Nanoparticle-enabled wireless monitoring and characterization of physical degradation kinetics in pharmaceutical gelatin films

Degradation kinetics of pharmaceutical excipient films effect their overall performance and drug release profile. Characterizing them is traditionally labor-intensive and time-consuming, requiring spectroscopy or periodic mass measurements. Here we present an alternative rapid technique for electrically (and wirelessly) measuring the polymeric matrix swelling and material degradation in aqueous media for characterizing functional films. The film is loaded with ferromagnetic nanoparticles and used as the core of a planar coil whose resonant frequency is monitored remotely. When placed in an aqueous solution, swelling and dissolution of the film induce contrasting changes in the capacitance and inductance of the coil, respectively, allowing identification of the swelling and dissolution phases. The dissolution profile of iron oxide-loaded gelatin is compared with spectrophotometry data, further demonstrating the technique can distinguish among films with various levels of crosslinking (showing a resonant frequency difference of 116 kHz between completely non-crosslinked and fully crosslinked gelatin). The key characteristics of the film degradation kinetics can be captured within 20–30 min of data collection.