Motor effects of copper in the caudate nucleus: reversible lesions with ion-exchange resin beads

Adenine-stabilized carbon dots for highly sensitive and selective sensing of copper(II) ions and cell imaging

Adenine-stabilized carbon dots (A-CDs) are shown to be a viable fluorescent probe for highly sensitive detection and imaging of Cu²⁺. The probe has a linear fluorometric response in the 1-700 nM concentration range and a 0.3 nM detection limit. The probe, with excitation/emission maxima at 380/435 nm, is highly selective for Cu²⁺ over other metal ions, anions, amino acids, and biomolecules. The fluorescence quenching mechanism of the A-CDs by Cu²⁺ is investigated using transmission electron microscopy images coupled with elemental mapping, X-ray photoelectron spectroscopy, X-ray-excited Auger electron spectroscopy, fluorescence lifetime, UV-visible spectroscopy, and cyclic voltammetry. The experimental results show that the fluorescence quenching is caused by the combination of Cu²⁺-coordination-induced aggregation of the A-CDs, the reduction of Cu²⁺ by the A-CDs, and the nonradiative photoinduced electron transfer process from the A-CDs to Cu²⁺ or metallic Cu. The high sensitivity and high selectivity of the sensor are ascribed to the chemical interactions between the A-CDs and Cu²⁺, the photophysical process between the A-CDs and Cu²⁺, and the high fluorescence quantum yield of the A-CDs (44.6%). The A-CDs have excellent water solubility, good stability to variation of pH values, high photostability, fast response time, and low cytotoxicity. They are successfully employed for intracellular imaging of Cu²⁺ in HepG2 cells and Cu²⁺ detection in the tap water samples.

Monoamine uptake in brain synaptosomes after administration of copper to rats

In our previous studies, divalent copper (Cu) has proved to be a potent inhibitor of monoamine uptake in rat brain synaptosomes in vitro. To study whether Cu affects monoamine uptake in the brain in vivo, rats were given Cu (as CuCl2) acutely as a single dose of 30, 100, 200 or 300 mg/kg by gavage, intravenously 9 mg/kg or subacutely in drinking water, 200, 400, or 600 mg/l Cu for 3 weeks. Control animals were given deionized water. Cu was an order of magnitude more toxic intravenously than orally as judged by the Cu dose. The high affinity uptake of dopamine, 5-hydroxytryptamine and noradrenaline did not change in striatal, hypothalamic and cortical synaptosomes, respectively, after these Cu administrations. A single dose of 300 mg/kg Cu orally was lethal and increased hypothalamic Cu by 13% and cortical Cu by 26%. Lower doses increased neither blood nor brain Cu significantly 24 hrs after administration of Cu. After the 3 week administration of 600 mg/l Cu in drinking water blood Cu had increased by 22% and cerebral Cu by 19%. The results indicate that Cu is not liable to affect monoamine uptake in nerve endings in vivo. This may be explained by effective endogenous protective mechanisms against Cu.