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Micromachines
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Microneedles
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Microneedles

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "B：Biology and Biomedicine".

Deadline for manuscript submissions: closed (30 December 2020) | Viewed by 41538

Special Issue Editors

Prof. Dr. Ryan Donnelly

E-Mail Website
Guest Editor
School of Pharmacy, Queen’s University Belfast, Belfast BT9 7BL, UK
Interests: drug delivery; pharmaceutical formulation; transdermal administration; microneedles; photodynamic therapy
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Dennis Douroumis

E-Mail Website
Guest Editor
Faculty of Engineering and Science, School of Science, University of Greenwich, Chatham Maritime, Chatham, Kent ME4 4TB, UK
Interests: 3D printing technologies for pharmaceutical dosage forms or novel medical devices (microneedles, bioresorbable scaffolds); continuous manufacturing processes for the development of medicinal products; nanomaterial synthesis and surface modification for cancer treatment
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The microneedles field is entering an exciting period. Almost 50 years since the first patents were filed, the first commercially available drug product seems to finally be within reach. This research area, based on systems microengineered from polymers, elemental silicon, metals, glass, or ceramic, continues to show high levels of innovation. The most common applications have been in vaccine delivery, cosmetic administration, drug delivery, and minimally invasive extraction of body fluids. A plethora of strategies has been employed and, as manufacturing tools become ever more sophisticated, the technology has only been limited by researchers’ imaginations. Alignment of thinking on critical quality attributes and standards of manufacture is bringing profound patient and commercial benefits. Microneedle research is truly interdisciplinary, harnessing expertise in engineering, computer science, pharmaceutical formulation, immunology, and pharmacology. Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on novel developments in microneedle technology and its use for various drug and vaccine delivery applications, cosmeceutical administration, as well as patient therapeutic drug monitoring and diagnosis.

Prof. Ryan Donnelly
Prof. Dennis Douroumis
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Micromachines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • microneedles
  • microarray patches
  • vaccines
  • drug delivery
  • formulation
  • manufacture
  • translation

Published Papers (6 papers)

