Stellate silicon microneedles for rapid point-of-care melanoma exosome isolation and detection via a lateral flow assay

Abstract

Melanoma is the most aggressive type of skin cancer with high mortality rates. Early diagnosis is crucial because it significantly improves treatment outcomes, but conventional methods relying on dermoscopy and lesion biopsy have limitations in accuracy during early stages and are invasive. Liquid biopsies offer a minimally invasive alternative, particularly for routine screening. The abundance of cancer cell-driven extracellular vesicles in interstitial fluid can be utilized for point-of-care cancer diagnostics. Here, we developed a stellate silicon microneedle patch, the ExoPatch, coated with Annexin V functionalized hydrogel to isolate melanoma-specific exosomes. The ExoPatch captures exosomes directly from the skin, followed by dissolution of the hydrogel to release the exosomes, which are then detected using a lateral flow immunoassay specific to melanoma markers (MCAM and MCSP). After validating with cell line derived extracellular vesicles and testing with mouse tissue, the ExoPatch isolated 11.5 times more protein from melanoma tissue compared to healthy tissue. Additionally, the ExoPatch effectively distinguished between melanoma and healthy tissues, with its specificity confirmed through Western Blot and electron microscopy analysis. The ExoPatch with melanoma mouse samples produced a 3.5-fold higher signal in the lateral flow immunoassay compared to that of healthy controls. The ExoPatch presents a promising point-of-care diagnostic tool for melanoma, offering significant advantages in terms of rapidness, minimal invasiveness, and ease of use. It has the potential to enhance early detection and routine monitoring in melanoma patients, ultimately improving patient outcomes by reducing the reliance on traditional, invasive biopsies.