Search Results (61)

Fluorescent chemosensors are increasingly becoming relevant in recognition chemistry due to their sensitivity, selectivity, fast response time, real-time detection capability, and low cost. Boronic acids have been reported for the recognition of mycolactone, the cytotoxin responsible for tissue damage in Buruli ulcer disease. A library of fluorescent arylboronic acid chemosensors with various signaling moieties with certain beneficial photophysical characteristics (i.e., aminoacridine, aminoquinoline, azo, BODIPY, coumarin, fluorescein, and rhodamine variants) and a recognition moiety (i.e., boronic acid unit) were rationally designed and synthesised using combinatorial approaches, purified, and fully characterised using a set of complementary spectrometric and spectroscopic techniques such as NMR, LC-MS, FT-IR, and X-ray crystallography. In addition, a complete set of basic photophysical quantities such as absorption maxima (λ_abs^max), emission maxima (λ_em^max), Stokes shift (∆λ), molar extinction coefficient (ε), fluorescence quantum yield (Φ_F), and brightness were determined using UV-vis absorption and fluorescence emission spectroscopy techniques. The synthesised arylboronic acid chemosensors were investigated as chemosensors for mycolactone detection using the fluorescent-thin layer chromatography (f-TLC) method. Compound 7 (with a coumarin core) emerged the best (λ_abs^max = 456 nm, λ_em^max = 590 nm, ∆λ = 134 nm, ε = 52816 M⁻¹cm⁻¹, Φ_F = 0.78, and brightness = 41,197 M⁻¹cm⁻¹). Full article

The design of suitable chemosensors for environmental pollutants and toxins detection at trace levels remains a critical area of research. Among various chemosensors, Zn(II) coordination polymers have garnered special interest as fluorescent probes for environmental applications. In this article, we report the synthesis of a nitrogen-rich luminescent Zn(II) coordination polymer, TDPAT-Zn-CP, designed for differential fluorescent sensing of antibiotics in an aqueous medium. TDPAT-Zn-CP was synthesized using a star-shaped 2,4,6-tris(di-2-pyridylamino)-1,3,5-triazine (TDPAT) fluorophore, a promising blue-emitting compound. The morphological and structural properties of TDPAT-Zn-CP were thoroughly analyzed using conventional spectroscopic and analytical techniques. The fluorescence titration studies in aqueous medium demonstrated that TDPAT-Zn-CP exhibits remarkable selectivity, sensitivity, and differential fluorescence sensing responses towards various antibiotics. Among the antibiotics tested, TDPAT-Zn-CP displayed a significant fluorescence quenching and high selectivity for sulfamethazine (SMZ), with a Stern–Volmer quenching constant of K_SV = 1.68 × 10⁴ M⁻¹ and an impressive sensitivity of 4.95 ppb. These results highlight the potential of TDPAT-Zn-CP as a practically useful, highly effective polymeric sensor for the differential fluorescence-based detection of antibiotics in water, offering a promising approach for environmental monitoring and contamination control. Full article

Heavy and transition metal (HTM) ions have significant harmful effects on the physical environment and play crucial roles in biological systems; hence, it is crucial to accurately identify and quantify any trace pollution. Molecular sensors which are based on organic molecules employed as optical probes play a crucial role in sensing and detecting toxic metal ions in water, food, air, and biological environments. When appropriate combinations of conduction and selective recognition are combined, fluorescent and colorimetric chemosensors are appealing instruments that enable the selective, sensitive, affordable, portable, and real-time investigation of the possible presence of heavy and transition metal ions. This feature article aims to provide readers with a more thorough understanding of the different methods of synthesis and how they work. As noted in the literature, we will highlight colorimetric and fluorometric sensors based on their receptors into multiple categories for heavy metal ion detection, such as Hg²⁺, Ag²⁺, Cd^2+, Pb²⁺, and In³⁺, and simultaneous multiple-ion detection. Full article

