Facile Photolithographic Fabrication of Zwitterionic Polymer Microneedles with Protein Aggregation Inhibition for Transdermal Drug Delivery.

Microneedle technology has received considerable attention in transdermal drug delivery system research owing to its minimally invasive and convenient self-administration with enhanced transdermal transport. The pre-drug loading microneedle method has been developed for several protein and chemical medicines. However, the protein activity and efficacy are severely affected owing to protein aggregation. Herein, we aim to develop non-degradable hydrogel photocross-linkable microneedles for suppressing protein aggregation. Four-point star-shaped microneedles are fabricated via a photolithography process, and sulfobetaine (SPB) monomer is combined with dextran-glycidyl methacrylate/acrylic acid to form the hydrogel network. Incorporating zwitterionic poly-sulfobetaine (poly-SPB) in the microneedles enables the protection of proteins from denaturation even under external stress, releases the proteins in their native state (without activity loss), and exhibits sufficient mechanical strength to penetrate porcine skin. The microneedles exhibit a high drug loading capacity along with an efficient drug release rate. The rhodamine B drug loading and release model shows that the microneedles can load 8 µg of drugs on one microneedle patch of 41 needles and release nearly 80% of its load within 1 h. We anticipate that this pre-drug loading platform and the advanced features of the microneedles can provide an effective option for administering therapeutic drugs.

Regulation of ionic current through a surround-gated nanopore via field effect control.

Ability to control ionic current flowing through a nanopore has been demonstrated using the electric field effect on an electrical gate surrounding the nanopore. The gate electrode was introduced onto a single nanopore by depositing an Au layer on a silicon nitride diaphragm prior to pore milling using a focused ion beam technique. A hafnium oxide layer was subsequently deposited onto the nanopore structure as an insulating layer to protect the gate electrode. The device operation was investigated in KCl electrolyte and the ionic current regulating ability was examined under the influence of the gate voltage and the nanopore size. It was found that the device shows significant ionic current response with respect to the applied gate voltage. The resulting electric field dependent behavior of the fabricated nanopore suggests that the ionic current is influenced by positive surface charge inside the nanopore. The gate influence was more pronounced in the smaller nanopore and with higher source-drain voltage. The gate and pore size dependence behavior allows the potential to regulate ionic current as a nanoscale valve in nanochannel applications.

Efficacy of a novel microneedle patch for rejuvenation of the nasolabial fold.

BACKGROUND: Skin rejuvenation plays a significant role in the esthetic medicine market. Microneedle patches have been developed for a wide range of applications based on the principles of transdermal drug delivery; however, clinical trials of microneedle patches for skin rejuvenation remain limited. AIMS: This study was conducted to examine the efficacy of microneedle patches for improving nasolabial folds. METHODS: A total of 23 Thai women completed this prospective clinical trial. The participants were treated according to a split-face design, with application of microneedle patch plus 1.8% hyaluronic acid solution to the right nasolabial fold and microneedle patch alone to the left nasolabial fold. The treatments were applied to the nasolabial fold for 8 weeks. The test areas were measured before treatment and at 2, 4, 8, 12, and 16 weeks after the use of the test product. RESULTS: Combination treatment using the microneedle patch plus hyaluronic acid solution and use of the microneedle patch alone both significantly improved the Merz esthetic scales for nasolabial folds. Measurement of the nasolabial fold showed an improvement in the two groups, with no significant differences between the groups. No adverse effects were reported during the study period. CONCLUSIONS: Application of a microneedle patch with 1.8% hyaluronic acid solution or a microneedle patch alone were both effective treatments for improving facial wrinkles in the nasolabial folds.

The efficacy of LED microneedle patch on hair growth in mice.

