Black phosphorus hydrogel inverse opal microneedle patches for psoriasis treatment

Microneedle patches (MNs) have demonstrated potentials in transdermal drug delivery for skin disease therapy. Effort is mainly focused on the improvement of MNs' materials, structures and functions to realize intelligent drug delivery. Here, we propose a novel black phosphorus (BP)-loaded hydrogel inverse opal MNs with photothermal responsive capacity and vivid structural color screening for psoriasis treatment. The MNs, composed of a BP-loaded N-isopropyl acrylamide (NIPAM)/poly(ethylene glycol) diacrylate (PEGDA) inverse opal hydrogel scaffold and the drug-carrying gelatin/agarose filler inside the scaffold pores, are fabricated through combined approaches of nanoparticle assembly, reversed-phase replication and micro-molding. Due to the photothermal conversion of BP, temperature-responsive shrinkage of NIPAM, and heat-sensitive gelatin, the resulting MNs obtain the ability of good hydrophobic drug loading and photothermal controllable drug release. In addition, profiting from the inverse opal structure with optical properties, the MNs exhibit a bright structural color and can generate characteristic wavelength shift during drug release, providing a real-time monitoring and feedback for drug delivery. Based on these features, the MNs show excellent in vivo drug administration and efficient psoriasis treatment in mice, indicating their potential as intelligent drug delivery vehicles for practical applications.