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Current method for monitoring patients for cancer recurrence after treatment requires patients to travel to a centralized laboratory, causing time in scheduling appointments/waiting for results, financial burden in travel costs to clinics, and invasive procedures (i.e., biopsies) leading to discomfort in patients. To improve convenience, outcomes, and enable more frequent monitoring of cancer recurrence, we propose using an implantable hydrogel sensor for remote cancer surveillance. Gold nanostars (GNS), efficient plasmonic nanomaterials, embedded in hydrogels, enhance Raman scattering signals of cancer biomarkers. A handheld Raman spectroscopy probe collects these signals, representing the unique vibrational molecular fingerprint. Toward this effort, this study demonstrates the performance of a GNS-embedded hydrogel for discriminating serum in two preclinical mouse prostate cancer models: NSG and C57BL/6J mice. GNS labeled with 4- mercaptobenzoic acid (4-MBA) were embedded in 70μL hydrogels. Six serum samples from NSG mice (3 with LNCaP subcutaneous tumors, 3 normal) and eight serum samples from C57BL/6J mice (3 wild type, 5 transgenic modified– TRAMP with prostate cancer) were obtained. Serum (70μL) was incubated overnight (4°C) with the hydrogel sample. Raman spectra were collected at five distinct locations using the Raman handheld probe. Spectral analysis involved intensity normalization, principal component analysis (PCA) for dimension reduction, and linear discriminate analysis (LDA) for classification with leave-one-spectra-out cross-validation. NSG mice exhibited band differences at 775-825 cm-1, 1202-1249 cm-1, and 1430-1478 cm-1 (LDA ROC AUC = 0.83), while C57BL/6J mice showed differences at 1152-1245 cm-1 and 1362-1407 cm-1 (LDA ROC AUC = 0.98). Successful discrimination of serum in mouse models demonstrates the presence of biomarkers that differentiate cancer-bearing mice and the potential for remote cancer monitoring.
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