Rourke-Funderburg Anna S, Walter Alec B, Carroll Braden, Mahadevan-Jansen Anita, Locke Andrea K
Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37240-0002, United States.
Vanderbilt Biophotonics Center, Vanderbilt University, Nashville, Tennessee 37240-0002, United States.
ACS Omega. 2023 Sep 5;8(37):33745-33754. doi: 10.1021/acsomega.3c03690. eCollection 2023 Sep 19.
The need for highly sensitive, low-cost, and timely diagnostic technologies at the point of care is increasing. Surface-enhanced Raman spectroscopy (SERS) is a vibrational spectroscopic technique that is an advantageous technique to address this need, as it can rapidly detect analytes in small or dilute samples with improved sensitivity compared to conventional Raman spectroscopy. Despite the many advantages of SERS, one drawback of the technique is poor reproducibility due to variable interactions between nanoparticles and target analytes. To overcome this limitation, coupling SERS with the coffee ring effect has been implemented to concentrate and localize analyte-nanoparticle conjugates for improved signal reproducibility. However, current coffee ring platforms require laborious fabrication steps. Herein, we present a low-cost, two-step fabrication process for coffee ring-assisted SERS, utilizing wax-printed nitrocellulose paper. The platform was designed to produce a highly hydrophobic paper substrate that supports the coffee ring effect and tested using gold nanoparticles for SERS sensing. The nanoparticle concentration and solvent were varied to determine the effect of solution composition on ring formation and center clearance. The SERS signal was validated using 4-mercaptobenzoic acid (MBA) and tested with bacteria to ensure functionality for chemical and biological applications. The limit of detection using MBA is 41.56 nM, and the biochemical components of the bacterial cell wall were enhanced with low spectral variability. The developed platform is advantageous due to ease of fabrication and use, representing the next step toward implementing low-cost coffee ring-assisted SERS for point-of-care sensing.
即时护理时对高灵敏度、低成本且及时的诊断技术的需求日益增加。表面增强拉曼光谱（SERS）是一种振动光谱技术，是满足这一需求的有利技术，因为与传统拉曼光谱相比，它可以在小样本或稀释样本中快速检测分析物，且灵敏度更高。尽管SERS有诸多优点，但该技术的一个缺点是由于纳米颗粒与目标分析物之间的相互作用可变，导致重现性较差。为克服这一限制，已将SERS与咖啡环效应相结合，以浓缩和定位分析物 - 纳米颗粒共轭物，从而提高信号重现性。然而，目前的咖啡环平台需要繁琐的制造步骤。在此，我们提出一种用于咖啡环辅助SERS的低成本两步制造工艺，利用蜡印硝化纤维素纸。该平台旨在生产一种支持咖啡环效应的高度疏水的纸质基底，并使用金纳米颗粒进行SERS传感测试。改变纳米颗粒浓度和溶剂，以确定溶液组成对环形成和中心间隙的影响。使用4 - 巯基苯甲酸（MBA）验证SERS信号，并对细菌进行测试，以确保其在化学和生物应用中的功能。使用MBA的检测限为41.56 nM，细菌细胞壁的生化成分得到增强，光谱变异性较低。所开发的平台因其易于制造和使用而具有优势，代表了朝着实现用于即时护理传感的低成本咖啡环辅助SERS迈出的下一步。
