Constructing Fe₃O₄/HA/L-ac Hybrid Nanocomposites as Excellent Antimicrobial Agents and Drug Delivery Vehicles

In recent decades, death rates from microbial infections and cancer have been increasing. This increase is triggered by the limited effectiveness of existing treatments, such as the use of antibiotics, which are considered less effective due to the development of antibiotic resistance. Furthermore, cancer treatments such as chemotherapy have been reported to produce negative effects on the patient's body. Therefore, alternative treatments are urgently needed, such as developing drug delivery platforms and nanomaterial-based antimicrobial agents. This study aims to develop new hybrid nanocomposites, combining inorganic-organic materials, namely Fe₃O₄/HA/L-ac (L-ac = L-aspartic acid and HA = hydroxyapatite), as antimicrobial agents and drug delivery vehicles. In this case, Fe₃O₄, a well-known nanomaterial for antimicrobial agents and drug delivery vehicles, was optimized by combining it with HA and L-ac. The successful formation of nanocomposites was confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. We found that the antimicrobial activity of the composites increased with increasing HA content. HA contributed to the formation of reactive oxygen species and released active ions from nanoparticles through the interaction between the active sites of proteins and antibacterial agents, causing cell lysis. The increased antimicrobial activity was also influenced by electrostatic interactions in the nanocomposite particles, which penetrated the membrane and damaged the microbial cells. As drug delivery vehicles for cancer treatment, the nanocomposites effectively released doxorubicin (DOX), achieving 70% release within the first 45 min and nearly 97%-99% overall. The increased release was associated with a proton exchange mechanism at the primary amine group of DOX. Therefore, the prepared Fe₃O₄/HA/L-ac hybrid nanocomposites possess high potential for dual applications as antimicrobial agents and drug delivery vehicles.