da Rocha Rodrigues Rebeca, Pellosi Diogo Silva, Caseli Luciano, Péres Laura Oliveira
Federal University of São Paulo, Laboratory of Hybrid Materials, Diadema, São Paulo 09913-030, Brazil.
Federal University of Paraná, Macromolecules and Interfaces Research Group, Curitiba, Paraná 81531-980, Brazil.
Langmuir. 2025 Sep 23;41(37):25729-25741. doi: 10.1021/acs.langmuir.5c03648. Epub 2025 Sep 9.
This study demonstrates the successful fabrication of nanostructured Langmuir-Blodgett (LB) films combining the conjugated copolymer poly(9,9-dioctylfluorene--3,4-ethylenedioxythiophene) (PDOF--PEDOT) with spherical and triangular silver nanoparticles (AgNP). The LB technique allowed precise control over the molecular arrangement and distribution of the nanoparticles at the air-water interface, resulting in compact, reproducible and structurally ordered nanocomposite films. The structural and morphological properties of the interfacial monolayers and LB films were investigated using surface pressure-area isotherms, Brewster angle microscopy, polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and quartz crystal microbalance. Monolayers and LB films containing anisotropic nanoparticles exhibited greater restriction in the molecular reorganization of the monolayers and in the degree of transfer and organization of the LB films. Physicochemical characterization confirmed that the organization of the films at the molecular level plays a key role in improving the performance of surface-enhanced Raman scattering (SERS). Films with spherical AgNP showed relatively intense and well-defined Raman signals for the pesticide chlorpyrifos (CLP), even at concentrations less than 6 × 10 mol L, outperforming analogous films prepared by spin coating. In contrast, films with triangular AgNP showed lower spectral reproducibility due to their lower colloidal and structural stability. The results show that the LB technique enables effective nanostructuring and synergistic integration of conducting polymers and plasmonic nanoparticles and offers a promising route to the development of SERS-active platforms. To our knowledge, this is one of the first studies to investigate the use of conjugated polymers as functional matrices and silver nanoparticles organized by the LB technique that can be exploited for SERS-based detection. This work also contributes to the under-explored field of hybrid LB films for chemical detection by highlighting their potential for the construction of highly structured and functionalized interfaces for molecular recognition.
本研究展示了将共轭共聚物聚（9,9 - 二辛基芴 - 3,4 - 乙烯二氧噻吩）（PDOF - PEDOT）与球形和三角形银纳米颗粒（AgNP）相结合，成功制备出纳米结构的朗缪尔 - 布洛杰特（LB）膜。LB技术能够精确控制纳米颗粒在空气 - 水界面的分子排列和分布，从而得到致密、可重现且结构有序的纳米复合膜。利用表面压力 - 面积等温线、布鲁斯特角显微镜、偏振调制红外反射吸收光谱（PM - IRRAS）和石英晶体微天平对界面单分子层和LB膜的结构及形态特性进行了研究。含有各向异性纳米颗粒的单分子层和LB膜在单分子层的分子重组以及LB膜的转移和组织程度方面表现出更大的限制。物理化学表征证实，膜在分子水平上的组织在改善表面增强拉曼散射（SERS）性能方面起着关键作用。即使在浓度低于6×10⁻⁹ mol/L时，含有球形AgNP的膜对农药毒死蜱（CLP）也显示出相对强烈且清晰的拉曼信号，性能优于通过旋涂制备的类似膜。相比之下，含有三角形AgNP的膜由于其较低的胶体和结构稳定性，光谱重现性较低。结果表明，LB技术能够实现导电聚合物和等离子体纳米颗粒的有效纳米结构化和协同整合，并为开发SERS活性平台提供了一条有前景的途径。据我们所知，这是首批研究将共轭聚合物用作功能基质以及通过LB技术组织的银纳米颗粒用于基于SERS检测的研究之一。这项工作还通过强调其在构建用于分子识别的高度结构化和功能化界面方面的潜力，为化学检测中尚未充分探索的混合LB膜领域做出了贡献。
