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Nonlinear tissue processing in ophthalmic surgery
Published in Pablo Artal, Handbook of Visual Optics, 2017
Such a propagation of light in a medium is the normal case and is referred to as linear propagation. If the amplitudes of the electromagnetic waves are extremely high, which corresponds to an intense light field such as those provided by lasers, the electrons may respond nonlinearly to the electric field of the light. These nonlinearities occur in certain crystal materials. They are responsible for effects such as the oscillation of the electrons do not oscillate harmonically with the frequency of the incoming filed but with, for example, twice the frequency. As a consequence, the emitted field has the double frequency or half the wavelength of the incoming field. Such a process, called frequency doubling or second harmonic generation. It is used today routinely when, for example, a Nd:YAG laser is focused into a KDP (monopotassium phosphate) crystal and its 1064 nm infrared wavelength is turned into 532 nm visible green light.
How subtle differences in polymer molecular weight affect doxorubicin-loaded PLGA nanoparticles degradation and drug release
Published in Journal of Microencapsulation, 2020
Natalya Kumskova, Yulia Ermolenko, Nadezhda Osipova, Aleksey Semyonkin, Natalia Kildeeva, Marina Gorshkova, Andrey Kovalskii, Tatyana Kovshova, Vadim Tarasov, Joerg Kreuter, Olga Maksimenko, Svetlana Gelperina
Copolymers of lactic and glycolic acids (PLGA) with a lactide–glycolide ratio of 50:50 and carboxylic end groups were obtained from Evonik Röhm GmbH, Germany [Resomer® RG 502 H], Lactel Absorbable Polymers, USA [Lactel®], and Corbion, Netherlands [Purasorb® PDLG 5002A]. Doxorubicin hydrochloride substance (Dox, 99.5% w/w) was purchased from Teva, Sicor, Italy. Polyvinyl alcohol (PVA, 9–10 kDa, hydrolysis degree 80%) and poloxamer 188 (Pluronic® F-68) were from Sigma-Aldrich, USA. Buffer solutions were prepared using PBS tablets (MP Biomedicals, LLC, USA), disodium phosphate (DSP), and monopotassium phosphate (MKP) salts (Panreac, Spain). All other reagents, including dichloromethane (DCM) and dimethyl sulfoxide (DMSO) were of analytical grade. Ultrapure water (type 1) produced by EasyPure UV 1053 (BarnStead Thermolyne, USA) was used for the experiments.
Preparation and characterization of insulin chitosan-nanoparticles loaded in buccal films
Published in Pharmaceutical Development and Technology, 2019
Nusaiba K. Al-Nemrawi, Sara S. M. Alsharif, Karem H. Alzoubi, Rami Q. Alkhatib
The insulin release from CS-NPs was studied in vitro using dialysis bags. Samples equivalent to 2.5 mg insulin were dispersed in 2 ml of artificial saliva and secured into the dialysis bags. Later, the dialysis bags were immersed in a beaker containing 8 ml of artificial saliva at 37 °C using a digital shaking water bath (Daihan Scientific, Korea) that agitated the samples at 100 rpm. The artificial saliva was prepared by dissolving 2.38 g of disodium phosphate, 0.19 g of monopotassium phosphate, and 8 g of sodium chloride in 1 L of distilled water, and the pH was adjusted with phosphoric acid to 7.4. Samples of 1 ml from each beaker were withdrawn at certain time points (0.25, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, and 6 h) and were replaced with the same amount of artificial saliva. Finally, the withdrawn samples were analyzed using HPLC-UV method described previously.
Exploring the mucoadhesive behavior of sucrose acetate isobutyrate: a novel excipient for oral delivery of biopharmaceuticals
Published in Drug Delivery, 2019
Stine Harloff-Helleberg, Lies A. L. Fliervoet, Mathias Fanø, Mechthild Schmitt, Maxim Antopolski, Arto Urtti, Hanne Mørck Nielsen
Labeling of insulin with 123I for SPECT/CT imaging was done by dissolving insulin (1 mg) in 800 µL 10 mM HCl. Then, 200 µL of 0.5 M monopotassium phosphate (KH2PO4) buffer (pH 5.0) was added to the solution. To 500 µL of the resulting solution, 300 µL of 0.2 M KH2PO4 buffer (pH 5.0) and 120 µL of Na-123I (109.2 MBq) were added. The reaction was started by addition of 10 µL of chloramine T solution (1 mg/mL). The reaction mixture was mixed well and left at RT. After 3 min, the reaction was stopped by addition of 10 µL of sodium thiosulfate (2.5 mg/mL) solution in ultrapure water. After 5 min, the reaction mixture was applied on an RP cartridge (Sep-Pac C18, Waters, Milford, MA), the cartridge was washed with 3 mL of deionized water to remove unreacted low molecular weight compounds and salt. The product was washed from the cartridge with 2 mL of 60% (v/v) acetonitrile containing 0.01% (v/v) HCl to give a mixture of insulin and radioactively labeled insulin (70 MBq). Then, solvents were removed in vacuum, and the residue was dissolved in 0.7 mL ethanol containing 0.1% (v/v) HCl, giving a radioactive yield of 64%. The radioactive purity was determined by HPLC (HP 1050, Agilent Technologies Inc., Palo Alto, CA), equipped with X bridgeTM C18 (5 µm, 4.6 × 150 mm, Waters, Milford, MA). The linear gradient for mobile phase B was set from 0 to 60% over 30 min with a flow rate of 1 mL/min. The mobile phase A consisted of 0.1% (v/v) TFA/99.1% (v/v) ultrapure water and B consisted of 0.1% TFA (v/v)/80% acetonitrile (v/v)/19.9% (v/v) ultrapure water.