Cast adhesive polyelectrolyte complex particle films of unmodified or maltose-modified poly(ethyleneimine) and cellulose
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ORIGINAL ARTICLE
Open Access
Cast adhesive polyelectrolyte complex particle films of unmodified or maltose-modified poly (ethyleneimine) and cellulose sulphate: fabrication, film stability and retarded release of zoledronate Bernhard Torger, David Vehlow, Birgit Urban, Samaa Salem, Dietmar Appelhans and Martin Müller*
Abstract The bone therapeutic drug zoledronate (ZOL) was loaded at and released by polyelectrolyte complex (PEC) particle films composed of either pure poly(ethyleneimine) (PEI) or maltose-modified poly(ethyleneimine) (PEI-M) and oppositely charged cellulose sulfate attached to model germanium (Ge) substrates by solution casting. Dispersions of colloidally stable polyelectrolyte complex (PEC) particles in the size range 11–141 nm were obtained by mixing PEI or PEI-M, CS and ZOL in defined stoichiometric ratios. TRANS-FTIR spectroscopy was used to determine the stability of the PEC films against detachment, in-situ-ATR-FTIR spectroscopy for the ZOL loss in the PEC film and UV–VIS spectroscopy for the ZOL enrichment of the release medium. Films of casted ZOL/CS/PEI-M or ZOL/CS/PEI particles were stable in contact to water, while films of the pure drug (ZOL) and of the binary systems ZOL/PEI-M or ZOL/PEI were not stable against detachment. Retarded releases of ZOL from various PEC films compared to the pure drug film were observed. The molecular weight of PEI showed a considerable effect on the initial burst (IB) of ZOL. No significant effect of the maltose modification of PEI-25 K on IB could be found. Generally, after one day the ZOL release process was finished for all measured ZOL/PEC samples and residual amounts of 0-30% were obtained. Surface adhesive drug loaded PEC particles are promising drug delivery systems to supply and release a defined amount of bone therapeutics and to functionalize bone substitution materials. Keywords: Bone healing; Interfacial drug delivery system; Polyelectrolyte complex particle; Poly(ethyleneimine); Zoledronate; In-situ ATR-FTIR spectroscopy
Background Functionalization of bone substitution materials (BSM) by local interfacial delivery systems for bone therapeutic drugs is a highly relevant strategy to improve bone healing after fractions associated with systemic bone diseases like osteoporosis or multiple myeloma [1]. Bisphosphonates (BP), especially nitrogen containing ones, are current drugs of choice for the therapy of osteoporosis [2]. Known examples of drug delivery systems (DDS) for BPs are based on calcium phosphate phases [3], sol–gel derived titania systems [4], acrylic * Correspondence: [email protected] Leibniz Institute of Polymer Research (IPF) Dresden, Hohe Straße 6, D-01069 Dresden, Germany
bone cements [5], bisphosphonate/fatty acid salt mixtures [6] and poly(D, L-lactide) coatings [7]. Target of this study is to develop an adhesive nanoparticular bisphosphonate delivery system based on biocompatible polyelectrolyte complexes. Typical release parameters like initial burst, residual amount and release rate of the drug are intended to be influence
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