Silica- and <i>Garcinia mangostana</i> Fruit Peel Extract-Modified Superparamagnetic Particles for Efficient DNA Isolation

Three types of superparamagnetic iron oxide particles (SPIOPs) were employed for the efficient isolation of salmon sperm DNA, including pristine SPIOP, silica-functionalized SPIOP (SPIOP@SiO2), and SPIOP modified with xanthones extracted from the fruit peel of Garcinia mangostana (SPIOP@XAN). The SPIOP@XAN variants were synthesized with different xanthone loadings (2.5, 5, 10, 20, and 25 g). Structural and physicochemical characterization of the synthesized particles was conducted using dynamic light scattering (DLS), vibrating sample magnetometry (VSM), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), confirmed the crystalline nature and successful modification of the particles. Among the materials tested, SPIOP@XAN with 10 wt % xanthone (SPIOP@X10/W90) exhibited the highest salmon sperm DNA adsorption efficiency at 30 min, achieving over 93%. The adsorption of salmon sperm DNA onto SPIOP followed the Langmuir isotherm model, with a maximum adsorption capacity of 228.8 mg·g–1, and conformed to pseudo-first-order kinetics, indicating a monolayer adsorption mechanism. In contrast, SPIOP@X10/W90 exhibited the best fit to the Freundlich and Redlich–Peterson isotherms, with a maximum adsorption capacity of 198.2 mg·g–1, and followed pseudo-second-order kinetics, suggesting a more complex and heterogeneous adsorption process. In similar vien, SPIOP@SiO2 was best described by the Freundlich and Redlich–Peterson isotherms, showing a maximum adsorption capacity of 38.0 mg·g–1, and conformed to pseudo-first-order kinetics, implying that the adsorption was predominantly governed by physical interactions. These findings underscore the potential of SPIOP@X10/W90 for high-efficiency magnetic DNA extraction and its applicability in future DNA biosensing technologies.