Tuning ligand vicinity towards development of “turn-on” fluorescence for cadmium(II) ions under physiological pH and bio-imaging

Discriminating between Different Heavy Metal Ions with Fullerene-Derived Nanoparticles

“…With specific regard to Cd 2+ , large fluorescence turn-on effects can occur in molecular chromophores due to PET mechanisms interacting with rearrangements of the molecular structure [ 31 ], and this can lead to LODs as low as 0.1 pM [ 66 ]. However, in most of the molecular sensors reported in the literature, values in the nanomolar range, reasonably comparable to the present ones, are reported [ 48 , 67 ]. On the other hand, as discussed in the introduction, few experimental works have been carried out so far on the peculiar properties of carbon nanomaterials, i.e., the multiple sensitivity of fluorescence quenching with simultaneous variation of absorbance.…”

“…As displayed in Figure 4 a, the progressive addition of cadmium ions to the reference UFQD solution produced the gradual increase of the fluorescence signal F without any appreciable change of the spectral profile. It should be noted that, to our knowledge, such a fluorescence turn-on effect had never been reported in GOQDs, whereas it is commonly observed in molecular fluorophores and semiconductor quantum dots [ 48 , 49 , 50 ]. At the same time, no variations were observed in the absorption spectra, as displayed in Figure 4 b, apart from the progressive rise of the curve below 250 nm, which is clearly due to the increasing concentration of NO 3− ions coming from the added cadmium nitrate.…”

Terpyridine Functionalized Oligothiophene: Cadmium(II) Ion Sensing via Visualization and Fluorescence

“…More interestingly, treatment with Cd 2+ elicited a slight ‘turn‐on’ fluorescence response by ca .1.2 fold due to blocking of ICT via metal ion coordination which can be defined as metal chelation enhanced fluorescence effect ,. It is to be noted that the recognition process of Cd 2+ by 3T‐terpy can be gradually restored via introduction of excess EDTA, which can be explained by the difference in the association constant between EDTA‐Cd 2+ and 3T‐Terpy‐Cd 2+ (Figure S6) . Unfortunately, alternating addition of metal ions and EDTA demonstrated reversibility of metal ion‐induced changes couldn't achieved, which could be explained by the presence of thermal equilibriums and possible formation of mono‐ or di‐nuclear complex in this studied system .…”

“…As shown in Figure S11, we can see probe 3T‐Terpy was very sensitive to pH when being used to detect metal ions in aqueous solution. While the detection process was almost independent of the sample pH in the range of 5.0∼8.0, because of the protonation of the N atoms of Terpy units in lower pH and the formation of cadmium hydroxyl in higher pH conditions ,,…”

A novel and fast responsive turn-on fluorescent probe for the highly selective detection of Cd2+ based on photo-induced electron transfer

“…Therefore, the uorescent probe/ sensor has attracted increasing attention for its design and development. [16][17][18][19][20][21][22] Although cadmium ion uorescent probes/ sensors have been reported in literature, [23][24][25][26][27][28] there are still some difficulties that need to be overcome such as the complicated synthesis procedure, poor water solubility and slow response speed.…”