Chitosan-based nanoparticles (NPs) are widely used in drug and gene delivery, therapies and medical imaging, but a molecular-level understanding of the internal morphology and nanostructure size, interface and dynamics, which is critical for building fundamental knowledge for the precise design and efficient biological application of the NPs, remains a great challenge. Therefore, the availability of a multiscale (0.1?100 nm) and nondestructive analytical technique for examining such NPs is of great importance for nanotechnology. Herein we present a new multiscale solid-state NMR approach to achieve this goal for the investigation of chitosan-poly (N-3-acrylamidophenylboronic acid) NPs. First, a recently developed 13C multiple cross-polarization magic-angle spinning (MAS) method enabled fast quantitative determination of the NPs? composition and detection of conformational changes of chitosan. Then, using an improved 1H spin-diffusion method with 13C detection and theoretical simulations, the internal morphology and nanostructure size were quantitatively determined. The interfacial coordinated interaction between chitosan and phenylboronic acid was revealed by one-dimensional MAS and two-dimensional (2D) triple-quantum MAS 11B NMR. Finally, dynamic-editing 13C MAS and 2D 13C-1H wideline separation experiments provided details regarding the componential dynamics of the NPs in the solid and swollen states. Based on these NMR results, a model of the unique nanostructure, interfacial interaction and componential dynamics of the NPs was proposed.
