Karel Balík

Polylactide nanofibers with hydroxyapatite as growth substrates for osteoblast-like cells

Various types of nanofibers are increasingly used in tissue engineering, mainly for their ability to mimic the architecture of tissue at the nanoscale. We evaluated the adhesion, growth, viability, and differentiation of human osteoblast-like MG 63 cells on polylactide (PLA) nanofibers prepared by needle-less electrospinning and loaded with 5 or 15 wt % of hydroxyapatite (HA) nanoparticles. On day 7 after seeding, the cell number was the highest on samples with 15 wt % of HA. This result was confirmed by the XTT test, especially after dynamic cultivation, when the number of metabolically active cells on these samples was even higher than on control polystyrene. Staining with a live/dead kit showed that the viability of cells on all nanofibrous scaffolds was very high and comparable to that on control polystyrene dishes. An enzyme-linked immunosorbent assay revealed that the concentration of osteocalcin was also higher in cells on samples with 15 wt % of HA. There was no immune activation of cells (measured by production of TNF-alpha), associated with the incorporation of HA. Moreover, the addition of HA suppressed the creep behavior of the scaffolds in their dry state. Thus, nanofibrous PLA scaffolds have potential for bone tissue engineering, particularly those with 15 wt % of HA.

Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites

Hydroxyapatite (HA) is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N) or micro-sized (M) HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v) (referred to as N0–N25 or M0–M25), and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%–15%), MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%–15% (v/v) nano-size or micro-size HA seems to be optimum.

Effects of thermal ageing on the static and cyclic mechanical properties of carbon fibres/PDMS composites for use in medicine.

composites for use in medicine T. Suchý, R. Sedláček*, Z. Sucharda, K. Balı́k and T. Bouda Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4, 166 07 Prague 6, Czech Republic; Department of Composite and Carbon Materials, Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, v.v.i, V Holešovickách 41, Prague 8, Czech Republic

Optimizing and evaluating the biocompatibility of fiber composites with calcium phosphate additives.

SummaryComposite materials based on a polyamide fabric (aramid) and a polydymethylsiloxane (PDMS) matrix were designed for application in bone surgery. In order to increase the bioactivity, 2, 5, 10, 15, 20, and 25 vol.% of nano/micro hydroxyapatite (HA) and tricalcium phosphate (TCP) were added. We studied the effect of the additives on the biocompatibility of the composite. It appears that nano additives have a more favorable effect on mechanical properties than microparticles. 15 vol.% of nano hydroxyapatite additive is an optimum amount for final application of the composites as substitutes for bone tissue: in this case both the mechanical properties and the biological properties are optimized without distinct changes in the inner structure of the composite.

Submicrostructural domains in human secondary osteons

Miroslav Petrtyl, Karel Balik, Ctibor Povysil, Margit Zaloudkova Laboratory of Biomechanics and Biomaterial Engineering, Department of Mechanics, Faculty of Civil Engineering, Czech Technical University, Prague, Czech Republic; Department of Composite and Carbon Materials, The Institute of Rock Structures and Mechanics, Academy of Sciences, Prague, Czech Republic; Institute of Pathology, 1 Medicine Faculty of Charles University, Prague, Czech Republic

Characterization of the Interphase in Carbon Fiber Reinforced Polymeric Composite by a Modulus Mapping Test

The effect of sterilization on the structural integrity of the polydimethylsiloxane (PDMS) matrix composite reinforced with carbon fibers (CF) is investigated by nanoindentation test. We present the investigation of the influence of sterilization processes on fiber/matrix interphase properties. The effect of multiple widely-used steam sterilization processes on fibers/matrix interphase region properties was studied by modulus mapping test.

Effect of Sterilization Processes on the Fiber/Matrix Interphase Properties of CF/PDMS Composite to be Used in Orthopaedics

In this study we present the investigation of the influence of multiple sterilization processes on micromechanical properties carried out on a composite based on carbon fibers (CF) and polymer matrix composite polydimethylsiloxane (PDMS). The effect of widely-used steam sterilization process on fibers/matrix interphase region properties was studied by nanoindentation.

The influence of sterilisation processes on the micromechanical properties of polyamide fibre-reinforced PDMS composites for orthopaedic applications

fibre-reinforced PDMS composites for orthopaedic applications R. Sedláček*, T. Suchý, Z. Sucharda, K. Balı́k, M. Sochor, J. Šepitka and J. Lukeš Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4, 166 07 Prague 6, Czech Republic; Department of Composite and Carbon Materials, Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, v.v.i, V Holešovickách 41, Prague 8, Czech Republic

Nanoindentation characterisation of poly(dl-lactide)/collagen nanocomposites

T. Suchý*, Š. Rýglová, Z. Sucharda, K. Balı́k, J. Šepitka and J. Lukeš Department of Composite and CarbonMaterials, Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, v.v.i, V Holešovickách 41, Prague 8, Czech Republic; Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4, 166 07 Prague 6, Czech Republic

Comparison of Nanofiber and Particle Form of GELATINE/HA Biocomposites

This report is about composites used for bone grafting. Targets the composites compact of organic chemical compounds (biopolymers) and anorganic chemical compounds (nanoparticles). These composites must be, among others, biocompatible, nontoxic for organism and their mechanical properties must be near to mechanical properties of bone. This report focused on biodegradable composites based on gelatine and nanopowder of hydroxyapatite in nanofiber and particle form.