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Research

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14 pages, 2389 KiB  
Article
Solvent-Free Polycaprolactone Dissolving Microneedles Generated via the Thermal Melting Method for the Sustained Release of Capsaicin
by Jaehong Eum, Youseong Kim, Daniel Junmin Um, Jiwoo Shin, Huisuk Yang and Hyungil Jung
Micromachines 2021, 12(2), 167; https://doi.org/10.3390/mi12020167 - 08 Feb 2021
Cited by 18 | Viewed by 4220
Abstract
(1) Background: Dissolving microneedles (DMNs), a transdermal drug delivery system, have been developed to treat various diseases in a minimally invasive, painless manner. However, the currently available DMNs are based on burst release systems due to their hydrophilic backbone polymer. Although hydrophobic biodegradable [...] Read more.
(1) Background: Dissolving microneedles (DMNs), a transdermal drug delivery system, have been developed to treat various diseases in a minimally invasive, painless manner. However, the currently available DMNs are based on burst release systems due to their hydrophilic backbone polymer. Although hydrophobic biodegradable polymers have been employed on DMNs for sustained release, dissolution in an organic solvent is required for fabrication of such DMNs. (2) Method: To overcome the aforementioned limitation, novel separable polycaprolactone (PCL) DMNs (SPCL-DMNs) were developed to implant a PCL-encapsulated drug into the skin. PCL is highly hydrophobic, degrades over a long time, and has a low melting point. Under thermal melting, PCL encapsulated capsaicin and could be fabricated into a DMN without the risk of toxicity from an organic solvent. (3) Results: Optimized SPCL-DMNs, containing PCL (height 498.3 ± 5.8 µm) encapsulating 86.66 ± 1.13 µg capsaicin with a 10% (w/v) polyvinyl alcohol and 20% (w/v) polyvinylpyrrolidone mixture as a base polymer, were generated. Assessment of the drug release profile revealed that this system could sustainably release capsaicin for 15 days from PCL being implanted in porcine skin. (4) Conclusion: The implantable SPCL-DMN developed here has the potential for future development of toxicity-free, sustained release DMNs. Full article
(This article belongs to the Special Issue Microneedles)
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16 pages, 2929 KiB  
Article
Optimisation of Design and Manufacturing Parameters of 3D Printed Solid Microneedles for Improved Strength, Sharpness, and Drug Delivery
by Sophia N. Economidou, Cristiane P. Pissinato Pere, Michael Okereke and Dennis Douroumis
Micromachines 2021, 12(2), 117; https://doi.org/10.3390/mi12020117 - 22 Jan 2021
Cited by 45 | Viewed by 5118
Abstract
3D printing has emerged as a powerful manufacturing technology and has attracted significant attention for the fabrication of microneedle (MN)-mediated transdermal systems. In this work, we describe an optimisation strategy for 3D-printed MNs, ranging from the design to the drug delivery stage. The [...] Read more.
3D printing has emerged as a powerful manufacturing technology and has attracted significant attention for the fabrication of microneedle (MN)-mediated transdermal systems. In this work, we describe an optimisation strategy for 3D-printed MNs, ranging from the design to the drug delivery stage. The key relationships between design and manufacturing parameters and quality and performance are systematically explored. The printing and post-printing set parameters were found to influence quality and material mechanical properties, respectively. It was demonstrated that the MN geometry affected piercing behaviour, fracture, and coating morphology. The delivery of insulin in porcine skin by inkjet-coated MNs was shown to be influenced by MN design. Full article
(This article belongs to the Special Issue Microneedles)
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12 pages, 2629 KiB  
Article
Safe Coated Microneedles with Reduced Puncture Occurrence after Administration
by Hye-Rin Jeong, Hyesun Jun, Hye-Ran Cha, Jae Myun Lee and Jung-Hwan Park
Micromachines 2020, 11(8), 710; https://doi.org/10.3390/mi11080710 - 22 Jul 2020
Cited by 17 | Viewed by 3473
Abstract
The goal of this study is the preparation of safer coated microneedles so that tips remaining after the initial use are less likely to be reinserted on a second use. Twelve groups of uncoated microneedles (u-MNs) were prepared from the combination of three [...] Read more.
The goal of this study is the preparation of safer coated microneedles so that tips remaining after the initial use are less likely to be reinserted on a second use. Twelve groups of uncoated microneedles (u-MNs) were prepared from the combination of three different aspect ratios (height to base width) and four kinds of polymer (polyethylene (PE), polypropylene (PP), nylon and polylactic acid (PLA)). After coating the u-MNs with polyvinyl alcohol formulation to make coated MNs (c-MNs), the force displacement of the u-MNs and the c-MNs was measured. The aspect ratio was reduced from 2.2, 2.5 and 3.0 with u-MNs to 1.3, 1.4 and 1.6 with c-MNs, respectively, after the coating formulation was applied to the MNs. All PLA MNs had a puncture performance of more than 95%. However, the puncture performance of u-MNs made of PE and of PP with a 3.0 aspect ratio was only 8% and 53%, respectively, whereas the rates of c-MNs made of PE and of PP were 82% and 95%, respectively. In animal experiments with PP MNs with a 3.0 aspect ratio, the 59% rate of puncture performance with u-MNs increased to above 96% with c-MNs and fell to 13% for r-MNs. Safe c-MNs can overcome the disadvantages of standard c-MNs by reducing the probable contamination of remaining tips after use. Safe c-MNs have advantages over standard c-MNs in terms of humidity resistance, reasonable cost, sterilization process and short processing time through the separate process of u-MN preparation and simple dip-coating. Full article
(This article belongs to the Special Issue Microneedles)
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12 pages, 1836 KiB  
Article
Novel Design Approaches in the Fabrication of Polymeric Microarray Patches via Micromoulding
by Inken K. Ramöller, Emma McAlister, Abigail Bogan, Ana S. Cordeiro and Ryan F. Donnelly
Micromachines 2020, 11(6), 554; https://doi.org/10.3390/mi11060554 - 30 May 2020
Cited by 26 | Viewed by 4296
Abstract
The focus on novel systems for transdermal delivery of therapeutic agents has increased considerably over recent years, as this administration route comes with many advantages. Polymeric microarray patches (MAPs) are minimally invasive devices that enable systemic delivery of a wide range of drugs [...] Read more.
The focus on novel systems for transdermal delivery of therapeutic agents has increased considerably over recent years, as this administration route comes with many advantages. Polymeric microarray patches (MAPs) are minimally invasive devices that enable systemic delivery of a wide range of drugs by overcoming the outer skin barrier. Conventionally, MAPs fabricated by micromoulding have a low needle density. In this study, the performance of hydrogel-forming MAPs cast using novel industrially manufactured micromoulds with a high needle density (600 needles/0.75 cm2) was compared to that of MAPs obtained using conventional moulds with a lower density (196 needles/0.89 cm2). Surrounding holders for micromoulds were designed for time-efficient fabrication of MAPs. The influence of needle densities on mechanical strength, insertion efficiency and in vitro permeation of ibuprofen sodium (IBU) was analysed. Insertion of both MAPs into an artificial skin model and neonatal porcine skin was comparable. No significant difference was observed in permeation studies of IBU (p > 0.05), with a delivery of 8.7 ± 1.7 mg for low-density and 9.5 ± 0.1 mg for high-density MAPs within 24 h. This highlights the potential of these novel micromoulds for manufacturing polymeric MAPs with a higher needle density for future applications. Full article
(This article belongs to the Special Issue Microneedles)
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Review

