Abstract
α-Tocopherol is the most bioavailable and active compound found in vitamin E with potential application in pharmaceutical, alimentary and cosmetic industries. However, its low solubility in aqueous medium and environmental instability limit its dosage. In this paper, we report the preparation of α-tocopherol loaded nanoparticles (TOC-NP) based on amphiphilic thermosensitive triblock copolymers PNIPAM-b-PCL-b-PNIPAM. The nanoparticles exhibited a core – shell structure, were positively charged and presented average diameters below 300 nm. TOC-NP presented controlled release of α-tocopherol at room temperature along 140h, and exhibited antioxidant properties in aqueous medium.
Highlights
MaterialsN-Isopropylacrylamide (NIPAM, 98%) was recrystallized from hexane, α,ω-dihydroxy-Poly(ε-caprolactone) of MN =10 and 45 kDa was purified by precipitation from a mixture of THF and methanol. 2-Bromoisobutyryl Bromide (BIBB, 98%), triethylamine (>99%), cupper(II) bromide (CuBr2, 98%) N,N,N’,N”,N”-Pentamethyldiethylenetriamine (PMDETA, 99%), anisole and α-tocopherol were used without any additional purification
In order to overcome its environmental susceptibility, The implementation of technologies based in block and improve its solubility in aqueous medium, encapsulation copolymers is stimulated by advances in controlled radical has been recently exploited by several authors[2,3,4]
Analogous to low molecular weight surfactants, obtained from triblock copolymers PNIPAM-b-PCL-bamphiphilic block copolymers composed of hydrophilic and PNIPAM synthesized via ARGETATRP
Summary
N-Isopropylacrylamide (NIPAM, 98%) was recrystallized from hexane, α,ω-dihydroxy-Poly(ε-caprolactone) of MN =10 and 45 kDa was purified by precipitation from a mixture of THF and methanol. 2-Bromoisobutyryl Bromide (BIBB, 98%), triethylamine (>99%), cupper(II) bromide (CuBr2, 98%) N,N,N’,N”,N”-Pentamethyldiethylenetriamine (PMDETA, 99%), anisole and α-tocopherol were used without any additional purification. N-Isopropylacrylamide (NIPAM, 98%) was recrystallized from hexane, α,ω-dihydroxy-Poly(ε-caprolactone) of MN =10 and 45 kDa was purified by precipitation from a mixture of THF and methanol. The preparation of α-tocopherol loaded nanoparticles was as follows: 10 mg of α-tocopherol and 50 mg of the corresponding copolymer were dissolved in 5 mL of acetone. The resulting dispersion was gently stirred during 1 hour under reduced pressure to eliminate acetone residuals. The aqueous suspensions were lyophilized, rinsed with hexane at room temperature to eliminate non-encapsulated α-tocopherol. The amount of encapsulated α-tocopherol was determined dissolving the polymer samples in acetone, and analyzing the content of this substance by HPLC. The loading-efficiency (DLE%) as well as the drug content (DLC%) were estimated using as follows: 2.2 Synthesis procedures. In a typical procedure for PCL Mn=10 KDa, 5 g of diol-ended PCL (0.35 mmol) was dissolved in 50 mL of anhydrous. The same procedure was used to modify PCL of 45KDa
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