Label-free and highly sensitive nanoplasmonic biosensor-based autophagy flux sensing for clinical application

Autophagy is a cellular catabolic process that plays significant roles in various diseases such as neurodegenerative diseases, infectious diseases, and cancers. The importance of microtubule-associated protein 1 light chain 3 (LC3) quantification is highlighted because it is a precise tool for measuring autophagy and is also known to be associated with cancer progression, functioning as a clinically significant marker in cancer diagnosis and prognosis. To date, the quest continues to develop an autophagic LC3 detection method with enhanced sensitivity, and which provides a means of quantification to meet the clinical application needs. Here, we present a simple and intuitive autophagy flux measurement by a single gold nanoparticle-based LC3 sensing platform. This nanoplasmonic sensor does not require additional labeling, consisted of only gold nanorods and monoclonal antibodies, which enables rapid total LC3 quantification within a wide dynamic concentration range, with a detection limit of 64.1 fM. Moreover, the sensing ability of the proposed biosensor in cell lysates mimicking clinical samples and human cancer cell lysates was proved by providing a simple autophagic flux analysis method based on LSPR shifts. This sensor is the first label-free, highly sensitive total LC3 quantification nanoplasmonic biosensor that can be used for autophagy measurement, employed for precise cancer diagnosis in combination with other biomarkers. It can serve as an effective tool for determining therapeutic drug dosage in the future.