Novel bioresorbable tricalcium phosphate/polyhydroxyoctanoate (TCP/PHO) composites as scaffolds for bone tissue engineering applications

Development of new composite materials for bone tissue engineering is a constantly growing field of medicine. Therefore there is a continuous need in creating novel materials that can not only regenerate the defected tissue but also nourish it while the healing process progresses. Here we present a novel type of composite material that fulfils these requirements. The study describes creation of a composite with macroporous bioceramic core that is infiltrated with a thin biopolymer layer. The ceramic component, namely tricalcium phosphate (TCP), due to its mechanistic and bioactive properties may promote new bone creation as shown through the in vitro studies. To the best of our knowledge the coating layer was created for the first time from a representative of bacterially derived medium chain length polyhydroxyalkanoate polymers (mcl-PHA), namely polyhydroxyoctanoate (PHO). This polymer layer not only profoundly changed the stress-strain characteristics of the bioceramic foam but also released (R)-3-hydroxyacids and their dimers/trimers to the investigated environment. In the manuscript we have in depth characterised these materials employing a set of basic procedures, through 3D structure reconstruction and finishing with prolonged in vitro experiments

Novel multicomponent organic-inorganic WPI/gelatin/CaP hydrogel composites for bone tissue engineering

The present work focuses on the development of novel multicomponent organic‐inorganic hydrogel composites for bone tissue engineering. For the first time, combination of the organic components commonly used in food industry, namely whey protein isolate (WPI) and gelatin from bovine skin, as well as inorganic material commonly used as a major component of hydraulic bone cements, namely α‐TCP in various concentrations (0‐70 wt.%) was proposed. The results showed that α‐TCP underwent incomplete transformation to calcium‐deficient hydroxyapatite (CDHA) during preparation process of the hydrogels. Microcomputer tomography showed inhomogeneous distribution of the calcium phosphate (CaP) phase in the resulting composites. Nevertheless, hydrogels containing 30‐70 wt.% α‐TCP showed significantly improved mechanical properties. The values of Young's modulus and the stresses corresponding to compression of a sample by 50% increased almost linearly with increasing concentration of ceramic phase. Incomplete transformation of α‐TCP to CDHA during preparation process of composites provides them high reactivity in simulated body fluid during 14‐day incubation. Preliminary in vitro studies revealed that the WPI/gelatin/CaP composite hydrogels support the adhesion, spreading, and proliferation of human osteoblast‐like MG‐63 cells. The WPI/gelatin/CaP composite hydrogels obtained in this work showed great potential for the use in bone tissue engineering and regenerative medicine applications

Wpływ dodatków modyfikujących na właściwości hydroksyapatytowych wielofunkcyjnych tworzyw implantacyjnych przeznaczonych na nośniki leków rozprawa doktorska /

Tyt. z ekranu tytułowego.Praca doktorska. Akademia Górniczo-Hutnicza im. Stanisława Staszica (Kraków), 2007.Zawiera bibliogr.Dostępna także w wersji drukowanej.Tryb dostępu: Internet.Bioceramika oparta o fosforany wapnia, układ CaO-P2O5, CaO-P2O5-H2O, hydroksyapatyt, Ca10(PO4)6(OH)2, struktura hydroksyapatytu, podstawowe właściwości, modyfikatory bioceramiki hydroksyapatytowej, ortofosforan (V) wapnia, Ca3(PO4)2, zastosowanie bioceramiki Hap, TCP w medycynie, porowate implanty hydroksypatytowe, wpływ porowatości, rozmiaru porów na osteogenezę w warunkach in vitro, in vivo, na wytrzymałość mechaniczną implantów hydroksyapatytowych, metody otrzymywania porowatych implantów ceramicznych, kostne cementy fosforanowo-wapniowe, cementy CaP, wymagania stawiane cementom kostnym, zastosowanie cementów fosforanowo-wapniowych, polimerowe, ceramiczne nośniki leków, pompy, badania rentgenograficzne, pomiary powierzchni właściwej, BET, badania stopnia zagęszczenia tworzyw, porozymetryczne, wytrzymałości mechanicznej tworzyw, mikroskopowe, czasu wiązania cementów kostnych, trwałości chemicznej tworzyw, ocena biologiczna tworzyw, badania kinetyki uwalniania leków z układów homo, heterogenicznych, mikroporowate spieki modyfikowanej bioceramiki hydroksyapatytowej, charakterystyka surowców wyjściowych, otrzymywanie proszku hydroksyapatytowego, charakterystyka wyjściowego proszku Hap, dodatki modyfikujące ceramikę Hap, przygotowanie próbek do badań biologicznych w warunkach in vitro, uwalniania leków, wpływ dodatków modyfikatorów na gęstość wyprasek w stanie surowym, wyniki badań stopnia zagęszczenia spieków, porozymetrycznych, składu fazowego, mikrostruktury, oceny biologicznej spieków, kinetyki uwalniania leków z układu heterogenicznego, cementy fosforanowo-wapniowe, αTCP, płyn wiążący, przygotowanie próbek cementów, wyniki pomiarów czasu wiązania, wytrzymałości mechanicznej cementów kostnych, trwałości chemicznej opracowanych cementów kostnych, kinetyki uwalniania PTX z układu homogeniczneg

