Detection In Aqueous Media Research Articles

Facile synthesis of yellow emissive heteroatom doped carbon quantum dots fluorescent probe with superior quantum yield for fast-track ionic detection in aqueous media

In this work, heteroatom (B and N) doped carbon quantum dots (CQDs) materials were synthesized via facile hydrothermal method using o-phenylenediamine (o-PD) as a nitrogen source and 3-aminophenyl boronic acid (3APBA) as a boron source. The synthesis parameters were optimized and optimal synthesis temperature and reaction time were 260 °C and 2 h, respectively. The chemical structures were characterized using various techniques. The experimental results showed that B,N co-doped CQDs had the strongest fluorescence intensity when the weight ratio of 3APBA:o-PD was 3:1 and showed a phenomenal quantum yield of 59% with high selectivity for Fe3+ and Hg2+ ions, with quenching constants 1.25 × 103 M–1 and 8.3 × 103 M–1, respectively. The high fluorescence quenching was attributed to the photoinduced electron transfer phenomenon, making it suitable for fluorescent sensing materials. Cytotoxicity data revealed synthesized materials are safe for biomedical applications within a 1–10 µg/mL concentration.

A Fluorescent Probe Derived from L‐Tryptophan for Copper (II) Ion Detection in Aqueous Media

AbstractCopper (Cu2+) is a transition metal ion extensively distributed in numerous foodstuffs of both animals and vegetables. An excess intake of Cu2+ ions cause injury, pneumonitis, a disorder in the nervous system, and gastrointestinal problems. Hence, we have developed a simple and novel Schiff base‐based fluorescence sensor for the detection of Cu2+ ions. The sensor, ‐3‐(1H‐indol‐3‐yl)‐2‐((4‐nitrobenzylidene) amino)propanoic acid (INAP), was synthesized from tryptophan and nitrobenzaldehyde by the reflux method and characterized by various analytical methods. The prepared INAP acted as a chemical sensor and displayed outstanding sensitivity and choosiness characteristics for Cu2+ ions an aqueous solvent. In the presence of Cu2+, it demonstrated a fluorescence change in an aqueous medium with a “turn‐off” phenomenon via complex‐mediated energy transfer characteristics, and the method of continuous variation suggested a 1 : 2 complex formation of the metal ion with INAP. The LOD of the sensor system was calculated to be 1.3 μM for the Cu2+ ion. In addition, the INAP fluorescent probe was applied to tap water samples and found acceptable recoveries. These results suggest that the newly fabricated sensor system would be explored as a chemosensor for the recognition of Cu2+ ions in environmental samples.

Thermally versatile maleimide-based polymeric thin film for detection and separation of picric acid from polluted areas

2,4,6-Trinitrophenol, commonly known as picric acid, is a powerful explosive that has been used historically in military ammunition. Picric acid is extremely toxic and sensitive to friction and heat; thus, it is prone to accidental detonation at high temperatures. It is critical to detect and separate picric acid from the impacted areas. In the present study, we designed and developed a fluorescent copolymer (P1) for temperature-dependent picric acid detection. The solvatochromic and aggregation-induced emission (AIE) properties of P1 were utilized to detect picric acid at a high temperature of 40 °C (high alert level) by turn-off emission. Additionally, a polymeric thin film (F1) was fabricated by immobilizing P1 onto the surface of quartz slide. Notably, F1 retained its emissive properties across a range of temperatures (both relatively low and high alert levels), facilitated by its AIE characteristics. The portable film, F1, displayed a nanomolar sensitivity toward picric acid, making it suitable for on-site detection in aqueous media (neutral pH). Furthermore, F1 demonstrated efficient separation of picric acid from nitroaromatic explosive mixtures with a separation efficiency of 70 % over four cycles. Importantly, F1 exhibited practical utility in detecting and separating picric acid in real samples, highlighting its potential for environmental monitoring applications.

