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Commercialized Microneedles
Published in Boris Stoeber, Raja K Sivamani, Howard I. Maibach, Microneedling in Clinical Practice, 2020
KangJu Lee, Seung Hyun Park, Ji Yong Lee, Won Hyoung Ryu
The first examples of an integrated microinjection system are the Soluvia™ from Becton Dickenson (BD) (Figure 9.2a) and the SCS (suprachoroidal space) microinjector from Clearside Biomedical Inc. (Figure 9.2b). The BD Soluvia™ prefillable microinjection system is a glass prefillable spring-based syringe system integrated with a 1.5 mm long 30 gauge stainless steel needle. The SCS microinjector is a prefillable suprachoroidal microinjection system with a height of approximately 700–800 μm for ocular injection. The SCS microinjector was fabricated from a 33G stainless steel needle with laser shaping and electropolishing [10]. BD conducted clinical trials involving more than 700 subjects and 3500 injections with BD Soluvia™ and demonstrated the safety and ease of use [11]. In addition, the BD clinical tests showed that the MN was barely perceptible when penetrating the skin, and effectively injected drug into the intradermal layer regardless of the subject's gender, ethnicity, and body mass [12]. Consequently, Sanofi Pasteur obtained FDA approval of Fluzone® Intradermal Quadrivalent (influenza vaccine) for adults using BD Soluvia™ in 2014. In addition, an FDA phase 3 clinical trial for suprachoroidal injection of CLS-TA (triamcinolone acetonide) in subjects with noninfectious uveitis (AZALEA) using the SCS microinjector has been completed in 2018.
Gases
Published in Frank A. Barile, Barile’s Clinical Toxicology, 2019
Cyanide compounds are also valuable industrial chemicals used in electroplating and electropolishing, the manufacture of plastics, and the extraction of gold and silver from ores; as fumigants; in fertilizer; and in artificial nail glue removers. Therapeutically, sodium nitroprusside, a direct arterial vasodilator used in the treatment of emergency hypertension, releases five molecules of CN when metabolized, which also accumulates with fast infusion rates (see Chapter 20). As with CO poisoning, fire victims are also prone to CN intoxication.
Nebulizers
Published in Anthony J. Hickey, Sandro R.P. da Rocha, Pharmaceutical Inhalation Aerosol Technology, 2019
John N. Pritchard, Dirk von Hollen, Ross H.M. Hatley
It was not until the mesh nebulizer was introduced to the market in the mid 1990s that nebulizer technology was revolutionized by providing a portable, quiet, and efficient means of nebulizing aqueous drug formulations. Mesh nebulizers also rely on a piezoelectric transducer for creation of the aerosol droplets, but instead of using the power of the ultrasonic waves to break the surface of the liquid apart, the vibrations from the piezo are used in combination with a fine mesh constructed of a thin substrate punctured with many holes. At the time of publication, the two main methods for mesh production were electroplating and laser cutting techniques; both are used to produce a tapered hole. A tapered hole is required to optimize mesh performance it amplifies flow at the nozzle and reduces viscous losses. The electroplating method relies on the use of a lithographic plate, and the eventual size of the mesh holes is determined by the duration of the electroplating process; the holes get smaller as the metal is deposited on the edge of the hole over time. Laser cutting involves the use of a laser beam to cut the mesh holes in a thin sheet of metal or polymer material; laser cutting metal can result in molten material being deposited around the hole, which is then removed by electropolishing. Most mesh nebulizer meshes are constructed from either metal alloy or ceramic materials, to give the rigidity, mass, durability, and inert chemical properties required for the aerosolization of different drug formulations, though some manufacturers have opted for laser drilled polymer meshes.
Demonstration of biofilm removal from type 304 stainless steel using pulsed-waveform electropolishing
Published in Biofouling, 2018
Mahadurage Sachintha Wijesinghe, Jianchuan Wen, Jung-Min Oh, Kwok-Fan Chow, Yuyu Sun
Electropolishing is an electrochemical technique that is employed in metal surface finishing. This process removes metal ions from a metal surface when an appropriate potential is applied to the metal in order to minimize micro-roughness and create a shiny surface (Park and Lee 2009; Mohammad and Wang 2016). Typically, electropolishing involves hazardous chemicals (eg phosphoric acid, sulfuric acid, and hydrogen fluoride) in order to remove the passivation layer on the metal surface when direct current is used in the process (Landolt 1987; Lee 2000; Inman et al. 2013). Alternatively, short potential pulses can be applied to remove the surface passivation layer under mild chemical conditions, eg in neutral electrolyte solutions (Datta and Landolt 1981; Landolt 1987; Taylor and Inman 2014). In this study, the latter method that can be conducted in a saline electrolyte solution was used. Under the experimental conditions used, this solution does not harm the biofilm, and thus its removal from the SS surface can be confirmed to be due to the short potential pulses that are applied to the SS wire, pointing to a simple, rapid, and toxic-chemical-free strategy to remove unwanted biofilms from metal surfaces.
