chain were synthesized, and their photolysis by ultraviolet irradiation below 260 nm were studied in film state. Photodimers of thymine derivatives were obtained by photochemical reaction of the carboxylic acid derivatives of thymine in aqueous solution irradiated above 270 nm. An attempt was made to resolve the isomers of the photodimers, and the two kinds of cis isomers [cis–syn(head to head), and cis–anti(head to tail)] were isolated successfully. The polyamides were prepared by condensation of the photodimers with diamine using an activated ester method. The photodissociation of the thymine photodimer in the polymer main chain caused the breakage of the polymer chains, leading to the production of oligomers and dimer compounds containing thymine bases at the ends of the molecule. The dissociation rate of the polymer did not depend on the kind of the thymine photodimer which was in the main chain of the polymer.     

纳米银与基体P(AMPS-MMA)的相互作用研究

在无引发剂和还原剂的条件下超声辐射双原位合成出纳米银/2-丙烯酰氨基-2-甲基丙磺酸与甲基丙烯酸甲酯共聚物[P(AMPS-MMA)]复合物.TEM表明,纳米银粒子的粒径5~15nm,均匀地分散在聚合物基体中;UV-Vis表明,超声时间影响纳米银的粒径大小及粒径分布;FT-IR、UV-Vis和荧光光谱表明纳米银与基体P(AMPS-MMA)之间存在一定的化学作用力;XPS证明了纳米银与基体P(AMPS-MMA)的作用力为纳米银与聚合物中酯基氧原子之间通过配位作用形成的化学作用力.     

Effect of interfacial molecular recognition of non-surface-active species on the main characteristics of monolayers

Recent progress in studies of the main characteristics of supramolecular assemblies formed by interfacial molecular recognition between an amphiphilic monolayer and a non-surface-active species, which is dissolved in the aqueous subphase, by complementary hydrogen bonding and/or electrostatic interaction at the air-water interface is reviewed. Systems consisting of an amphiphilic melamine-type monolayer and an pyrimidine derivative dissolved in the aqueous subphase are representative model systems for molecular recognition on the basis of complementary hydrogen bonding. Most of the studies have been performed with 2,4-di(n-undecylamino)-6-amino-1,3,5-triazine (2C11H23-melamine) monolayers as host component and thymine, uracil or barbituric acid as dissolved non-surface-active pyrimidine derivatives. The combination of surface pressure studies with Brewster angle microscopy (BAM) imaging and Grazing incidence X-ray diffraction (GIXD) measurements is optimal for the characterization of the change in structure and phase behavior at the interfacial recognition process. The molecular recognition of all pyrimidine derivatives dissolved in the aqueous subphase changes drastically and in a specific way the characteristic features (pi-A isotherms, morphology of the condensed phase domains) of the 2C11H23-melamine monolayer. The small condensed phase domains of the pure 2C11H23-melamine monolayer are compact without an inner texture. The monolayers of the supramolecular 2C11H23-melamine entities with thymine or uracil form specifically well-shaped condensed phase domains with an inner alkyl chain texture essentially oriented parallel to the periphery. The completely different morphology of the 2C11H23-melamine-barbituric acid monolayers is characterized by the formation of large homogeneous areas of condensed phase that transfer at smaller areas per molecule to a homogeneous condensed monolayer. The striking differences in the main characteristics between the supramolecular entities are related to their different chemical structures: complementary hydrogen bonding of two thymine or uracil molecules by one 2C11H23-melamine molecule and a linearly extended hydrogen bonding network between 2C11H23-melamine and barbituric acid. The high values of hydrogen bonding energy obtained by quantum chemical calculations on the basis of the semi-empirical PM3 method state the high stability of the supramolecular entities. The GIXD results reveal that the formation of hydrogen-bond based superstructures between the polar head groups of the amphiphilic 2C11H23-melamine monolayer and the non-surface-active pyrimidine derivatives gives rise only to quantitative changes in the two-dimensional lattice structure of the alkyl chains. The alternative possibility to construct interfacial molecular recognition systems on the basis of acid-base interaction is demonstrated by the experimental results obtained by molecular recognition of the heptadecyl-benzamidinium chloride monolayers with dissolved non-surface-active phenylacetate ions. The formation of supramolecular assemblies causes also drastical changes of the surface features in these systems. Here, the development of a substructure in the condensed phase domains consisting of long filigree strings and the favoured formation of bilayers overgrowing the strings indicates a linearly extended amidinium-carboxylate interfacial structure of the base and acid component in alternating sequence.