Multifunctional fluorescent switch based on a 3D Co-CP for selective detection of hypochlorite, nitrofuran antibiotics and acetylacetone

The abuse of biological and environmental related materials, such as pharmaceutical antibiotics, volatile organic chemicals and toxic ions has become a topical issue that draws the global attention. Thus, the exploration of effective methods for the rapid recognition of contaminants at low concentrations is critical for curtailing pollution and identifing environmental risks. Previous reports have shown that NH2-functionalized LCPs can serve as effective traps of hypochlorite owing to their rapid chemical reaction with hypochlorite. Herein, we strategically prepared a novel three-dimensional (3D) CP, [Co2(edda)(datrz)(H2O)2]·EtOH (Co-CP), using NH2-decorated triazole ligand 3,5-diamino-1,2,4-triazole (datrz) combined with semirigid tetracarboxylic acid 5,5′-(ethane-1,2-diylbis(oxy)) diisophthalic acid (H4edda). The prepared Co-CP features a pcu topology with point symbol of {412.63}. This material exhibits high structural stability in acidic-basic aqueous solution of broad pH scope (1–11), which is favorable for fluorescence detection in aqueous medium. As expected, the open -NH2 sites within the framework endow this fluorescent CP with remarkable detectability towards hypochlorite in aqueous media. Furthermore, Co-CP also displays satisfactory fluorescence response for sensing nitrofuran antibiotics (NFT and NFZ) and acetylacetone with high sensitivity and selectivity along with great interference immunity. Through exhaustive theories calculations and experimental surveys, the possible mechanisms have also been thoroughly investigated. The CP-based multifunctional fluorescent switch designed in this work expands the application of such materials in biological and environmental related areas.

Electrochemical sensing platform using cerium tungstate for highly sensitive sensing of chromium in water

Chromium, in some forms and large amounts, can be hazardous to human health and the environment. In particular, hexavalent chromium Cr(VI) and its derivatives are the most poisonous forms of Cr, whose toxicity depends on its oxidation state. Herein, cerium tungstate (CeW) is demonstrated as an efficient sensing material for Cr(VI) detection in aqueous medium. Two different surfactants are used to hydrothermally synthesize flake-like and sphere-like morphology. The flake-like morphology shows excellent Cr(VI) detection ability owing to its larger surface area, oxygen vacancy defects, and electrochemically active surface area. The sensitivity and limit of detection (LoD) value of the CeW nanoflakes are found to be 0.71 μA/ppb and 6.1 ppb, respectively. The LoD is lower than the WHO recommended standard value, which suggests that the synthesized material can be used for determining Cr(VI) concentration in domestic and potable water. The presence of different ions, such as Fe3+, Zn2+, Cu2+, Hg2+and Pb2+in the medium is found not interfere the Cr(VI) detection ability of CeW nanoflakes and thereby enhancing its practical applicability in Cr(VI) detection.

Surface decorated graphene oxide with porphyrin: A promising on-off sensor for Mn2+ ions detection in aqueous media

In this study, meso‑tetrakis(4-carboxyphenyl)porphyrin (TCPP) was chemically bonded to the surface of graphene oxide (GO) nanosheets and characterized by various techniques. The sensing prowess of the prepared composite towards metal ions was investigated through photoluminescence (PL) spectroscopy. Our results indicate that TCPP-GO can detect Mn2+ ions through fluorescence quenching. Therefore, experiments related to concentration, selectivity, detection limit, and response time were conducted to study the performance of the TCPP-GO sensor. A linear response of fluorescence intensity of TCPP-GO and Mn2+ in the 25–270 μM range with a detection limit of 1.8 μM was observed. The competition test displayed that the presence of other ions such as Sn2+, Pt2+, Ca2+, Na+, Fe3+, Fe2+, Zn2+, Cu2+, Cr2+, Co2+, Ni2+ had no significant effect on detecting Mn2+ ions. Furthermore, the suggested sensor demonstrated excellent performance for sensing manganese ions in real water samples.

