Chitin Microneedles for an Easy‐to‐Use Tuberculosis Skin Test

Abstract

An easy-to-use tuberculosis skin test is developed with chitin microneedles that deliver purified protein derivative at the correct skin depth and result in a positive test in BCG-immunized guinea pigs.

Chitin Nanofiber Transparent Paper for Flexible Green Electronics

“…[32] Chitin is mechanically robust, nontoxic, biocompatible, and biodegradable. [33,34] Like cellulose, chitin naturally occurs as supramolecular crystalline nanofibers (3-5 nm), [35] which are further held by strong hydrogen bonds to form fiber bundles of larger scales; this underlies the insolubility and recalcitrance of chitin. Accordingly, the production of ChNF transparent papers basically adopts fabrication techniques and solvent systems similar to those used for CNF.…”

“…In the final step, we apply a calendering process [2] to an as-fabricated ChNF paper at 100 °C using a vacuum hot pressing not only to further enhance the flatness but also to eliminate residual HFIP (bp 58 °C) that might have remained inside ( Figure S3, Supporting Information). [33] Foldability and printability are two primary hallmarks of ordinary papers, and thus these properties are also examined for our ChNF paper.…”

Sample-free quantification of blood biomarkers via laser-treated skin

“…Recently, microneedle (MN) array-based minimally invasive diagnosis has attracted attention for rapidly detecting blood biomarkers through the skin [4,11,12]. Several surface modified MN arrays have been fabricated, capable of recognizing circulating viral proteins and specific antibodies in mouse dermis, allowing biomarker detection without blood collection and sample processing [13,14].…”

Electrodeposited Iron as a Biocompatible Material for Microneedle Fabrication

“…Microneedle Fabrication: Microneedles were prepared in asimilar fashion to aprevious report [4].H ollow polymer microneedles were prepared using al aserd irectw rite system utilizing two-photon polymerization. First, aC AD file was createdi nt he desired shape and dimensions of the microneedle and was uploadedt ot he laser direct writing operatings oftware (GOLD3D).…”

“…vaccines), from the skin surface to deeper tissues,a nd have most recently been investigated for use in tissue suture and diagnostic applications [1][2][3].S olid, degradable,a nd hollow microneedles comprise the mainn eedle geometries used. Fors ensing applications,h ollow microneedles are preferred that can be integrated with am icrofluidic diagnostic chip [4,5], while diffusion-based analytec ollection methods have been shown to circumvent issues associated with extraction of interstitial fluid using hollow microneedles [6][7][8].Hollow microneedles allow for larger volumestobedelivered comparedt oc oated or degradable needles however specialc onsideration must be taken to prevent clogging after insertioni nto the skin [ 9].A no ffset bore allows for increased fluid delivery and improved fluid extraction [10,11].S everalf abrication techniques existt hat are capable of creating arrays of hollowm icroneedles with offset bores.I nitiale fforts concentrated on conventional silicon microfabricationt echniquesw hich still remain in common use [12].R ecently,alow cost approach that involvesacombination of UV lithography [a] Abstract:E lectroplated iron wasi nvestigated as an ovel material for microneedle fabrication due to its recent success as ab iocompatiblem etal in other medical devicea pplications.H ollow polymerm icroneedles were made using al aser direct write processt hat involvedt wophoton polymerization of ac ommercially available Class 2a biocompatible polymera nd subsequent electroplating of this structure with iron.E lectroplating bath and deposition conditions were shown to affect the mechanical properties of both iron plated microneedles and iron plated on planarp olymer substrates.C onditions for depositingt he iron coatings were investigatedi nt erms of grain size,r esidual strain, and elemental composition for planar iron samples.F racture strength and puncture mechanics into ex vivo porcine skin for ironc oated hollow microneedlesw ere examined. Biocompatibility testing wasp erformed usingt he MTT assay against human epidermal keratinocytesw ith several concentrations of iron extract to investigate iron as am aterial used for transdermal applications.I ron coatings proved to significantly improve the strength of the hollowp olymerm icroneedles and sustained structural integrityu pt o7i nsertions into porcine skin without bending.Acommercially available device (Medtronic MiniMedQ uick-Serter )w as used for controlled application of microneedles into porcines kin and estimations of insertion forces for the device were made.P lating conditionsw ere optimized such that an adherent, uniform,a nd high purity iron coating was deposited onto polymer substrates and polymerm icroneedles without delamination or fracturing of the microneedles upon ex vivo insertion into porcines kin.…”