Ratiometric Fluorescence Detection Research Articles

Coumarin-based fluorescent probes for colorimetric and ratiometric fluorescent detection of sulfite: Structure-activity relationship

Six coumarin-based fluorescent probes were designed and synthesized for the detection of sulfite. The probes were constructed based on “fluorophore-receptor/linker-steric group” mode with N,N-diethyl-7-aminocoumarin (DEA) or 2,3,5,6-1H,4H-tetrahydro-quinolazino-(9,9a,1-gh)coumarin (THQ) as the fluorophore, 2-naphthyl ketone (N) or phenyl ketone (B) as the steric group and vinyl (1) or 1,3-butadienyl (2) as the receptor/linker. The effects of the fluorophore, the linker and the steric group on the photophysical properties and sensing performance were systematically studied. Among all the probes, DEA-N2 exhibited the most excellent spectral responses toward sulfite: upon addition of sulfite, the absorption and emission maxima shifted from 488 nm to 405 nm and–from 684 nm to 484 nm, respectively. I484/I688 displayed good linear relationship with sulfite concentration in the range of 3–50 μM, with a detection limit of 0.31 μM. The experimental results demonstrate that DEA-N2 has potential in ratiometric fluorescent imaging of mitochondrial sulfite in living cells.

Synthesis and fluorescence properties of a two-dimensional Cd-complex for the ratiometric fluorescence detection of Zn2+ ions

The two-dimensional complex [Cd3(L)(2,2'-bpy)2]n (1) was synthesized solvothermally from 4,5-di(3,5-dicarboxylphenoxy)phthalic acid (H6L) and 2,2'-bipyridine (2,2'-bpy) and fully characterized by elemental analysis, infrared spectroscopy, single crystal and powder X-ray diffraction. Complex 1 displays high stability in water and resistance towards acidic and basic media. Fluorescence studies revealed that it may be acted as a ratiometric fluorescence probe to detect Zn2+ ions in water with a superior detection limit of 3.48 nM. The fluorescence recognition mechanism stems from weak interactions between Zn2+ ions and complex 1. Its pronounced stability and recyclability suggest that the new material may be used for high-precision detection of Zn2+ ions in real-life aqueous samples, even under acidic and basic conditions.

Deep eutectic solvent-assisted synthesis of CeO2/CuO nanozymes for polymer dots integrated ratiometric fluorescence detection of glutathione

The current designs of ratiometric fluorescence sensing strategies primarily make use of the opposite responses of analyte target to two fluorescence probes, often overlooking their potential capabilities for signal amplification. Herein, a novel ratiometric fluorescence sensor was constructed for sensitive detection of glutathione (GSH) by combining CeO2/CuO nanozymes with poly[2,7-(9,9′-dioctylfluorene)-alt-4,7-bis(thiophen-2-yl) benzo-2,1,3-thiadiazole] (PFO-DBT)-based polymer dots (Pdots). The CeO2/CuO nanozymes with high oxidase-like activity were prepared via a deep eutectic solvent (DES) strategy and used for catalytic oxidization of o-phenylenediamine to produce fluorescent 2,3-diaminophenazine (DAP), which concurrently quenched the fluorescence of Pdots through photoinduced electron transfer (PET), thus amplifying the ratiometric signal. Upon addition of target GSH, the oxidase-like activity of CeO2/CuO were inhibited due to its blocking to metal active sites and scavenging superoxide anion (O2‧−), which responsively decreased the amount of produced DAP, and thus increased the fluorescence of Pdots. The designed CeO2/CuO-OPD-Pdots system showed a linear ratiometric response to GSH concentration within the range of 2 μM to 20 μM, with a limit of detection (LOD) determined as 1.24 μM. The proposed method could be used for selective detection of GSH in serum samples, and thus possessed potential application in clinic analysis.