C. Halicacabum derived “turn-on-off” non-invasive molecularly imprinted polymer for selective profiling of 2-(3,4-dihydroxy phenyl) ethylamine in human fluid samples

A rationally designed “Turn on-off” molecularly imprinted fluorescent probe SCDs-MPs serves as a robust platform for the specific identification of aberrant dopamine (DA) levels. In this study, carbon dots (SCDs) were synthesized usingCardiospermum Halicacabum leaf extract as a carbon source via a step hydrothermal process. The synergistic integration of the synthesized fluorophore SCDs (QY–27.6 %) with molecularly imprinted elements via reverse micro-emulsion technique forms novel C. Halicacabum derived SCDs-MPs nanocomposite. The synthesized SCDs-MPs possess various inimitable properties such as hydrophilicity (WCA of 12.9°) suitability for detection in aqueous media, the narrow bandgap of 3.45 eV attributed to the electron-donating nature, and photostability. Fluorescence lifetime, from 6.38 ns to 6.17 ns after adding dopamine to SCDs-MPs, and zeta potential studies (–32.9 mV to –23.9 mV) validate the static fluorescence quenching mechanism in SCDs-MPs. Under various modifications and experimental conditions, SCDs-MPs consistently achieved a low dopamine detection limit of 6.4 pM within the range of 0–50 µM. Excellent recovery experiments in human fluid samples (98–102 %) confirm the fluorescent probe’s empirical reliability. The MTT assay confirms the superior biocompatibility of SCDs-MPs, with cell viability remaining at ± 24.03 % at a concentration of 200 µg/ml suggesting the safe usage for invitro administration. This opens new possibilities for utilizing C. Halicacabum derived SCDs-MPs material in biomedical contexts.

A One‐Pot Synthesized Chemodosimetric Chemosensor for Highly Sensitive Cyanide Ion Detection in Aqueous Media and from Tobacco Smoke

AbstractA sustainable future world consistently attributes to the development of eco‐friendly methods and materials for detection and elimination of toxic substances from the environment. While addressing the issues, pyrazole carbonitrile derived Schiff base PYR−TZ has been designed and employed for colorimetric and turn on fluorometric cyanide ion sensing. PYR−TZ demonstrated high cyanide ion (CN−) sensitivity with a 1 : 1 binding stoichiometry in aqueous solution. By preventing intramolecular charge transfer, the PYR−TZ sensor demonstrated excellent selectivity towards CN, which caused a color transition from colorless to yellow and impressive “turn‐on” fluorescence emission. The detection thresholds for CN− are 6.5 nm for absorbance spectra and 0.396 nm emission spectra, respectively. Under typical ecological and physiological settings (pH 1–12), the PYR−TZ sensor can function as an effective chemical sensor for detecting the CN− ions. Additionally, the sensor can find CN in tobacco commercial products like cigarettes and cigars. PYR−TZ is a great cyanide sensor probe that has a number of benefits, which includes simple synthesis, distinct color and emission change, a high degree of selectivity, lesser limit of detection, reversibility, and good anti‐interference ability to analyze solution and tobacco commercial things, together with fluorescence imaging. The theoretical optimized structure and electronic transitions were confirmed by DFT and TDDFT studies. On the basis of theoretical and experimental calculations (DFT), the mechanism of the metal ion complex is postulated.

AIE-active cyclometalated iridium(iii) complexes for highly efficient picric acid detection in aqueous media

Three Ir(iii) complex-based AIEgens have been developed to detect picric acid efficiently in aqueous solution. The bright emission of these complexes in the aggregated and crystalline states is supported by crystal structure and triplet state TDDFT study.

