Microneedles: A New Frontier in Nanomedicine Delivery

Abstract

This review aims to concisely chart the development of two individual research fields, namely nanomedicines, with specific emphasis on nanoparticles (NP) and microparticles (MP), and microneedle (MN) technologies, which have, in the recent past, been exploited in combinatorial approaches for the efficient delivery of a variety of medicinal agents across the skin. This is an emerging and exciting area of pharmaceutical sciences research within the remit of transdermal drug delivery and as such will undoubtedly continue to grow with the emergence of new formulation and fabrication methodologies for particles and MN. Firstly, the fundamental aspects of skin architecture and structure are outlined, with particular reference to their influence on NP and MP penetration. Following on from this, a variety of different particles are described, as are the diverse range of MN modalities currently under development. The review concludes by highlighting some of the novel delivery systems which have been described in the literature exploiting these two approaches and directs the reader towards emerging uses for nanomedicines in combination with MN.

Hollow microneedle-mediated intradermal delivery of model vaccine antigen-loaded PLGA nanoparticles elicits protective T cell-mediated immunity to an intracellular bacterium

“…There are other benefits in using microneedles compared to traditional hypodermic needles, like possible painless vaccination, the requirement of less trained personnel and reduced contamination risk [2]. Nowadays a wide variety of these microneedles exist, including solid, coated, dissolving and hollow microneedles [3,4].…”

“…Delivery of vaccine protein antigens over the cellular membrane can be achieved using delivery systems and over the past decades different types of them, such as polymeric nanoparticles, emulsions and lipid-based nanoparticles have been developed [10][11][12]. Nano-encapsulation of antigens has several advantages, such as stabilization of antigens in vivo, enhancement of the uptake by pAPC and also reduction of antigen release into systemic circulation [4,13]. The immune outcome can be potentially shaped by using nanoparticles with difference size [14] and surface charge [15], and by co-encapsulating antigen and adjuvant into the nanoparticles [16,17].…”

Delivery of Nucleic Acids for Cancer Gene therapy: Overcoming extra- and intra-cellular Barriers

“…Microneedles have gained much attention in the pharmaceutical field since they present a novel way of overcoming the stratum corneum, a major barrier to transdermal drug delivery of a wide range of drugs and vaccines [141]. A range of microneedle formulations exist, including hollow, solid, coated, dissolvable and hydrogel forming microneedles, and microneedles are produced using a variety of materials [142].…”

Pharmacological Targeting of the Epidermal Barrier

“…When applied to the skin surface, they bypass the SC without stimulating dermal nerves. The holes created by the needles can be used to deliver drugs on the skin surface to the dermal microcirculation [117].…”