Because circulating tumor cells (CTCs) have been proven to be an important clue of the tumor metastasis, their detection thus plays a pivotal role in the diagnosis and prognosis of cancer. Herein, we fabricate an electrochemical sensor by directly conjugating two cell-specific aptamers, TLS1c and TLS11a, which specifically recognize MEAR cancer cells, to the surface of a glassy carbon electrode (GCE) via the formation of amide bonds. The two aptamers are simultaneously conjugated to the GCE surface via precisely controlled linkers: TLS1c through a flexible linker (a single-stranded DNA T15; ss-TLS1c) and TLS11a through a rigid linker (a double-stranded DNA T15/A15; ds-TLS11a). It is found that such ss-TLS1c/ds-TLS11a dual-modified GCEs show greatly improved sensitivity in comparison with those modified with a single type of aptamer alone or ds-TLS1c/ds-TLS11a with both rigid linkers, suggesting that our optimized, rationally designed electrode-aptamer biosensing interface may enable better recognition and thus more sensitive detection of tumor cells. Through the utilization of this dual-aptamer-modified GCE, as few as a single MEAR cell in 10(9) whole blood cells can be successfully detected with a linear range of 1-14 MEAR cells. Our work demonstrates a rather simple yet well-designed and ultrasensitive tumor cell detection method based on the cell-specific aptamer-modified GCE, showing a promising potential for further CTC-related clinical applications.
In this study, the UV-Fenton process was used to treat a spent electroless nickel plating bath, and to recover high purity ferric phosphate which could be used as a raw material in lithium ferric phosphate batteries. The effects of different parameters such as the H 2 O 2 dosage, the H 2 O 2 and Fe 2+ feeding modes and the initial temperature on the treatment efficiency of the process were investigated. The results indicated that the UV-Fenton process could effectively remove the chemical oxidation demand by about 96.1%. Meanwhile, the phosphate produced from the complete oxidation of hypophosphite and phosphite was recovered as a precipitation of ferric phosphate. According to the results, about 99.9% of the phosphorus in the spent electroless nickel plating bath can be recovered. Recovered ferric phosphate particles were high in purity and nanometer-sized. This method utilizes relatively clean and economical reagents in the recovery of phosphorus resources, and does not generate hazardous substances. It will provide a new green method for the spent electroless nickel plating bath treatment.
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