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Peptide-based fluorescent probes have found widespread applications in biomedical research, including bio-imaging, disease diagnosis, drug discovery, and image-guided surgery. Their favorable properties-such as small molecular size, low toxicity, minimal immunogenicity, and high targeting specificity-have contributed to their growing utility in both basic research and translational medicine. This review provides a comprehensive overview of recent advances in peptide-based fluorescent probes, emphasizing design strategies, biological targets, and diverse functional applications. Key areas of focus include the integration of molecular targeting with imaging capabilities, the emergence of multimodal imaging techniques, and the development of activatable probes responsive to specific biological stimuli. Applications are discussed in the context of tumor cell membrane recognition, subcellular organelle targeting, non-cancer disease diagnosis, and detection of both metal ions and non-metal ions. Notably, responsive probes for reactive oxygen species (ROS) and other biologically relevant non-metal ions are also highlighted, underscoring their diagnostic and therapeutic potential. The review also addresses key limitations-such as poor in vivo stability, limited targeting accuracy, and delivery efficiency-and outlines future directions including smart peptide probe platforms, self-reporting systems, and high-throughput screening based on peptide libraries to accelerate next-generation probe development.

Metal phthalocyanines (MPcs) are promising materials for electrochemical sensing due to their physicochemical properties, including redox activity, structural versatility, and chemical stability. These materials can incorporate various metals into their central core, ensuring tunable catalytic activity and enhanced sensitivity and selectivity. This makes MPcs valuable for designing advanced electrochemical sensors, which require precise and reliable performance for applications ranging from environmental monitoring to biomedical diagnostics. This review discusses the advancements in MPc‐based catalysts for electrochemical sensors, focusing on their superior catalytic properties, stability under diverse operating conditions, and high functionalization potential. The unique redox behavior of the metal center in MPcs ensures improved detection capabilities of analytes like biomolecules, heavy metal ions, and environmental pollutants, positioning MPc materials as a cornerstone in future sensor technology. MPc‐based sensors have diverse applications across various fields, including environmental sensing, medical diagnostics, and industrial process monitoring. Recent reports highlight the practical relevance and growing importance of MPcs in real‐world applications. Challenges associated with MPc‐based sensors include scalability, environmental stability, and integration into practical devices. The review concludes with a discussion on the future outlook on MPcs in the design and development of next‐generation electrochemical sensors, paving the way for more efficient, cost‐effective, and reliable detection technologies. This review highlights the recent advancements in metal phthalocyanine (MPc)‐based electrochemical sensors, focusing on their application in detecting a broad range of analytes, including biomolecules, pharmaceutical molecules, and environmental pollutants. It covers the basic principles of electrochemical sensors, MPcs' unique redox activity, chemical structure, synthesis strategy, and applications. Furthermore, the review summarizes the challenges, scope, perspective, and future direction.

The preparation of a highly water stable and porous lanthanide metal-organic framework (MOF) nanoparticles (denoted SUMOF-7II; SU refers to Stockholm University) is described. SUMOF-7II was synthesized starting from the tritopic linker of 2,4,6-tri-p-carboxyphenyl pyridine (H 3 L2) and La(III) as metal clusters. SUMOF-7II forms a stable dispersion and displays high fluorescence emission with small variation over the pH range of 6 to 12. Its fluorescence is selectively quenched by Fe(III) ions compared to other metal ions. The intensity of the fluorescene emission drops drops linearly in 16.6–167 μM Fe(III) concentration range, and Stern-Volmer plots are linear. The limit of detection (LOD) is 16.6 μM (at an S/ N  ratio of >3). This indicator probe can also be used for selective detection of tryptophan among several amino acids. Compared to the free linker H 3 L2, SUMOF-7II offers improved sensitivity and selectivity of the investigated species. Graphical abstract A water-stable porous lanthanide metal-organic framework SUMOF-7II (La) has shown to be an excellent probe for the detection of ferric ions among other metal ions, and tryptophan among other amino acids in aqueous solution. The new probe displays high and stable fluorescence signal in a wide pH range (6–12).

