UV absorption/electrochemistry dual-readout method for Al3+detection based on neochlorogenic acid
Objective To develop a novel dual-readout method for the detection of Al3+in biological samples based on the interactions between neochlorogenic acid(NCGA)and Al3+via electrochemical and spectroscopic properties of NCGA.Methods NCGA was immobilized onto the glass carbon(GC)electrode surface via single-walled carbon nanotubes(CNTs)through π-π interactions to generate an NCGA/CNTs/GC electrode.Once immersed in Al3+solution,the modified electrodes showed a current decrease in the oxidation peak at+0.23 V(vs.Ag/AgCl)due to the interactions-driven binding of Al3+on the surface of electrodes,which validated Al3+detection with the current decrease of the NCGA/CNTs/GC electrode as the electrochemical signal readout.Upon addition of Al3+into NCGA solution,the UV-vis absorbance of NCGA significantly decreased in NCGA at 325 nm and generated a new absorption band centred at 365 nm with a clear isosbestic points at 277 and 340 nm unchanged,which enabled the Al3+quantification with the ration of absorbance at 365 nm to 325 nm(i.e.,A365/A325)as the absorption readout.Results The NCGA-based anlytical method for Al3+showed dynamic linear concentration of Al3+at 0.1～100 μmol·L-1 with a detection limit of 0.034 μmol·L-1 and ranges of 0.01～0.1 μmol·L-1,0.1～10 μmol·L-1,and 10～100μmol·L-1 with a detection limit of 0.45 nmol·L-1.The method based on both the UV absorption and electrochemical analysis was highly selective against other metal ions and coexisting species in the biological samples within their physiological concentrations.As with the animal experiment,the dual-readout method proved selective and effective for Al3+quantification in the rat serum.The spiked recoveries for serum sample ranged 97.4％～101％(n=3)for the UV absorption and 98.5％～99.4％(n=3)for the electrochemical analysis,respectively.Conclusion The method is linear,selective,and accurate,and can be used for the accurate quantification of Al3+in the rat serum,facilitating more applications in physiological and pathological research associated with Al3+.
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