Comparative study on physicochemical properties of alpha-TCP / calcium sulphate dihydrate biomicroconcretes containing chitosan, sodium alginate or methylcellulose

Recently, the attention has been drawn to complex systems – biomicroconcretes composed of a bone cement matrix and resorbable granules or microspheres. This paper presents novel bone substitutes composed of α-tricalcium phosphate (α-TCP; cement matrix), calcium sulphate dihydrate granules (GCSD; aggregates in biomicroconcrete) and various polymers (chitosan, sodium alginate, methylcellulose) used for the improvement of material properties. The aim of this work was to study α-TCP-GCSD-polymer interactions and to compare the impact of organic additives on the physicochemical properties of biomicroconcretes. Methods: Scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), X-ray diffractometry (XRD) as well as universal testing machine (INSTRON), Gilmore apparatus and pH/ conduct-meter were used. Results: The chemical bonding between α-TCP matrix and CSD granules resulted in a compressive strength appropriate for low-load bearing applications (7–12 MPa) and clinically relevant setting times (8–33 min). Biomicroconcretes consisting of sodium alginate possessed the highest mechanical strength (12 ± 2 MPa). It has also been found that the dissolution-precipitation reactions of the α-TCP were retarded with the addition of chitosan and acetic acid. This effect was not observed in the case of methylcellulose and sodium alginate. Chemical stability and bioactivity of materials were demonstrated during in vitro studies in simulated body fluid. Conclusions: Materials containing calcium sulphate-based granules were surgically handy, possessed promising physicochemical properties and are supposed to ensure desired macroporosity as well as gradual resorption in vivo. It has been demonstrated that the presence of CSD granules and polymers influenced the physicochemical properties of composites

Vimentin cytoskeleton architecture analysis on polylactide and polyhydroxyoctanoate substrates for cell culturing

Polylactide (PLA), widely used in bioengineering and medicine, gained popularity due to its biocompatibility and biodegradability. Natural origin and eco-friendly background encourage the search of novel materials with such features, such as polyhydroxyoctanoate (P(3HO)), a polyester of bacterial origin. Physicochemical features of both P(3HO) and PLA have an impact on cellular response 32, i.e., adhesion, migration, and cell morphology, based on the signaling and changes in the architecture of the three cytoskeletal networks: microfilaments (F-actin), microtubules, and intermediate filaments (IF). To investigate the role of IF in the cellular response to the substrate, we focused on vimentin intermediate filaments (VIFs), present in mouse embryonic fibroblast cells (MEF). VIFs maintain cell integrity and protect it from external mechanical stress, and also take part in the transmission of signals from the exterior of the cell to its inner organelles, which is under constant investigation. Physiochemical properties of a substrate have an impact on cells’ morphology, and thus on cytoskeleton network signaling and assembly. In this work, we show how PLA and P(3HO) crystallinity and hydrophilicity influence VIFs, and we identify that two different types of vimentin cytoskeleton architecture: network “classic” and “nutshell-like” are expressed by MEFs in different numbers of cells depending on substrate features

