51 research outputs found
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Responsive foams for nanoparticle delivery
We have developed responsive foam systems for nanoparticle delivery. The foams are easy to make, stable at room temperature, and can be engineered to break in response to temperature or moisture. Temperature-responsive foams are based on the phase transition of long chain alcohols and could be produced using medical grade nitrous oxide as a propellant. These temperature-sensitive foams could be used for polyacrylic acid (PAA)-based nanoparticle delivery. We also discuss moisture-responsive foams made with soap pump dispensers. Polyethylene glycol (PEG)-based nanoparticles or PMMA latex nanoparticles were loaded into Tween 20 foams and the particle size was not affected by the foam formulation or foam break. Using biocompatible detergents, we anticipate this will be a versatile and simple approach to producing foams for nanoparticle delivery with many potential pharmaceutical and personal care applications
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Microfluidic generation of droplets with a high loading of nanoparticles
Microfluidic approaches for controlled generation of colloidal clusters, for example, via encapsulation of colloidal particles in droplets, have been used for the synthesis of functional materials including drug delivery carriers. Most of the studies, however, use a low concentration of an original colloidal suspension (60 wt %) particle concentrations. Three types of microfluidic devices, PDMS flow-focusing, PDMS T-junction, and microcapillary devices, are investigated for direct encapsulation of a high concentration of polystyrene (PS) nanoparticles in droplets. In particular, it is shown that PDMS devices fabricated by soft lithography can generate droplets from a 25 wt % PS suspension, whereas microcapillary devices made from glass capillary tubes are able to produce droplets from a 67 wt % PS nanoparticle suspension. When the PS concentration is between 0.6 and 25 wt %, the size of the droplets is found to change with the oil-to-water flow rate ratio and is independent of the concentration of particles in the initial suspensions. Drop sizes from âŒ12 to 40 ÎŒm are made using flow rate ratios Qoil/Qwater from 20 to 1, respectively, with either of the PDMS devices. However, clogging occurs in PDMS devices at high PS concentrations (>25 wt %) arising from interactions between the PS colloids and the surface of PDMS devices. Glass microcapillary devices, on the other hand, are resistant to clogging and can produce droplets continuously even when the concentration of PS nanoparticles reaches 67 wt %. We believe that our findings indicate useful approaches and guidelines for the controlled generation of emulsions filled with a high loading of nanoparticles, which are useful for drug delivery applications
Regional permeability of salmon calcitonin in isolated rat gastrointestinal tracts: Transport mechanism using Caco-2 cell monolayer
The objective of the study was to determine the region of maximum permeation of salmon calcitonin (sCT) through the gastrointestinal tract and to investigate the mechanism of permeation. For regional permeability determination, male Sprague-Dawley rats (250â300 g) were anesthetized and the gastrointestinal tissues were isolated. Stomach, duodenum, jejunum, ileum, or colon tissues were mounted on Navicyte side-by-side diffusion apparatus. Salmon calcitonin solutions (50 ÎŒM in phosphate-buffered saline, pH 7.4, 37°C) were added to the donor side, and the samples were removed from the receiver compartment and analyzed by competitive radioimmunoassay (RIA). For mechanistic studies, Caco-2 cells were grown on Transwell inserts (0.4-ÎŒm pore size, 0.33 cm2 area) in a humidified 37°C incubator (with 5% CO2). Transport experiments were conducted for sCT solutions (50 ÎŒM in Dulbecco's modified eagle's medium [DMEM], pH 7.4) from the apical-to-basolateral (A-to-B) direction and B-to-A direction at 37°C and from the A-to-B direction at 4°C. Cell monolayer integrity was monitored by mannitol permeability and transepithelial electrical resistance (TEER) measurements. The permeability coefficients (Ă 10â9, cm/sec) for sCT through rat stomach, duodenum, jejunum, ileum, and colon tissues were 0.482±0.086, 0.718±0.025, 0.830±0.053, 1.537±0.32, and 0.934±0.15, respectively. The region of maximum sCT permeability is ileum followed by colon, jejunum, duodenum, and stomach. The permeability coefficients (Ă 10â6, cm/sec) for sCT through Caco-2 cell monolayer were 8.57±2.34 (A-to-B, 37°C), 8.01±1.22 (A-to-B, 4°C), and 6.15±1.97 (B-to-A, 37°C). The mechanism of its permeation is passive diffusion through the mucosa as determined from the Caco-2 monolayer permeability of sCT
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