快速扫描吸附伏安法及其重金属离子超灵敏现场检测应用研究

There is a great demand for sensitive, accurate, simple, rapid and low-cost on-site detection of heavy metal ions. However, existing methods cannot fully satisfy the requirement due to various reasons such as the need of large apparatus and professionals, limited sensitivity, complicated procedure, poor repeatability, long analytical cycle and high cost, etc. In this proposal, functionalized bionanomaterials are designed and synthesized using aptamers for heavy metal ions as specific recognition device and DNA three-dimensional nanostructure as coupling media. Thus, adsorption state of target heavy metal ions can be formed by their immobilization on the surface of the electrode in nanometer scale. Then, fast scan adsorptive voltammetry can be established when fast scan voltammetry is used as excitation source with kV/s～MV/s potential scan rates. Under the given working conditions, peak currents are proportional to potential scan rates, electrochemical signals increase about thousands to millions times, and pmol/L～fmol/L heavy metal ions could be detected. Afterwards, integrated fast scan circuit system is designed based on the principle of on-line potential pre-compensation, which can eliminate the distortion of the ohmic drop and charge current in real time. Based on it, handheld devices can be developed in combination with screen-printed electrode, and nano-bio electrochemical sensing platform can be set up. Hence, ultrasensitive, accurate, simple, rapid, low-cost on-site detection methods for heavy metal ions can be achieved. And, it could be practically applied to biological and environmental samples analysis. Thus, this proposal has important scientific significance, social benefits and application prospects.

重金属离子的灵敏、准确、简单、快速、价廉的现场检测是重大需求，但由于需要大型仪器和专业人员、灵敏度有限、步骤繁多、重现性差、分析周期长、成本高昂等不同原因，现有方法尚难满足。本项目以核酸适配体为特异性识别元件，以DNA三维纳米结构为偶联媒介，设计并合成功能化生物纳米材料，将靶标重金属离子固载于电极表面纳米尺度之内，形成吸附状态，以kV/s～MV/s扫描速度的快速扫描伏安法为激发源，创立快速扫描吸附伏安法。在既定工作条件下，峰电流与扫描速度成正比，电化学信号增强万倍至千万倍，可检测pmol/L～fmol/L级重金属离子。基于在线电位预补偿原理，设计一体化快速扫描电路系统，实时消除欧姆降和充电电流影响，结合丝网印刷电极，开发手持式设备，构建纳米生物电化学传感平台，实现重金属离子的超灵敏、准确、简单、快速、价廉的现场检测，并可实际应用于生物、环境样品分析。具有重要科学意义、社会效益和应用前景。

重金属在大气、水、土壤中的存留、积累和迁移，引起环境污染，危害国民经济建设，威胁人类健康和社会和谐发展。因此，对浓度低至nmol/L级别甚至接近0的重金属离子进行高灵敏、准确、快速的现场检测，非常重要。本项目围绕重金属离子现场检测的重大需求，设计和制备功能化生物纳米材料，构建重金属离子在电极表面的特殊吸附状态，以快速扫描伏安法作为激发，创立快速扫描吸附伏安法，可采用高达1000 V/s的扫描速率，准确、灵敏、快速、简单、价廉地检测pmol/L～fmol/L重金属离子，检测灵敏度提高千倍以上。首次提出在线电位预补偿原理，通过组合一体化快速扫描电路和丝网印刷电极制备出手持式设备，建立了重金属离子超灵敏纳米生物传感现场检测技术平台，可实际应用于生物、食品、环境等实际样品中重金属离子的现场检测，具有潜在的应用价值。另外，快速扫描吸附伏安法与本组独创的法拉第笼式电化学免疫分析相结合，不仅可以检测重金属离子，也可检测蛋白质、DNA，并特别适用于高灵敏检测μm级别的大体积目标物如致病菌、细胞等，这是其他现有电化学技术所难以做到的。值得一提的是，基于快速扫描伏安法对银离子探针的原位氧化还原，构建了一个全新概念的轴模式电子给体-DNA-电子受体界面系统，根据电流随距离衰变规律、电流的加和性、电流与碱基的无关性，探明DNA分子内部电子传递为隧穿机制而非跳跃机制，这对DNA分子电子元件、装置、设备的设计与制造具有重要的科学意义。