Photosensitive Chitosan-Based Injectable Hydrogel Chemically Cross-Linked by Perylene Bisimide Dopamine with Robust Antioxidant and Cytotoxicity Enhancer Properties for In Vitro Photodynamic Therapy of Breast Cancer

Mussel-inspired chitosan and its applications in the biomedical field

Chitosan (CS) has physicochemical properties including solubility, crystallinity, swellability, viscosity, and cohesion, along with biological properties like biocompatibility, biodegradation, antioxidant, antibacterial, and antitumor effects. However, these characteristics of CS are greatly affected by its degree of deacetylation, molecular weight, pH and other factors, which limits the application of CS in biomedicine. The modification of CS with catechol-containing substances inspired by mussels can not only improve these properties of CS, but also endow it with self-healing property, providing an environmentally friendly and sustainable way to promote the application of CS in biomedicine. In this paper, the properties of CS and its limitation in the biomedical filed are introduced in detail. Then, the modification methods and properties of substances with catechol groups inspired by mussels on CS are reviewed. Finally, the applications of modified CS in the biomedical field of wound healing, drug delivery, anticancer therapy, biosensor and 3D printing are further discussed. This review can provide valuable information for the design and exploitation of mussel-inspired CS in the biomedical field.

Structure and Photonic Properties of a Perylenediimide Monolayer Assembled by the Langmuir-Blodgett Technique

The photonic responses of densely packed dye molecule assemblies are strongly dependent on their organization and environment. The precise control of molecular orientations and distances relative to the substrate and to each other is thus a key point in the design of photonic molecular materials. Herein, we report the preparation of a homogeneous and well-organized single monolayer of the perylenediimide (PDI) derivative by means of the Langmuir-Blodgett technique. Its optical properties disclose an intense charge-transfer excitonic absorption band related to important intermolecular coupling. Furthermore, an important immunity to photobleaching is observed for such a molecular assembly. The dipolar orientations of the molecules along the substrate have been unambiguously determined by angle-of-incidence-resolved polarized absorption and back-focal-plane fluorescence mapping. In addition, time-resolved spectroscopy reveals a fast two-dimensional diffusion of excitons consistent with strong π-stacking of adjacent PDI molecules.