Abstract
Microneedles have attracted increasing interest among various medical fields due to their painless, noninvasive, and efficient way of drug delivery. However, practical applications of these microneedles in different epidermal locations and environments are still restricted by their low adhesion and poor antimicrobial activity. Here, inspired by the antibacterial strategy of Paenibacillus polymyxa and adhesion mechanisms of mussel byssi and octopus tentacles, we develop hierarchical microneedles with multifunctional adhesive and antibacterial abilities. With polydopamine hydrogel as the microneedle base and a loop of suction-cup-structured concave chambers encircling each microneedle, the generated microneedles can fit the skin well; keep strong adhesion in dry, moist, and wet environments; and realize self-repair after being split into two parts. Besides, as polymyxin is loaded into both the hydrogel tips and the polydopamine base, the microneedles are endowed with excellent ability to resist common bacteria during storage and usage. We have demonstrated that these microneedles not only showed excellent adhesion when applied to knuckles and ideal antibacterial activity but also performed well in drug-sustained release and treatment for the osteoarthritis rat model. These results indicate that bioinspired multifunctional microneedles will break through the limitation of traditional methods and be ideal candidates for versatile transdermal drug delivery systems.
Highlights
Microneedles (MNs) could penetrate the skin without touching blood capillaries and nerve endings, providing a painless, noninvasive, and effective way for drug delivery [1, 2]
The resultant MNs were found to replicate well the structure of the negative mold, with orderly aligned conical tips and their ambient concave chambers, as shown in Figures 2(c) and 2(d). It could be clearly seen from the scanning electron microscope (SEM) images that each concave chamber had a dome-like protuberance situated inside (Figures 2(e)–2(g))
We have presented bioinspired adhesive and antibacterial MNs which can be employed in versatile transdermal drug delivery
Summary
Microneedles (MNs) could penetrate the skin without touching blood capillaries and nerve endings, providing a painless, noninvasive, and effective way for drug delivery [1, 2]. As most hydrogel MNs could not adjust well to the skin and would fall off from the skin, they highly rely on auxiliary equipment such as the medical adhesive tape to achieve ideal penetration and fixation. This poor adhesion ability seriously limits many practical applications of the hydrogel MNs, especially for the parts with high mobility and a large range of motion, such as joints. Hydrogel MNs with improved adhesion and antibacterial ability for drug delivery is highly desired
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