Bioinspired Adhesive and Antibacterial Microneedles for Versatile Transdermal Drug Delivery

Abstract

<jats:p>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 <jats:italic>Paenibacillus polymyxa</jats:italic> 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.</jats:p>

Smart Microneedles for Therapy and Diagnosis

“…Besides, the body parts where adhesive microneedles are applied can move as usual, improving the comfort of users. Typically, there are three ideas to prepare adhesive microneedles: designing specially structured microneedle tips [ 33 ], choosing swellable materials to fabricate microneedle tips [ 34 , 35 ], and making the supporting layer adhesive [ 36 ].…”

“…In addition to designing the features of microneedle tips, developing microneedle supporting layers with special materials or structures can also generate adhesive microneedles [ 36 ]. In terms of materials, biocompatible adhesive hydrogels such as chitosan gel, tannin gel, and polydopamine gel are ideal candidates for microneedle supporting layers.…”

“…Microneedles could be imparted with antibacterial ability and applied to treating bacterial infections. For this purpose, many kinds of microneedles have been prepared, which are composed of antibacterial materials like chitosan or contain antibacterial particles like silver nanoparticles, antibacterial peptides, and bioactive extracts [ 36 ]. For example, microneedles containing antimicrobial agents, chloramphenicol, were fabricated and employed to treat bacterial biofilms [ 57 ].…”

“…Reproduced with permission from Ref. [ 36 ], copyright 2020, American Association for the Advancement of Science.…”

Chinese herb microneedle patch for wound healing

“…Therefore, wound healing has been regarded as a hot topic both in fundamental research field and in clinical medicine, becoming a grave threat to socioeconomic development around the world [ [7] , [8] , [9] , [10] , [11] ]. Microneedle (MN) patch has been proposed as a versatile technique and gained a great deal of remarkable achievements in the field of wound healing, as well as disease therapy, biosensing, dermal vaccination, and so on [ [12] , [13] , [14] , [15] , [16] , [17] , [18] ]. Because of their well-designed microstructures and superior loading capacity compared to those regular drug delivery carriers, MN can effectively realize the load and delivery of the favored active drugs [ [19] , [20] , [21] , [22] , [23] ].…”