## 1 Introduction  
Polysaccharides are basic biological molecules that have attracted scientific attention for decades. Their structural diversity and functional significance in biological, medical, and industrial applications drive ongoing research [1, 2, 3]. Historically, early studies on their structures relied on chemical degradation and chromatographic techniques. Scientists used these techniques to figure out their monosaccharide composition and glycosidic bonds [4]. With the progress of analytical technology, nuclear magnetic resonance (NMR) spectroscopy has changed the field by providing direct and non-destructive ways to understand the complex structures of polysaccharides [5, 6]. In the 1980s, the breakthrough of 1D NMR spectrum laid the foundation for detailed research on polysaccharides [7]. Subsequently, in the 1990s, two-dimensional NMR technology was developed, such as COSY, HSQC and TOCSY, enabling researchers to analyze overlapping signals and identify glycosidic bonds [6]. For example, [PERSON] et al. summarized different NMR methods used for conformational analysis in a systematic way [8]. However, their review did not include new technologies like nuclear dynamic polarization (DNP). Similarly, [PERSON] et al. concentrated on the structural analysis of sulfate polysaccharides in seaweed [9]. However, they did not deal with the application of NMR in the analysis of complex matrices such as food systems. The aim of this review is to fill these gaps by focusing on three key aspects. First, it assesses the latest progress in NMR technology including DNP, multidimensional NMR techniques, and integrated computational modeling to improve structural analysis. Second, it points out the expanding role of NMR in different fields. For example, in food science, it can help make the texture of food better, and in microbiology, it is useful for understanding how biofilms work. Finally, we investigated the complementary use of mass spectrometry and molecular dynamics simulations, which improved the accuracy and depth of polysaccharide structure studies. The review provides an interdisciplinary perspective and comprehensively summarizes the development of NMR in polysaccharide science by combining academic research and industrial applications.  
The development of cross-polarization magic-angle spinning (CP/MAS) and DNP techniques has made the sensitivity of ssNMR better, allowing scientists to distinguish the difference between crystalline and amorphous regions in polysaccharide samples [10]. In addition, using advanced isotope labeling strategies like \({}^{13}\)C enrichment has made it easier to perform a detailed structural analysis of microbial polysaccharides and how they interact with host cells [11; 12]. These advances also expand the scope of polysaccharide research to areas like biofilm formation, food texture improvement, and the development of therapies based on polysaccharides [13; 14; 15].  
The goal of the review is to put these advances together, focusing on how magnetic resonance spectroscopy can be used to figure out the structure, conformations, and dynamics of polysaccharides. The article provides an overview of the past development and basic methods of polysaccharide research using NMR. It thoroughly studies the solution-state and solid-state NMR methodologies, showing examples of using these techniques to figure out the complex structures and functional interactions of polysaccharides. The review thoroughly examines the application of NMR in biomedicine, food, and environmental science to highlight its revolutionary impact. It also explores challenges such as signal overlap and limited sensitivity, which drive advancements in NMR spectroscopy for polysaccharide research. By analyzing the key findings, we aim to emphasize the contribution of NMR to polysaccharide research and explore future directions in the developing field.