Protein‐Capturing Microgel‐Integrated Microneedle Array Patches for Enhanced Tip‐Loading, Storage Stability, and Transdermal Delivery of Recombinant Proteins

Why It Matters

Enhanced tip‑loading and ambient‑temperature stability address two major bottlenecks in transdermal protein delivery, opening a viable path for needle‑free vaccines and biologics.

Key Takeaways

• Microgel integration concentrates proteins at microneedle tips
• MI‑MAP stabilizes proteins at 25 °C for 28 days
• Enhanced immune response versus subcutaneous injection in mice
• Works with diverse proteins: toxin, interferon, SARS‑CoV‑2 RBD
• No severe inflammation observed after application

Pulse Analysis

Microneedle arrays have emerged as a promising conduit for bypassing the skin barrier, yet their utility for fragile biologics remains limited by low payload capacity and rapid degradation. Traditional hydrogel‑based microneedles often disperse proteins throughout the matrix, resulting in sub‑optimal dosing and the need for cold‑chain logistics. By embedding protein‑capturing microgels directly within the needle shafts, the MI‑MAP design localizes cargo to the tip, where it can be released efficiently into the dermis, while phenolic cross‑links protect the molecules from denaturation.

The experimental data underscore the platform’s practical advantages. MI‑MAP retained the activity of botulinum neurotoxin, human interferon‑α2a, and the SARS‑CoV‑2 spike receptor‑binding domain after a month of storage at room temperature—outperforming a control patch lacking microgels. In vivo, mice receiving the CpG‑adjuvanted RBD via MI‑MAP exhibited a quicker rise in neutralizing antibodies and a pronounced germinal‑center B‑cell response, surpassing both a hydrogel‑only patch and conventional subcutaneous injection. Importantly, histological analysis revealed minimal local inflammation, confirming the biocompatibility of the microgel matrix.

These findings have immediate relevance for the biotech and vaccine sectors, where cold‑chain constraints and patient compliance are persistent challenges. A needle‑free, stable delivery system could accelerate rollout of protein‑based vaccines, especially in resource‑limited settings, and streamline distribution of high‑value biologics. Future work will likely explore scale‑up manufacturing, broader antigen panels, and integration with wearable monitoring technologies, positioning MI‑MAP as a versatile platform at the intersection of drug delivery innovation and public‑health impact.