The development of optical chemosensors for the sensitive and selective detection of trace-level metal ions in aqueous solutions has drawn a lot of attention from the scientific community in recent years. Organic sensors offer a number of advantages over traditional identification techniques, including low cost, high sensitivity, selectivity, and simplicity of synthesis. We will focus on colorimetric and fluorometric sensors based on their receptors for the real-time detection of certain first-row transition metal ions like Cr³⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺ Cu²⁺, and Zn²⁺. The development of these sensors will aid in the rapid and simple resolution of several problems linked to the detection of potentially hazardous metal ions at trace levels in diverse biological and environmental components. This review article not only gives a comprehensive understanding of the existing techniques, but also encourages more research efforts to address the evolving demands in the field of trace transition metal ion detection. Full article

Artificial enzymes or nanozymes (NZs) are gaining significant attention in biotechnology due to their stability and cost-effectiveness. NZs can offer several advantages over natural enzymes, such as enhanced stability under harsh conditions, longer shelf life, and reduced production costs. The booming interest in NZs is likely to continue as their potential applications expand. In our previous studies, we reported the “green” synthesis of copper hexacyanoferrate (gCuHCF) using the oxidoreductase flavocytochrome b₂ (Fcb₂). Organic–inorganic micro-nanoparticles were characterized in detail, including their structure, composition, catalytic activity, and electron-mediator properties. An SEM analysis revealed that gCuHCF possesses a flower-like structure well-suited for concentrating and stabilizing Fcb₂. As an effective peroxidase (PO) mimic, gCuHCF has been successfully employed for H₂O₂ detection in amperometric sensors and in several oxidase-based biosensors. In the current study, we demonstrated the uniqueness of gCuHCF that lies in its multifunctionality, serving as a PO mimic, a chemosensor for ammonium ions, a biosensor for L-lactate, and exhibiting perovskite-like properties. This exceptional ability of gCuHCF to enhance fluorescence under blue light irradiation is being reported for the first time. Using gCuHCF as a PO-like NZ, novel oxidase-based sensors were developed, including an optical biosensor for L-arginine analysis and electrochemical biosensors for methanol and glycerol determination. Thus, gCuHCF, synthesized via Fcb₂, presents a promising platform for the development of amperometric and optical biosensors, bioreactors, biofuel cells, solar cells, and other advanced devices. The innovative approach of utilizing biocatalysts for nanoparticle synthesis highlights a groundbreaking direction in materials science and biotechnology. Full article

A novel rhodamine-6G derivative RdN was synthesized by condensing rhodamine glyoxal and 3-hydroxy-2-naphthoic hydrazide using a microwave irradiation-assisted reaction. Colorimetric and photophysical studies have demonstrated that the molecule produced can selectively sense Pb²⁺ and Cu²⁺ ions in a solution of CH₃CN/H₂O (9:1, v/v). The spirolactam ring of RdN opens upon complexation with the cations, forming a highly fluorescent complex and a visible color change in the solution. The compound RdN was further studied with the help of computational methods such as the Density Functional Theory (DFT) method and time-dependent density theory (TD-DFT) calculations to study the binding interactions and properties of the molecule. DFT calculations and job plot data supported the 2:1 complex formation between RdN and Pb²⁺/Cu²⁺. The limit of detection for Pb²⁺ was determined to be 0.112 µM and 0.130 µM for Cu²⁺. The probe RdN was applied to the image of Pb²⁺ and Cu²⁺ ions in living cells and is safe for biomedical applications. It is used to monitor Pb²⁺ in environmental water samples. Full article

Copper, along with gold, was among the first metals that humans employed. Thus, the copper pollution of the world’s water resources is escalating, posing a significant threat to human health and aquatic ecosystems. It is crucial to develop detection technology that is both low-cost and feasible, as well as ultra-selective and sensitive. This study explored the use of the NH₂-Xxx-His motif-derived peptide from phage display technology for ultra-selective Cu²⁺ detection. Various Cu-binding M13 phage clones were isolated, and their affinity and cross-reactivity for different metal ions were determined. A detailed analysis of the amino acid sequence of the unique Cu-binding peptides was employed. For the development of an optical chemosensor, a peptide with an NH₂-Xxx-His motif was selected. The dansyl group was incorporated during solid-phase peptide synthesis, and fluorescence detection assays were employed. The efficacy of the Cu²⁺-binding peptide was verified through spectroscopic measurements. In summary, we developed a highly selective and sensitive fluorescent chemosensor for Cu²⁺ detection based on a peptide sequence from a phage display library that carries the N-terminal Xxx-His motif. Full article

