Microneedles integrated with a triboelectric nanogenerator: an electrically active drug delivery system.

In this study, a combined system of microneedles and a triboelectric nanogenerator (TENG) has been developed for drug delivery. A triboelectric device, which converts mechanical energy into alternating current (AC), was chosen to replace the electrophoresis (EP) effect. To directly generate triboelectricity from salmon deoxyribonucleic acid (SDNA)-based microneedles, a triboelectric series of SDNA film and chargeable polymers (polyimide and Teflon) was studied. The electrical output of the two charged polymers was compared to find a material that could be highly charged with SDNA. The electrical output was also compared as a function of the concentration of a drug embedded in the SDNA film, and the results confirmed that drug intercalation affected the carrier diffusion. The mechanical strength of the microneedles was assessed by histological analysis of their penetration into porcine cadaver skin. Furthermore, the output voltage of a system incorporating microneedles and TENG in cadaver skin, and in vitro drug release into gelatin were evaluated to examine potential application as an electrically active drug delivery system. The electrical output voltage of this system was ∼95 V. The mechanism of triboelectric perturbation to the skin has also been discussed. The system developed in this work is a new, facile approach toward effective drug delivery that replaces the existing EP method and expands the application of TENGs.

Transparent Displays Utilizing Nanopatterned Quantum Dot Films.

We report the realization of a transparent display using glass covered by a nanopatterned quantum dot (QD) film with good transmittance. The film was fabricated by nanoimprint lithography (NIL) and spin coating of colloidal QDs with specificexcitation maxima. The produced nanopatterned QD film was attached to transparent glass, enabling active image generation using a laser light source of a specific wavelength. Selective light emission was induced by strongly exciting the laser-exposed film surface, creating desired images, with color modulationenabled by controlling the QD layer (dozens of nanometers in size) via nanopatterning. The nanopatterned QD film used for image generation exhibits excellent transmittance (>80%), and can be used for transparent displays, with image realization in both bright and dark spaces. The fabricated displays have wide viewing anglesowing to their good light emission characteristics, and the fabrication through spin coating renders the fabrication process simple and applicable to large areas.

Drug-Delivery System Based on Salmon DNA Nano- and Micro-Scale Structures.

Microneedles, fabricated by nano-moulding technology show great promise in the field of drug delivery by enabling the painless self-administration of drugs in a patient-friendly manner. In this study, double-stranded salmon DNA (SDNA) was used as both a drug-delivery vehicle and structural material with a microneedle system. SDNA is non-toxic and demonstrates good mechanical robustness, mouldability, biocompatibility, bio-absorbability, and binding affinity with drug molecules for bio-functional applications. Benign fabrication conditions to protect temperature-sensitive biomolecules are used to produce SDNA structures of various sizes with a high aspect ratio (4: 1). Unlike existing dissolving microneedle structure materials, the special binding characteristics of doxorubicin hydrochloride, anti-cancer drug molecules, and SDNA demonstrate the stability of drug-molecule encapsulation via UV-absorption and photoluminescence analyses. Based on COMSOL simulation and in vitro analysis of the stratum corneum of porcine skin, the mechanical functionality of SDNA microneedles was evaluated in vitro by penetrating the stratum corneum of porcine skin. The SDNA microneedle dissolved and drug permeation was assessed using rhodamine, a drug surrogate. Owing to its many beneficial characteristics, we anticipate that the SDNA microneedle platform will serve as an effective alternative for drug delivery.

Enhanced depth imaging detects lamina cribrosa thickness differences in normal tension glaucoma and primary open-angle glaucoma.

OBJECTIVE: To confirm the advantages of the enhanced depth imaging (EDI) mode over the standard mode of the Heidelberg Spectralis spectral domain optical coherence tomography (SD-OCT) for imaging of the lamina cribrosa, and to compare laminar thicknesses of various glaucoma types with or without disc hemorrhage in a similar state of visual field loss. DESIGN: Cross-sectional, case-control design. PARTICIPANTS: We included 137 glaucoma patients and 49 healthy controls. METHODS: Optic nerve head B-scans were obtained by both the standard and EDI modes of the Spectralis OCT. Laminar thickness was measured at the center of mid-superior, central, and mid-inferior horizontal B-scans. Laminar thickness in patients with normal tension glaucoma (NTG) was compared with that in patients with primary open-angle glaucoma (POAG). To verify the reproducibility of EDI imaging, intraclass correlation coefficients and test-retest variability were calculated from selected B-scans. MAIN OUTCOME MEASURES: Laminar thickness and mean deviation values on standard automatic perimetry. RESULTS: The EDI OCT imaging showed significantly better intraobserver, interobserver, intravisit, and intervisit reproducibility than those by standard imaging. Laminar thickness in mid-superior, central, and mid-inferior regions was thinner in the POAG and NTG groups than in the normal control group (P<0.001). The mid-superior, central, and mid-inferior regions of the lamina were also significantly thinner in patients with NTG and disc hemorrhage than in those with NTG but no disc hemorrhage. CONCLUSIONS: The EDI mode of the Heidelberg Spectralis SD-OCT detected differences in the lamina cribrosa by glaucoma type. The lamina cribrosa was thinner in NTG eyes and in NTG eyes with disc hemorrhage. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Direct enantiomer separation of thyroxine in pharmaceuticals using crown ether type chiral stationary phase.

Thyroxine is the tyrosine based hormone produced by the thyroid gland, containing a chiral center in its molecular structure. Synthetic thyroxine is commercially available to treat thyroid dysfunctions, but only a few direct analytical methods to determine its optical purity have been reported. This study attempted to find an optimized liquid chromatographic condition for direct enantiomer separation on crown ether type chiral stationary phase. Among various mobile phases tested, 100% methanol solution containing 10 mM H(2)SO(4) was found to be most appropriate. This chromatographic method was validated and applied to measure the optical purity of six different L-thyroxine products from three domestic pharmaceutical companies and four commercially available D- and L-thyroxine reagents. The chromatographic results showed that every pharmaceutical product had quite high optical purity of above 97% (all but one were higher than 99%) while two of four thyroxine reagents demonstrated relatively higher enantiomer impurity (5-6%).