Centre for Applied Nanosciences (CAN), Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal 576104, India.
Centre for Nanosciences, Indian Institute of Technology Kanpur, Kanpur 208016, India.
Anal Chem. 2024 Jun 4;96(22):9141-9150. doi: 10.1021/acs.analchem.4c00831. Epub 2024 May 23.
Droplet assay platforms have emerged as a significant methodology, providing distinct advantages such as sample compartmentalization, high throughput, and minimal analyte consumption. However, inherent complexities, especially in multiplexed detection, remain a challenge. We demonstrate a novel strategy to fabricate a plasmonic droplet assay platform (PDAP) for multiplexed analyte detection, enabling surface-enhanced Raman spectroscopy (SERS). PDAP efficiently splits a microliter droplet into submicroliter to nanoliter droplets under gravity-driven flow by wettability contrast between two distinct regions. The desired hydrophobicity and adhesive contrast between the silicone oil-grafted nonadhesive hydrophilic zone with gold nanoparticles is attained through (3-aminopropyl) triethoxysilane (APTES) functionalization of gold nanoparticles (AuNPs) using a scotch-tape mask. The wettability contrast surface facilitates the splitting of aqueous droplets with various surface tensions (ranging from 39.08 to 72 mN/m) into ultralow volumes of nanoliters. The developed PDAP was used for the multiplexed detection of Rhodamine 6G (Rh6G) and Crystal Violet (CV) dyes. The limit of detection for 120 nL droplet using PDAP was found to be 134 pM and 10.1 nM for Rh6G and CV, respectively. These results align with those from previously reported platforms, highlighting the comparable sensitivity of the developed PDAP. We have also demonstrated the competence of PDAP by testing adulterant spiked milk and obtained very good sensitivity. Thus, PDAP has the potential to be used for the multiplexed screening of food adulterants.
液滴分析平台已经成为一种重要的方法，具有样品分隔、高通量和最小分析物消耗等明显优势。然而，固有复杂性，特别是在多重检测方面，仍然是一个挑战。我们展示了一种用于多重分析物检测的等离子体液滴分析平台（PDAP）的新策略，实现了表面增强拉曼光谱（SERS）。PDAP 通过两个不同区域之间的润湿性对比，在重力驱动的流动下将微升液滴有效地分成亚微升至纳升液滴。通过使用 Scotch 胶带掩模对金纳米粒子（AuNPs）进行（3-氨丙基）三乙氧基硅烷（APTES）官能化，实现了硅氧烷油接枝非粘性亲水区与金纳米粒子之间所需的疏水性和粘附性对比。润湿性对比表面有利于将具有不同表面张力（范围从 39.08 到 72 mN/m）的水性液滴分割成超低体积的纳升。开发的 PDAP 用于 Rhodamine 6G（Rh6G）和 Crystal Violet（CV）染料的多重检测。使用 PDAP 对 120 nL 液滴的检测限分别为 Rh6G 和 CV 的 134 pM 和 10.1 nM。这些结果与之前报道的平台一致，突出了开发的 PDAP 的相当敏感性。我们还通过测试掺杂物污染的牛奶来证明 PDAP 的能力，并获得了非常好的灵敏度。因此，PDAP 有可能用于食品掺杂物的多重筛选。