Detecting heavy metal ions is essential for maintaining environmental safety, ensuring industrial quality control, and protecting public health. In this study, we have synthesized a novel Rhodamine B-based fluorescent probe, RhB-DCT, which is functionalized with 2,4-dichloro-1,3,5-triazine (DCT) to enhance selectivity and sensitivity for metal ions detection. The probe functions through a “turn-on” fluorescence mechanism activated by the opening of the spiro-lactam ring induced by Fe[sup.3+] ions, resulting in a distinct color change from colorless to deep pink. The RhB-DCT probe demonstrated a rapid and robust fluorescence response within seconds, exhibited a broad pH stability from 4 to 13, showed excellent reversibility, and possessed a low detection limit of 0.0521 μM, surpassing numerous existing fluorescent probes. The RhB-DCT probe exhibited significant selectivity for Fe[sup.3+] than other competing metal ions. The integration of high sensitivity, rapid response, and strong stability positions RhB-DCT as a viable option for real-time detection of Fe[sup.3+] ions in aqueous settings. This study demonstrates the efficacy of the RhB-DCT probe in environmental monitoring, water quality assessment, and analytical sensing platforms, serving as an effective and dependable tool for detecting heavy metal ions.

Over the past few decades, nanoparticles of iron oxide Fe3O4 (magnetite) gained significant attention in both basic studies and many practical applications. Their unique properties such as superparamagnetism, low toxicity, synthesis simplicity, high surface area to volume ratio, simple separation methodology by an external magnetic field, and renewability are the reasons for their successful utilisation in environmental remediation, biomedical, and agricultural applications. Moreover, the magnetite surface modification enables the successful binding of various analytes. In this work, we discuss the usage of core–shell nanoparticles and nanocomposites based on Fe3O4 for the modification of the GC electrode surface. Furthermore, this review focuses on the heavy metal ions electrochemical detection using Fe3O4-based nanoparticles-modified electrodes. Moreover, the most frequently used electrochemical methods, such as differential pulse anodic stripping voltammetry and measurement conditions, including deposition potential, deposition time, and electrolyte selection, are discussed.

Detecting heavy metal ions is essential for maintaining environmental safety, ensuring industrial quality control, and protecting public health. In this study, we have synthesized a novel Rhodamine B-based fluorescent probe, RhB-DCT, which is functionalized with 2,4-dichloro-1,3,5-triazine (DCT) to enhance selectivity and sensitivity for metal ions detection. The probe functions through a “turn-on” fluorescence mechanism activated by the opening of the spiro-lactam ring induced by Fe3+ ions, resulting in a distinct color change from colorless to deep pink. The RhB-DCT probe demonstrated a rapid and robust fluorescence response within seconds, exhibited a broad pH stability from 4 to 13, showed excellent reversibility, and possessed a low detection limit of 0.0521 μM, surpassing numerous existing fluorescent probes. The RhB-DCT probe exhibited significant selectivity for Fe3+ than other competing metal ions. The integration of high sensitivity, rapid response, and strong stability positions RhB-DCT as a viable option for real-time detection of Fe3+ ions in aqueous settings. This study demonstrates the efficacy of the RhB-DCT probe in environmental monitoring, water quality assessment, and analytical sensing platforms, serving as an effective and dependable tool for detecting heavy metal ions.

Heavy metal pollution has attracted global attention because of its high toxicity, non-biodegradability, and carcinogenicity. Electrochemical sensors are extensively employed for the detection of low concentrations of heavy metal ions (HMIs). However, their applicability is often limited to the detection of ions that exhibit electrochemical signals exclusively in aqueous solutions. In this study, we proposed a multi-responsive detection platform based on the modification of horseradish peroxidase@zeolitic imidazolate frameworks-8/thionine/gold/ionic liquid-reduced graphene oxide (HRP@ZIF-8/THI/Au/IL-rGO). This platform demonstrated its capability to detect various metal ions, including those without conventional electrochemical signals. The Au/IL-rGO composite structure enhanced the specific surface area available for the reaction. Furthermore, the in situ growth of HRP@ZIF-8 not only shielded the THI signal prior to detection but also protected the electrode material. It was important to note that the introduced edetate disodium dihydrate (EDTA) had the ability to complex with various HMIs. When excess EDTA was present, it could cleave ZIF-8 and release HRP. In the presence of hydrogen peroxide (H 2 O 2 ), HRP promoted the oxidation of THI previously reduced by the electrode and thus showed excellent sensitivity for HMIs detection. The proposed method overcame the limitation of traditional electrochemical sensors, which solely relied on electrochemical signals for detecting metal ions. This offers a novel approach to enhance electrochemical ion sensing detection. Graphical Abstract

