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In this work, a solid-state electrochemiluminescence (ECL) sensor based on resonance energy transfer (RET) was proposed using MoS2QDs@g-C3N4 as a donor and NH2-SiO2@PTCA as an acceptor. Herein, MoS2QDs could significantly facilitate the stability and efficiency of the ECL of g-C3N4. PTCA provided a large platform to anchor NH2-SiO2 nanoparticles. The prepared MoS2QDs@g-C3N4 exhibited good spectral overlap with the UV–vis absorption spectrum of NH2-SiO2@PTCA. Based on this, we designed an "off–on" ECL sensing strategy for sensitive and selective detection of glutathione (GSH). Under the best conditions, the linear range of the sensor for GSH detection was from 0.001 to 100 μM with a detection limit of 0.63 nM (S/N = 3). More importantly, GSH in commercial samples can be detected using the proposed sensor, which indicated its superior detection capabilities and potential application value in commercial medicines. [ABSTRACT FROM AUTHOR]

• The multidirectional hybridization chain reaction (mHCR) was used to detect exosomes. • The electrochemical assay is characterized by low detection limit of 285 exosomes/μL. • The mHCR shows simple and efficient way for electrochemical signal amplification. • The specific aptamer enables discrimination between tumorous or nontumorous exosomes. Exosomes-based liquid biopsy is an anticipated application, in which high sensitivity detection with good selectivity is an important determinant of assay quality. Herein, we propose an electrochemical aptasensor for the selective and sensitive detection of tumorous exosomes. It is based on multidirectional hybridization chain reaction (mHCR) for signal amplification. The aptamers are first immobilized on gold electrode surface to capture exosomes by binding to the exosomal membrane proteins. After target capture, cholesterol-modified H shape-like DNA unit 1 (cH1) is capable of plunging cholesterol into the exosomal lipid bilayer and anchoring on the exosomal membrane. The mHCR is therefore carried out at cH1 in the presence of H shape-like DNA unit 1 (H1) and H shape-like DNA unit 2 (H2) to form a large DNA nanostructure, which enables to recruit multiple signal molecules for electrochemical signal amplification. Under the optimal conditions, the electrochemical aptasensor exhibits high sensitivity with a low limit of detection (LOD) of 285 exosomes/μL. In addition, it shows selective discrimination between tumorous and non-tumorous exosomes from cells and serum samples. Overall, the proposed aptasensor shows potential value for exosomes detection in the early diagnosis and screening of cancers. [ABSTRACT FROM AUTHOR]