A Highly Sensitive and Selective Fluorescein-Based Cu2+ Probe and Its Bioimaging in Cell

Abstract

Copper is a vital trace metal in human body, which plays the significant roles in amounts of physiological and pathological processes. The application of copper-selective probe has attracted great interests from environmental tests to life process research, yet a few of sensitive Cu2+ tests based on on-site analysis have been reported. In this paper, a novel fluorescein-based fluorescent probe N4 was designed, synthesized, and characterized, which exhibited high selectivity and sensitivity to Cu2+ comparing with other metal ions in ethanol–water (1/1, v/v) solution. The probe N4 bonded with Cu2+ to facilitate the ring-opening, and an obvious new band at 525 nm in the fluorescence spectroscopy appeared, which could be used for naked-eye detection of Cu2+ within a broad pH range of 6–9. Meanwhile, a good linearity between the fluorescence intensity and the concentrations of Cu2+ ranged 0.1–1.5 eq. was observed, and the limit of detection of N4 to Cu2+ was calculated to be as low as 1.20 μm. In addition, the interaction mode between N4 and Cu2+ was found to be 1:1 by the Job's plot and mass experiment. Biological experiments showed that the probe N4 exhibited low biological toxicity and could be applied for Cu2+ imaging in living cells. The significant color shift associated with the production of the N4-Cu2+ complex at low micromolar concentrations under UV light endows N4 with a promising probe for field testing of trace Cu2+ ions.

Synthesis of CuO and PAA-Regulated Silver-Carried CuO Nanosheet Composites and Their Antibacterial Properties

“…It is a p-type semiconductor with a narrow band gap of 1.2 eV and has been reported as a promising material for different applications due to its chemical stability, nontoxic nature, high efficiency, and low production cost [32,33]. In addition, the antibacterial activity of copper ions (Cu 2+ ) has been reported by many researchers [34,35] and Cu 2+ has been reported to possess other valuable biological features such as enhancing the cell activity and proliferation of osteoblastic cells [36], improving the angiogenesis of bioactive scaffolds, wound healing [37], anti-cancer [38,39], and biological imaging probes [40]. Owing to these distinct properties, it is noteworthy to investigate the antimicrobial activities of CuO [41].…”