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The encapsulation of an amphiphile into polystyrene microspheres of narrow size distribution.

Pellach M, Margel S - Chem Cent J (2011)

Bottom Line: Encapsulation of compounds into nano- or microsized organic particles of narrow size distribution is of increasing importance in fields of advanced imaging and diagnostic techniques and drug delivery systems.We use hydrogen bonding of acid and base, combined with a pseudo salting out effect, for the entrapment of the amphiphile in the organic phase of a biphasic system.Following the entrapment in the organic phase, we demonstrated, using fluorescein and (antibiotic) tetracycline as model molecules, that the swelling method usually used only for hydrophobes can be expanded and applied to amphiphilic molecules.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, Bar-Ilan University, Ramat Gan 52900, Israel. shlomo.margel@mail.biu.ac.il.

ABSTRACT
Encapsulation of compounds into nano- or microsized organic particles of narrow size distribution is of increasing importance in fields of advanced imaging and diagnostic techniques and drug delivery systems. The main technology currently used for encapsulation of molecules within uniform template particles while retaining their size distribution is based on particle swelling methodology, involving penetration of emulsion droplets into the particles. The swelling method, however, is efficient for encapsulation only of hydrophobic compounds within hydrophobic template particles. In order to be encapsulated, the molecules must favor the hydrophobic phase of an organic/aqueous biphasic system, which is not easily achieved for molecules of amphiphilic character.The following work overcomes this difficulty by presenting a new method for encapsulation of amphiphilic molecules within uniform hydrophobic particles. We use hydrogen bonding of acid and base, combined with a pseudo salting out effect, for the entrapment of the amphiphile in the organic phase of a biphasic system. Following the entrapment in the organic phase, we demonstrated, using fluorescein and (antibiotic) tetracycline as model molecules, that the swelling method usually used only for hydrophobes can be expanded and applied to amphiphilic molecules.

No MeSH data available.


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Tetracycline (A), its entrapment into the organic phase of a biphasic system (B) and its encapsulation into polystyrene microspheres (C) Original magnification ×600.
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Figure 10: Tetracycline (A), its entrapment into the organic phase of a biphasic system (B) and its encapsulation into polystyrene microspheres (C) Original magnification ×600.

Mentions: In order to show that our model was not solely applicable to fluorescein, we searched for a molecule with similar properties. Tetracycline is a widely available antibiotic, with amphiphilic properties. Its planar ring structure gives it hydrophobic properties, and its primary amine and five hydroxyl groups give it hydrophilic character (Figure 10A). Tetracycline is somewhat soluble in DCM, and while its solubility in certain organic solvents may be considered adequate, on addition of an aqueous surfactant solution tetracycline behaves similarly to fluorescein and migrates to the aqueous phase. Simple salting out, using brine, did not achieve remigration back to the organic phase. However, treatment of a solution of tetracycline in DCM with TEA followed by a molar equivalent of AcOH resulted in successful entrapment in the organic phase, also in presence of an SDS aqueous solution (Figure 10B). Following entrapment, tetracycline could also be encapsulated into polystyrene, using swelling and deswelling. Since the fluorescence quantum yield of tetracycline is low [19,20], the resulting fluorescent signal of the polystyrene microspheres containing the tetracycline is relatively week, as shown in Figure 10C.


The encapsulation of an amphiphile into polystyrene microspheres of narrow size distribution.

Pellach M, Margel S - Chem Cent J (2011)

Tetracycline (A), its entrapment into the organic phase of a biphasic system (B) and its encapsulation into polystyrene microspheres (C) Original magnification ×600.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285059&req=5

Figure 10: Tetracycline (A), its entrapment into the organic phase of a biphasic system (B) and its encapsulation into polystyrene microspheres (C) Original magnification ×600.
Mentions: In order to show that our model was not solely applicable to fluorescein, we searched for a molecule with similar properties. Tetracycline is a widely available antibiotic, with amphiphilic properties. Its planar ring structure gives it hydrophobic properties, and its primary amine and five hydroxyl groups give it hydrophilic character (Figure 10A). Tetracycline is somewhat soluble in DCM, and while its solubility in certain organic solvents may be considered adequate, on addition of an aqueous surfactant solution tetracycline behaves similarly to fluorescein and migrates to the aqueous phase. Simple salting out, using brine, did not achieve remigration back to the organic phase. However, treatment of a solution of tetracycline in DCM with TEA followed by a molar equivalent of AcOH resulted in successful entrapment in the organic phase, also in presence of an SDS aqueous solution (Figure 10B). Following entrapment, tetracycline could also be encapsulated into polystyrene, using swelling and deswelling. Since the fluorescence quantum yield of tetracycline is low [19,20], the resulting fluorescent signal of the polystyrene microspheres containing the tetracycline is relatively week, as shown in Figure 10C.

Bottom Line: Encapsulation of compounds into nano- or microsized organic particles of narrow size distribution is of increasing importance in fields of advanced imaging and diagnostic techniques and drug delivery systems.We use hydrogen bonding of acid and base, combined with a pseudo salting out effect, for the entrapment of the amphiphile in the organic phase of a biphasic system.Following the entrapment in the organic phase, we demonstrated, using fluorescein and (antibiotic) tetracycline as model molecules, that the swelling method usually used only for hydrophobes can be expanded and applied to amphiphilic molecules.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, Bar-Ilan University, Ramat Gan 52900, Israel. shlomo.margel@mail.biu.ac.il.

ABSTRACT
Encapsulation of compounds into nano- or microsized organic particles of narrow size distribution is of increasing importance in fields of advanced imaging and diagnostic techniques and drug delivery systems. The main technology currently used for encapsulation of molecules within uniform template particles while retaining their size distribution is based on particle swelling methodology, involving penetration of emulsion droplets into the particles. The swelling method, however, is efficient for encapsulation only of hydrophobic compounds within hydrophobic template particles. In order to be encapsulated, the molecules must favor the hydrophobic phase of an organic/aqueous biphasic system, which is not easily achieved for molecules of amphiphilic character.The following work overcomes this difficulty by presenting a new method for encapsulation of amphiphilic molecules within uniform hydrophobic particles. We use hydrogen bonding of acid and base, combined with a pseudo salting out effect, for the entrapment of the amphiphile in the organic phase of a biphasic system. Following the entrapment in the organic phase, we demonstrated, using fluorescein and (antibiotic) tetracycline as model molecules, that the swelling method usually used only for hydrophobes can be expanded and applied to amphiphilic molecules.

No MeSH data available.


Related in: MedlinePlus