Amoxicillin-loaded chitosan coated magnetic nanocarriers as a dual-platform for anaerobic bacterial preconcentration and gene-sensing in periodontal pathogen detection

Periodontitis, a progressive inflammatory condition, causes periodontal tissue destruction, pain, chewing difficulties, and tooth loss, primarily due to pathogenic oral biofilms dominated by low abundance periodontopathic bacteria. Accurate diagnosis is hindered by the limited bacterial presence in saliva, necessitating effective enrichment techniques. This study introduces novel amoxicillin-loaded chitosan-coated magnetic nanocarriers (AMX-CS-MNCs) designed for rapid capture, enrichment, and DNA extraction of Gram-positive and Gram-negative anaerobic periodontal pathogens, including Porphyromonas gingivalis and Parvimonas micra , from artificial and clinical saliva samples collected at Kangmei Dental Hospital, facilitating highly sensitive PCR-based detection. The chitosan coating enhances biocompatibility and dispersibility, while amoxicillin acts as a broad-spectrum targeting ligand. Comprehensive characterization using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), zeta-potential analysis, dynamic light scattering (DLS), vibrating sample magnetometry (VSM), and energy-dispersive X-ray spectroscopy (EDS) confirms successful functionalization and drug loading. AMX-CS-MNCs demonstrate exceptional bacterial capture efficiency (>90 %) at low concentrations following preconcentration, integrating with PCR to achieve a limit of detection (LOD) of 10 CFU/mL—a 1000-fold improvement over conventional PCR. Validation with patient samples demonstrated robust DNA amplification, highlighting this platform's potential for early, sensitive, and selective periodontitis clinical diagnosis and targeted therapy.