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

As nanoscaled extracellular vehicles inheriting genetic and protein information from source cells, detection of exosomes is promising for early diagnosis of cancer. However, optical sensors with high specificity and low medium background remain challenging for detection of exosomes. We herein develop the first luminescent nanosensor that bypasses real‐time light excitation for multiplex differentiation of cancer exosomes. Such an afterglow luminescent nanosensor is composed of a near‐infrared (NIR) semiconducting polyelectrolyte (ASPN) electrostatically complexed with a quencher‐tagged aptamer. The afterglow signal of the nanocomplex (ASPNC) is initially quenched due to the efficient electron transfer between ASPN and the quencher. However, the presence of aptamer‐targeted exosome increases ASPN/quencher distance, turning on afterglow signal. Because the afterglow detection is conducted after cessation of light excitation, the sample background signal is greatly minimized, affording the limit of detection that is nearly two order of magnitudes lower than fluorescence detection in cell culture medium. More importantly, ASPNC can be easily tailored to detect different exosomal proteins simply by changing the sequence of aptamer. Such a structural versatility of ASPNC enables orthogonal analysis of multiple exosome samples, potentially permitting accurate identification of the cellular origin of exosomes for cancer diagnosis.

from A via a.sfakia on Inoreader http://bit.ly/2Bgx9AS