Reinforced clusteroluminescent cellulose nanospheres by strengthening hydrogen bonds networks

Understanding the strengthening process of the hydrogen-bond network in cellulose is of great significance for enhancing clusteroluminescence performance of the non-conjugated clusteroluminescent cellulose nanomaterials. In this study, clusteroluminescent cellulose nanospheres were synthesized from pulp fibers through a controlled enzymatic-acid hydrolysis process, allowing for the precise analysis of particle diameter, rigidity, and surface functional groups. The cellulose nanospheres exhibit cluster luminescence with wavelength-dependent excitation, multiple emission peaks (400-600 nm), and red-shifted emission upon increasing excitation wavelength. Interestingly, the luminescence intensity and quantum yield (up to 15.98%) of cellulose nanospheres were enhanced by increasing rigidity and reducing the HOMO-LUMO energy gap induced by surface functional groups aggregation. Meanwhile, the hydrogen-bond networks in cellulose nanospheres were reinforced by adding tannic acid or lowering temperature, suppressing its non-radiative rotational and vibrational motions and blocking self-quenching pathways. Notably, the cellulose nanospheres with excellent biocompatibility can efficiently load photothermal agent, forming a photothermal antibacterial wound dressing that promotes the healing of drug-resistant bacteria infected wounds. This study provides a new path for the designing of non-conjugated clusteroluminescent nanomaterials, while stimulating innovations in broadening the application scope of cellulose nanospheres.