ABSTRACT
Poly ( aspartic acid-co-leucine) was synthesized, modified via ethylenediamine, conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and finally chelated with gadoliniumⅢ, yielding PL-A2-DOTA-Gd. The T1-relaxivity (15. 3 mmol-1 ·L·s-1 ) of PL-A2-DOTA-Gd was 2. 6 times than that of Gd-DOTA (5. 8 mmol-1·L·s-1) in D2O. The results of magnetic resonance imaging experiments showed significant enhancement in the rat liver after intravenous administration of PL-A2-DOTA-Gd, which persisted longer than Gd-DOTA. The mean percentage enhancements of liver parenchyma were 65. 1%±5. 2%and 21. 3%±4. 9%, for PL-A2-DOTA-Gd and Gd-DOTA, respectively.
ABSTRACT
Palladium nanoparticle/carbon nanofibers(Pd/CNFs) were prepared by electrospinning technique with subsequent thermal treatments and were employed to modify glassy carbon electrode (Pd/CNF-GCE/ CME). Pd/CNF-GCE/CME exhibited excellent electrocatalytic activities towards catechol and hydroquinone,and the reversibility of catechol and hydroquinone were significantly improved. The effects of pH value on the oxidation peak current and potential of catechol and hydroquinone were studied by differential pulse voltamme-try(DPV),and 0. 1 mol/L PBS(pH 8.0) was selected as the supporting electrolyte. Under the optimized conditions,the oxidation peak current of catechol was linearly with the concentration of catechol in the range of 1-90μmol/L in the presence of 50 μmol/L hydroquinone with the detection limit of 0.3μmol/L(S/V =3) and the oxidation peak current of hydroquinone was linearly with the concentration of hydroquinone in the range of 2 - 100μmol/L in the presence of 50 μmol/L catechol with the detection limit of 1. 0μmol/L. Furthermore,the modified electrode exhibited good reproducibility and selectivity. The modified electrode has been used for the determination of catechol and hydroquinone in imitative water samples with satisfactory results.
ABSTRACT
A poly(amino black 10B)/Nafion modified glassy carbon(GC) electrode for the detection of dopamine(DA) has been developed. The modified electrode showed an excellent electrocatalytic effect on the oxidation of DA. In cyclic votammetric measurements, the redox peak current increased linearly with the concentration of DA in the range of 2.0×10~(-7) 3.0×10~(-5) mol/L in PBS of pH 6.0, with a correlation coefficient of 0.9993 and 0.9991, respectively. The detection limit(S/N=3) was 1.0×10~(-7) mol/L. Moreover, the modified electrode exhibited good repeatability and long-time stability, and avoided the interference of ascorbic acid. The modified electrode has been used for the determination of DA in the injections and calf serum with good recovery and reproducibility.