A comprehensive review on the synthesis and applications of carbohydrate dyes

Carbohydrate-based fluorescent dyes form an increasingly diverse group of functional materials whose value lies in the intrinsic biocompatibility of carbohydrate scaffolds, their structural tunability, and their compatibility with a wide range of biological and materials-oriented applications, including bioimaging and chemical sensing. This review summarises recent progress in the synthesis of monovalent dye-carbohydrate conjugates, carbohydrate dimers, fluorescent supramolecular gelators, and dye-polymer systems. The synthetic approaches, such as click chemistry, carbomoylation, amide coupling, and others, are highlighted on the basis of their utility in producing well-defined dye-carbohydrate frameworks. Variations in structural features of carbohydrates have been shown to significantly influence photophysical responses, self-assembling behaviour, and molecular recognition, as demonstrated by representative systems reported in the literature. These structural property relationships allow applications such as lectin recognition, cellular imaging, chemical sensing, antibacterial activity, and the development of stimulus-responsive soft materials. In summary, this review provides a integrated framework that connects synthetic design with the performance of carbohydrate-based fluorescent materials.