A bio-inspired swellable microneedle adhesive for mechanical interlocking with tissue

Abstract

Achieving significant adhesion to soft tissues while minimizing tissue damage poses a considerable clinical challenge. Chemical-based adhesives require tissue-specific reactive chemistry, typically inducing a significant inflammatory response. Staples are fraught with limitations including high-localized tissue stress and increased risk of infection, and nerve and blood vessel damage. Here, inspired by the endoparasite Pomphorhynchus laevis which swells its proboscis to attach to its host’s intestinal wall, we have developed a biphasic microneedle array that mechanically interlocks with tissue through swellable microneedle tips, achieving ~ 3.5 fold increase in adhesion strength compared to staples in skin graft fixation, and removal force of ~ 4.5 N/cm2 from intestinal mucosal tissue. Comprising a poly(styrene)-block-poly(acrylic acid) swellable tip and non-swellable polystyrene core, conical microneedles penetrate tissue with minimal insertion force and depth, yet high adhesion strength in their swollen state. Uniquely, this design provides universal soft tissue adhesion with minimal damage, less traumatic removal, reduced risk of infection and delivery of bioactive therapeutics.

Microneedle-array patches loaded with hypoxia-sensitive vesicles provide fast glucose-responsive insulin delivery

“…To realize ease of administration, we further loaded the GRVs into a MN-array patch for painless (31)(32)(33)(34) insulin delivery (Fig. 1B).…”

Microneedle Manufacture: Assessing Hazards and Control Measures

“…There are five principal classes of microneedle used for drug delivery applications: solid, drug coated solid, hollow, dissolvable, and swellable [1][2][3][8][9][10][11][12][13][14][15][16][17][18][19]. The fabrication of solid MN arrays is procedurally the simplest approach and can be constructed from a variety of conventional and inexpensive polymers such as polystyrene, polycarbonate, and polymethylmethacrylate [8][9][10][11][12].…”

Toward Biofunctional Microneedles for Stimulus Responsive Drug Delivery

“…These systems will be required to exhibit good conformance to the skin during dynamic motion and therefore microneedle compliance, shear strength and fatigue performance will play a more significant role in material selection. Hydrogel-based microneedles that become more compliant on swelling or systems mounted to flexible backing layers, may be advantageous for this purpose 72 . Designing and developing biofunctional microneedle patches will require improved methods of sterilisation, precision location and adhesion.…”

“…The PS-b-PPA microneedles achieved adhesion strength 3.5 times stronger than staples in skin graft fixation as well as a removal force of 4.5N/cm 2 . 72 Microneedle-based sensing can be performed either ex vivo or in vivo. SRMS devices, which perform ex vivo sensing, could extract interstitial fluid and carry out sensing using a microfluidic biomarker sensor.…”