Light penetration depth in the scalp is a key limitation of low-level light therapy for the treatment of androgenetic alopecia (AGA). A novel light emitting diode (LED) microneedle patch was designed to achieve greater efficacy by enhancing the percutaneous light delivery. The study aimed to investigate the efficacy and safety of this device on hair growth in mice. Thirty-five male C57BL/6 mice which their dorsal skin was split into upper and lower parts to receive either LED irradiation alone or LED irradiation with a microneedle patch. Red (629 nm), green (513 nm), and blue light (465 nm) at an energy dose of 0.2 J/cm2 were applied once daily for 28 days. Outcomes were evaluated weekly using digital photographs. Histopathological findings were assessed using a 6 mm punch biopsy. A significant increase in hair growth was observed in the green light, moderate in the red light, and the lowest in the blue light group. The addition of the microneedle patch to LED irradiation enhanced greater and faster anagen entry in all the groups. Histopathology showed an apparent increase in the number of hair follicles, collagen bundles in the dermis, angiogenesis, and mononuclear cell infiltration after treatment with the green-light LED microneedle patches. No serious adverse effects were observed during the experiment. Our study provides evidence that the newly developed green-light LED microneedle patch caused the optimal telogen-to-anagen transition and could lead to new approaches for AGA. Microneedle stimulation may aid percutaneous light delivery to the target hair follicle stem cells.

Self-Assembled Three-Dimensional Bi2Te3 Nanowire-PEDOT:PSS Hybrid Nanofilm Network for Ubiquitous Thermoelectrics.

Thermoelectric generation capable of delivering reliable performance in the low-temperature range (<150 °C) for large-scale deployment has been a challenge mainly due to limited properties of thermoelectric materials. However, realizing interdependence of topological insulators and thermoelectricity, a new research dimension on tailoring and using the topological-insulator boundary states for thermoelectric enhancement has emerged. Here, we demonstrate a promising hybrid nanowire of topological bismuth telluride (Bi2Te3) within the conductive poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) matrix using the in situ one-pot synthesis to be incorporated into a three-dimensional network of self-assembled hybrid thermoelectric nanofilms for the scalable thermoelectric application. Significantly, the nanowire-incorporated film network exhibits simultaneous increase in electrical conductivity and Seebeck coefficient as opposed to reduced thermal conductivity, improving thermoelectric performance. Based on comprehensive measurements for electronic transport of individual nanowires revealing an interfacial conduction path along the Bi2Te3 core inside the encapsulating layer and that the hybrid nanowire is n-type semiconducting, the enhanced thermoelectricity is ascribed to increased hole mobility due to electron transfer from Bi2Te3 to PEDOT:PSS and importantly charge transport via the Bi2Te3-PEDOT:PSS interface. Scaling up the nanostructured material to construct a thermoelectric generator having the generic pipeline-insulator geometry, the device exhibits a power factor and a figure of merit of 7.45 µW m-1 K-2 and 0.048, respectively, with an unprecedented output power of 130 µW and 15 day operational stability at Δ T = 60 °C. Our findings not only encourage a new approach to cost-effective thermoelectric generation, but they could also provide a route for the enhancement of other applications based on the topological nanowire.

Piezoelectric-Induced Triboelectric Hybrid Nanogenerators Based on the ZnO Nanowire Layer Decorated on the Au/polydimethylsiloxane-Al Structure for Enhanced Triboelectric Performance.

Here, we demonstrate a novel device structure design to enhance the electrical conversion output of a triboelectric device through the piezoelectric effect called as the piezo-induced triboelectric (PIT) device. By utilizing the piezopotential of ZnO nanowires embedded into the polydimethylsiloxane (PDMS) layer attached on the top electrode of the conventional triboelectric device (Au/PDMS-Al), the PIT device exhibits an output power density of 50 µW/cm2, which is larger than that of the conventional triboelectric device by up to 100 folds under the external applied force of 8.5 N. We found that the effect of the external piezopotential on the top Au electrode of the triboelectric device not only enhances the electron transfer from the Al electrode to PDMS but also boosts the internal built-in potential of the triboelectric device through an external electric field of the piezoelectric layer. Furthermore, 100 light-emitting diodes (LEDs) could be lighted up via the PIT device, whereas the conventional device could illuminate less than 20 LED bulbs. Thus, our results highlight that the enhancement of the triboelectric output can be achieved by using a PIT device structure, which enables us to develop hybrid nanogenerators for various self-power electronics such as wearable and mobile devices.