Dually cross-linked supramolecular hydrogels for sensor applications

提交的项目涉及基于具有超分子主/客体结构的（水）凝胶的传感器的研究。作为有趣的和相关的分析物，特殊的生物标志物（精胺，亚精胺），掺杂物质（n -甲基己烷胺）和杀菌剂（二苯醚康唑）被鉴定出来。（水）凝胶作为活性物质已被确立多年。在换能器的帮助下，体积变化作为对刺激的反应可以用来产生传感器信号。适当的主/客体（HG）结构的结合提供了对被检测分析物的高选择性。在提出的项目理念中，交联是通过将客体分子包含到宿主分子中形成物理相互作用而产生的。因此，宿主分子形成拓扑空腔。穿透这个空腔并与宿主相互作用的分子被概括为客体分子。这两种物质之间形成的相互作用是纯物理的，不是共价的，因此是可逆的。在具有HG交联的“智能”水凝胶中，可能结合的客体分子的带宽将用于引发凝胶的物质特异性反应。为了实现这一目标，一种能够与宿主相互作用的外来分子将被递送到HG系统（HG1）。与宿主分子空腔的非常特殊的相互作用导致另一HG复合物（HG2）的竞争性形成，导致原始客体从宿主空腔排斥。由于这种交换，交联在水凝胶的膨胀中断裂和产生。除了由于在凝胶中包含溶剂而产生的原始膨胀外，双交联水凝胶的膨胀是由于交联程度的进一步降低而产生的。虽然有几种分子可以作为客体物种，如果它们适合宿主腔，但可能的宿主分子的选择更加有限。在这个项目中特别感兴趣的是环糊精（a- cd和b-CD）以及柱芳烃（P[6]0a和P[6]a）。为了正确检测被分析物，宿主/客体对的结合常数应低于宿主/被分析物（HA）对。另一方面，结合常数不能太小，否则将不会观察到分析物添加的影响。100应该是绑定常数（HA / HG）的适当比率。在微型传感器中，“智能”水凝胶（化学-机械传感器）的膨胀变化最终由传感器信号中的压阻硅压力传感器（机电传感器）引起。

The submitted project deals with the investigation of sensors based on (hydro-)gels having supramolecular host/guest structures incorporated. As interesting and relevant analytes special biomarker (spermine, spermidine), doping substances (N-methyl hexane amine) and fungicides (difenoconazole) were identified. (Hydro-)gels are established as active materials since some years. With the aid of a transducer the volume change as reaction to a stimulus can be utilized to generate a sensor signal. The incorporation of suitable host/guest (HG) structures offer to achieve a high selectivity regarding the examined analyte. In the presented project idea the cross-linking yields from the formation of physical interactions by inclusion of the guest molecule into the host molecule. Hereby, the host molecule forms a topological cavity. Molecules that penetrate this cavity and interact with the host are summarized as guest molecules. The kind of interaction being formed between the two species is purely physical and not covalent and hence, reversible. In “intelligent” hydrogels with HG cross-linking the band width of possible bindable guest molecules will be used to initiate a substance specific reaction of the gel. To achieve this a foreign molecule that is also able to interact with the host will be delivered to the HG system (HG1). The very particular interaction with the cavity of the host molecule lead to a competing formation of another HG complex (HG2) resulting in a repulsion of the original guest from the host cavity. Due to this exchange the cross-link breaks and yields in a swelling of the hydrogel in an (aqueous) environment. In addition to the primary swelling due to inclusion of solvent in the gel dually cross-linked hydrogels swells by additional decrease of the degree of cross-linking. While several molecules can act as guest species if they fit into the host cavity the choice of possible host molecules is more limited. Of particular interest within this project are cyclodextrins (a-CD and b-CD) as well as the pillar arenes (P[5]a and P[6]a). For a proper detection of the analyte the host/guest pair shall have a lower binding constant than the host/analyte (HA) pair. On the other side the binding constant must not be too small since then no effect with analyte addition will be observed. 100 is expected to be a proper ratio of the binding constants (HA / HG). In a micro sensor the swelling change of an “intelligent” hydrogel (chemo-mechanical transducer) will finally result by a piezo-resistive Si pressure sensor (mechano-electric transducer) in a sensor signal.