Influence of Natural Polysaccharides on Properties of the Biomicroconcrete-Type Bioceramics

In this paper, novel hybrid biomicroconcrete-type composites were developed and investigated. The solid phase of materials consisted of a highly reactive α -tricalcium phosphate (α-TCP) powder, hybrid hydroxyapatite-chitosan (HAp-CTS) material in the form of powder and granules (as aggregates), and the polysaccharides sodium alginate (SA) or hydroxypropyl methylcellulose (HPMC). The liquid/gel phase in the studied materials constituted a citrus pectin gel. The influence of SA or HPMC on the setting reaction, microstructure, mechanical as well as biological properties of biomicroconcretes was investigated. Studies revealed that manufactured cement pastes were characterized by high plasticity and cohesion. The dual setting system of developed biomicroconcretes, achieved through α-TCP setting reaction and polymer crosslinking, resulted in a higher compressive strength. Material with the highest content of sodium alginate possessed the highest mechanical strength (~17 MPa), whereas the addition of hydroxypropyl methylcellulose led to a subtle compressive strength decrease. The obtained biomicroconcretes were chemically stable and characterized by a high bioactive potential. The novel biomaterials with favorable physicochemical and biological properties can be prosperous materials for filling bone tissue defects of any shape and size

Effect of Gold Nanoparticles and Silicon on the Bioactivity and Antibacterial Properties of Hydroxyapatite/Chitosan/Tricalcium Phosphate-Based Biomicroconcretes

Bioactive, chemically bonded bone substitutes with antibacterial properties are highly recommended for medical applications. In this study, biomicroconcretes, composed of silicon modified (Si-αTCP) or non-modified α-tricalcium phosphate (αTCP), as well as hybrid hydroxyapatite/chitosan granules non-modified and modified with gold nanoparticles (AuNPs), were designed. The developed biomicroconcretes were supposed to combine the dual functions of antibacterial activity and bone defect repair. The chemical and phase composition, microstructure, setting times, mechanical strength, and in vitro bioactive potential of the composites were examined. Furthermore, on the basis of the American Association of Textile Chemists and Colorists test (AATCC 100), adapted for chemically bonded materials, the antibacterial activity of the biomicroconcretes against S. epidermidis, E. coli, and S. aureus was evaluated. All biomicroconcretes were surgically handy and revealed good adhesion between the hybrid granules and calcium phosphate-based matrix. Furthermore, they possessed acceptable setting times and mechanical properties. It has been stated that materials containing AuNPs set faster and possess a slightly higher compressive strength (3.4 ± 0.7 MPa). The modification of αTCP with silicon led to a favorable decrease of the final setting time to 10 min. Furthermore, it has been shown that materials modified with AuNPs and silicon possessed an enhanced bioactivity. The antibacterial properties of all of the developed biomicroconcretes against the tested bacterial strains due to the presence of both chitosan and Au were confirmed. The material modified simultaneously with AuNPs and silicon seems to be the most promising candidate for further biological studies

Biomicroconcretes based on the hybrid HAp/CTS granules, α-TCP and pectins as a novel injectable bone substitutes

In this work, novel bone substitutes in the form of biomicroconcretes with high surgical handiness and satisfactory mechanical properties were developed. Materials were composed of hybrid hydroxyapatite/chitosan (HAp/CTS) granules as aggregate, α-TCP as a setting phase, and pectin solutions as a liquid phase. Two types of low esterified amidated pectins from citrus peels (CP) and apple pomace (AP) and also two fractions of HAp/CTS granules of size between 300 and 400 µm and 400–600 µm were used. The presence of pectins significantly improved surgical handiness and allowed to obtain injectable biomicroconcretes. Synergistic effect of fast internal crosslinking of low esterified pectins, induced by Ca2+ released from α-TCP, together with setting reaction of highly reactive α-TCP (dual setting system) resulted in excellent cohesion of the final materials. By the use of different type of pectins (AP, CP) one can control mechanical properties of the materials. The results showed that pectins from citrus peels more effectively improved compressive strength. The biomicroconcretes obtained in this work showed great potential for the use as novel bone substitutes, however, they require further studies, especially biological evaluation