Microspheres surface morphology

The properties of nanoparticles depend on surface morphology, specific surface area, particle size distribution, bulk density, drug incorporation, capacity, release, hydrophobicity, bioadhesiveness, and biodegradability. Nanoparticles (microspheres) loaded with the drug product can be formulated using copolymers, e.g., poly(lactide-co-glycolide) (PLG) or poly(lactide-co-ethylphosphate), by solvent extraction/evaporation technique. 

Controlled-release biodegradable PLG polymers loaded with parathyroid hormone were formulated as a freeze-dried form with particle size ranging from 27 to 47 i. The freeze-dried method did not alter the surface morphology, particle size, and parathyroid hormone content or release rate of the microspheres. The freeze-dried microspheres resuspended very rapidly and uniformly in solution. In vitro release studies indicated that except for a slight early burst ranging from 4-18%, release of parathyroid hormone from the nanoparticles was very slow over the first 14 days. At 15 days, release of parathyroid hormone accelerated rapidly. 

Lee, Y. Y, Z. Cheng, and H. Jeong, Generation of monodisperse mesoporous silica microspheres with controllable size and surface morphology in a microfluidic device. Advanced Functional Materials, 18, 4014-4021, 2008. 

Bouissou C, Rouse JJ, Price R, van der Walle CF. The influence of surfactant on PLGA microsphere glass transition and water sorption Remodeling the surface morphology to attenuate the burst release. Pharmaceutical Research. June 2006 23(6) 1295-1305. PubMed PMID 16715359. 

Poly (Vinyl Acetate-co-Methacrylic acid) copolymeric microspheres crosslinked with N, N -methylene bisacrylamide have been prepared by free radical emulsion polymerization. The microspheres have been characterized by differential scanning calorimetry (DSC) and x-ray diffractometry (X-RD) to understand about the drag dispersion in microspheres. Scanning electron microscopy (SEM) was used to assess the surface morphology of particles prepared, and observe the spherical nature... 

Kim H S (2007) Fracture surface morphology in thermosets modified with hollow microspheres,... 

Gelation and characterization of alginate microspheres mixed with other polymers are well described previously in the literature (7,2). However, no references for the interaction of emulsan and other polymers were found. Comparative optical microscopy of alginate and emulsan-alginate microspheres showed different surface morphologies (Figure 3). The results were confirmed by SEM (Figure 4). 

Weerakody et al. prepared chitosan microspheres for encapsulation of a-lipoic acid (LA) using the spray drying technique [20]. LA-loaded microspheres had smooth surface morphology. Particle size distribution of LA-loaded microspheres indicated that 50% of the particles were less than 7.89pm diameter. The antioxidant activity of encapsulated LA demonstrated a significant level (75%) of retention of activity when compared to free LA. 

The chain arrangement of this morphology was schematically proposed as in Fig. 10. The cell of the microsphere has a hexagonal surface, and the AB diblock copolymers form a bilayer between the microspheres. From this schematic arrangement, the optimal blend ratio of the AB block copolymer in this system was calculated as 0.46. This value was very close to the blend ratio of the AB type block copolymer 0.5 at which the blend showed the hexagonal packed honeycomb-like structure. 

Crystallisation of isotactic PP from homogeneous solution in supercritical propane yielded open-cell foams of high surface area. Their morphology usually consisted of microspheres with a dense core and a porous periphery... 

In a later study by the Schmidt group (27), electron microscopy was used to characterize morphological changes in microspheres (<0.6 cm in diameter) of Pt, Rh, Pd, and Pt-Rh alloy in a number of reaction environments the reactions were ammonia oxidation, ammonia decomposition, and propane oxidation. No other experimental techniques, such as weight-loss measurements, were employed. After prolonged exposure to reaction mixtures of ammonia and air at temperatures less than 727°C, the surfaces of the spheres were reconstructed to favor specific crystal planes. The structure of the facets was found to be a function of the reaction mixture, temperature, and metal (Fig. 13). In the same reaction mixtures, as well as in pure ammonia at higher temperatures... 

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