Department of Molecular and Biomolecular Physics, National Institute for Research and Development of Isotopic and Molecular Technologies, 400293 Cluj-Napoca, Romania.
Department of Molecular and Biomolecular Physics, National Institute for Research and Development of Isotopic and Molecular Technologies, 400293 Cluj-Napoca, Romania; Faculty of Physics, Babeş-Bolyai University, 400084 Cluj-Napoca, Romania.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Feb 15;247:119149. doi: 10.1016/j.saa.2020.119149. Epub 2020 Nov 4.
Advanced chemometric methods, such as fuzzy c-means, a semi-supervised clustering method, and fuzzy linear discriminant analysis (FLDA), a new robust supervised classification method in combination with principal component analysis (PCA), namely PCA-FLDA, have been successfully applied for characterization and classification of bacterial species detected at single-cell level by surface-enhanced Raman scattering (SERS) spectroscopy. SERS spectra of three species (S. aureus, E. faecalis and P. aeruginosa) were recorded in an original fashion, using in situ laser induced silver spot as metallic substrate. The detection process of bacteria was isolated inside a hermetically sealed in-house built microfluidic device, connected to a syringe pump for injecting the analytes and a portable Raman spectrometer as detection tool. The obtained results (fuzzy partitions) and spectra of the prototypes (robust fuzzy spectra mean corresponding to each fuzzy partition) clearly demonstrated the efficiency and information power of the advanced fuzzy methods in bacteria characterization and classification based on SERS spectra, and allowed a rationale assigning to a specific group. Also, this powerful detection and classification methodology generates the premises for future investigations of Raman and other spectroscopic data obtained for various samples.
先进的化学计量学方法，如模糊 c-均值，一种半监督聚类方法，以及模糊线性判别分析（FLDA），一种与主成分分析（PCA）相结合的新稳健监督分类方法，即 PCA-FLDA，已成功应用于通过表面增强拉曼散射（SERS）光谱在单细胞水平检测到的细菌种类的特征化和分类。使用原位激光诱导银斑作为金属基底，以新颖的方式记录了三种细菌（金黄色葡萄球菌、粪肠球菌和铜绿假单胞菌）的 SERS 光谱。细菌的检测过程在密封的内部构建的微流控设备内部进行，该设备与注射器泵相连，用于注入分析物和便携式拉曼光谱仪作为检测工具。获得的结果（模糊分区）和原型（每个模糊分区对应的稳健模糊光谱均值）清楚地证明了基于 SERS 光谱的细菌特征化和分类中先进的模糊方法的效率和信息量，并允许对特定组进行合理分配。此外，这种强大的检测和分类方法为未来对各种样品获得的拉曼和其他光谱数据的研究奠定了基础。
