Design of a Novel Delivery Efficiency Feedback System for Biphasic Dissolving Microarray Patches Based on Poly(Lactic Acid) and Moisture‐Indicating Silica

Abstract Dissolving microarray patches (DMAPs) represent an innovative approach to minimally invasive transdermal drug delivery, demonstrating efficacy in delivering both small and large therapeutic molecules. However, concerns raised in end‐user surveys have hindered their commercialization efforts. One prevalent issue highlighted in these surveys is the lack of clear indicators for successful patch insertion and removal time. To address this challenge, a color‐change‐based feedback system is devised, which confirms the insertion and dissolution of DMAPs, aiming to mitigate the aforementioned problems. The approach combines hydrophilic needles containing model drugs (fluorescein sodium and fluorescein isothiocyanate (FITC)‐dextran) with a hydrophobic poly(lactic acid) baseplate infused with moisture‐sensitive silica gel particles. The successful insertion and subsequent complete dissolution of the needle shaft are indicated by the progressive color change of crystal violet encapsulated in the silica. Notably, distinct color alterations on the baseplate, observed 30 min and 1 h after insertion for FITC‐dextran and fluorescein sodium DMAPs respectively, signal the full dissolution of the needles, confirming the complete cargo delivery and enabling timely patch removal. This innovative feedback system offers a practical solution for addressing end‐user concerns and may significantly contribute to the successful commercialization of DMAPs by providing a visualized drug delivery method.