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18 pages, 1877 KiB  
Review
Microneedles: A New Generation Vaccine Delivery System
by Ipshita Menon, Priyal Bagwe, Keegan Braz Gomes, Lotika Bajaj, Rikhav Gala, Mohammad N. Uddin, Martin J. D’Souza and Susu M. Zughaier
Micromachines 2021, 12(4), 435; https://doi.org/10.3390/mi12040435 - 14 Apr 2021
Cited by 86 | Viewed by 12805
Abstract
Transdermal vaccination route using biodegradable microneedles is a rapidly progressing field of research and applications. The fear of painful needles is one of the primary reasons most people avoid getting vaccinated. Therefore, developing an alternative pain-free method of vaccination using microneedles has been [...] Read more.
Transdermal vaccination route using biodegradable microneedles is a rapidly progressing field of research and applications. The fear of painful needles is one of the primary reasons most people avoid getting vaccinated. Therefore, developing an alternative pain-free method of vaccination using microneedles has been a significant research area. Microneedles comprise arrays of micron-sized needles that offer a pain-free method of delivering actives across the skin. Apart from being pain-free, microneedles provide various advantages over conventional vaccination routes such as intramuscular and subcutaneous. Microneedle vaccines induce a robust immune response as the needles ranging from 50 to 900 μm in length can efficiently deliver the vaccine to the epidermis and the dermis region, which contains many Langerhans and dendritic cells. The microneedle array looks like band-aid patches and offers the advantages of avoiding cold-chain storage and self-administration flexibility. The slow release of vaccine antigens is an important advantage of using microneedles. The vaccine antigens in the microneedles can be in solution or suspension form, encapsulated in nano or microparticles, and nucleic acid-based. The use of microneedles to deliver particle-based vaccines is gaining importance because of the combined advantages of particulate vaccine and pain-free immunization. The future of microneedle-based vaccines looks promising however, addressing some limitations such as dosing inadequacy, stability and sterility will lead to successful use of microneedles for vaccine delivery. This review illustrates the recent research in the field of microneedle-based vaccination. Full article
(This article belongs to the Special Issue Microneedles)
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30 pages, 3981 KiB  
Review
Microneedles: Characteristics, Materials, Production Methods and Commercial Development
by Amina Tucak, Merima Sirbubalo, Lamija Hindija, Ognjenka Rahić, Jasmina Hadžiabdić, Kenan Muhamedagić, Ahmet Čekić and Edina Vranić
Micromachines 2020, 11(11), 961; https://doi.org/10.3390/mi11110961 - 27 Oct 2020
Cited by 86 | Viewed by 10446
Abstract
Although transdermal drug delivery systems (DDS) offer numerous benefits for patients, including the avoidance of both gastric irritation and first-pass metabolism effect, as well as improved patient compliance, only a limited number of active pharmaceutical ingredients (APIs) can be delivered accordingly. Microneedles (MNs) [...] Read more.
Although transdermal drug delivery systems (DDS) offer numerous benefits for patients, including the avoidance of both gastric irritation and first-pass metabolism effect, as well as improved patient compliance, only a limited number of active pharmaceutical ingredients (APIs) can be delivered accordingly. Microneedles (MNs) represent one of the most promising concepts for effective transdermal drug delivery that penetrate the protective skin barrier in a minimally invasive and painless manner. The first MNs were produced in the 90s, and since then, this field has been continually evolving. Therefore, different manufacturing methods, not only for MNs but also MN molds, are introduced, which allows for the cost-effective production of MNs for drug and vaccine delivery and even diagnostic/monitoring purposes. The focus of this review is to give a brief overview of MN characteristics, material composition, as well as the production and commercial development of MN-based systems. Full article
(This article belongs to the Special Issue Microneedles)
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