Lee Mon-Juan, Duan Fei-Fan, Wu Po-Chang, Lee Wei
Department of Bioscience Technology, Chang Jung Christian University, Guiren Dist., Tainan 71101, Taiwan.
Department of Medical Sciences Industry, Chang Jung Christian University, Guiren Dist., Tainan 71101, Taiwan.
Biomed Opt Express. 2020 Aug 7;11(9):4915-4927. doi: 10.1364/BOE.398858. eCollection 2020 Sep 1.
Conventional liquid crystal (LC)-based biosensing at the LC-glass interface requires the assembly of an LC cell formed by two glass substrates with an LC film sandwiched in between. As most biochemical and clinical assays are performed on a single solid substrate, the feasibility of a single-substrate biodetection platform based on a thin film of LC-photopolymer composite was explored in this study. The LC mixture, consisting of nematic LC, E7 or AY40-006, doped with a small amount (≤ 5 wt%) of a photocurable prepolymer was spin-coated on a glass substrate modified with dimethyloctadecyl[3-trimethoxysilyl)propyl] ammonium chloride (DMOAP), a vertical alignment reagent, followed by irradiation with ultraviolet (UV) light. During the photopolymerization process, the accumulated and polymerized NOA65 at the LC-glass interface weakened the anchoring strength of DMOAP, resulting in a decrease in the pretilt angle of LC and allowing the LC molecules to be more easily disturbed in the presence of biomolecules, compared with vertically aligned LC in the absence of polymerized NOA65. Incorporating NOA65 in the LC film therefore provides a means for signal amplification. When an LC-photopolymer composite film consisting of AY40-006 and 4-wt% NOA65 was exposed to UV at 15 mW/cm for 30 s and utilized as the biosensing mesogen, the limits of detection were 1.6 × 10 g/ml for the direct detection of bovine serum albumin (BSA) and 2.1 × 10 g/ml for the immunoassay of the cancer biomarker CA125, significantly lower than those detected with AY40-006 alone or AY40-006/NOA65 mixture without UV irradiation. The results from this study offer a compelling implication on the biomedical application of LC-photopolymer composites in label-free and single-substrate biodetection.
基于液晶（LC）的传统生物传感在LC-玻璃界面处需要组装一个由两个玻璃基板形成的LC盒，中间夹有一层LC膜。由于大多数生化和临床检测是在单个固体基板上进行的，因此本研究探讨了基于LC-光聚合物复合材料薄膜的单基板生物检测平台的可行性。将由向列型LC、E7或AY40-006组成的LC混合物，掺杂少量（≤5 wt%）的光固化预聚物，旋涂在经二甲基十八烷基[3-三甲氧基甲硅烷基）丙基]氯化铵（DMOAP，一种垂直取向试剂）改性的玻璃基板上，然后用紫外线（UV）照射。在光聚合过程中，在LC-玻璃界面处积累并聚合的NOA65削弱了DMOAP的锚定强度，导致LC的预倾角减小，与不存在聚合NOA65时垂直取向的LC相比，在生物分子存在的情况下，LC分子更容易受到干扰。因此，在LC膜中加入NOA65提供了一种信号放大的手段。当由AY40-006和4 wt% NOA65组成的LC-光聚合物复合膜在15 mW/cm的UV下暴露30 s并用作生物传感介晶时，直接检测牛血清白蛋白（BSA）的检测限为1.6×10 g/ml，癌症生物标志物CA125免疫测定的检测限为2.1×10 g/ml，显著低于单独使用AY4OS-006或未进行UV照射的AY40-006/NOA65混合物检测到的检测限。本研究结果对LC-光聚合物复合材料在无标记单基板生物检测中的生物医学应用具有重要意义。