In recent years, the development of optical chemosensors for the sensitive and selective detection of trace level metal ions in aqueous media has garnered significant attention within the scientific community. This review article provides a comprehensive overview of the synthesis strategies and applications of optical chemosensors dedicated to the detection of metal ions at low concentrations in water-based environments. The discussion encompasses a wide range of metal ions, including but not limited to heavy metals, transition metals, and rare earth elements, emphasizing their significance in environmental monitoring, industrial processes, and biological systems. The review explores into the synthesis methodologies employed for designing optical chemosensors, discovering diverse materials like organic dyes, nanoparticles, polymers, and hybrid materials. Special attention is given to the design principles that enable the selective recognition of specific metal ions, highlighting the role of ligand chemistry, coordination interactions, and structural modifications. Furthermore, the article thoroughly surveys the analytical performance of optical chemosensors in terms of sensitivity, selectivity, response time, and detection limits. Real-world applications, including water quality assessment, environmental monitoring, and biomedical diagnostics, are extensively covered to underscore the practical relevance of these sensing platforms. Additionally, the review sheds light on emerging trends, challenges, and future prospects in the field, providing insights into potential advancements and innovations. By synthesizing the current state of knowledge on optical chemosensors for trace level metal ions detection. The collective information presented herein not only offers a comprehensive understanding of the existing technologies but also inspires future research endeavors to address the evolving demands in the realm of trace metal ion detection.

Herein, we present a family of 7‐(diethylamino)coumarin‐3‐carboxamides, bearing three different aza‐crown moieties (chelating unit). All synthesized compounds have shown a colorimetric response and fluorescence ON–OFF behavior to the presence of lead, calcium, magnesium, and copper, with higher affinity toward the latter, even in the presence of other cations in solution. Optical spectroscopies, X‐ray crystallography, and EPR experiments show that Cu(II) induces an irreversible oxidation on the coumarin core, with the concomitant formation of Cu(I) and an organic radical species. The emergence of an absorption band in the visible region upon radical formation results in the appearance of blue color, which fades over time, highlighting the potential of these sensors for rapid detection of copper(II) ion under the naked eye.

Carbon dots have attracted much attention due to their high fluorescence intensity, easy modification, good stability, and biocompatibility. However, the realization of low‐cost mass production of high‐quality carbon dots still faces great challenges. Biomass is of non‐toxic and environmentally friendly organism, but a lot of biomass is treated as waste for burning and landfill at present, causing irreparable pollution to the environment. In fact, many biomass resources are ideal candidates for preparing carbon dots. This review focuses on carbon dots including carbon quantum dots (CQDs) and graphene quantum dots (GQDs) which using biomass as carbon source on the aspects of plants and their derivatives, animals and their derivatives and municipal waste. The characterization of the structure and composition of biomass carbon dots, the regulation of fluorescence color and the methods of improving quantum yield (QY) including heteroatom doping and surface modification are introduced in detail. Moreover, biomass carbon dots for detecting metal ions and non‐metal molecules and their quenching mechanism are emphatically introduced in addition to summarizing the luminescence mechanism, and some promising prospects and challenges in this uplifting field are discussed. Biomass carbon dots have shown great potential application in many fields due to their high fluorescence intensity, easy modification and good stability. This review elaborates on biomass carbon dots from three main carbon sources and their synthesis methods, characterizations, properties, luminescence mechanisms and applications in sensing to meet the interest of relevant researchers in this field.