Aloe emodin-ferulic acid binary co-amorphous mixture: enhanced solubility, stability, and photodynamic antimicrobial activity

Aloe-emodin (AE), a natural photosensitizer, suffers from poor aqueous solubility that limits its photodynamic efficacy. This study developed a novel food-friendly co-amorphous system using ferulic acid (FA) as a co-former to enhance AE’s solubility and photodynamic performance. The AE-FA co-amorphous mixture was characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy (FTIR) with molecular dynamics simulations confirming hydrogen bond formation. Results demonstrated that this complexation effectively reduced the lattice energy of AE, leading to significantly improved solubility and physical stability of the CAM system. Furthermore, AE-FA CAM exhibited enhanced antimicrobial photodynamic activity against Staphylococcus aureus compared to pure AE, which was attributed to reduced molecular agglomeration and alleviated fluorescence quenching. This study aims to develop a novel, food-friendly co-amorphous system to simultaneously enhance the solubility and photodynamic efficacy of AE. This work presents the first report of a co-amorphous system between AE and FA specifically designed for photodynamic applications, providing an effective strategy to overcome solubility limitations of natural photosensitizers in food safety applications.