A Semi-Dissolving Microneedle Patch Incorporating TEMPO-Oxidized Bacterial Cellulose Nanofibers for Enhanced Transdermal Delivery.

Ji Eun Song,Seung-Hyun Jun,Nae-Gyu Kang,Sun-Gyoo Park

doi:10.3390/polym12091873

Abstract

Although dissolving microneedles have garnered considerable attention as transdermal delivery tools, insufficient drug loading remains a challenge owing to their small dimension. Herein, we report a one-step process of synthesizing semi-dissolving microneedle (SDMN) patches that enable effective transdermal drug delivery without loading drugs themselves by introducing TEMPO-oxidized bacterial cellulose nanofibers (TOBCNs), which are well dispersed, while retaining their unique properties in the aqueous phase. The SDMN patch fabricated by the micro-molding of a TOBCN/hydrophilic biopolymer mixture had a two-layer structure comprising a water-soluble needle layer and a TOBCN-containing insoluble backing layer. Moreover, the SDMN patch, which had a hole in the backing layer where TOBCNs are distributed uniformly, could offer novel advantages for the delivery of large quantities of active ingredients. In vitro permeation analysis confirmed that TOBCNs with high water absorption capacity could serve as drug reservoirs. Upon SDMN insertion and the application of drug aqueous solution through the drug inlet hole, the TOBCNs rapidly absorbed the solution and supplied it to the needle layer. Simultaneously, the needle layer dissolved in body fluids and the drug solution to form micro-channels, which enabled the delivery of larger quantities of drugs to the skin compared to that enabled by solution application alone.

Highlights

The stratum corneum (SC), which is the outermost layer of the skin with a thickness of 10 to15 μm, acts as a strong barrier to transdermal drug delivery systems
We observed that TEMPO-oxidized bacterial cellulose nanofibers (TOBCNs) were localized only to the backing layer of the semi-dissolving microneedle (SDMN) patch (Figure 2c), which exhibited a uniform distribution of TOBCNs
In contrast to the dissolving microneedles (DMNs) patch, which completely dissolved in water (Figure 2g), the SDMN patch containing the water-insoluble TOBCNs in the backing layer retained its shape after the water droplet evaporated (Figure 2e, left)

Summary

Introduction

The stratum corneum (SC), which is the outermost layer of the skin with a thickness of 10 to15 μm, acts as a strong barrier to transdermal drug delivery systems. Microneedles that are a few hundred micrometers in length can physically pierce the skin with minimal invasion, which enables the simple, painless, and effective delivery of active ingredients into the skin. Their applicability has been widely studied in various fields, such as cosmetics, biomedicines, and vaccines [1,2,3,4,5]. SMNs create transient micro-channels in the skin through which drugs that are applied topically or coated on the needles are delivered. If the needles break within the skin, they can remain within the skin for a long time and cause adverse events such as inflammatory responses

Methods

Results

Conclusion