Skin permeability and magnetic susceptibility analysis of hyaluronic acid-based magnetized microneedles containing iron oxide nanoparticles

Iron oxide nanoparticles (NPs) are biocompatible, have excellent magnetic properties, respond to external magnetic fields, and have been used in many studies on drug delivery systems. In this study, hyaluronic acid (HA)–superparamagnetic microneedles containing superparamagnetic iron oxide nanoparticles were manufactured using HA as the matrix material. Optical and scanning electron microscopy (SEM) were used to investigate the characteristics of the magnetized microneedles (MMNs). The mechanical rigidity of MMNs for in vivo evaluation is expected to be sufficient, as evidenced by a transmittance greater than 90%. Additionally, the superconducting quantum interference device-vibrating sample magnetometer measurement results confirmed that the magnetic characteristics did not change, even after the magnetic nanoparticles (MNPs) were manufactured. The hysteresis curves of the NPs confirmed the maintenance of the magnetic properties, including a coercivity of 60 Oe and susceptibility of 4 × 10-6 emu/gOe. Based on these results, MNPs are expected to be useful as a delivery material for transdermal drug delivery systems, magnetic resonance imaging, and molecular imaging.