A wide range of analytical strategies and approaches have been developed, accomplishing significant advances in searching for efficient, fast, reliable, sensitive, and accurate protocols for sample analysis in recent decades. Chemical sensors are also low-cost, portable, and ecologically friendly, making them a preferred method of choice for a broad spectrum of sample analysis in various matrices of complexity. Of particular interest are sensors based on fluorescent molecules, nanoparticles, nanoclusters, quantum dots, carbon nanotubes, molecularly imprinted polymers, sol-gels, dyes, porphyrins, ionic liquids, organized media, and fluorescent sensor arrays in microfluidic chips. This review highlights and provides concise and in-depth coverage of recent innovations, challenges, advances, and applications of a variety of fluorescence-based sensors for sample analysis between 2018 and 2022. Emphasis is placed on instrumentation design and the applications of sensors in analytical, environmental, pharmaceutical, agricultural, food, and forensic sample analysis. Recent innovations and the practical utility of fluorescent chemical sensors relevant to biological systems, biomedical sample measurements, and clinical diagnosis are extensively reviewed. Future directions and trajectories of fluorescent chemical sensors for various utilities, applications, and sample measurements are highlighted and discussed.

Plastics are in high demand for various uses worldwide because of their low cost, versatility, lightweight, low density, flexibility, high strength, and durability. An increase in single-use plastics and ineffective solid waste disposal and recycling strategies have resulted in a global microplastic (MP) pollution epidemic, with negative implications for the ecosystem and public health safety. Analytical methods, including thermogravimetry and chromatography, have been developed to detect MPs. Nevertheless, molecular spectroscopy methods such as Near Infrared (NIR), Fourier Transform Infrared (FTIR), Raman, and fluorescence spectroscopy for MP analysis have gained attention in recent years due to their rapidity, low cost, accuracy, and portability of spectrometers. This review article provides in-depth coverage of the survey of current literature on the challenges, toxicity, sample pretreatment, and spectroscopic (Fluorescence, Raman, FTIR) and real-time (satellite imagery, unmanned aerial vehicles, and aquatic drone technology) microplastic detection methods. Machine learning, micro-hyperspectral imaging, and chemometrics approach to microplastic detections are discussed. The challenges, future directions, and prospects for decreasing global MP pollution and their analysis are discussed.

High operational costs of modern medical devices and the required specialized, skilled personnel with certifications to operate most medical instrumentation remains a challenge and an impediment to rapid medical diagnosis and clinical analysis. The simplicity, portability, and ease of operation makes Raman spectrometers appealing for rapid medical diagnosis and clinical analysis at an affordable cost. Besides, the combined use of Raman spectroscopy and multivariate analyses has further facilitated effective pattern recognition providing accurate classification, and/or differentiation of biological and clinical samples. This review article highlights recent advances in Raman spectroscopy in medical diagnosis and clinical analysis between January 2018 and December 2020. Recent innovations in the use of Raman spectroscopy for chemical analysis in human specimens are discussed. Applications of Raman spectroscopy in cancer immunotherapy, cancer imaging, and detecting disease biomarkers in clinical samples are further highlighted. The review article highlights recent innovations in the use of Raman spectroscopy for the detection of various pathogens in human specimens. Moreover, recent innovations of combined uses of Raman spectroscopy and multivariate regression analyses for pattern recognition, and/or classification of clinical samples are discussed. Furthermore, insights into the projection in the use of Raman spectroscopy in medical diagnosis and clinical sample analysis are discussed.

Formation of functional monolayers on surfaces of carbon materials is inherently difficult because of the high bond strength of carbon and because common pathways such as S(N)2 mechanisms cannot take place at surfaces of solid materials. Here, we show that the radical initiators can selectively abstract H atoms from H-terminated carbon surfaces, initiating regioselective grafting of terminal alkenes to surfaces of diamond, glassy carbon, and polymeric carbon dots. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) demonstrate formation of self-terminating organic monolayers linked via the terminal C atom of 1-alkenes. Density functional theory (DFT) calculations suggest that this selectivity is at least partially thermodynamic in origin, as significantly less energy is needed to abstract H atoms from carbon surfaces as compared to typical aliphatic compounds. The regioselectivity favoring binding to the terminal C atom of the reactant alkenes arises from steric hindrance encountered in bond formation at the adjacent carbon atom. Our results demonstrate that carbon surface radical chemistry yields a versatile, selective, and scalable approach to monolayer formation on H-terminated carbon surfaces and provide mechanistic insights into the surface selectivity and regioselectivity of molecular grafting.