Encapsulation of Strongly Fluorescent Carbon Quantum
Dots in Metal–Organic Frameworks for Enhancing Chemical Sensing
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Abstract
Novel highly fluorescent (FL) metal–organic
frameworks (MOFs)
have been synthesized by encapsulating branched poly-(ethylenimine)-capped
carbon quantum dots (BPEI-CQDs) with a high FL quantum yield into
the zeolitic imidazolate framework materials (ZIF-8). The as-synthesized
FL-functionalized MOFs not only maintain an excellent FL activity
and sensing selectivity derived from BPEI-CQDs but also can strongly
and selectively accumulate target analytes due to the adsorption property
of MOFs. The selective accumulation effect of MOFs can greatly amplify
the sensing signal and specificity of the nanosized FL probe. The
obtained BPEI-CQDs/ZIF-8 composites have been used to develop an ultrasensitive
and highly selective sensor for Cu<sup>2+</sup> ion, with a wide response
range (2–1000 nM) and a very low detection limit (80 pM), and
have been successfully applied in the detection of Cu<sup>2+</sup> ions in environmental water samples. It is envisioned that various
MOFs incorporated with FL nanostructures with high FL quantum yields
and excellent selectivity would be designed and synthesized in similar
ways and could be applied in sensing target analytes