Phase-Transition Microneedle Patches for Transdermal Protein Delivery

The harmful covalent bonding step is extracted and removed from the microneedle fabrication process. Instead, the patent uses physical cross-linking methods (hydrogen bonding, ionic interactions, or crystalline domain formation) that achieve the desired structural strength without introducing chemicals that could react with the loaded medicines, thus eliminating the safety concern while maintaining mechanical integrity.

The patent introduces water or aqueous buffers as an intermediary medium to facilitate cross-linking through physical mechanisms rather than chemical reactions. This intermediary enables the formation of stable microneedle structures through hydrogen bonding or ionic interactions with multiply charged ions that do not denature proteins, avoiding direct chemical contact between cross-linking agents and therapeutic molecules.

The patent employs a nested structure where hollow or porous microneedles contain internal cavities or channels that serve as drug reservoirs. The microneedle shell maintains structural integrity for skin penetration, while the nested internal space provides substantial drug loading capacity and diffusion pathways, allowing the therapeutic to be delivered through the created channels without compromising mechanical strength.

The patent utilizes porous microneedle materials or structures with controlled porosity that provide both mechanical strength and internal void space for drug loading. The porous architecture creates interconnected channels that facilitate drug diffusion from the loading reservoir through the microneedle body and into the skin, simultaneously addressing structural integrity and drug delivery capacity requirements.