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Process and formulation variables in the preparation of injectable and biodegradable magnetic microspheres.

Zhao H, Gagnon J, Häfeli UO - Biomagn Res Technol (2007)

Bottom Line: Non-magnetic and magnetic microspheres had very similar size, morphology, and size distribution, as shown by scanning electron microscopy.The optimized conditions yielded microspheres with 13.7 weight% of magnetite and an average diameter of 1.37 microm.Such biodegradable magnetic microspheres seem appropriate for vascular administration followed by magnetic drug targeting.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada. hongzhao@interchange.ubc.ca

ABSTRACT
The aim of this study was to prepare biodegradable sustained release magnetite microspheres sized between 1 to 2 microm. The microspheres with or without magnetic materials were prepared by a W/O/W double emulsion solvent evaporation technique using poly(lactide-co-glycolide) (PLGA) as the biodegradable matrix forming polymer. Effects of manufacturing and formulation variables on particle size were investigated with non-magnetic microspheres. Microsphere size could be controlled by modification of homogenization speed, PLGA concentration in the oil phase, oil phase volume, solvent composition, and polyvinyl alcohol (PVA) concentration in the outer water phase. Most influential were the agitation velocity and all parameters that influence the kinematic viscosity of oil and outer water phase, specifically the type and concentration of the oil phase. The magnetic component yielding homogeneous magnetic microspheres consisted of magnetite nanoparticles of 8 nm diameter stabilized with a polyethylene glycole/polyacrylic acid (PEG/PAA) coating and a saturation magnetization of 47.8 emu/g. Non-magnetic and magnetic microspheres had very similar size, morphology, and size distribution, as shown by scanning electron microscopy. The optimized conditions yielded microspheres with 13.7 weight% of magnetite and an average diameter of 1.37 microm. Such biodegradable magnetic microspheres seem appropriate for vascular administration followed by magnetic drug targeting.

No MeSH data available.


Related in: MedlinePlus

TEM picture of a (A) non-magnetic PLGA microsphere, for comparison purposes, and a (B) MMS to show internal magnetite nanoparticle distribution. The size bar for both pictures is 100 nm long.
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Figure 9: TEM picture of a (A) non-magnetic PLGA microsphere, for comparison purposes, and a (B) MMS to show internal magnetite nanoparticle distribution. The size bar for both pictures is 100 nm long.

Mentions: Using the optimized conditions found for the non-magnetic microspheres, magnetite microspheres were prepared that contained 13.7 weight% of the magnetite nanoparticles. With a d50 size of 1.37 μm, these MMS were statistically indistinguishable from the non-magnetic microspheres with a d50 of 1.23 μm. Their size distributions given in Figure 7 were also very close and as narrow as needed for future in vivo applications. SEM pictures (Figure 8) confirm that the size and surface morphology of microspheres were not changed by adding magnetite to the formulation. In combination with information from TEM pictures, it is possible to confirm that the magnetic nanoparticles are dispersed well inside the MMS (Figure 9B). Furthermore, the jagged edges seen by TEM are not seen in the SEM, which means that the magnetic nanoparticles are embedded well by the microspheres' matrix material PLGA.


Process and formulation variables in the preparation of injectable and biodegradable magnetic microspheres.

Zhao H, Gagnon J, Häfeli UO - Biomagn Res Technol (2007)

TEM picture of a (A) non-magnetic PLGA microsphere, for comparison purposes, and a (B) MMS to show internal magnetite nanoparticle distribution. The size bar for both pictures is 100 nm long.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1863415&req=5

Figure 9: TEM picture of a (A) non-magnetic PLGA microsphere, for comparison purposes, and a (B) MMS to show internal magnetite nanoparticle distribution. The size bar for both pictures is 100 nm long.
Mentions: Using the optimized conditions found for the non-magnetic microspheres, magnetite microspheres were prepared that contained 13.7 weight% of the magnetite nanoparticles. With a d50 size of 1.37 μm, these MMS were statistically indistinguishable from the non-magnetic microspheres with a d50 of 1.23 μm. Their size distributions given in Figure 7 were also very close and as narrow as needed for future in vivo applications. SEM pictures (Figure 8) confirm that the size and surface morphology of microspheres were not changed by adding magnetite to the formulation. In combination with information from TEM pictures, it is possible to confirm that the magnetic nanoparticles are dispersed well inside the MMS (Figure 9B). Furthermore, the jagged edges seen by TEM are not seen in the SEM, which means that the magnetic nanoparticles are embedded well by the microspheres' matrix material PLGA.

Bottom Line: Non-magnetic and magnetic microspheres had very similar size, morphology, and size distribution, as shown by scanning electron microscopy.The optimized conditions yielded microspheres with 13.7 weight% of magnetite and an average diameter of 1.37 microm.Such biodegradable magnetic microspheres seem appropriate for vascular administration followed by magnetic drug targeting.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada. hongzhao@interchange.ubc.ca

ABSTRACT
The aim of this study was to prepare biodegradable sustained release magnetite microspheres sized between 1 to 2 microm. The microspheres with or without magnetic materials were prepared by a W/O/W double emulsion solvent evaporation technique using poly(lactide-co-glycolide) (PLGA) as the biodegradable matrix forming polymer. Effects of manufacturing and formulation variables on particle size were investigated with non-magnetic microspheres. Microsphere size could be controlled by modification of homogenization speed, PLGA concentration in the oil phase, oil phase volume, solvent composition, and polyvinyl alcohol (PVA) concentration in the outer water phase. Most influential were the agitation velocity and all parameters that influence the kinematic viscosity of oil and outer water phase, specifically the type and concentration of the oil phase. The magnetic component yielding homogeneous magnetic microspheres consisted of magnetite nanoparticles of 8 nm diameter stabilized with a polyethylene glycole/polyacrylic acid (PEG/PAA) coating and a saturation magnetization of 47.8 emu/g. Non-magnetic and magnetic microspheres had very similar size, morphology, and size distribution, as shown by scanning electron microscopy. The optimized conditions yielded microspheres with 13.7 weight% of magnetite and an average diameter of 1.37 microm. Such biodegradable magnetic microspheres seem appropriate for vascular administration followed by magnetic drug targeting.

No MeSH data available.


Related in: MedlinePlus