Rapid and reliable ratiometric fluorescence detection of isoquercitrin based on a high-nuclearity Zn(II)-Nd(III) nanomolecular sensor

Rapid and quantitative detection of isoquercitrin (Isq) has been attracting much attention due to its outstanding pharmacological and physiological activities. Herein, an interesting 48-metal Zn(II)-Nd(III) nanocluster (1, molecular sizes 1.3 × 2.8 × 3.1 nm) with salen-type Schiff base ligand was constructed as molecular sensor for the luminescence detection of Isq. 1 exhibits visible ligand-centered emission and NIR luminescence of Nd(III), and shows ratiometric fluorescence response to Isq with high sensitivity even in the presence of other interferences. The fluorescence sensing behavior can be expressed by a second-order equation I1060nm/I480nm = A*[Isq]2 + B*[Isq] + C, which is used to quantitatively analyze the Isq concentrations in DMF and FCS. The LODs to Isq for the ligand-centered and lanthanide emissions of 1 in DMF are 0.21 μM and 0.11 nM, respectively. The quenching of the ligand-centered emission of 1 caused by Isq is attributed to the competitive absorption of light energy and “inner effect”, while, the luminescence enhancement is due to the “antenna effect”.

Ratiometric Fluorescence Detection of Levofloxacin Based on a Cube-like Zn(II)-Eu(III) Nanocluster: Functionalized Sodium Alginate Film for the Detection in Serum and Medicine.

A cube-like Zn(II)-Eu(III) nanocluster 1 (molecular sizes: 1.8 × 2.0 × 2.0 nm) was constructed by the use of a new long-chain Schiff base ligand. It shows a ratiometric fluorescence response to levofloxacin (LFX) with high sensitivity and selectivity, which can be expressed as I615nm/I550nm = A*[LFX]2 + B*[LFX] + C. It is used to quantitatively detect the LFX concentrations in fetal calf serum (FCS) and tablets sold in pharmacy. Filter paper strips bearing 1 can be used to qualitatively detect LFX by a color change to red under a UV lamp. 1 and its hybrid with sodium alginate (SA), 1@SA, display potential applications in the qualitative detection of LFX in FCS and the medicine. The limit of detection of 1 to LFX is as low as 2.1 × 10-2 nM.

Construction of MOF@COF-derived composites for ratiometric fluorescence detection of water with ultralow background

A ratiometric sensor with ultralow background is highly desired due to its low environmental influence and high sensitivity. Herein, inspired by the solubility difference of carboxylate in aqueous and organic solvents, we prepared a core–shell structure porous zirconia–covalent organic framework (COF) composite through thermal hydrolysis of UiO-66-COF precursors in organic alkali solution. The ligand 2-aminoterephthalic acids (H2BDC-NH2) of UiO-66 were transformed into 2-aminoterephthalate salts (ATA salts) that existed in zirconium-oxo clusters building units. The composites emitted only yellow emission (597 nm) from the COF in organic solvent due to the insolubility of ATA salts that induce aggregation-caused quenching (ACQ) and the protection of the COF shell. Contrarily, when water was added into mixture, the ATA salts were released into solution and its fluorescence recovered at 446 nm, while the fluorescence of COF was quenched due to the blockage of the intramolecular charge transfer (ICT) process by water. Thus, a high-sensitivity ratiometric fluorescence method is obtained with ultralow background signal and fast response (less than 1 min) for sensing water in organic solvent. We believe that the proposed ratiometric fluorescence sensor based on the zirconia–COF composite will provide the guidance for detection with wide applications.

Portable ratiometric fluorescence detection of Cu2+and thiram.

Food contaminants pose a danger to human health, but rapid, sensitive and reliable food safety detection methods can offer a solution to this problem. In this study, an optical fiber ratiometric fluorescence sensing system based on carbon dots (CDs) and o-phenylenediamine (OPD) was constructed. The ratiometric fluorescence response of Cu2+and thiram was carried out by the fluorescence resonance energy transfer (FRET) between CDs and 2,3-diaminophenazine (ox-OPD, oxidized state o-phenylenediamine). The oxidation of OPD by Cu2+resulted in the formation of ox-OPD, which quenched the fluorescence of CDs and exhibited a new emission peak at 573 nm. The formation of a [dithiocarbamate-Cu2+] (DTC-Cu2+) complex by reacting thiram with Cu2+, inhibits the OPD oxidation reaction triggered by Cu2+, thus turning off the fluorescence signal of OPD-Cu2+. The as-established detection system presented excellent sensitivity and selectivity for the detection of Cu2+and thiram in the ranges of 1 ∼ 100μM and 5 ∼ 50μM, respectively. The lowest detection limits were 0.392μM for Cu2+and 0.522μM for thiram. Furthermore, actual sample analysis indicated that the sensor had the potential for Cu2+and thiram assays in real sample analysis.

