Wu Hsin-Pin, Cheng Tian-Lu, Tseng Wei-Lung
Department of Chemistry, National Sun Yat-sen University, Taiwan, Faculty of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan.
Langmuir. 2007 Jul 3;23(14):7880-5. doi: 10.1021/la700555y. Epub 2007 Jun 12.
For the first time, an aqueous solution, comprising 6-nm phosphate-modified titanium dioxide (P-TiO2) nanoparticles (NPs) and fluorescein, has been used for sensing dopamine (DA), levodopa (L-DOPA), adrenaline, and catechol. The complexes obtained by means of chelation of surface Ti(IV) ions with an enediol group exhibit strong absorption at 428 nm; thus, they can be designed as efficient quenchers for fluorescein. The fluorescence of a fluorescein solution containing 1.4 mM P-TiO2 NPs at pH 8.0 decreases if the solution comprises DA, L-DOPA, adrenaline, and catechol, but not noradrenaline, ascorbic acid, and salicylic acid. We consider that P-TiO2 NPs have a number of advantages over bare TiO2 NPs, such as ease of preparation, high selectivity, and high stability. By measuring fluorescence quenching, the limits of detection at a signal-to-noise ratio of 3 are calculated as 33.5, 81.8, 20.3, and 92.1 nM for DA, L-DOPA, adrenaline, and catechol, respectively. In contrast, UV-vis absorption reveals the relatively poor sensitivity of these compounds. We have validated the applicability of our method by means of analyses of DA in urine samples. High-performance liquid chromatography in combination with an electrochemical cell has been used to further confirm our results. We believe that this approach has great potential for diagnostic purposes.
首次将包含6纳米磷酸改性二氧化钛（P-TiO₂）纳米颗粒（NPs）和荧光素的水溶液用于检测多巴胺（DA）、左旋多巴（L-DOPA）、肾上腺素和儿茶酚。通过表面Ti(IV)离子与烯二醇基团螯合得到的配合物在428纳米处有强烈吸收；因此，它们可被设计为荧光素的高效猝灭剂。如果溶液中含有DA、L-DOPA、肾上腺素和儿茶酚，而不含有去甲肾上腺素、抗坏血酸和水杨酸，则pH值为8.0、含有1.4 mM P-TiO₂ NPs的荧光素溶液的荧光会减弱。我们认为P-TiO₂ NPs比裸露的TiO₂ NPs有许多优点，如易于制备、高选择性和高稳定性。通过测量荧光猝灭，计算出在信噪比为3时，DA、L-DOPA、肾上腺素和儿茶酚的检测限分别为33.5、81.8、20.3和92.1 nM。相比之下，紫外-可见吸收显示这些化合物的灵敏度相对较差。我们通过分析尿液样本中的DA验证了该方法的适用性。高效液相色谱结合电化学池已被用于进一步证实我们的结果。我们相信这种方法在诊断方面有很大潜力。