Three decades after A. P. de Silva’s seminal paper introduced the concept of logic gates at the molecular level, the field of molecular logic gates (MLGs) has witnessed significant advancements. MLGs are devices designed to perform logical operations, utilizing one or more physical or chemical stimulus signals (inputs) to generate an output response. Notably, MLGs have found diverse applications, with optical detection of analytes emerging as a notable evolution of traditional chemosensors. Organic synthesis methods are pivotal in crafting molecular architectures tailored as optical devices capable of analyte detection through logical functions. This review delves into the fundamental aspects and physical–chemical properties of MLGs, with a particular emphasis on synthetic strategies driving their design. Full article

The few commercially available chemosensors and published probes for in vitro Zn²⁺ detection in two-photon microscopy are compromised by their flawed spectroscopic properties, causing issues in selectivity or challenging multistep syntheses. Herein, we present the development of an effective small molecular GFP chromophore-based fluorescent chemosensor with a 2,2′-bipyridine chelator moiety (GFZnP BIPY) for Zn²⁺ detection that has straightforward synthesis and uncompromised properties. Detailed experimental characterizations of the free and the zinc-bound compounds within the physiologically relevant pH range are presented. Excellent photophysical characteristics are reported, including a 53-fold fluorescence enhancement with excitation and emission maxima at 422 nm and 492 nm, respectively. A high two-photon cross section of 3.0 GM at 840 nm as well as excellent metal ion selectivity are reported. In vitro experiments on HEK 293 cell culture were carried out using two-photon microscopy to demonstrate the applicability of the novel sensor for zinc bioimaging. Full article

The expansion of global industry results in the release of harmful volatile acid vapors into the environment, posing a threat to various lifeforms. Hence, it is crucial to prioritize the development of swift sensing systems capable of monitoring these volatile acid vapors. This initiative holds great importance in safeguarding a clean and safe environment. This paper presents the synthesis and characterization of pyrene-based covalent organic frameworks (COFs) that exhibit exceptional crystallinity, thermal stability, and intense fluorescence. Three COFs—PP–COF, PT–COF, and PE–COF—were synthesized, demonstrating large surface areas and robust thermal stability up to 400 °C. The fluorescence properties and intramolecular charge transfer within these COFs were significantly influenced by their Schiff base bonding types and π-stacking degrees between COF layers. Notably, PE-COF emerged as the most fluorescent of the three COFs and exhibited exceptional sensitivity and rapid response as a fluorescent chemosensor for detecting HCl in solution. The reversible protonation of imine bonds in these COFs allowed for the creation of highly sensitive acid vapor sensors, showcasing a shift in spectral absorption while maintaining structural integrity. This study highlights the potential of COFs as reliable and reusable sensors for detecting harmful acid vapors and addressing environmental concerns arising from industrial activities. Full article

MXenes have received worldwide attention across various scientific and technological fields since the first report of the synthesis of Ti₃C₂ nanostructures in 2011. The unique characteristics of MXenes, such as superior mechanical strength and flexibility, liquid-phase processability, tunable surface functionality, high electrical conductivity, and the ability to customize their properties, have led to the widespread development and exploration of their applications in energy storage, electronics, biomedicine, catalysis, and environmental technologies. The significant growth in publications related to MXenes over the past decade highlights the extensive research interest in this material. One area that has a great potential for improvement through the integration of MXenes is sensor design. Strain sensors, temperature sensors, pressure sensors, biosensors (both optical and electrochemical), gas sensors, and environmental pollution sensors targeted at volatile organic compounds (VOCs) could all gain numerous improvements from the inclusion of MXenes. This report delves into the current research landscape, exploring the advancements in MXene-based chemo-sensor technologies and examining potential future applications across diverse sensor types. Full article