Oxidized TMB mediated dual-optical sensing-based paper analytical device for high-throughput visual monitoring of 2,4-dichlorophenoxyacetic acid

High-throughput and accurate monitoring of pesticide residues is extremely crucial, but remains challenging. Herein, oxidized 3,3′,5,5′-tetramethylbenzidine (oxTMB) mediated dual-optical sensing-based paper analytical device (PAD) was unveiled for on-site visual detection of 2,4-dichlorophenoxyacetic acid (2,4-D) in real samples. Colorimetric blue oxTMB (652 nm) can be reduced to colorless TMB by ascorbic acid (AA). Meanwhile, oxTMB was demonstrated for the first time to switch oxidation and condensation reactions between o-phenylenediamine and AA to produce yellow-emission (564 nm) and blue-emission (429 nm) probes. Thus, colorimetric and ratiometric fluorescent dual-mode detection system was developed for 2,4-D detection by combining with alkaline phosphatase (ALP) initiating AA generation (ascorbic acid-2-phosphate as the substrate). Notably, the developed method can correct itself to improve the accuracy due to the dual-response signals. Using the principle, ALP-loaded PAD (array 3 × 10) was designed for efficient and high-performance detection of 2,4-D in turnip and cauliflower with good sensitivity (0.09 μg/mL for colorimetry, 0.06 μg/mL for fluorometry), satisfactory recovery (98.0 %–107.2 %), and high consistency (relative error ≤ 3.1 %). This work demonstrated a promising strategy for high-throughput visual detection of 2,4-D, which may provide a new pathway for the further development of dual-mode sensing platforms to efficiently detect other targets for food safety.

A ratiometric fluorescence probe for bisulfite detection in live cells and meat samples

The development of reliable probe technology for the detection of bisulfite (HSO3-) in situ in food and biological samples is contributing significantly to food quality and safety assurance as well as community health. In this work, a responsive probe, EHDI, is developed for ratiometric fluorescence detection of HSO3- in aqueous solution, meat samples, and living cells. The probe is designed based on the HSO3- triggered 1,4-addition of electron deficit C = C bond of EHDI. As a result of this specific 1,4-addition, the π-conjugation system was destructed, resulting in blue shifts of the emission from 687 to 440 nm and absorption from 577 to 355 nm. The probe has good water solubility, high sensitivity and selectivity, allowing it to be used for imaging of HSO3- internalization and production endogenously. The capability of probe EHDI for HSO3- was then validated by traditional HPLC technology, enabling accurately detect HSO3- in beef samples. The successful development of this probe thus offers a new tool for investigating HSO3- in situ in food and biological conditions.

Ratiometric fluorescence detection of dopamine based on copper nanoclusters and carbon dots

Nanoclusters for fluorescence detection are generally comprised of rare and expensive noble metals, and the nanoclusters based on more affordable transition metal have attracted increasing attention. This study designed a ratiometric fluorescent probe to detect dopamine (DA), an important neurotransmitter. With carbon dots encapsulated within silica (CDs@SiO2) as the reference, the emitted reference signal was almost unchanged due to the protection of inert silicon shell. Meanwhile, copper nanoclusters modified with 3-aminophenyl boronic acid (APBA-GSH-CuNCs) provided the sensing signal, in which the phenylboric acid could specifically recognize the cis-diol structure of DA, and caused the fluorescence quenching by photoinduced electron transfer. This dual emission ratiometric fluorescent probe exhibited high sensitivity and anti-interference, and was able to selectively responded to DA with a linear range of 0–1.4 mM, the detection limit of 5.6 nM, and the sensitivity of 815 mM−1. Furthermore, the probe successfully detected DA in human serum samples, yielding recoveries ranging from 92.5% to 102.7%. Overall, this study highlights the promising potential of this ratiometric probe for detecting DA.

