Accelerator mass spectrometry for quantification of micro- and therapeutic-dose diclofenac in microdialysis samples.

Background: Microdialysis sampling after drug microdosing may provide tissue pharmacokinetic data early in clinical drug development. However, low administered doses and small sample volumes pose an analytical challenge, particularly for highly protein-bound drugs. Materials & methods: Carbon-14 [14C]diclofenac was used as a model drug to assess the technical and analytical feasibility of in vivo microdialysis after microdose administration in an in vitro setup. Results: [14C]diclofenac dialysate concentrations were accurately quantified with accelerator MS. [14C]diclofenac dialysate recoveries were similar in the presence and absence of therapeutic diclofenac concentrations but were considerably decreased when albumin was added to the immersion solution, suggesting high protein binding. Conclusion: These results demonstrate the feasibility of combining microdosing and microdialysis to assess tissue pharmacokinetics.

Pharmacokinetics of 2-phenoxyethanol and its major metabolite, phenoxyacetic acid, after dermal and inhaled routes of exposure: application to development PBPK model in rats.

2-Phenoxyethanol (PE), ethylene glycol monophenyl ether, is widely used as a preservative in cosmetic products as well as in non-cosmetics. Since PE has been used in many types of products, it can be absorbed via dermal or inhaled route for systemic exposures. In this study, the pharmacokinetic (PK) studies of PE and its major metabolite, phenoxyacetic acid (PAA), after dermal (30 mg and 100 mg) and inhaled administration (77 mg) of PE in rats were performed. PE was administered daily for 4 days and blood samples were collected at day 1 and day 4 for PK analysis. PE was rapidly absorbed and extensively metabolized to form PAA. After multiple dosing, the exposures of PE and PAA were decreased presumably due to the induction of metabolizing enzymes of PE and PAA. In dermal mass balance study using [14C]-phenoxyethanol ([14C]PE) as a microtracer, most of the PE and its derivatives were excreted in urine (73.03%) and rarely found in feces (0.66%). Based on these PK results, a whole-body physiologically-based pharmacokinetic (PBPK) model of PE and PAA after dermal application and inhalation in rats was successfully developed. Most of parameters were obtained from the literatures and experiments, and intrinsic clearance at steady-state (CLint,ss) were optimized based on the observed multiple PK data. With the developed model, systemic exposures of PE and PAA after dermal application and inhalation were simulated following no-observed-adverse-effect level (NOAEL) of 500 mg/kg/day for dermal application and that of 12.7 mg/kg/day for inhalation provided by the Environmental Protection Agency. The area under the concentration-time curve at steady state (AUCss) in kidney and liver (and lung for inhalations), which are known target organs of exhibiting toxicity of PE, as well as AUCss in plasma of PE and PAA were obtained from the model.

Multifunctional reduced graphene oxide-CVD graphene core-shell fibers.

The insufficient electrical conductivity and mechanical stretchability of conventional graphene fibers based on reduced graphene oxide liquid crystals (rGO-LCs) has limited their applications to numerous textile devices. Here, we report a simple method to fabricate multifunctional fibers with mechanically strong rGO cores and highly conductive CVD graphene shells (rGO@Gr fibers), which show an outstanding electrical conductivity as high as ∼137 S cm-1 and a failure strain value of 21%, which are believed to be the highest values among polymer-free graphene fibers. We also demonstrate the use of the rGO@Gr fibers for high power density supercapacitors with enhanced mechanical stability and durability, which would enable their practical applications in various smart wearable devices in the future.

Infrared Invisibility Cloak Based on Polyurethane-Tin Oxide Composite Microtubes.

An invisibility cloak based on visible rays with a refractive index similar to that of air can effectively conceal people or objects from human eyes. However, even if an invisibility cloak based on visible rays is used, an infrared (IR) thermography camera can detect the heat (thermal radiation) emitted from different types of objects including living things. Therefore, both visible and IR rays should be shielded using an invisibility cloak produced by an appropriate technology. Herein, we developed a textile cloak that can almost completely conceal people or objects from IR vision. If a person or object is covered with an IR- and thermal-radiation-shielding textile woven with polyurethane (PU)-tin oxide (SnO2) composite microtubes, serving as an IR invisibility cloak, IR and thermal radiation emitted from the person or object can be simultaneously blocked. Furthermore, the IR- and thermal-radiation-shielding characteristics could be improved further by filling the core of the PU-SnO2 composite microtubes with heat-absorbing materials such as water and paraffin oil in place of air. In addition, the external surface of the IR- and thermal-radiation-shielding textile serving as an IR-reflecting cloak can be waterproofed to enable certain IR- and thermal-radiation-shielding functions under various environmental conditions.

Observation of a water droplet motion by using an oxide nanowire transistor covered by a nanofiber mesh.

The motion, in particular the flow speed and dropping height, of a water droplet was observed using a tin oxide (SnO2) nanowire transistor with a polyurethane (PU) nanofiber mesh as a selective filter. The changes in the SnO2 nanowire transistor characteristics, particularly the threshold voltage and on-current, were due to the adsorbed water molecules that acted as electron donors on the surface of the oxide nanowire semiconducting channel. The role of the PU nanofiber mesh, allowing the passage of water vapor while blocking liquid water, was to restrict the direct contact between the water droplet and the oxide nanowire semiconducting channel and electrodes, which could cause abnormal transistor characteristics. The selective filtering properties of the PU nanofiber mesh could be controlled by changing the number of PU layers.