Dual engine-driven bionic microneedles for early intervention and prolonged treatment of Alzheimer's disease

The microneedle (MN) delivery system presents an attractive administration route for patients with Alzheimer's disease (AD). However, the passive drug delivery mode and low drug loading of MNs often result in unsatisfactory therapeutic efficiency. To address these dilemmas, we developed dual engine-drive bionic MNs for robust AD treatment. Specifically, free rivastigmine (RVT) and RVT particles were co-loaded within the MNs to construct the valve and chambers of the guava, respectively, which can serve as an active engine to promote drug permeation by generating capillary force. K2CO3 and citric acid were introduced as a pneumatic engine into the MNs to promote the permeation of free RVT into deeper skin layers for early intervention in AD. Further, the RVT particles served as a drug depot to provide continuous drug release for prolonged AD treatment. Compared with free RVT-loaded MNs, the dual engine-driven bionic MNs showed an increase in drug loading, cumulative transdermal permeability, and normalized bioavailability of approximately 40%, 22%, and 49%, respectively. Pharmacodynamic studies further confirmed that the dual engine-driven bionic MNs were most effective in restoring memory and recognition functions in mice with short-term memory dysfunction. Therefore, the dual engine-driven bionic MNs hold great promise for highly efficient AD treatment.

Hyaluronidase-powered microneedles for significantly enhanced transdermal delivery efficiency

Microneedles (MNs) with enhanced delivery efficiency have revolutionized the transdermal drug delivery system for treating systemic illness. However, the bioavailability of MNs was still far from the clinical requirements by only overcoming the stratum corneum barrier. Herein, hyaluronidase (HAase)-powered MNs were developed as a top-down permeation-enhancement strategy to hijack the sequential transdermal barriers for improved bioavailability. HAase MNs with robust mechanical strength showed excellent skin penetration ability and significantly enhanced the transdermal delivery efficacy of macromolecular drugs as compared to that of HAase-absent MNs, resulting in considerable effect to subcutaneous injection in terms of biodistribution, bioavailability, and therapeutical efficacy. As evidenced from the distribution of trypan blue and fluorescence underlying skin, the positive effects exerted by HAase MNs could be ascribed to the depolymerization of HA that would loosen the subcutaneous space and destruct the extracellular matrix barrier to promote drug diffusion and permeation in larger area and greater depth. Notably, the transient interconversion of keratin from α-helix to β-sheet that might assist the drug residues on the skin surface permeate across the stratum corneum during administration might be another reason not to be ignored. As a labor-saving strategy, HAase-powered MNs offers a promising and painless administration route for macromolecules.