title: Fabrication of microspheres via solvent volatization induced aggregation of self-assembled nanomicellar structures and their use as a pH-dependent drug release system.
abstract: A series of oleamide derivatives, (C(18)H(34)NO)(2)(CH(2))(n) [n = 2 (1a), 3 (1b), 4 (1c), or 6 (1d); C(18)H(34)NO = oleic amide fragment] and (C(18)H(34)NO)(CH(2))(6)NH(2) (2), have been synthesized and their self-assembly is investigated in ethanol/water media. Self-assembly of 1a and 1b in ethanol/water (1/0.1 v/v) solution (5 mg mL(-1)) yields microspheres (MSs) with the average diameter ∼10 μm via a gradual temperature reduction and solvent volatilization process. Under the same self-assembly conditions, microrods (average diameter ∼6 μm and several tens of micrometers in length), micronecklace-like, and shape-irregular microparticles are formed from the self-assembly of 1c, 1d, and 2, respectively. The kinetics of evolution for their self-assemblies by dynamic light scattering technique and in situ observation by optical microscopy reveals that the microstructures formation is from a well-behaved aggregation of nanoscale micelles induced by solvent volatilization. The FT-IR and temperature-dependent (1)H-NMR spectra demonstrate the hydrogen bonding force and π-π stacking, which drove the self-assembly of all oleamide derivatives in ethanol/water. Among the fabricated microstructures, the MSs from 1a exhibit the best dispersity, which thus have been used as a scaffold for the in vitro release of doxorubicin. The results demonstrate a pH-sensitive release process, enhanced release specifically at low pH 5.2.
authors.affiliation: The WCU Center for Synthetic Polymer Bioconjugate Hybrid Materials, Department of Polymer Science and Engineering, Pusan National University, Pusan 609 735, Korea.
authors.forename: Lidong
authors.initials: L
authors.lastname: Zhang
authors.forename: Young-Il
authors.initials: YI
authors.lastname: Jeong
authors.forename: Sudan
authors.initials: S
authors.lastname: Zheng
authors.forename: Hongsuk
authors.initials: H
authors.lastname: Suh
authors.forename: Dae Hwan
authors.initials: DH
authors.lastname: Kang
authors.forename: Il
authors.initials: I
authors.lastname: Kim
mesh_terms: D002460:Cell Line; D016503:Drug Delivery Systems; D000431:Ethanol / Q000737:chemistry; D006801:Humans; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D018613:Microscopy, Confocal; D008863:Microspheres; D015394:Molecular Structure; D009829:Oleic Acids / Q000138:chemical synthesis / Q000737:chemistry; D010316:Particle Size; D012997:Solvents / Q000737:chemistry; D014835:Volatilization; D014867:Water / Q000737:chemistry
chemical_list: D008823:Micelles; D009829:Oleic Acids; D012997:Solvents; D014867:Water; D000431:Ethanol; C029407:oleylamide