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Abstract:
Multifunctional composite biomaterials (3b-PU/CH_M) consisting of chitosan microspheres (CH-M) that provide drug release functionality and crosslinked polyester-urethane (3b-PU) matrix responsible for shape memory properties were designed. A series of 3b-PU/CH_M bio-composites with varying weight fraction of CH-M (2.5, 5, and 10 wt %) embedded into 3b-PU matrix were synthesized. The ATR-FTIR confirmed the presence of covalent bonds between 3b-PU matrix and CH-M as well as enhanced hydrogen bonds interaction within bio-composites matrix in comparison to neat 3b-PU. It was found that CH-M had not impaired the shape memory properties of 3b-PU matrix and even slightly improved the shape recovery (Rr %). The Rr value increased to 100% for 3b-PU/CH 2.5% M and 3b-PU/CH 5% M after the third thermo-mechanical cycle. Moreover, the transition temperature (Ttrans) of shape recovery tailored to 30 °C by the chemical composition of the 3b-PU network was not affected by CH-M. Effectiveness of the application of the composites as a controlled drug delivery system at various pH conditions was confirmed in an in vitro release study of ciprofloxacin hydrochloride (Cpx-HCl) used as a model drug. In vitro biocompatibility studies revealed that the materials do not alter the cells' ability to proliferate and differentiate.

Keywords:
multifunctional composites, smart materials, shape memory behavior, multifunctional properties, drug release

Abstract:
Physical and chemical factors resulting from the sterilization methods may affect the structure and properties of the materials which undergo this procedure. Poly(l-lactide-co-glicolide) (PLGA) is commonly used for medical applications, but, due to its inadequate mechanical properties, it is not recommended for load-bearing applications. One of the methods for improving PLGA mechanical properties is addition of hydroxyapatite nanoparticles (nHAp). The aim of this study was to evaluate the effect of nanoparticles addition on PLGA structure and properties after gamma radiation. According to our results, reduction of the molecular mass caused by gamma radiation was lower for PLGA with nHAp addition. Differential scanning calorimetry (DSC) analysis indicates an increase of crystallinity caused both by nHAp and gamma radiation. The first phenomenon can be explained by heteronucleation, while the second one is most probably related to higher molecular mobility of degrading polymer. Moreover, addition of nanoparticles increases thermal stability and affects the Young's modulus changes after gamma radiation.

Abstract:
Cells sense subtract stiffness, elasticity and transduce that information into morphological changes and lineage specification. Polymer molecular order and mechanical properties, specially stiffness and elasticity indicate influence on cellular response during in- vitro study [e.g. Bershadskye et al 2013]. The aim of proposed presentation is to evaluate the effect of tailored crystallinity and mechanical properties of one- and bicomponent polymer films in terms of cells morphology and proliferation without changing other parameters. Polycaprolactone (PCL) and Gelatin (Ge) were used. As a solvents: Hexafluoroisopropanole (H), Acetic Acid (AA) were chosen. Two methods of foil preparation were analysed: forming from melt (onecomponent), forming from solution (one- and bicomponent).In both methods, the degree of crystallinity was modified mainly by the different type of PCL molecular weight, solvent type and/or annealing. Films were analysed using polarizinginterference microscopy allowing characterization of spherulities morphology. Degree of crystallinity was analysed by differential scanning calorimetry. Foils topography was analysed by atomic force microscopy, selected mechanical properties and hydrophilicity (contact angle) as the significant from the viewpoint of cellular activity were determined as well. L929 cells adhesion and morphology ware analysed by immunohistochemical staining for actin and nuclei. Cell activity and proliferation were analysed also. It is evident that conditions of PCL films preparation affect the morphology of spherulites. All samples were birefringent, indicating in general crystallinity, being different for particular samples. Maltese cross was observed in few samples. Crystallinity of PCL films determined from DSC measurements was in range 0,45-0,70 depending on solvent and polymer molecular weight used. Young Modulus strongly depends on Mw of PCL and Ge additive. L929 cells interact with subtract; morphology and proliferation degree change with crystallinity and elasticity of one- and bicomponet films.

Keywords:
crystallinity, PCL, mechanical properties, casted films