| Chemiluminescence(CL)and electrochemiluminescence(ECL)assay have been widely applied to commercial bioassay and clinical diagnosis with their merits of low background signal,high sensitivity,wide dynamic range,and simple equipment.The luminophores for commercial CL and ECL bioassay are all molecular chemicals with their CL and/or ECL confined in eye-visible region,developing efficient CL and ECL systems with nanoparticles as luminophores is strongly anticipated for the evolution of CL and ECL assays.To overcome the limitation of low CL efficiency as well as high ECL-triggering-potential from nanoparticles,herein,the CL and ECL nature of thiol-capped CuInS2@ZnS(CIS@ZnS-Thiol)nanocrystals(NCs)are extensively explored to achieve efficient NCs CL as well as low-triggering-potential NCs ECL for bioassays.(1)A general method for the preparation of thiol-capped and carboxylated CIS@ZnS-Thiol NCs were independently developed with thiol and sodium citrate as stabilizers,the effects of thiol-capping-agents on CL of CIS@ZnS-Thiol were systematically investigated.CL of same CIS@ZnS-Thiol can be conveniently turned from flash type to glow type as well as from eye-visible region to NIR region via extensively exploring the redox nature of different CL triggering reagents.The same luminophore of CIS@ZnS-Thiol NCs not only can be utilized to construct glow-type CL systems with reductant as CL triggering reagents,but also can be employed to develop flash-type CL systems with oxidant as CL triggering reagents.Taking thiosalicylic acid(TSA)capped CIS@ZnS NCs(CIS@ZnS-TSA)as model,CIS@ZnS-TSA/N2H4 is a glow-type CL system,in which CL reaction is initiated via injecting electrons onto NCs with N2H4H 2O.CIS@ZnS-TSA/H2O2 is a flash-type CL system,in which CL reaction is initiated via injecting holes onto NCs with H2O2.The CL wavebands of CIS@ZnS-TSA can be adjusted in a wide range from 730 to 823 nm via employing different CL triggering agents.Promisingly,the co-existed reductant of N2H4H 2O and oxidant of H2O2 can be employed as dual-triggering-reagents to enhance the CL of CIS@ZnS-TSA to eye-detectable.The maximum intensity for the flash CL of CIS@ZnS-TSA/N2H4-H2O2 is 101 folds to that for the glow CL of CIS@ZnS-TSA/N2H4 and 22 folds to that for the flash CL of CIS@ZnS-TSA/H2O2,respectively.The flash CL from CIS@ZnS-TSA/N2H4-H2O2 is qualified for high sensitive detection of carcinoembryonic antigens and whole operating processes can be completed in 35 minutes,enabling high-efficiency CL immunoassays.(2)The effects of thiol-capping-agents on ECL of CIS@ZnS-Thiol/N2H4 system was systematically explored with glutathione(GSH)-coated CIS@ZnS(CIS@ZnS-GSH)NCs as model luminophores,a promising strategy to achieve low ECL-triggering-potential is proposed via adjusting the dispersion state of luminophores.The ECL-triggering-potential of CIS@ZnS-GSH/N2H4 system is located around 0.78 V(*vs.Ag/AgCl)with CIS@ZnS-GSH of monodispersed state,and can be adjusted to 0.32 V(*vs.Ag/AgCl)via immobilizing CIS@ZnS-GSH on Au surface.An ECL sensor of ultra-low triggering potential was developed with CIS@ZnS-GSH as the ECL label,which can be utilized to sensitively detect K-RAS gene with a linear range of 1-500 pM and a detection limit of 0.5 pM.The ultra-low ECL-triggering-potential of CIS@ZnS-Thiol/N2H4 ECL system can effectively avoid electrochemical interference in ECL assays. |
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