Ultrathin two-dimensional (2D) nanosheets have been considered as one of the powerful platforms for chemical sensing of biomolecules. However, few 2D nanosheets with intrinsic chromatism exist for the specific and effective detection of some biomarkers. Here, we report a novel ultrathin chromic polydiacetylene (PDA) nanosheet via the self-assembly and photopolymerization of an amphiphilic guanidinium-capped diacetylene monomer (PCDA-Gu). The PDA-Gu nanosheets exhibit specific combination of lysophosphatidic acid (LPA), a biomarker for ovarian cancer, based on the synergistic salt-bridge interactions and hydrophobic interactions between the PDA-Gu nanosheets and LPA, and induced both color and fluorescence change. The linear correlation between the colorimetric response (CR) (or fluorescence intensity) and the concentration of LPA enable effective quantitative analysis of LPA in the biologically relevant low concentration range. Owing to their chromic properties and ultrathin lamellar structure, the PDA-Gu nanosheets have opportunity to act as a powerful indicator for LPA.

超薄二维（2D）纳米片被认为是生物分子化学传感的强大平台之一。但是，很少有具有固有色度的2D纳米片可用于某些生物标记的特异性和有效检测。在这里，我们通过两亲胍基二乙炔单体（PCDA-Gu）的自组装和光聚合反应，报告了一种新型的超薄铬酸聚二乙炔（PDA）纳米片。PDA-Gu纳米片基于PDA-Gu纳米片和LPA之间的协同盐桥相互作用和疏水相互作用，显示出卵巢癌生物标记物溶血磷脂酸（LPA）的特定组合，并诱导了颜色和荧光变化。比色响应（CR）（或荧光强度）与LPA浓度之间的线性相关性使得能够在生物学相关的低浓度范围内对LPA进行有效的定量分析。PDA-Gu纳米片由于具有铬的性质和超薄的层状结构，因此有机会充当LPA的有力指示剂。