Aptamer/AuNP Biosensor for Colorimetric Profiling of Exosomal Proteins

Abstract

Exosomes constitute an emerging biomarker for cancer diagnosis since they carry multiple proteins reflecting the origins of parent cells. Assessing exosome surface proteins provides a powerful means of identifying a combination of biomarkers for cancer diagnosis. We report a sensor platform that profiles exosome surface proteins in minutes by the naked eye. The sensor consists of a gold nanoparticle (AuNP) complexed with a panel of aptamers. The complexation of aptamers with AuNPs protects the nanoparticles from aggregating in a high salt solution. In the presence of exosomes, the non-specific and weaker binding between aptamers and the AuNP is broken, and the specific and stronger binding between exosome surface protein and the aptamer displaces aptamers from the AuNP surface and results in AuNP aggregation. This aggregation results in a color change of AuNP, and generate patterns for identification of multiple proteins on the exosome surface.

Exosomes for Non‐Invasive Cancer Monitoring

“…Effective signal generation methods are required for accurate identification of specific biomarkers that are highly expressed on the isolated exosomes. Until now, various signaling methods, including surface plasmon resonance, electrochemistry, colorimetry, and fluorometry, have been employed for this purpose . In the following section, key methods for the detection of specific exosome markers developed using these approaches are presented with emphasis given to their major components and techniques used.…”

Near‐Infrared Afterglow Semiconducting Nano‐Polycomplexes for the Multiplex Differentiation of Cancer Exosomes

“…Among them, MCF7‐secreted exosomes expressed the highest levels of MUC1, HER2, and EpCAM, while the highest expression level of CD63 was found in HeLa‐secreted exosomes. These findings were consistent with previous reports showing a drastically upregulated transcription level of cellular MUC1 in MCF‐7 and exosomal CD63 in HeLa . These data also verify the capability of ASPNC to differentiate the subtle variation of protein levels in exosomes from different source cells.…”

A Single Extracellular Vesicle (EV) Flow Cytometry Approach to Reveal EV Heterogeneity

“…[3] Existing methods for EV study are primarily focused on bulk analysis of al arge number of EVs,b ecause the small physical dimensions of EVs limit the total amounts of biomolecules to be carried in each EV,g reatly enhancing the difficulty in molecular profiling. [5] However, subtle molecular differences at the single EV level may yield significant variation in EV biological functions, [6] and the highly heterogeneous nature of EV population demands the development of techniques capable of profiling individual EVs. [4] Most recently,s ingle EV counting with an anochip [7] and imaging single vesicles with advanced fluorescence microscopy [8] have been reported, and showed that EVs from different cell of origin can carry distinct surface markers mimicking their parent cells.S till, they require EV immobilization steps,limiting the down-stream investigations on EV functions and biogenesis.…”