title: Biomedical applications of microneedles in therapeutics: recent advancements and implications in drug delivery.
abstract: BACKGROUND
  The skin, as the largest organ, is a better option for drug delivery in many diseases. However, most transdermal delivery is difficult due to the low permeability of therapeutics across the various skin layers. There have been many innovations in transdermal drug delivery to enhance the therapeutic efficacy of the drugs administered. Microneedles (MN), micron sized needles, are of great interest to scientists as a new therapeutic vehicle through transdermal routes, especially for vaccines, drugs, small molecules, etc.
  
  
  METHODS
  This review covers new insights into different types of MNs such as solid, hollow, coated and dissolving MNs (SMNs, HMNs, CMNs, and DMNs) for selected biomedical applications in detail. Specific focus has been given to CMNs and DMNs for vaccine and drug delivery applications with recent developments in new MNs covered.
  
  
  CONCLUSIONS
  This review explores the feasibility of innovative MNs used as a drug delivery carrier. Because most of the SMNs and HMNs have many limitations, it is difficult to achieve therapeutic efficacy. Therefore, many scientists are investigating functional modifications of MNs through covalent and non-covalent methods, especially for CMNs and DMNs. The biomedical applications of MNs are growing and new exciting improvements could be achieved, thus resulting in better micro/nano technologies in the near future.
authors.affiliation: a Department of Chemical and Biomolecular Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon , Republic of Korea.
authors.forename: N Sanoj
authors.initials: NS
authors.lastname: Rejinold
authors.affiliation: a Department of Chemical and Biomolecular Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon , Republic of Korea.
authors.forename: Ju-Hyung
authors.initials: JH
authors.lastname: Shin
authors.affiliation: a Department of Chemical and Biomolecular Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon , Republic of Korea.
authors.forename: Hae Yong
authors.initials: HY
authors.lastname: Seok
authors.affiliation: a Department of Chemical and Biomolecular Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon , Republic of Korea.
authors.forename: Yeu-Chun
authors.initials: YC
authors.lastname: Kim
mesh_terms: D000279:Administration, Cutaneous; D016503:Drug Delivery Systems / Q000295:instrumentation*; D008845:Microinjections / Q000295:instrumentation*; D009339:Needles; D009508:Nevus, Pigmented; D012867:Skin / Q000378:metabolism; D012869:Skin Absorption; D012878:Skin Neoplasms; D014612:Vaccines / Q000008:administration & dosage*
chemical_list: D014612:Vaccines
keywords: drug delivery; microneedles; types of; vaccine delivery