exosomes (exosomes) are extracellular vesicles secreted by small cells of 30-120 nm, carrying various molecular components of their source cells, including protein , lipids, mRNA and microRNA. They can be released from many types of cells, including dendritic cells, lymphocytes, platelets, mast cells, epithelial cells, endothelial cells, and neurons, and are found in blood, saliva, urine and tears in almost all body fluids.
Initially, exosomes were thought to simply serve as "garbage bags" for cells to get rid of unwanted components. However, increasing evidence shows that exosomes play a crucial role in cell-to-cell communication, as well as cancer metastasis. Therefore, scientists began to try to use it as a potential biomarker for cancer diagnosis and for application in various biomedical fields. However, traditional detection methods based on immune and microRNA analysis take at least 18 hours to isolate exosomes and require expensive and space-consuming laboratory equipment. Therefore, the application of potential biomarkers leading to these important roles has been limited.
In a new study published in "Advanced Functional Materials" on August 10, 2022, a research team led by the Terasaki Institute for Biomedical Innovation (TIBI) developed a smart contact lens , which is embedded with Microchambers combined with antibodies can easily capture exosomes in tears, thus providing a simple, fast, sensitive, economical, non-invasive and supportive diagnostic platform for cancer pre-screening. The team says the breakthrough could open the door to cheap, one-size-fits-all disease screening programs.
In this new study, the team designed an antibody-conjugated signaling microchamber-based contact lens (ACSM-PCL) platform to detect and capture intact exosomes in tears. Researchers say tears are a more ideal and cleaner source of exosomes than blood, urine and saliva. Schematic diagram of
ACSM-PCL
ACSM-PCL has high optical transparency and mechanical properties, as well as good biocompatibility and sensitivity to exosomes, and uses gold nanoparticle colorimetry to visualize captured exosomes.
ACSM-PCL can detect exosomes in a pH range of 6.5-7.4 (similar to the pH of human tears) and has strong recovery in bovine serum albumin solutions.
The team also facilitated and optimized the preparation of ABSM-CL by using alternative methods. When creating microcavities (microchambers) for lenses, the researchers used direct laser cutting and engraving instead of traditional casting molding to maintain the structure of the microchambers and lenses.
Additionally, they optimized the procedure for conjugating capture antibodies to ACSM-PCL microchambers and conjugated different ( positive control ) detection antibodies to gold nanoparticles, which can be visualized spectroscopically. Both antibodies are specific for two different surface markers found on exosomes.
In initial validation experiments, the researchers used ACSM-PCL to test exosomes secreted from supernatants from 10 different tissues and cancer cell lines. The spectral shift observed in all tested samples compared to the negative control validated the ability of ACSM-PCL to capture and detect exosomes.
Subsequently, the researchers obtained similar results when testing different tear samples collected from 10 volunteers.
In the final experiment, ACSM-PCL successfully identified exosomes in solutions of three cell lines with different surface markers and using different combinations of antibodies. This result verified the ability of ABSM-CL to accurately capture and detect exosomes with different surface markers.
Exosomes are a rich source of markers and biomolecules that can be used in a variety of biomedical applications. Therefore, the new method developed by the team will greatly enhance scientists' ability to mine this resource.
Based on these encouraging results, they say, ACSM-PCL has the potential to become a powerful diagnostic tool for diseases ranging from cancer to viral infections.
paper link:
https://doi.org/10.1002/adfm.202206620
Source: China Biotechnology Network
Arrangement: Dai Wei, Xia Bingbing
