title: Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes.
abstract: The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA) n stereocomplex and the cores with and without the polymeric (PSS/PAH) n /PLL multilayer precursor (PEM). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) were used to characterize the chemical composition and molecular weight of poly(lactic acid) polymers. Both multilayer structures, with and without polymeric precursor, were firstly fabricated and characterized on planar supports. A quartz crystal microbalance (QCM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and ellipsometry were used to evaluate the thickness and mass of the multilayers. Then, hollow, spherical microcapsules were obtained by the removal of the CaCO3 sacrificial template. The chemical composition of the obtained microcapsules was confirmed by differential scanning calorimetry (DSC) and wide X-ray diffraction (WXRD) analyses. The microcapsule morphology was evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The experimental results confirm the successful fabrication of this innovative system, and its full biocompatibility makes it worthy of further characterization as a promising drug carrier for sustained release.
authors.affiliation: Department of Informatics, Bioengineering, Robotics and Systems Engineering, University of Genova, Via all' Opera Pia 13, 16145 Genova, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Dellacasa
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, E1 4NS London, UK.
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.affiliation: State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, P. R. China.
authors.forename: Gesheng
authors.initials: G
authors.lastname: Yang
authors.affiliation: Department of Informatics, Bioengineering, Robotics and Systems Engineering, University of Genova, Via all' Opera Pia 13, 16145 Genova, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Pastorino
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, E1 4NS London, UK.
authors.forename: Gleb B
authors.initials: GB
authors.lastname: Sukhorukov
keywords: biocompatibility; layer-by-layer assembly; microcapsules; poly(lactic acids); stereocomplex