Tryptophan-based fluorescent sensor for selective Cu2+ detection in aqueous media and its docking study for anticancer effects

In this study, an efficient copper (II) chemosensor was introduced. This chemosensor had a different response in fluorescent spectra, and the interaction between Cu2+ and tryptophan hydrazide (TH) was substantiated as a static quencher. In addition, there is a good relationship between the fluorescent intensity of tryptophan-based fluorescent and the concentration of Cu2+ ions with a detection limit of LOD = 24.32 x 10−5 M. The interference by many other cations was also evaluated, which was almost negligible. The docking calculation of this chemical with protein PDB: 5vc3 and PDB: 2xp2 protein PDB: 5vc3 and PDB: 2xp2 was performed, exhibiting significant anticancer potential as well. The present research also focused on the use of molecular docking calculation with a significant role in drug design. The protein three-dimensional (3D) structure of protein PDB: 5vc3 and PDB: 2xp2 were isolated from the protein data bank and docked with tryptophan derivatives. The docking results confirmed that the tryptophan derivatives had the best docking score −7.5–7.6 kcal/mol with PDB: 5vc3 and PDB: 2xp2 protein for breast cancer. The study demonstrated that this compound can function as both a chemosensor for the detection of metal ions and as a bioactive agent with potential anticancer properties.

Exploiting halide perovskites for heavy metal ion detection.

Heavy metal ions such as mercury (Hg), copper (Cu), and cadmium (Cd) pose significant threats to ecosystems and human health due to their toxicity and bioaccumulation potential. With growing environmental concerns over heavy metal ion pollution, there is an urgent need to develop efficient detection methods for safeguarding public health and the environment. Various materials, including polymers, nanomaterials, and porous substances, have been used for heavy metal ion detection and have shown promising performance for different scenarios. However, each of these materials has certain limitations as probes. Metal halide perovskites (MHPs), known for their exceptional optoelectronic properties and high structural and chemical tunability, have gained great attention in applications such as photovoltaics and LEDs. Yet, their potential as metal ion probes remains rarely explored. This review assesses MHPs as prospective materials for heavy metal ion detection, taking their structure, chemical properties, and responses to external stimuli into consideration. Three key detection mechanisms-cation exchange (CE), electron transfer (ET), and fluorescence resonance energy transfer (FRET), are explored to understand how metal ions trigger fluorescence changes on perovskites, enabling their detection. Finally, current avenues of developing perovskite probes are discussed, which include exploration of lead-free perovskites to mitigate environmental concerns arising from lead leakage and the pursuit of achieving high-sensitivity and stable detection in aqueous media, summarizing the existing and promising strategies in this field.

A rhodamine-6G based chromo and fluorogenic sensor for the selective turn-ON detection of Fe3+ in aqueous medium with potential applications as INHIBIT logic gate, memory device and live cell imaging

A novel rhodamine-6G based biocompatible chromo- and fluorogenic “OFF-ON” sensor L2, having amide based metal ion receptor, has been synthesized using Michael addition reaction and characterized by IR, NMR and HRMS spectroscopic studies. It exhibits an excellent selectivity and sensitivity towards Fe3+ in aqueous medium over mono- and di-valent and other trivalent metal ions. A 14-fold enhancement of fluorescence intensity was found upon addition of 11.5 equivalent Fe3+ ion into the probe L2 in H2O (pH 7.2, 10 mM HEPES buffer) with colour change from colourless to reddish yellow, providing an opportunity for naked eye detection of Fe3+. The corresponding binding constant Kf was evaluated to be (1.16 ± 0.04) x 104 M−1 with 1:1 stoichiometry. Quantum yields of L2 and [L2 - Fe3+] complex in H2O (pH 7.2, 10 mM HEPES buffer) were found to be 0.013 and 0.523, respectively using Rhodamine-6G as standard. LOD of L2 for Fe3+ detection in aqueous medium determined by 3σ/slope method was found to be 4.184 μM. Cyanide ion scavanges Fe3+ from [L2 - Fe3+] resulting quenching of fluorescence due to re-attainment of the non-fluorescent spirolactam ring form of the probe. As the sensing phenomenon is reversible, it helps to frame INHIBIT logic gate and memory devices.

