Pupel Krystian, Jędrzejewski Kacper, Kasztelan Mateusz, Żołądek Sylwia, Pałys Barbara
Faculty of Chemistry, University of Warsaw, Warsaw 02-093, Poland.
ACS Omega. 2024 Dec 16;9(52):51679-51689. doi: 10.1021/acsomega.4c09696. eCollection 2024 Dec 31.
Gold nanobowls (AuNBs) synthesized by the template-free method were deposited on graphene oxide (GO) to obtain an ultrasensitive surface enhanced Raman spectroscopy (SERS) platform for folic acid (FA) detection. GO was conditioned in aqueous solutions at various pH values to optimize the adsorption of the FA molecule and the intensity of the SERS signal. It was found that the conditioning procedure influences the orientation of FA on the SERS supports and the quality of the spectra in result. The limit of detection (LOD) for FA was equal to 10 M for the best combination of GO conditioned at pH = 1 and AuNBs (GO-1/AuNBs). The composites of AuNBs with GO conditioned in solutions of higher pH were less efficient. The LOD values were equal to 10 M for AuNBs deposited on GO conditioned at pH = 5.6 (GO-5.6/AuNBs) and 10 M for AuNBs deposited on GO conditioned at pH = 13 (GO-13/AuNBs). The high sensitivity of the GO-1/AuNBs composite has been explained by the high adsorption of FA and the molecular orientation with a -aminobenzoic ring attached to the surface. We suppose that such an orientation fosters efficient charge transfer between the adsorbed molecule and the support, which in turn enhances the SERS intensity by the chemical effect in addition to the electromagnetic enhancement yield by AuNBs. The adsorbed FA molecules attain the random conformation or adsorption through the pteridine ring on the supports with GO conditioned at higher pH. Such orientation results in less efficiency in obtaining the enhancement through the chemical mechanism.
通过无模板法合成的金纳米碗（AuNBs）沉积在氧化石墨烯（GO）上，以获得用于叶酸（FA）检测的超灵敏表面增强拉曼光谱（SERS）平台。将GO在不同pH值的水溶液中进行处理，以优化FA分子的吸附和SERS信号强度。发现该处理过程会影响FA在SERS载体上的取向以及最终光谱的质量。对于在pH = 1条件下处理的GO和AuNBs的最佳组合（GO-1/AuNBs），FA的检测限（LOD）等于10⁻⁹ M。在较高pH值溶液中处理的GO与AuNBs的复合材料效率较低。对于沉积在pH = 5.6条件下处理的GO上的AuNBs（GO-5.6/AuNBs），LOD值等于10⁻⁸ M，对于沉积在pH = 13条件下处理的GO上的AuNBs（GO-13/AuNBs），LOD值等于10⁻⁷ M。GO-1/AuNBs复合材料的高灵敏度归因于FA的高吸附以及带有连接到表面的对氨基苯环的分子取向。我们认为这种取向促进了吸附分子与载体之间的有效电荷转移，这除了通过AuNBs的电磁增强效应外，还通过化学效应增强了SERS强度。在较高pH值条件下处理的GO载体上，吸附的FA分子通过蝶啶环以随机构象或吸附方式存在。这种取向导致通过化学机制获得增强的效率较低。
