New Fluorescent Metal-Ion Detection Using a Paper-Based Sensor Strip Containing Tethered Rhodamine Carbon Nanodots

Abstract

A strip of tethered rhodamine carbon nanodots (C-dots) was designed for selective detection of Al(3+) ion using a Förster resonance energy transfer (FRET)-based ratiometric sensing mechanism. The probe consisted of rhodamine B moieties immobilized on the surface of water-soluble C-dots. Upon exposure to Al(3+), the rhodamine moieties showed a much enhanced emission intensity via energy transfer from the C-dots under excitation at their absorption wavelength. The detection mechanism was related to the Al(3+)-induced ring-opening of rhodamine on C-dots through the chelation of the rhodamine 6G moiety with Al(3+), leading to a spectral overlap of the absorption of C-dots (donor) and the emission of ring-opened rhodamine (acceptor). In addition, a paper-based sensor strip containing the tethered rhodamine C-dots was prepared for practical, versatile applications of Al(3+) sensing. The paper-based sensor could detect Al(3+) over other metal ions efficiently, even from a mixture of metal ions, with increased emission intensity at long-wavelength emission via FRET. Sensing based on FRET of C-dots is color-tunable, can be recognized with a naked eye, and may provide a new platform for specific metal-ion sensing.

Fluorescent nanoprobes for sensing and imaging of metal ions: Recent advances and future perspectives

“…For example, Guo et al [244] developed a simple, one-step hydrothermal method for the synthesis of highly fluorescent CNPs with a high quantum yield (68%) and good photo-stability, and can be used to detect Hg 2+ in an aqueous solution. CDs have also been used to detect other ions such as Sn 2+ , Cu 2+ , Ag + , and Al 3+ [245]. …”

Understanding the Photoluminescence Mechanism of Nitrogen‐Doped Carbon Dots by Selective Interaction with Copper Ions

“…Generally, metal‐CDs interactions have been widely implemented in fluorescent‐based sensor applications. For example, FRET‐based fluorescence detection of metal ions such as Al 3+ and K + have been separately accomplished using CDs …”

“…For example, FRETbased fluorescenced etectiono fm etal ions such as Al 3 + and K + have been separately accomplished using CDs. [21,22] Copper is an essential element in the human body,p resent in numerousk ey enzymesi ncluding cytochrome co xidase, superoxide dismutase, and tyrosinase. Similart oo ther metal ions, as urplusa mount of copperi nt he body causesr enal disordersa nd damages in the central nervouss ystem.…”

Sensitive distance-based paper-based quantification of mercury ions using carbon nanodots and heating-based preconcentration

“…Although many mPAD applications have emerged over the last decade in elds such as diagnostics, biological samples, food safety, and environmental analysis, [24][25][26][27][28][29][30] mPADs continue to be developed for various aspects of metal detection. Kim et al 31 reported a new uorescent method for Al 3+ and Hg 2+ detection using a paperbased sensor strip containing tethered rhodamine carbon nanodots. The sensor could efficiently detect Al 3+ over other metal ions via forester resonance energy transfer (FRET).…”

“…Sensing based on FRET of NCDs is color-tunable and can be identied with the naked eye, providing a new platform for specic metal-ion sensing. Unfortunately, the method still suffers from low sensitivity with limits of detection for Al 3+ 31 and Hg 2+ 32 at around 1 mg L À1 . These levels are insufficient for monitoring aluminum and mercury in drinking water where the maximum allowable aluminum and mercury levels established by the WHO are at 0.1 and 6 mg L À1 , respectively.…”