Fluorene and Tetraphenylsilane Based Conjugated Microporous Polymer Nanoparticles for Highly Efficient Nitroaromatics Detection in Aqueous Media

AbstractConjugated microporous polymers (CMPs) are considered promising sensing materials for the detection of nitroaromatics. Unfortunately, the photoluminescence (PL) sensing application in water media is limited, owing to the poor solubility/dispersion in aqueous media. Here, two novel CMPs named poly(dimethylfluorene‐co‐tetrakis(4‐phenyl)silane)s (P4SiF) and poly(dimethylfluorene‐co‐tetrakis(3‐phenyl)silane)s (P3SiF) nanoparticles based on fluorene group and tetraphenylsilane unit are prepared using Suzuki coupling in water/toluene miniemulsion. P4SiF and P3SiF possess spherical particle morphology with sizes of 45 and 60 nm, respectively, and porous structure with pore diameters of both 1.9 nm. PL sensing experiments based on P4SiF and P3SiF nanoparticles in aqueous media show a sensitive and selective detection toward 2,4,6‐trinitrophenol (TNP). It is worth noting that the PL quenching effect toward TNP is not significantly changed after the addition of other nitro compounds, proving the excellent anti‐interference characteristic and highly selective detection of the polymers in water. Moreover, the t‐test indicates that the PL sensing method using P4SiF and P3SiF nanoparticles as sensing materials realizes the reliable detection of TNP in actual water samples at a 95% confidence level. Finally, the PL sensing mechanism is investigated, showing that the inner filter effect is the main factor in the PL quenching process of TNP in aqueous media.

A simple dual responsive chemosensor for selective sensing of Cs+ for environmental monitoring and mimicking molecular logic gates

Detection of toxic metals is of vital importance to safeguard both public health and the ecosystem. Herein, we investigate the newly designed and synthesised isoxazole-based azo dye, (E)-cyclopentyl(5-((5-(4-fluorophenyl) isoxazole-3-yl) diazenyl)-2-hydroxyphenyl) methanone (FPAZ), as a dual chromogenic and fluorogenic sensor. FPAZ demonstrates high selectivity, reusability and ultra-sensitivity towards Cs+ ions manifested through naked eye detection in aqueous medium by employing simple and economic optical spectroscopy techniques. The color change from colourless to dark yellow and enhancement of fluorescence intensity reveal about FPAZ-Cs+ complexation by UV–Vis and fluorescence spectroscopy respectively. The complexation is also supported by DFT calculations. The LOD is estimated to be 0.476 µM, which by far, is the lowest LOD obtained for Cs+ detection. Further, FPAZ is fabricated with various flexible materials (paper, cotton, non-woven fabric) which provide information about on-site Cs+ ion contamination by means of change in relative RGB values using a handy smart-phone camera. Besides this, the logic gate as IMPLICATION and INHIBIT is designed employing Cs+ and Cl- ions as inputs and absorbance maxima as output. Overall, the developed chemosensor is simple, quick, and more promising than previously reported systems, as it does not need any chemical modification, expensive instruments, or expertise.

Design of smart polymeric sensor based on poly(N-isopropylacrylamide) and anthrapyrazolone derived fluorescent crosslinker for the detection of nitroaromatics in aqueous medium

