Transdermal Delivery of Living and Biofunctional Probiotics through Dissolvable Microneedle Patches

Bioactive functional probiotics play an important role in many health applications such as maintaining skin health and the immunity of the human host. Artificial supplementation of probiotics would enhance immune functions as well as regulate skin health. However, simple and effective methods to deliver probiotics into the dermis to regulate local dermal tissue are still lacking. Furthermore, microneedles have been used for transdermal drug delivery in a pain-free manner, yet there were few reported methods to deliver living microbes via microneedles. In this work, we developed a technique to deliver bioactive functional probiotics, using lactobacillus as the model probiotic, into local dermis by dissolvable microneedles. The transdermal delivery of probiotics might enhance local skin regulation and immunity, and dissolvable microneedles served as a safe and pain-free tool for dermal microbial delivery. Lactobacillus was encapsulated in dissolvable microneedles with high viability by a centrifugation casting method. The microneedles rapidly dissolved after skin penetration, releasing the lactobacillus into the subcutaneous space, without causing local tissue irritation. The lactobacillus was functionally bioactive following transdermal delivery, actively synthesizing lactic acid both ex vivo and in vivo. Our technique provided a safe, effective, and convenient approach for the transdermal delivery of probiotics into local skin, with the potential to improve skin health and immunity.