Cyanine based ratio fluorescent probe and its application in hypochlorite detection

Hypochlorite (ClO−), a weakly acidic reactive oxygen species, plays a crucial role in antibacterial and anti-inflammatory defense mechanisms. However, elevated levels of ClO− or disruptions in endogenous sites can lead to tissue damage and various diseases including cardiovascular disease, neuronal degeneration, and arthritis. To address this, the development of a specific fluorescent probe with a built-in self-calibration ratio mode for the analysis and biological imaging of ClO− is essential. In this study, a cyanine-based fluorescent probe (Cy-H) was designed for ratiometric fluorescent detection of ClO−, utilizing its aggregation behavior as a novel approach in this field. Upon exposure to ClO−, the phenolic hydroxyl group in probe Cy-H was oxidized into benzoquinone, leading to the formation of cyanine products that displayed a strong tendency to aggregate. As a result, the maximum emission peak of the probe shifted from 700 nm to 485 nm. Notably, a linear relationship was observed between the peak intensity ratio (I485/I700) and the concentration of hypochlorite, with a limit of detection (LOD) of 0.49 μM. Furthermore, this probe was successfully employed for imaging analysis of hypochlorite in living cells and zebrafish.

Electrophilicity Modulation for Sub-ppm Visualization and Discrimination of EDA.

Precise and timely recognition of hazardous chemical substances is of great significance for safeguarding human health, ecological environment, public security, etc., especially crucial for adopting appropriate disposition measures. Up to now, there remains a practical challenge to sensitively detect and differentiate organic amines with similar chemical structures with intuitive analysis outcomes. Here, a unique optical probe with two electrophilic recognition sites for rapid and ultra-sensitive ratiometric fluorescence detection of ethylenediamine (EDA) is presented, while producing distinct fluorescence signals to its structural analog. The probe exhibits ppb/nmol level sensitivity to liquidous and gaseous EDA, specific recognition toward EDA without disturbance to up to 28 potential interferents, as well as rapid fluorescence response within 0.2 s. By further combining the portable sensing chip with the convolutional algorithm endowed with image processing, this work cracked the problem of precisely discriminating the target and non-targets at extremely low concentrations.

A ternary dual-emission Eu(III)-functionalized HOF/COF hybrid: Tryptophan, 5-hydroxyindoleacetic acid ratiometric fluorescence detection and latent fingerprint identification

Fluorescent covalent organic framework (COFs) and lanthanide functionalized hydrogen-bonded organic framework have been widely studied in the field of fluorescence sensing due to their excellent properties. To our knowledge, there is no report about HOF/COF composites by combining HOF and COF. In our work, we propose a simple in-situ growth method to synthesize HOF/COF by adding pre-synthesized fluorescent COF into HOF preparation system. Based on the coordination post-synthetic modification, the ternary Eu(III) functional HOF/COF hybrid material (Eu@HOF/COF) is obtained, in which partial organic linkers of HOF are transformed to a new structure induced by Eu(III). At the single excitation wavelength, Eu@HOF/COF has two emission peaks corresponding to COF and Eu(III), respectively, and its luminescence is little affected by water molecules, which is relatively rare in previous work. Eu@HOF/COF, as a ratiometric fluorescence sensor can detect tryptophan and its metabolite 5-hydroxyindoleacetic acid with high selectivity, fast response, good sensitivity and recovery. Eu@HOF/COF has good fluorescence emission of Eu(III) and COF, and a large number of free carboxyl groups of HOF react with residues in latent fingerprint (LFP), which is beneficial in LFP identification. In summary, this study not only provides a useful reference for the construction of hybrid materials with Eu(III) and COF dual-emission centers, but also reveals that the new structure formed after the coordination of Eu(III) and HOF to sensitize Eu(III) luminescence, and also has the potential for the early detection of depression and diagnosis of carcinoid tumors.

Design of a dual-mode ratiometric fluorescent probe via MOF-on-MOF strategy for Al (III) and pH detection

