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Exosomes are considered as potential biomarkers that can reflect information from their parent cell-associated cancer microenvironment. Recently, aptasensors have been widely used for cancer and tumor exosome detection. Aptamers related to exosome surface proteins are usually used to introduce a sequence; the aptamer is used for exosome recognition, and the introduced sequence is used to form G-quadruplexes and for signal amplification. In this paper, we found that the EpCAM aptamer is rich in guanine and unimolecular G-quadruplex with a two-layer G-tetrad under acidic conditions, and we investigated its topology, thermal stability and dissociation constant with hemin. Based on this, our proposed colorimetric aptamer sensor combines the unmodified EpCAM aptamer with hemin to construct a hemin/G-quadruplex DNAzyme and catalyze the TMB–H2O2 system to generate a strong colorimetric signal. Therefore, colorimetric signal changes were negatively correlated with the exosome concentration. The linear range of the 1 h assay was 106–108 particles per mL, and the detection limit was 3.94 × 105 particles per mL. In addition, this method can detect exosomes in complex fetal bovine serum samples with good specificity and high sensitivity toward exosomes from breast, liver, and lung cancers with abnormal EpCAM protein expression. [ABSTRACT FROM AUTHOR]

As a highly electrochemically active transition-metal oxide (TMO), cobalt monoxide (CoO) has been extensively investigated for applications in lithium-ion batteries and electrochemical oxygen evolution. However, its capacitive performance has been rarely studied due to the intrinsic low conductivity and poor stability. Here, we report an asymmetric supercapacitor with excellent electrochemical capacity based on an ultrathin carbon shell entrapped Co-doped CoO heterostructure (CoO/Co@C). The metallic conductivity and mesoporous configuration make the as-prepared CoO/Co@C deliver a dramatic specific capacitance of 2165.7 F g−1 at a scan rate of 10 mV s−1. Besides the contribution to double-layer capacitance, more importantly, the amorphous carbon shell effectively prevents the CoO/Co heterostructure from further oxidation, thus resulting in a significantly improved long-term storage stability in air. An asymmetric supercapacitor cell fabricated using CoO/Co@C and active carbon achieves a maximum energy density of 146.3 W h kg−1 at a power density of 1800 W kg−1, and the maximum of 27 000 W kg−1 can be obtained with a remaining energy density of 63.0 W h kg−1. The easy preparation, high performance, and excellent cycling stability of the CoO/Co@C nanocomposite make it a promising material for catalyst and battery applications. [ABSTRACT FROM AUTHOR]