Quaternary ammonium chitosan film loading ultrasmall calcium phosphate nanoclusters for biomimetic mineralization with antibacterial ability

Dental caries, primarily induced by plaque biofilm, is a significant challenge in oral health due to the disruption of the equilibrium between mineralization and demineralization processes. The primary objective in caries management is to preserve biofilm homeostasis while promoting the repair and regeneration of dental hard tissues, thereby restoring the structural integrity and functionality of the affected teeth. This study aimed to develop a multifunctional film with mineralizing and antibacterial abilities by incorporating ultrasmall amorphous calcium phosphate (ACP) nanoclusters (~1 nm) into hydroxypropyl trimethyl ammonium chloride chitosan (HACC) matrix. The ACP nanoclusters were synthesized using polyacrylic acid and polyaspartic acid as stabilizers and were homogeneously dispersed into the HACC matrix to form ACP@HACC film. The capacity for Ca and P ions release from ACP@HACC film was evaluated by inductively coupled plasma-mass spectrometry, demonstrating a sustained ion release over a period of 7 days. The ACP@HACC film induced the mineralization of type I collagen fibrils within 4 days. In vivo studies further confirmed the occurrence of dentin remineralization after 4 days. The remineralization process mediated by the ACP@HACC film significantly restored the elastic modulus and microhardness of demineralized dentin. Additionally, cytotoxicity assessments confirmed the excellent biocompatibility of the ACP@HACC film. Dentin treated with the ACP@HACC film demonstrated antibacterial ability against Streptococcus mutans in vitro. The ACP@HACC film integrates the dual functionalities of mineralization and antibacterial activity while maintaining excellent biocompatibility. This innovative approach shows potential for the treatment of early carious lesions, offering a clinically viable supplement to conventional restorative strategies.