BackgroundThe construction of ratiometric fluorescent MOF sensors with integrated self-calibration and dual-channel detection can efficiently overcome the deficiencies of single-signal sensing. In this regard, the rational design of structurally functionalized MOFs is paramount for enhancing their performance in ratiometric fluorescent sensors. Lately, the concept of MOF-on-MOF design has garnered notable interest as a potential strategy for regulating the structural parameters of MOFs by integrating two or more distinct MOF types. Great efforts have been dedicated to exploring new MOF-on-MOF hybrids and developing their applications in diverse fields. Even so, these materials are still in the stage of advancement in the sensing field. ResultsHerein, a Zr-based metal-organic framework anchored on a rare-earth metal-organic framework (UiO-66(OH)2@Y-TCPP) was prepared for the ratiometric fluorescence detection toward Al (III) and pH. In this probe, the UiO-66(OH)2 featured hydroxyl active sites for Al (III), leading to a significant enhancement in fluorescence intensity upon the addition of Al (III), while the signal emitted by the red-emitting Y-TCPP, serving as the reference, remained constant. UiO-66(OH)2@Y-TCPP exhibited excellent selectivity for Al (III) sensing with a wider linear range of 0.1–1000 μM, and a lower detection limit of 0.06 μM. This probe has also been utilized for the quantitative determination of Al (III) in hydrotalcite chewable tablets with satisfactory results. In addition, the probe realized ratiometric pH sensing in the range of 7–13 using UiO-66(OH)2 as an interior reference. The paper-based probe strip was developed for visual pH sensing. By installing color recognition and processing software on a smartphone, real-time and convenient pH sensing could be achieved. SignificanceThis is the first ratiometric fluorescent sensor for Al (III) and pH detection based on a MOF-on-MOF composite probe, which yields two different response modes. The detection results of Al (III) in hydrotalcite chewable tables and smartphone imaging for pH test paper demonstrate the practicability of the probe. This work opens up a new outlook on constructing a multi-functional application platform with substantial potential for employment in environmental and biological analysis tasks.

A zwitterionic probe for ratiometric fluorescent detection of aluminium(III) ion in aqueous medium and its application in bioimaging

In the present study, we have synthesized an aminobenzoic acid containing Schiff base (compound 1) and its structure was confirmed through single crystal X-ray study. Importantly, the compound 1 crystallizes in the zwitterionic form, with an anionic carboxylate group (–COO−) and a cationic iminium group (–C = NH+–). The compound 1 is highly soluble in water due to its zwitterionic feature in the solid state. Interestingly, compound 1 acts as a ratiometric fluorescent probe for the selective detection of Al3+ ion in aqueous solution without organic cosolvent. It can also detect Al3+ ion by visual colour change to bluish-green fluorescence under 365 nm UV light. The association constant between compound 1 with Al3+ ion was estimated to be 1.67 × 104 M−1. The lowest detection limit for Al3+ ion was calculated to be 7.05 × 10−8 M in water. Compound 1 in combination with Al3+ ion demonstrated fluorescent imaging potential of the nucleus of in RAW 264.7 murine macrophage cell line. In addition, the sensing model is developed as paper based sensor ''Test Kit' 'for its practical applicability.

FRET-Based Host-Guest Supramolecular Probe for On-Site and Broad-Spectrum Detection of Pyrethroids in the Environment.

The massive use of pyrethroid pesticides in agriculture has brought growing concerns about food safety due to their several harmful effects on human health, especially through the accumulation of the food chain. To date, most of the available analytical methods for pyrethroids still suffer from insufficient detection universality, complicated sample pretreatment, and detection processes, which severely limit their practical applications. Herein, a novel Förster resonance energy transfer (FRET)-assisted host-guest supramolecular nanoassembly is reported, for the first time, successfully realizing ratiometric fluorescent detection of pyrethroids in real samples through the indicator displacement assay (IDA) mechanism. This method is capable of detecting a broad spectrum of pyrethroids, including bifenthrin, cyfluthrin, cypermethrin, deltamethrin, etofenprox, fenvalerate, and permethrin, with ultrahigh detection sensitivity, great selectivity, high anti-interference ability, and, in particular, distinct emission color response from red to green. Such a large chromatic response makes this method available for fast and on-site detection of pyrethroids in real samples with the aid of several simple portable analytical apparatuses.

Novel lignin-derived carbon dots nanozyme cascade-amplified for ratiometric fluorescence detection of xanthine oxidase and intracellular imaging

The development of lignin-derived carbon dots with dual functionality of fluorescence and enzyme-like activity was realized by hydrochloric acid mediated carbon dots modification, and then a ratiometric fluorescence sensing strategy to detect xanthine oxidase activity was constructed. Sodium lignosulfonate (LS) was used as the carbon source and modified lignin carbon dots (CDs) with both fluorescence and peroxidase-like activities were prepared. DFT theoretical calculations and experiments demonstrated that carbonyl, carboxyl, and chloride on the surface of carbon dots were potential active sites to catalyze production of ·OH from H2O2. Xanthine oxidase generated H2O2 in the process of catalyzing the production of uric acid from the substrate xanthine. The ·OH produced via LS-CDs catalyzed H2O2 oxidized residual o-phenylenediamine (OPD) groups on surface of OPD-CDs to enhance yellow fluorescence, accompanied by blue fluorescence quenching of LS-CDs. The realization of a highly sensitive, highly selective, and visualized ratiometric fluorescence sensing strategy was achieved. The linear range of the established fluorescence sensing system for xanthine oxidase was 0.5–120 U/L with detection limit of 0.13 U/L. The cascade reaction signal transduction improves the designability of sensing method. Finally, the system successfully realized the sensing of xanthine oxidase in serum and cells.

