Poly(ethylene glycol) based hydrogel microparticles were developed for pulmonary drug delivery. Hydrogels are particularly attractive for pulmonary delivery because they can be size engineered for delivery into the bronchi, yet also swell upon reaching their destination to avoid uptake and clearance by alveolar macrophages. To develop enzyme-responsive hydrogel microparticles for pulmonary delivery a new synthesis method based on a solution polymerization was developed. This method produces spherical poly(ethylene glycol) (PEG) microparticles from high molecular weight poly(ethylene glycol) diacrylate (PEGDA)-based precursors that incorporate peptides in the polymer chain. Specifically, we have synthesized hydrogel microparticles that degrade in response to matrix metalloproteinases that are overexpressed in pulmonary diseases. Small hydrogel microparticles with sizes suitable for lung delivery by inhalation were obtained from solid precursors when PEGDA was dissolved in water at a high concentration. The average diameter of the particles was between 2.8 and 4 μm, depending on the molecular weight of the precursor polymer used and its concentration in water. The relation between the physical properties of the particles and their enzymatic degradation is also reported, where an increased mesh size corresponds to increased degradation.
Hydrogel microparticles are particularly attractive for pulmonary drug delivery. Their size can be engineered for efficient delivery into the bronchi, where they subsequently swell, avoiding macrophage uptake. In this study, enzyme-responsive peptide functionalized poly(ethylene glycol) (PEG) based hydrogel microparticles were synthesized by an emulsion polymerization. Here, we demonstrate that these microparticles are nontoxic and demonstrated their viability as a drug carrier by studying the encapsulation and release of three types of drugs: a hydrophobic (dexamethasone), a hydrophilic (methylene blue) and a protein (horseradish peroxidase)-based drug. The release of each of these three drugs was studied in the presence of varying concentrations of matrix metalloproteinase (MMP). Each of the three types of drugs were able to be encapsulated in the microparticles, and we further showed that the protein is still functional after release.
Magnetically soft NiZn ferrite (Ni0.5Zn0.5Fe2O4) nanoparticles are embedded within a permalloy (Ni-Fe) matrix via an electro-infiltration process as thin films intended for use as on-chip inductor cores in the MHz frequency regime. A layer of NiZn ferrite nanoparticles is first deposited, and then permalloy is electroplated through the voids to encapsulate the particles and form three-dimensional ferrite/alloy nanocomposites. The composites are estimated to contain 37% ferrite by volume and exhibit a relative permeability of ∼320, a saturation of ∼1.15 T, and an operational bandwidth of 93 MHz. Compared to a permalloy thin film of similar thickness, the nanocomposite exhibits 39% higher electrical resistivity and 50% higher bandwidth.
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