The rapid increase in global plastic production has led to widespread environmental accumulation and the formation of microplastics (MPs), raising concerns regarding their distribution, sources, and ecological impact. Understanding the environmental fate and potential risks associated with MPs requires analytical methods capable of reliably detecting and characterizing these particles across complex environmental matrices. For this, optical techniques are indispensable tools for MP analysis due to their accessibility, relative simplicity, and ability to provide visual information on particle size, morphology, and colour. This review critically examines currently used optical methods for MP detection, with a particular emphasis on fluorescence-based techniques in which organic dyes are used to stain or label MPs. We survey major classes of fluorescent probes used for MP detection, including the widely used Nile Red (NR) dye, other hydrophobic fluorophores, emerging dye systems, and dye-functionalized materials which are designed to improve staining procedure, selectivity, and performance. A focus is also placed on staining methodology, probe-MP interactions, and key performance parameters reported. By critically evaluating existing methodologies, identifying procedural differences across studies, and highlighting key performance parameters, this review aims to clarify the current state of dye-based optical MP detection and outline future directions for the development of novel optical approaches capable of supporting environmental monitoring and MP research.
MXenes represent a distinct category of two-dimensional transition metal carbides, nitrides, and carbonitrides with high electrical conductivity, large surface area, and tunable surface chemistry. This makes them promising candidates for a wide range of applications, including catalysis, environmental remediation, energy storage, and biomedicine. However, their practical use is limited by rapid oxidation, nanosheet restacking, and reduced long-term stability, especially in aqueous and biological environments. Integrating MXenes with polymers is an effective strategy for overcoming these limitations. Polymers improve MXene stability, prevent aggregation, and provide functional groups for bioreceptor immobilization, while the MXene promotes efficient charge transfer, significantly improving the electrochemical performance of the sensor interface. This review discusses recent progress in the design and engineering of MXene–polymer interfaces for high-performance analytical sensors and biosensors. Special attention is given to synthesis methods, interfacial interactions, polymer-assisted stabilization, bioreceptor immobilization, and their influence on sensing performance. Current challenges, including reproducibility, stability, real-sample analysis, and practical application, are also highlighted. Finally, we discuss future directions toward multimodal and in vivo-compatible biosensors, positioning MXene-polymer interfaces as a central platform for advancing analytical chemistry.
Pharmaceutical analysis presents challenges for impurity profiling, quality control, and particularly for stereoisomer assessment. Covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) have recently emerged as very promising separations media in chromatography and capillary electrochromatography. Their large surface areas, tunability, ordered porous structures and surface chemistries facilitate multiple separation mechanisms combining molecular sieving with a range of interactions, such as electrostatics, host-guest recognition, or π-π stacking, to improve separation efficiency and selectivity. COFs and MOFs have been utilized in high performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrochromatography (CEC) as stationary phases to separate pharmaceuticals and chiral compounds. This review summarizes the recent advances (2024-mid-2026) in COFs and MOFs-engineered CEC, HPLC, and GC for separations of pharmaceuticals and chiral compounds. The stationary phase design, column preparation methods and separation principles of CEC, HPLC and GC are discussed. Moreover, the applications of these stationary phases for separation of chiral and pharmaceutical analytes with their separation mechanisms are also evaluated. Finally, current challenges associated with synthesis, reproducibility, stability, separation mechanisms exploration and real-sample application with future perspective of next-generation COFs- and MOFs-based separation systems are outlined.
Per- and polyfluoroalkyl substances (PFAS) are contaminants whose vast chemical diversity poses substantial challenges to environmental monitoring. Among them, cationic and zwitterionic PFAS have largely remained under the radar, with limited information available on their environmental fate and effects. One of the primary challenges in analyzing these precursors is the limited availability of native reference standards and surrogate internal standards, precluding accurate quantification. Some methods originally developed for anionic PFAS underperformed at extracting cationic and zwitterionic PFAS, and these precursors can also transform during sample processing, further confounding the analysis. This paper provides a critical overview of the chemical diversity, origins, environmental occurrence, and analytical methods for cationic and zwitterionic PFAS. The individual steps of the analytical process, including sample collection and pre-treatment strategies, extraction techniques, chromatographic separation, and mass spectrometry detection, are reviewed, with particular attention to method limitations and pitfalls. We also summarize the analytical figures of merit attained in the literature, including limits of detection, extraction efficiency, and matrix effects. This review should be useful to end-users wishing to expand existing PFAS workflows to cationic and zwitterionic compounds.
By 2050, the global population is projected to approach 10 billion, requiring substantial increases in crop productivity under growing land, water, and climate constraints. In this context, plant wearables have emerged as powerful AgriTech tools, highlighted by the inclusion of wearable plant sensors in the World Economic Forum’s Top 10 Emerging Technologies report of 2023 and autonomous biochemical sensing in 2025. Among these technologies, microneedle (MN) electrochemical sensors provide minimally invasive access to plant biofluids and are rapidly becoming a promising platform for real-time chemical monitoring in living plants. In this review, we examine the key design requirements, analytical challenges, and applications of MN-based in-planta sensors for monitoring nutrients, agrochemicals, phytohormones, growth precursors, and stress biomarkers. We first discuss the plant–MN interface, relating plant organs, biofluid composition, and tissue mechanics to MN design considerations. We then describe the principal MN architectures and electroanalytical techniques used to develop sensing platforms. Representative case studies illustrate how MN sensors can resolve the spatial and temporal dynamics of target analytes directly in plants, with emphasis on analytical performance under realistic or in vivo conditions. We further assess the main challenges limiting the translation of MN sensors from laboratory prototypes to autonomous systems suitable for field deployment. Finally, we outline opportunities arising from advances in flexible electronics, wireless communication, Internet-of-Things infrastructures, and artificial-intelligence-driven data analysis. Overall, this review provides an analytical framework for microneedle-based plant (bio)sensing and highlights their potential role in next-generation smart agriculture. We analyzed a collection of over 150 references (2016-2026) identified by database searches, pertinent keywords, and recognized contributions in this field.
