Bioinspired Barbed Microneedle for Anchored and Enhanced Transdermal Delivery via Iontophoresis

Large molecules and hydrophilic drugs suffer from low delivery efficiency in transdermal drug delivery systems due to their passive transport. This study established an iontophoresis-driven microneedle drug delivery platform that uses electric field force to drive drug molecules to accelerate to the target and release. The microneedle array with a bionic porcupine barb structure significantly improves skin adhesion, overcomes the mechanical deficiencies, and ensures that the microneedle tips can completely penetrate into the subcutaneous tissue for action. Iontophoretic stimulation actively accelerates drug release from the hydrogel matrix and aids drug diffusion into deeper tissue layers after the formation of microchannels through microneedle puncture. By adjusting the electrical stimulation parameters, precise quantitative adjustment of the drug release rate is achieved. Compared with microneedle administration alone, the iontophoresis synergy significantly increases the total release amount and penetration depth of the drug, with a cumulative release rate as high as 90%. This system provides a new model and method for future local drug transdermal delivery.