A Novel Electrostimulated Drug Delivery System Based on PLLA Composites Exploiting the Multiple Functions of Graphite Nanoplatelets

A novel drug delivery system based on poly(l-lactide) (PLLA), graphite, and porphyrin was developed. In particular, 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (THPP) was chosen because, besides its potential as codispersing agent of graphite, it is a pharmacologically active molecule. Graphite nanoplatelets, homogeneously dispersed in both the neat PLLA and the PLLA/porphyrin films, which were prepared by solution casting, turned out to improve the crystallinity of the polymer. Moreover, IR measurements demonstrated that unlike PLLA/porphyrin film, where the porphyrin was prone to aggregate causing variable concentration throughout the sample, the system containing also GNP was characterized by a homogeneous dispersion of the above molecule. The effect of graphite nanoplatelets on the thermal stabilization, electrical conductivity, and improvement of mechanical properties of the polymer resulted to be increased by the addition of the porphyrin to the system, thus demonstrating the role of the molecule in ameliorating the filler dispersion in PLLA. The porphyrin release from the composite film, occurring both naturally and with the application of an electrical field, was measured using an UV-vis spectrophotometer. Indeed, voltage application turned out to improve significantly the kinetic of drug release. The biocompatibility of the polymer matrix as well as the mechanical and thermal properties of the composite together with its electrical response makes the developed material extremely promising in biological applications, particularly in the drug delivery field

Star poly(ε-caprolactone)-based electrospun fibers as biocompatible scaffold for doxorubicin with prolonged drug release activity

Abstract In this work, a novel drug delivery system consisting of poly(e-caprolactone) (PCL) electrospun fibers containing an ad-hoc-synthesized star polymer made up of a poly(amido-amine) (PAMAM) core and PCL branches (PAMAM-PCL) was developed. The latter system which was synthesized via the ring opening polymerization of e-caprolactone, starting from a hydroxyl-terminated PAMAM dendrimer and characterized by means of 1H NMR, IR and DSC, was found to be compatible with both the polymer matrix and a hydrophilic chemotherapeutic drug, doxorubicin (DOXO), the model drug used in this work. The preparation of the dendritic PCL star product with an average arm length of 2000 g/mol was characterized using IR and 1H NMR measurements. The prepared star polymer possessed a higher crystallinity and a lower melting temperature than that of the used linear PCL. Electrospun fibers were prepared starting from solutions containing the neat PCL as well as the PCL/PAMAM-PCL mixture. Electrospinning conditions were optimized in order to obtain defect free fibers, which was proven by the structural FE-SEM study. PAMAM moieties enhanced the hydrophilicity of the fibers, as proved by comparing the water absorption for the PCL/PAMAM-PCL fibers to that neat PCL fibers. The drug-loaded system PCL/PAMAM-PCL was prepared by directly introducing DOXO into the electrospinning solutions. The DOXO-loaded PCL/PAMAM-PCL showed a prolonged release of the drug with respect to the DOXO-loaded PCL fibers and elicited effective controlled toxicity over A431 epidermoid carcinoma, HeLa cervical cancer cells and drug resistant MCF-7 breast cancer cells. On the contrary, the drug-free PCL/PAMAM-PCL scaffold demonstrated no toxic effects on human dermal fibroblasts, suggesting the biocompatibility of the proposed system which can be used in cellular scaffold applications

Preparation and Characterization of Novel Electrospinnable PBT/POSS Hybrid Systems Starting from c-PBT

Novel hybrid systems based on poly(butyleneterephthalate) (PBT) and polyhedral oligomeric silsesquioxanes (POSS) have been prepared by applying the ring-opening polymerization of cyclic poly(butyleneterephthalate) oligomers. Two types of POSS have been used: one characterized by hydroxyl functionalities (named POSS-OH) and another without specific reactive groups (named oib-POSS). It was demonstrated that POSS-OH acts as an initiator for the polymerization reaction, leading to the direct insertion of the silsesquioxane into the polymer backbone. Among the possible applications of the PBT/POSS hybrid system, the possibility to obtain nanofibers has been assessed in this work

Hyperbranched PDLA-polyglicerol: A novel additive for tuning PLLA electrospun fiber degradation and properties

In this paper, it was developed the synthesis of a novel polymer additive potentially capable of modifying the features of electrospun fibers based on poly(L-lactide) (PLLA). Indeed, the above molecule, which was designed by taking into account both the features of the polymer matrix and the specific applications of the final material, was made up of a high-molecular-mass hyperbranched polyglicerol (HBPG) core and poly(D-lactide) (PDLA) arms (HBPG-PDLA). 1H NMR characterization allowed to assess the successful preparation of the dendritic HBPG-PDLA, synthesized by means of ring opening polymerization (ROP) of D-lactide, as well as the number average molecular weight per arm, that is about 1100 g/mol. Moreover, by combining 1H NMR and TGA results, it was determined an average number of polylactide arms of about 300. Electrospun fibers based on PLLA and HBPG-PDLA were prepared by directly adding the as-synthesized dendritic additive into the electrospinning solution to a final concentration of ca. 25 wt.%. FE-SEM analysis of the system, prepared by applying the optimized electrospinning conditions, demonstrated the formation of defect-free fibers without separated, micrometric domains of the additive. The thermal properties of both neat PLLA and composite fibers were studied by DSC analysis. The partial stereocomplexation of the systems containing HBPG-PDLA, resulting from the combination of the PDLA arms of the dendritic polymer with the chains of PLLA, was confirmed by calorimetric measurements as well as by X-ray diffraction analysis. The dendritic additive, featuring the hyperbranched polyglycerol core, was found to enhance the hydrophilicity of the fibers and consequently their enzymatic degradation rate, which turned out to be much higher than that of the neat PLLA fibers. Unlike the organic additives usually applied to modify the properties of PLLA, the addition of HBPG-PDLA to the fibers was also found to lead to an increase of the mechanical properties of the composite systems, that is an increment of their Young's modulus

On stereocomplexed polylactide materials as support for PAMAM dendrimers: Synthesis and properties

Stereocomplexed polylactide materials functionalized with poly(amido-amine) (PAMAM) dendrimer units were prepared by solution blending dendritic poly(d-lactide) (PDLA) star oligomers into a commercial poly(l-lactide) (PLLA), where the dendritic PDLA star oligomers were built up by ring-opening polymerization of d-lactide using a PAMAM dendrimer as macroinitiator. Whereas the synthesized poly(d-lactide)s (whose star-like architecture, comprising the PAMAM dendrimer as the core and a multi-arm PDLA shell, was demonstrated by means of 1H NMR spectroscopy) were observed to hardly structure/crystallize, their blended films, as revealed by DSC and WAXD measurements, proved capable of easy stereocomplexation in solution and melt crystallization alike. The stereocomplex, whose content and characteristics are greatly affected by the structure of the PDLA stars, affords improved thermal and chemical resistance, while simultaneously providing a strong link for the PAMAM units to the polymer matrix. The PAMAM dendrimers can thus manifest themselves, while being anchored onto a water/(solvent) insoluble, easy-processable polymeric support, which, in addition, is bio-based and bio-degradable and keeps the characteristics of biocompatibility. Indeed, thanks to the presence of the PAMAM functionalities, and unlike the neat polylactide, the resulting materials were shown to possess significant water-absorbency and Pd(ii)-uptake-ability. This latter property was exploited for the removal of Pd catalyst from a homogeneous reaction system