## 4 Discussion
Particularly noteworthy is that in saliva samples, the system detected various exosomal markers such as CD9, CD63, CD81, and TSG101 at uniformly high levels. According to [PERSON] et al., saliva is a non-invasively obtained sample that can contain biomarkers for not only oral diseases but also systemic diseases, making it diagnostically valuable [40]. The automated system developed in this study can effectively isolate various exosome subpopulations in saliva, which is expected to greatly enhance the potential clinical application of saliva-based liquid biopsy in the future. While this study validated the efficiency of exosome isolation using EGCG-modified magnetic beads for various biofluids, several limitations exist. First, we primarily evaluated exosome isolation efficiency based on protein marker expression. However, to fully understand the integrity and functional characteristics of exosomes, additional characterization through morphological analysis via electron microscopy, size distribution measurements via nanoparticle tracking analysis (NTA), and analysis of RNA content in the isolated exosomes is necessary. [PERSON] et al. emphasized the importance of diverse characterization methods in exosome research [41]. Second, follow-up studies comparing healthy controls and patient samples with various disease states are needed to further clarify the clinical utility of the method developed in this study. In particular, analyzing differences in exosome profiles across various pathological conditions such as cancer, neurodegenerative diseases, and cardiovascular diseases is crucial for demonstrating the diagnostic value of this method. [PERSON] et al. reported that serum exosome profiles from cancer patients could show significant differences compared to those of healthy controls [42]. Third, while the current automated system is optimized for small-scale research environments, scaling up to systems with a higher throughput and reproducibility is necessary for large-scale clinical applications. [PERSON] et al. emphasized that the development of standardized high-throughput isolation methods is essential for the clinical application of exosome-based biomarkers [43]. Future research should focus on improving the chemical stability of the EGCG@T complex and developing techniques for the selective isolation of specific exosome subpopulations through surface functionalization. In particular, the development of EGCG@T complexes conjugated with antibodies or aptamers that can selectively capture exosomes related to specific cancers or diseases could greatly enhance the specificity and sensitivity of liquid biopsy. [PERSON] et al. reported a method for selectively isolating specific cancer-related exosomes using magnetic beads coupled with targeting antibodies [9]. These types of studies are expected to further expand the potential clinical applications of EGCG-modified magnetic bead-based exosome isolation methods. Given the exploratory nature of this study, statistical comparisons were not performed at this stage. However, future work will incorporate a greater number of biological replicates and statistical analyses (e.g., ANOVA) to validate the reproducibility and significance of the observed trends. Despite the absence of formal statistical tests, we evaluated exosome enrichment using known high-abundance non-exosomal proteins. Although THP and albumin are not classical negative markers, they serve as representative contaminants in urine and plasma, respectively. Their reduced presence in the eluted fraction supports the selectivity of our isolation method.