Porphyrin assemblies as chemical sensors
Porphyrin assemblies as chemical sensors
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DOI：
10.1016/s0010-8545(99)00106-x
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发表时间：
1999-09-01
影响因子：
20.6
通讯作者：
Lauceri, R
中科院分区：
文献类型：
--
作者：
Purrello, R;Gurrieri, S;Lauceri, R
采用一种简单的“非共价”方法，通过“混合”市售的化学物质，如阳离子或阴离子水溶性卟啉和多肽，获得敏感和特定的pH、DNA和金属离子传感器。例如，在适当的条件下，阴离子中四基（4-磺酰基）卟啉（H2TPPS）与质子化形式的聚赖氨酸之间形成的超分子络合物可以作为ph传感器。事实上，在pH 5.5-12范围内，H2TPPS以单体形式存在，其荧光不依赖于pi- i。然而，在低pH值（小于或等于7）下，质子化的聚赖氨酸促进卟啉结合和自聚集。当pH值高于9-10时，卟啉在溶液中主要以自由单体存在，并具有强烈的荧光发射。因此，H2TPPS荧光强度随pH值的变化呈s型曲线。有趣的是，导致这些聚集体形成的分子识别过程也可以通过使用不同性质和长度的基质以及使用含有具有特定配位几何形状的不同中心金属离子的卟啉来调节。通过这种方式，我们已经能够开发出一整套覆盖大范围ph值的传感器。这些超分子聚集体也可以用作DNA的传感器。事实上，在预先形成的H2TPPS/聚赖氨酸体系（FH小于或等于7）中加入DNA（它是一个多阴离子）会导致结合在多阳离子基质上的卟啉位移，从而增加溶液的荧光强度。因此，由于荧光发射的变化与加入DNA的浓度呈线性关系，我们利用这种超分子体系建立了一种简单快速的溶液中DNA定量测定方法。最后，当阳离子卟啉单分散在负电荷基质（如阴离子聚谷氨酸）表面时，观察到铜（II）和锌（II）在阳离子卟啉中的插入速度显著加快。这种特性使我们能够为这两种金属离子开发一种特殊的荧光传感器，即使在纳摩尔范围内的极低浓度下也能检测到它们的存在。(C) 1999 Elsevier Science S.A.版权所有
A simple "non-covalent' approach was employed to obtain sensitive and specific sensors for pH, DNA and metal ions, by 'mixing' commercially available chemicals such as cationic or anionic water-soluble porphyrins and polypeptides. For example, under the appropriate conditions, the supramolecular complex formed between the anionic meso-tetrakis(4-sulfonatophenyl)porphine (H2TPPS) and the protonated form of poly-lysine can behave as pH-sensor. In fact, H2TPPS in the pH range 5.5-12 exists in a monomeric form, and its fluorescence is not pi-I-dependent. However, at low pH values (less than or equal to 7), the protonated poly-lysine promotes porphyrins binding and self-aggregation. with consequent strong quenching of their fluorescence, while at pH values higher than 9-10, the porphyrins exist in solution essentially as free monomers and are characterized by an intense fluorescence emission. As a consequence, the H2TPPS fluorescence intensity versus pH behavior shows a sigmoidal profile. Interestingly, the molecular recognition processes leading to the formation of these aggregates can be also modulated by using matrices of different nature and length as well as employing porphyrins containing different central metal ions with particular coordination geometries. In such a way we have been able to develop a whole family of sensors covering a wide range of pH. These supramolecular aggregates can also be employed as sensors for DNA. In fact, the addition of DNA (which is a poly-anion) to a preformed H2TPPS/poly-Lysine system (FH less than or equal to 7), causes a displacement of the porphyrin bound to the poly-cationic matrix with consequent increase in the fluorescence intensity of the solution. Therefore, since the variation in fluorescence emission is linearly related to the concentration of DNA added, we have employed such supramolecular system to develop a simple and rapid method for the quantitative determination of DNA in solution. Finally, a remarkable acceleration of the insertion of copper(II) and zinc(II) in cationic porphyrins is observed when these porphyrins are monodispersed on the surface of negatively charged matrices, such as anionic poly-Glutamate. Such peculiarity allowed us to develop a specific fluorescent sensor for both metal ions capable of detecting their presence even at very low concentrations in the nanomolar range. (C) 1999 Elsevier Science S.A. All rights reserved.