Explosive detection in aqueous medium using fluorometric titrations is of paramount importance for security and safety, as it offers a susceptible and rapid method to identify potential threats in water sources or aqueous environments, ensuring the protection of critical infrastructure and public safety. Previously, we have investigated fluorescence-based explosive detection via π-electron-rich anthrapyrazolone-derived fluorophore moiety (dye) as an effective sensor in an organic medium. However, the dye's solubility in water makes it difficult to identify nitroaromatics (NACs) in aqueous media. In the current study, thermoresponsive crosslinked polymer (TCP) with dye [DHBBI(MA)2] added as a crosslinker between the polymer chains is synthesised by straightforward and easy free radical polymerization. The emission intensity of TCP is significantly reduced with interaction with NACs like TNP, ATNP, DNP, and PNP, primarily through static quenching attributed to a photoinduced electron transfer (PET) process. TNP exhibited the most efficient quenching, with a Ksv value of 10.7 × 102 M−1 for TCP and 6.189 × 102 M−1 for DHBBI(MA)2. The limit of detection (LOD) was 0.12 nM for TCP and 0.135 nM for DHBBI(MA)2. TCP proved to be approximately 1.72 and 1.12 times more efficient in TNP detection than DHBBI(MA)2 in terms of Ksv value and LOD. At higher temperatures beyond the LCST of the polymer, TCP exhibits additional fluorescence quenching, making it effective for NAC detection. This switch in fluorescence quenching near the cloud point temperature (TCP) of PNIPAM in aqueous media indicates TCP's potential for real-world applications, including rapid detection and identification of nitroaromatics and environmental monitoring in soil and water.

Tetraphenylethene-Based Cross-Linked Conjugated Polymer Nanoparticles for Efficient Detection of 2,4,6-Trinitrophenol in Aqueous Phase.

The cross-linked conjugated polymer poly(tetraphenylethene-co-biphenyl) (PTPEBP) nanoparticles were prepared by Suzuki-miniemulsion polymerization. The structure, morphology, and pore characteristics of PTPEBP nanoparticles were characterized by FTIR, NMR, SEM, and nitrogen adsorption and desorption measurements. PTPEBP presents a spherical nanoparticle morphology with a particle size of 56 nm; the specific surface area is 69.1 m2/g, and the distribution of the pore size is centered at about 2.5 nm. Due to the introduction of the tetraphenylethene unit, the fluorescence quantum yield of the PTPEBP nanoparticles reaches 8.14% in aqueous dispersion. Combining the porosity and nanoparticle morphology, the fluorescence sensing detection toward nitroaromatic explosives in the pure aqueous phase has been realized. The Stern-Volmer quenching constant for 2,4,6-trinitrophenol (TNP) detection is 2.50 × 104 M-1, the limit of detection is 1.07 μM, and the limit of quantification is 3.57 μM. Importantly, the detection effect of PTPEBP nanoparticles toward TNP did not change significantly after adding other nitroaromatic compounds, indicating that the anti-interference and selectivity for TNP detection in aqueous media is remarkable. In addition, the spike recovery test demonstrates the potential of PTPEBP nanoparticles for detecting TNP in natural environmental water samples.

Pencil lead graphite electrochemically modified with polyglutamic acid as a sensor for detection of enrofloxacin in aqueous media

This study investigates the modification of pencil lead graphite electrodes with polyglutamic acid using an effective and fast static method to develop a sensor for the detection of enrofloxacin (ENR). The successful fabrication of pGA on the electrode surface was confirmed by scanning electron microscopy, energy dispersive X-ray analysis, and Fourier-transform infrared spectroscopy. The conditions of electrochemical modification, including the applied potentials and number of cycles in the potentiostatic process, were systematically investigated to determine their effects on the ENR electrochemical response. The pH of the electrolyte media was also explored to elucidate the electrochemical reaction mechanism of ENR. The developed electrochemical sensor was evaluated using square wave stripping voltammetry for ENR detection. Under optimal conditions, the sensor demonstrated good reproducibility with a relative standard deviation of 4.3% (from five measurements) for ENR signal detection. A linear relationship between ENR concentration and its peak current was observed in the concentration range of 0.1 to 5 μM, with a high correlation coefficient of 0.9988. The limit of detection for ENR using the sensor was 0.12 μM. Our findings provide valuable insights into the design and optimisation of pencil lead graphite electrode-based sensors for ENR detection in aqueous media.

Al3+-Responsive Ratiometric Fluorescent Sensor for Creatinine Detection: Thioflavin-T and Sulfated-β-Cyclodextrin Synergy.