A fluorescence grating sensor based on a pyridine derivative was synthesized. The results showed that it can rapidly identify and detect toxic heavy metal ions, such as Cr²⁺, Hg²⁺, Ni²⁺ and Co²⁺. When these toxic heavy metal ions were added to the fluorescence array sensor, different fluorescent responses were produced due to the different binding capacities of the metal ion complex. These toxic heavy metal ions present in environmental water were identified using the fluorescence grating sensor. This sensor provides a fast and convenient method for monitoring toxic heavy metal ions in wastewater. Full article

Developing colorimetric devices for detecting chemical species is essential in many fields; nevertheless, developing effective chemosensors for many heavy and transition metal ions remains an important issue. As a result, in recent years, the use of colorimetric sensors for the selective and sensitive detection of metal ions has grown in popularity. Pyrazolones and their derivatives are heterocyclic compounds that have attracted interest due to their biological and pharmacological features. As a result, they have been used in various areas, including agriculture, medicine, organic synthesis, and analytical chemistry. However, the potential for chemosensing has yet to receive much attention. In this study, thiomethyl-substituted (4Z)-4-[(pyrazol-4-yl)methylene]pyrazolone was synthesized, and its ability to act as an optical chemosensor for several metals was evaluated. According to preliminary results, this molecule could be an optical chemosensor to detect Fe³⁺, Sn²⁺, and Al³⁺. Full article

Bearing in mind the interest in the development and application of amino acids/peptides as bioinspired systems for sensing, a series of new phenylalanine derivatives bearing thiosemicarbazone and hydrazone units at the side chain were synthesised and evaluated as fluorimetric chemosensors for ions. Thiosemicarbazone and hydrazone moieties were chosen because they are considered both proton-donor and proton-acceptor, which is an interesting feature in the design of chemosensors. The obtained compounds were tested for the recognition of organic and inorganic anions (such as AcO⁻, F⁻, Cl⁻, Br⁻, I⁻, ClO₄⁻, CN⁻, NO₃⁻, BzO⁻, OH⁻, H₂PO₄⁻ and HSO₄⁻) and of alkaline, alkaline-earth, and transition metal cations, (such as Na⁺, K⁺, Cs⁺, Ag⁺, Cu⁺, Cu²⁺, Ca²⁺, Cd²⁺, Co²⁺, Pb²⁺, Pd²⁺, Ni²⁺, Hg²⁺, Zn²⁺, Fe²⁺, Fe³⁺ and Cr³⁺) in acetonitrile and its aqueous mixtures in varying ratios via spectrofluorimetric titrations. The results indicate that there is a strong interaction via the donor N, O and S atoms at the side chain of the various phenylalanines, with higher sensitivity for Cu²⁺, Fe³⁺ and F⁻ in a 1:2 ligand-ion stoichiometry. The photophysical and metal ion-sensing properties of these phenylalanines suggest that they might be suitable for incorporation into peptide chemosensory frameworks. Full article

pH regulation is essential to allow normal cell function, and their imbalance is associated with different pathologic situations, including cancer. In this study, we present the synthesis of 2-(((2-aminoethyl)imino)methyl)phenol (HL1) and the iron (III) complex (Fe(L1)₂Br, (C1)), confirmed by X-ray diffraction analysis. The absorption and emission properties of complex C1 were assessed in the presence and absence of different physiologically relevant analytes, finding a fluorescent turn-on when OH⁻ was added. So, we determined the limit of detection (LOD = 3.97 × 10⁻⁹ M), stoichiometry (1:1), and association constant (K_as = 5.86 × 10³ M⁻¹). Using DFT calculations, we proposed a spontaneous decomposition mechanism for C1. After characterization, complex C1 was evaluated as an intracellular pH chemosensor on the human primary gastric adenocarcinoma (AGS) and non-tumoral gastric epithelia (GES-1) cell lines, finding fluorescent signal activation in the latter when compared to AGS cells due to the lower intracellular pH of AGS cells caused by the increased metabolic rate. However, when complex C1 was used on metastatic cancer cell lines (MKN-45 and MKN-74), a fluorescent turn-on was observed in both cell lines because the intracellular lactate amount increased. Our results could provide insights about the application of complex C1 as a metabolic probe to be used in cancer cell imaging. Full article