We report a facile and eco-friendly strategy for the fabrication of green fluorescent carbon nanodots (CDs), and demonstrate their applications for bio-imaging, patterning, and staining. A one-pot hydrothermal method using various plant petals yields bright green-emitting CDs, providing an easy way for the production of green fluorescent CDs without the need for a tedious synthetic methodology or the use of toxic/expensive solvents and starting materials. The as-prepared CDs show small size distribution and excellent dispersibility. Their strong green fluorescence is observed when the excitation wavelength is between 430 nm and 490 nm. Moreover, they exhibit high tolerance to various external conditions, such as pH values, external cations, and continuous excitation. Due to minimum toxicity as well as good photoluminescence properties, these CDs can be applied to in vitro and in vivo imaging, patterning, and staining. According to confocal fluorescence imaging of human uterine cervical squamous cell carcinoma cells, CDs penetrate into the cell and enter the cytoplasm and the nucleus. More strikingly, carp is directly fed with CDs for in vivo imaging and shows bright green fluorescence at an excitation wavelength of 470 nm. In addition, the obtained CDs are used as fluorescent inks for drawing luminescence patterns. Finally, we also apply the CDs as a fluorescent dye. Interestingly, the absorbent filter paper with staining emits dramatic fluorescence under 470 nm excitation.
The AuNCs@Tf-Cu2+ system for the sensitive and selective detection of endogenous glutathione (GSH) can illuminate tumor cells rather than normal cells, which implied its great potential application in cancer diagnosis.
Herein, we present a simple and economical
synthesis for the first
multianalyte probe able to selectively quantify the concentrations
of Fe3+, NO2
–, and cysteine.
It comprises H+-triggered self-assembled gold nanoclusters
(AuNCs@EW/H+, AuEHs), showing enhanced red fluorescence
at 640 nm. The AuEH is a good fluorescent nanosensor for Fe3+ and NO2
– with detection limits of 1.40
and 2.82 nM, respectively. Iron detection, through fluorescence quenching,
occurs because of nanocluster aggregation elicited by the complexation
of Fe3+ with amino acids on the surface of AuEH; nitrite
detection likely proceeds through fluorescence quenching via the disassembly
of the nanoclusters following irreversible oxidation by nitrite. This
selectivity is good enough that it can be used to quantify the nitrite
concentration in commercially available processed meat. Cysteine detection
occurs through the restoration of fluorescence of iron-quenched samples;
similar molecules including homocysteine and glutathione are unable
to restore fluorescence, showing the specificity of the interaction.
Applications, including as a detecting ink and as a biocompatible
probe, show promise because of the lack of observable toxicity of
the AuEHs, demonstrating their promise as specific and sensitive biosensors.
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