Water-stable Cu-based coordination polymer for ratiometric fluorescence detection of riboflavin

Riboflavin was first isolated from milk and widely used in food, biological and pharmaceutical fields. Accurate detection of riboflavin content is of great significance for the treatment of related diseases and the supervision of food/drug quality. In this paper, a 1D chain copper-based coordination polymer with excellent water stability was synthesized by hydrothermal method using rigid ligand 1,10-phenanthroline and flexible ligand 1,4-phenylenedioxydiacetic acid, named Cu-phen-PEDA. Based on the Förster resonance energy transfer (FRET) and dynamic quenching detection mechanism, the emission spectrum of Cu-phen-PEDA overlaps with the absorption spectrum of riboflavin. As an energy donor in this case, Cu-phen-PEDA significantly increases the fluorescence intensity of riboflavin (energy acceptor), while simultaneously decreasing its own fluorescence intensity, which is an effective proportional-building strategy. In the lower concentration range, riboflavin can be specifically recognized by ratiometric fluorescence with a good linear relationship, and the detection limit is as low as 23 nM. The potential aspects of its specificity, stability, reusability and practical application were explored.

Spatial confinement of styryl pyridine salt derivative in MCM-22 molecular sieve network for boosted fluorescence emission and stable ratiometric sensing of bacillus anthracis biomarkers

In this work, a stable ratiometric nanofluorescent probe for the detection of 2,6-dipicolinic acid (DPA), a Bacillus anthracis biomarker, was developed based on confinement-induced emission enhancement of cationic styrylpyridine salt derivative L in MCM-22 molecular sieve pores. The cationic L and the lanthanide Tb3+ were loaded into the pores of the molecular sieve by electrostatic interaction with the negatively charged AlO4 tetrahedron unit, and L exhibited enhanced red fluorescence emission as a stable fluorescence reference mark in the nanoprobe platform due to the restricted molecular torsion of L in the pores of MCM-22. At the same time, the characteristic green fluorescence emission of Tb3+ can be excited by energy transfer due to the “antenna effect” of DPA. The prepared Tb-L@MCM-22 nanoprobe showed specific selectivity and stable fluorescence ratiometric detection of DPA in tap water, lake water, bovine serum and actual bacterial spores. Benefiting from the confinement-induced fluorescence enhancement effect of L in the MCM-22 molecular sieve pores, the obtained Tb-L@MCM-22 can provide a stable reference signal for the fluorescence ratiometric detection of DPA with a limit of detection (LOD) of 78.6 nM and 1.310 × 104 spores per mL. More importantly, combining of the Tb-L@MCM-22 based DPA detection test strips with a smartphone app demonstrated a stable, convenient and rapid method for detecting of anthrax biomarkers.

Chemical surface modification of carbon dots with Germanium: A highly sensitive and selective ratiometric fluorescence probe for Mg2+ detection using DFT and TD-DFT

In this study, we chemically modified carbon dots (Cdots) using germanium, enhancing their sensitivity and selectivity as a ratiometric fluorescence probe for precise detection of Mg2+ ions. Excitation of the modified Cdots resulted in a distinct emission peak at 527 nm, enabling accurate measurement of Mg2+ concentrations across a linear range. The surface modification with germanium led to the creation of novel emitting centers on the Cdots' surface. Theoretical calculations using density functional theory (DFT) revealed the effective suppression of these emitting centers through a photo-induced electron transfer (PET) process, utilizing the nitrogen lone pair electrons on the Cdots' surface. Furthermore, adjacent Cdots' surface pyrazino[2,3-f][1,10]-phenanthroline (PPT) nitrogen atoms formed chemical bonds with Mg2+ ions, resulting in the formation of aggregated Cdots. Consequently, the intricate complexation terminated the PET process, resulting in a novel emission peak at longer wavelengths. This study presents a highly sensitive and selective ratiometric fluorescent detection system with exceptional low concentration detection limit for precise Mg2+ ion detection.