Innovative model of surface-enhanced Raman spectroscopy for exosomes identification: An approach for the diagnosis of hepatocellular carcinoma

Cancer diagnosis using label-free SERS-based exosome analysis

“…To achieve more precise classification results, researchers commonly incorporate more sophisticated methods independently or after applying PCA to the data and extracting relevant features. These advanced techniques may include support vector machines 31 , 42 , linear discriminant analysis (LDA) 39 , 40 , 42 , 49 , partial least squares discriminant analysis (PLS-DA) 38 , 49 . By leveraging these supervised pattern recognition methods, researchers can capitalize on the simplified and meaningful representations obtained from PCA, allowing for more accurate and comprehensive analyses, especially when PCA is used as an initial step.…”

“…Additionally, it is a moderately time-consuming method that typically does not require complex sample pretreatments. Consequently, ultracentrifugation (UC)-based techniques have gained significant popularity in SERS analysis exploring exosomes 28 , 32 - 34 , 38 - 40 , 42 , 48 , 51 , 56 , 57 , 59 , 60 , 63 . Size exclusion chromatography (SEC) 31 - 33 , 36 , 40 , 45 - 47 , 55 and ultrafiltration 37 , 38 , 41 , 58 are popular size-based exosome isolation techniques.…”

“…Such discrepancies in the definitions and equations of EFs emerge from varying perspectives, including the single molecule viewpoint, SERS substrate viewpoint, and analytical chemistry viewpoint 69 . Besides, EF calculation from different research are based on different materials such as methylene blue (MB) 28 , rhodamine 6G (R6G) 34 , 45 , 4-mercaptobenzoic acid (4-MBA) 49 , crystal violet 35 , exosome 38 , 42 , 50 , 55 . It should be noted that a vague EF emerges, wherein essential normalization concerning non-SERS conditions is occasionally disregarded, a factor of significant importance.…”

“…In this research, APTES was also utilized as a linking molecule. Another example of using antibodies as linking molecules in label-free exosome analysis involves SERS analysis based on AuNPs through polyethylene glycol and bio-receptors 42 . Besides, cysteamine also serves as a valuable biofunctionalization linker.…”

“…Label-free SERS enables the characterization of exosomes by capturing their unique fingerprint, which corresponds to the specific biochemical compounds present on their surface. Based on this advantage, label-free SERS has demonstrated promising applications in diagnosing various types of cancers, including lung cancer [31][32][33] breast cancer [34][35][36][37], melanoma [38], oral and oropharyngeal squamous cell carcinoma [39], head and neck cancer [40], urogenital cancer [41], hepatocellular carcinoma [42], nasopharyngeal cancer [43] and gastric cancer [44]. Moreover, this technique allows for simultaneous diagnosis of multiple cancers [28,45] and can accurately identify cancer in patients at different stages [46].…”