目前,利用脂质聚合物膜的味道传感器用于定量评估食品的味道。在这个过程中,识别和量化基本口味至关重要,例如,酸味和甜味,同时确保对无味物质没有反应。例如,抑制对阴离子的反应,就像蔬菜中含有的无味NO3-离子,是必不可少的。然而,尚未进行系统的电化学研究来实现这一目标。在这项研究中,我们制造了三个含有油胺(OAm)的带正电荷的脂质聚合物膜,三辛基甲基氯化铵(TOMACl),或溴化四十二烷基铵(TDAB)作为脂质,和由这些膜组成的传感器,以研究这些传感器在含有不同阴离子(F-,Cl-,Br-,NO3-,I-).每种阴离子溶液减少膜上的正电荷并在负方向上移动膜电位的能力按以下顺序:I->NO3->Br->Cl->F-。这个顺序很好地反映了水合离子的大小顺序,与它们的水合能量有关。此外,OAm传感器显示低离子选择性,而TOMACl和TDAB传感器显示出与OAm传感器相关的高离子选择性。建议离子选择性的这种特征是由于在OAm传感器的情况下正电荷随环境的pH和OAm分子的堆积密度而变化,以及由于在TOMACl和TDAB传感器的情况下由脂质的完全电离产生的强且恒定的正电荷。此外,揭示了离子选择性通过改变每个膜中的脂质浓度而变化。这些结果有助于开发选择性地响应不同阴离子种类的传感器膜,并产生能够抑制对无味阴离子的响应的味道传感器。
Currently, taste sensors utilizing lipid polymer membranes are utilized to assess the taste of food products quantitatively. During this process, it is crucial to identify and quantify basic tastes, e.g., sourness and sweetness, while ensuring that there is no response to tasteless substances. For instance, suppression of responses to anions, like tasteless NO3- ions contained in vegetables, is essential. However, systematic electrochemical investigations have not been made to achieve this goal. In this study, we fabricated three positively charged lipid polymer membranes containing oleylamine (OAm), trioctylemethylammonium chloride (TOMACl), or tetradodecylammonium bromide (TDAB) as lipids, and sensors that consist of these membranes to investigate the potential change characteristics of these sensors in solutions containing different anions (F-, Cl-, Br-, NO3-, I-). The ability of each anion solution to reduce the positive charge on membranes and shift the membrane potential in the negative direction was in the following order: I- > NO3- > Br- > Cl- > F-. This order well reflected the order of size of the hydrated ions, related to their hydration energy. Additionally, the OAm sensor displayed low ion selectivity, whereas the TOMACl and TDAB sensors showed high ion selectivity related to the OAm sensor. Such features in ion selectivity are suggested to be due to the variation in positive charge with the pH of the environment and packing density of the OAm molecule in the case of the OAm sensor and due to the strong and constant positive charge created by complete ionization of lipids in the case of TOMACl and TDAB sensors. Furthermore, it was revealed that the ion selectivity varies by changing the lipid concentration in each membrane. These results contribute to developing sensor membranes that respond to different anion species selectively and creating taste sensors capable of suppressing responses to tasteless anions.