Electrochemical Sensors Based On Fluorescein Hydrazide Compounds For Quantitative Detection Of Cu(Ⅱ) Ions

With the development of industry, heavy metal ions affect human health via many directly or indirectly approach, such as water, earth, and food. So find effective approach for detection heavy mental ions is still such a big issue. In this paper, Fluorescein hydrazide derivatives were choose to modification nano-materials, such as carboxyl functionalized graphene, Ti O2 nanosphere, and gold nanoparticles, and rhodamine B hydrazide and Fluorescein Hydrozine-3,6-Diacetic Acid were choose as probes to detect Cu2+ ions.First part, a strategy for fabricating a Cu2+ sensor based on rhodamine B hydrazide(RBH)-immobilized graphene oxide(GO) was developed. The thiol-modified gold electrode was functionalized by carboxyl functionalized GO(CGO) through intermolecular interaction, followed by the chemical bonding with RBH. The chemical structures of the as-prepared graphene oxide-based nanocomposites were characterized by X-ray photoelectron spectroscopy. And the developed nanocomposite was used as an electrochemical sensor for Cu2+ detection in aqueous solution using electrochemical impedance spectroscopy analysis with a detection limit of 0.061 n M within a range from 0.1 n M to 50 n M. Additionally, the interference from potentially interfering ions such as K+, Na+, Ca2+, Ba2+, Mg2+, Mn2+, Co2+, Ni2+, and Fe2+ associated with Cu2+ analysis could be effectively inhibited. In addition, the developed Cu2+ sensor could be reproduced up to 10 cycles.Second part, a novel electrochemical sensor for the sensitive detection of Cu(II) ions based on hollow Ti O2 spheres modified by fluorescein hydrozine-3,6-diacetic acid(FH). The resulting Au- Ti O2-FH was used to develop the electrochemical sensor for the highly sensitive detection of Cu2+ in aqueous solution because of the coordination between Cu2+ and FH, the whole process of which was determined via electrochemical impedance spectroscopy. The results showed that a detection limit of 4.29 p M of the developed sensor within the range from 5 p M to 1 mM was obtained. Furthermore, the interference from other metal ions, such as K+, Na+, Ni2+, Ag+,Mn2+, Zn2+, Mg2+, and Fe3+, associated with Cu2+ analysis could be effectively inhibited. Most importantly, the developed electrochemical sensor could be reproduced and degraded by UV light irradiation because of the light degradation ability of Ti O2 toward FH.Third part, Gold nanoparticles(GNPs) which have excellent biocompatibility and optical properties were used as chemical electrochemical sensor sensitive layer to detection Cu2+ in aqueous solution. And rhodamine B hydrazide was choose as the probe. X-ray photoelectron spectroscopy and FTIR were employed to character the elemental composition of the GNPs based sensor surface. Electrochemical impedance spectroscopy(EIS) was choose to detection Cu2+, the former with a detection limit of 4.49 f M within a range from 0.1 to 50 p M. Most importantly, the method with simple steps and has a high sensitivity and selectivity.