【作者】 李峰；

【导师】 陈劲春；

【作者基本信息】 北京化工大学 ， 生物化工， 2007， 硕士

【摘要】 无机结合肽是一类存在于生物体内对相应无机物（金属单质、氧化物、无机盐等）具有特异吸附结合能力的小肽，大多数无机结合肽的长度在7-20AA之间。无机结合肽在生物体内作为无机组织形成的模板和促发剂，对生物组织功能结构的形成有重要意义。Pt结合肽是一类对Pt元素具有特异吸附结合力的具有7个氨基酸残基的多肽，目前发现了4个序列：QSVTSTK、DRTSTWR、TSPGQKQ、SSSHLNK，（为了研究方便我们一次命名为PT1、PT2、PT3、PT4）。实验首先验证了PT1和PT2离开体内温和中性的环境后对铂的作用力。在离体条件下，0.5mg／m1的多肽和1.0mmol／L的Na₂PtCl₆室温PH中性放置24h后，TEM检测发现了直径在1nm左右团聚在一起的呈方形和球形晶体，经EDX分析显示晶体的元素组成中Pt远大于Cl的含量，显然晶体不可能是PtCl₄或PtCl₂晶体，因此晶体为铂单质。运用可见-紫外光谱仪对混合溶液全波长扫描发现，PtCl₆²⁺在258nm处的吸收峰随着时间进行逐渐减弱，24小时后完全消失，说明PtCl₆^<sup>2+已经消耗殆尽。用固定化于PET膜上无机结合肽制备出铂微晶体，SEM检测显示所得微晶体的直径在1-2微米之间，其XPS谱图中出现了结合能值为71.0ev峰(Pt^4f标准值71.1ev)，确认晶体为铂纳晶，由此推断铂结合肽在无细胞状态下能够作为模板仿生合成铂晶体。对反应前后的多肽进行原二色谱扫描后，发现多肽在200nm处的吸收峰逐渐减弱，200hm处一般被认为是无规则卷曲的吸收峰，因此证明多肽在吸附还原铂离子的过程中自身的构象也发生了变化。无机结合肽在跟PtCl₆²⁺作用的过程中，起到了激发剂、还原剂和模板的作用，为了进一步使制备所得的纳米粒子的大小可控，我们在反应体系中添加了3种典型的表面活性剂，PVP（聚乙烯吡咯烷酮）、聚丙烯酸钠和壳聚糖来控制铂晶体结晶的速度，使制备的铂晶体的大小可控。TEM结果证明，三种表面活性剂均能显著的改善纳米粒子的团聚情况，使制备出的纳米粒子的大小均匀。然后对表面活性剂的种类和用量进行讨论，发现三种表面活性剂用量为pt⁴⁺的5倍的时候效果最佳，过少的稳定剂所得纳米粒子容易团聚，而过多的稳定剂则由于稳定剂分子间过多的相互作用使所得纳米粒子沉淀。因此在10倍稳定剂存在下，所得三种结果均不如5倍时理想。基于以上实验结果以及受核-壳结构的启发，对可控大小制备纳米铂粒子的实验进行了改进。事先采用T．Terranish等的方法，用甲醇还原法制备5-6nm的较小的纳米铂颗粒。对反应各阶段的产物检测发现在回流到30min的时候溶液中的PtCl₆²⁺已经消耗完全。然后用还原法制备的Pt晶体作为核，加入到0.5m10.6mol的H₂PtCl₆．6H₂O和新鲜配制的0.5mlPT1溶液中，制备出直径在12nm左右的纳米粒子。继续用12nm的Pt晶体作为核，加入到0.5m10.6mol的H₂PtCl₆．6H₂O和新鲜配制的0.5mlPT1溶液中，制备出了16nm左右的纳米粒子。更多还原

【Abstract】 Inorganic binding peptides, one kind of 7-20AA peptides that are found in virto of some kind of microorganism have the ability of binding to some inorganic compounds,include metal. It serve as template and in process of synthesis of organic invito.Pt binding peptides is a kind of 7 AA peptides that have particular binding ability to platinum.There are four sequeces have been digged out so far: QSVTSTK、DRTSTWR、TSPGQKQ、SSSHLNK,（naming as PT1,PT2,PT3 and PT4 coresspondingly）.In this report the synthesized peptide PT2（DRTSTWR） has been employed as template for preparation of platinum nanoparticles. Platinum crystallites were obtained by the way that PtCl₄ reacted with PT2 immobilized on the surface of protonated PET-N（CH₃） ₂ film. The platinum nanoparticles that ranged from 1nm to 2nm in size were obtained with the free PT2 and PtCl₄ mixed together in solution at room temperature and pH 7 for 24h. Both the crystallites and nanoparticles of platinum were characterized by TEM, XPS and EDX. Based on the data above, that PT2 could be utilized as template for biomimetic synthesis of platinum nanoparticles in vitro was confirmed.Subsequently, in order to prepare shape and size controllable nanoparticles of platinum two stabilizing agents chitosan and sodium polyacrylate with different concentration were added into the reaction solution respectively resulting in the variation of the size and shape of the platinum particles. Specifically, platinum particles that ranged from 12nm to 15．5nm in size and are inclined to array in line were obtained when the molar proportion of chitosan to Pt⁴⁺ was 5/1 in the solution. In the presence of sodium polyacrylate whose amount is 5 times of Pt⁴⁺, more uniformly spherical platinum particles of 7-8nm in size were synthesized.Illumined by core-shell construction, a new and more efficiency route was designed.first,5-6nm nanopaticles were synthsysed following Terranish’s route,methenal deoxidization method.All of PtC16²⁺ have been used up in the beginning 30 minutes tested by UV spectrum. 12nm Pt nanopatícles were prepared by adding 5-6nm Pt crystals into fresh prepared PT2 and PtCl6²⁺ solution mixture and warmed in 68℃for 2 hours. 16nm Pt nanopaticles were prepared by adding 12nm Pt crystals into fresh prepared PT2 and PtCl6²⁺ solution mixture and warmed in 68℃for 2 hours.更多还原