Kidney disorders are a rising global health issue, necessitating early diagnosis for effective treatment. Creatinine, a metabolic waste product from muscles, serves as an ideal biomarker for kidney damage. The existing optical methods for creatinine detection often involve labor-intensive synthesis processes and present challenges with the aqueous solubility and sensitivity to experimental variations. In this study, we introduce a straightforward fluorescence "turn-on" ratiometric sensor system for creatinine detection in aqueous media with a limit of detection of 0.5 μM. The sensor is based on sulfated-β-cyclodextrin (SCD)-templated H-aggregate of a commercially available, ultrafast rotor dye thioflavin-T (ThT). The Al3+ ion-induced dissociation of ThT-SCD aggregates, followed by reassociation upon creatinine addition, generates a detectable signal. The modulation of monomer/aggregate equilibrium due to the disassembly/reassembly of the ThT-SCD system under Al3+/creatinine influence serves as the optimal strategy for ratiometric creatinine detection in aqueous media. Our sensor framework offers several advantages: utilization of the readily available dye ThT, which eliminates the need for a laborious synthesis of custom fluorescent probes; ratiometric sensing, which improves quantitative analysis accuracy; and compatibility with complex aqueous media. The sensor's practical utility has been successfully demonstrated in artificial urine samples. In summary, our sensor system represents a significant advancement in the rapid, selective, and sensitive detection of the clinically crucial bioanalyte creatinine, offering potential benefits for the early diagnosis and management of kidney disorders.

Dabcyl as a Naked Eye Colorimetric Chemosensor for Palladium Detection in Aqueous Medium.

Industrial activity has raised significant concerns regarding the widespread pollution caused by metal ions, contaminating ecosystems and causing adverse effects on human health. Therefore, the development of sensors for selective and sensitive detection of these analytes is extremely important. In this regard, an azo dye, Dabcyl 2, was synthesised and investigated for sensing metal ions with environmental and industrial relevance. The cation binding character of 2 was evaluated by colour changes as seen by the naked eye, UV-Vis and 1H NMR titrations in aqueous mixtures of SDS (0.02 M, pH 6) solution with acetonitrile (99:1, v/v). Out of the several cations tested, chemosensor 2 had a selective response for Pd2+, Sn2+ and Fe3+, showing a remarkable colour change visible to the naked eye and large bathochromic shifts in the UV-Vis spectrum of 2. This compound was very sensitive for Pd2+, Sn2+ and Fe3+, with a detection limit as low as 5.4 × 10-8 M, 1.3 × 10-7 M and 5.2 × 10-8 M, respectively. Moreover, comparative studies revealed that chemosensor 2 had high selectivity towards Pd2+ even in the presence of other metal ions in SDS aqueous mixtures.

Photoluminescent Copper Nanoclusters in “Turn-Off/Turn-On” Sensing of Picric Acid/Hydrogen Peroxide

In this paper, we illustrate the synthesis, characterization, and application of a Bovine Serum Albumin-stabilized copper nanocluster (BSA@CuNCs)-based photoluminescence (PL) bifunctional sensor for the selective and rapid sensing of picric acid (PA) and hydrogen peroxide (H2O2). Blue-emitting copper nanoclusters were synthesized using one-pot synthesis at room temperature. The PL intensity of BSA@CuNCs was shown to be quenched (“Turn-off”) with an increase in the concentration of PA and intensified (“Turn-on”) with the addition of H2O2. The quenching of PL intensity of BSA@CuNCs was shown to be extremely selective and rapid towards PA. A linear decrease in the PL emission intensity of BSA@CuNCs was observed with a PA concentration in the range of 0–15 μM. An extremely low detection limit of 60 nM (3σ/k) was calculated. The as-prepared BSA@CuNCs also exhibited superior selectivity for PA detection in aqueous medium. The developed sensor was also utilized for the sensing of PA in natural water samples. The probe was found to be extremely sensitive towards the detection of H2O2. An increase in the PL intensity of BSA@CuNCs was seen with the addition of H2O2, with a detection limit of 0.11 μM.