Porous silicon based intravitreal platform for dual-drug loading and controlled release towards synergistic therapy
Published in Drug Delivery, 2018
David Warther, Ying Xiao, Fangting Li, Yuqin Wang, Kristyn Huffman, William R. Freeman, Michael Sailor, Lingyun Cheng
pSi microparticles were prepared by electrochemical etch of highly doped, (100)-oriented, P++-type silicon wafers (boron-doped, 1.04 × 10−3 Ω.cm resistivity) purchased from Virginia Semiconductors or Siltronix. The wafers were mounted into a 54 cm2 etch cell fitted with a platinum counter electrode. New wafers were cleaned as follows prior to any actual porous layer etch. The first porous layer was etched in 150 ml of a 3:1(vol/vol) solution of 48% aqueous hydrofluoric acid (HF)/absolute ethanol (EtOH) under a current of 100 mA cm−2 for 1 min. The porous layer was then dissolved by a 2 N KOH solution in water. The cleaned wafer was finally rinsed with deionized water 3 times, ethanol 3 times, and carefully dried under nitrogen. The porous material was then created through an electrochemical etch in 240 ml of a 1:1 (vol/vol) solution of 48% HF/EtOH at a continuous current of 30 mA cm−2 for 960 s followed by a pulse of current at 176 mA cm−2 for 0.3 s. After allowing the electrolyte to homogenize by stopping the current for 1 s, 30 mA cm−2 were applied for an additional 960-s period. The resulting porous layer was then washed once with EtOH and lifted off by electropolishing in a 1:29 solution of 48% HF/EtOH for 400 s at a current of 6 mA cm−2. The porous material obtained through each cycle was stored in EtOH in individual glass vials (30 ml). Etching and electropolishing procedures were repeated up to 8 times per wafer. The pSi particles were obtained by ultrasound fracturation of the pSi films (20 µm thickness) in EtOH in an ultrasonic cleaner. The films were sonicated for 15 min and the material was allowed to settle down. The supernatant was removed and the material was washed twice with EtOH then sonicated for an additional 15-min period. After sedimentation and removal of the supernatant, the particles were washed with EtOH until the supernatant remained clear (absence of very small particles).
Micro to nanoneedles: a trend of modernized transepidermal drug delivery system
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Pravin Shende, Mrunmayi Sardesai, R. S. Gaud
Comparative aspects of microneedles and nanoneedlesThe main microneedle fabrication methods are based on certain conventional techniques of microfabrication such as adding, removing, and copying microstructures, which use processes such as silicon etching, laser cutting, metal electroplating, electropolishing, micromolding and photolithographic processes.The most general method of fabrication of microneedles is by moulding, where micro moulds are prepared using photolithography and moulding processes. Laser cutting is another technique used for cutting microneedles from stainless steel sheets using an infrared laser. Electropolishing is the technique used to clean microneedles, and make the edges sharp for effective penetration. This is usually done using a combination of glycerine, orthophosphoric acid and water.Nanoneedle fabrication methods are gaining potential, as more and more types of fabrication techniques in the nanometre scale range are undergoing experimental research.Nanoneedles have been made using boron-nitride nanotube, which is attached to a glass pipette and coated with a thin layer of gold. The different types of microneedles today are being studied for enabling DNA vaccine delivery to the skin.On a large scale, nanoneedles have been fabricated using carbon nanotubes (CNTs) and silicon. It is of great interest and necessity now to fabricate nanoneedles using various other materials. Electrodeposition has been used to fabricate functional nanoneedles since metals, metal oxides, polymers can be coated to the desired location of the conducting nanoneedle. It has been observed that the microneedle and nanoneedle electrode fabrication method using CNT and electrodeposition method is simple. It can also be used with a variety of materials, producing needle like electrodes with desired properties.