Accurate and highly sensitive detection of Alzheimer's disease-related extracellular vesicles via förster resonance energy transfer.

Alzheimer's disease (AD) is the most common neurodegenerative disease in the world and poses a huge challenge to global healthcare. Early and accurate detection of amyloid-ß (1-42) (Aß42), a key biomarker of AD, is crucial for effective diagnosis and intervention of AD. Specific or overexpressed proteins on extracellular vesicles (EVs) describe a close correlation with the occurrence and development of diseases. EVs are a very promising non-invasive biomarker for the diagnosis of AD and other diseases. As a sensitive, simple and rapid analytical method, fluorescence resonance energy transfer (FRET) has been widely applied in the detection of EVs. Herein, we developed a dual labelling strategy for simultaneously detecting EV membrane proteins of Aß42 and CD63 based on FRET pair consisting of Au nanoclusters (AuNCs) and polydopamine nanospheres (PDANSs). The constructed nanoprobe, termed EVMPFAP assay, could specifically measure the Aß42 and CD63 on EVs with excellent sensitivity, high specificity and satisfactory accuracy. The limit of detection of EVMPFAP assay was 1.4 × 103 particles mL-1 and the linear range was from 104 to 108 particles mL-1. EVMPFAP assay was successfully used to analyze plasma EVs to distinguish AD and healthy mice. We expect that EVMPFAP assay can be routinely applied for early diagnosis and development-monitoring of AD, thus facilitating the fight against AD.

Safe engineering of cancer-associated fibroblasts enhances checkpoint blockade immunotherapy.

Abundant cancer-associated fibroblasts (CAFs) in highly fibrotic breast cancer constitute an immunosuppressive barrier for T cell activity and are closely related to the failure of immune checkpoint blockade therapy (ICB). Inspired by the similar antigen-processing capacity of CAFs to professional antigen-presenting cells (APCs), a "turning foes to friends" strategy is proposed by in situ engineering immune-suppressed CAFs into immune-activated APCs for improving response rates of ICB. To achieve safe and specific CAFs engineering in vivo, a thermochromic spatiotemporal photo-controlled gene expression nanosystem was developed by self-assembly of molten eutectic mixture, chitosan andfusion plasmid. After photoactivatable gene expression, CAFs could be engineered as APCs via co-stimulatory molecule (CD86) expression, which effectively induced activation and proliferation of antigen-specific CD8 + T cells. Meanwhile, engineered CAFs could also secrete PD-L1 trap protein in situ for ICB, avoiding potential autoimmune-like disorders caused by "off-target" effects of clinically applied PD-L1 antibody. The study demonstrated that the designed nanosystem could efficiently engineer CAFs, significantly enhance the percentages of CD8+ T cells (4-folds), result in about 85% tumor inhibition rate and 83.3% survival rate at 60 days in highly fibrotic breast cancer, further inducing long-term immune memory effects and effectively inhibiting lung metastasis.