Molecular photonic spectroscopy for environmental monitoring: Fluorescence and Raman strategies for ultra-trace detection of industrial pollutants

Environmental pollution arising from industrial activities has intensified the need for highly sensitive, selective, and rapid detection technologies capable of identifying trace levels of hazardous contaminants. Conventional analytical methods, while accurate, are often limited by high operational costs, labour-intensive workflows, and the inability to provide real-time or on-site monitoring. Molecular photonic spectroscopy particularly fluorescence and Raman-based techniques has emerged as a powerful alternative due to its exceptional sensitivity, molecular specificity, non-destructive nature, and compatibility with portable device platforms. This review highlights recent advancements in fluorescence and Raman spectroscopic strategies for ultra-trace detection of major industrial pollutants, including heavy metals, VOCs, pesticides, POPs, and emerging contaminants such as microplastics. Special emphasis is placed on innovations in probe chemistry, nanostructured substrate engineering, aggregation-induced emission (AIE) mechanisms, and surface-enhanced Raman scattering (SERS) platforms. The integration of these photonic sensing approaches offers promising pathways toward next-generation environmental monitoring systems that support rapid decision-making and sustainable pollution management.