Zofia Paszkiewicz

The FTIR spectroscopy and QXRD studies of calcium phosphate based materials produced from the powder precursors with different CaP ratios

Abstract Six precipitates of calcium phosphates with Ca P molar ratios in the range of 1.502–1.717 have been prepared by the wet method. After shaping and sintering at 1250 °C the phase composition of the obtained materials was examined by QXRD and FTIR spectroscopy methods.

Application of β-1,3-glucan in production of ceramics-based elastic composite for bone repair

BackgroundUnsatisfactory surgical handiness is a commonly known disadvantage of implantable granular bioceramics. To overcome this problem, β-1,3-glucan, biotechnologically derived polysaccharide, has been proposed as a joining agent to combine granular ceramics into novel compact and elastic composite. Hydroxyapatite/glucan elastic material was processed and evaluated as a potential bone void filler.MethodologyThe procedure of composite formation was based on gelling properties of glucan. Its properties were studied using X-ray microtomography, SEM-EDS, FTIR spectroscopy, compression test and ultrasonic method. Sorption index was determined in phosphate buffered saline; bioactivity in simulated body fluid; sterility in growth broth and human blood plasma; implantation procedure in dog model.ResultsHAp/glucan composite is sterilizable, flexible and self-adapting to defect shape. It exhibits bioactivity, good surgical handiness, high sorption index and profitable mechanical properties, resembling those of spongy bone. Results of pilot clinical experiment on animal (dog) patients of a local clinic of animal surgery suggested good healing properties of the composite and its transformation into new bone tissue within critical-size defect.ConclusionsThe results obtained in this study confirm that flexible HAp/glucan composite has potential as a bone-substituting material. Promising results of pilot clinical experiment suggest that further in vivo experiments should be performed.

The kinetics of pentoxifylline release in vivo from drug-loaded hydroxyapatite implants

Porous hydroxyapatite implants were evaluated as potential skeletal delivery systems for sustained delivery of drugs. Pentoxifylline (PTX) was employed as a model agent and 50 mg of PTX powder was loaded into hollow cylindrical implants. The kinetics of PTX release from the implants was studied both in vitro, employing phosphate buffer (pH 7.35) at the temperature of 37°C, and in vivo, implanting drug-containing cylinders into rabbit iliac bones. For the sake of comparison rabbits were also administered a single i.v. or i.m. dose of 50 mg PTX. Serum PTX concentration levels were measured using the HPLC method. Results of analyses carried out employing the mercury porosimetry method and the hydrostatic weighing method showed that the investigated biomaterial was characterized by a large number of pores ranging in size from 0.4 to 6 μm and with open and total porosity values of 31.8 and 35.6%, respectively. Studies in vitro revealed typical sigmoid-type drug release patterns with a lag time. After 40 h, the amount of released PTX reached a plateau and equaled 78% of the total amount of drug loaded into an implant. Studies in vivo demonstrated that due to decelerated PTX release from cylinders implanted in rabbit iliac bones, its serum concentration values were maintained at measurable levels almost eight times longer than following the systemic administration of PTX. The serum half-life following PTX administration via implants was significantly higher than the value calculated after systemic administration and equaled 6.3 h. The authors also showed that despite differences in the temporal distribution of PTX concentration values, its bioavailability was similar after i.m. injections and administration via implants. As it follows from the investigations, hydroxyapatite implants manifest positive drug-release patterns both in vitro and in vivo.

Characterization of calcium phosphate coatings doped with Mg, deposited by pulsed laser deposition technique using ArF excimer laser

Calcium phosphate layers were deposited on Ti6Al4V substrates with TiN buffer layers by use of pulsed laser deposition method. With this technique three pressed pellets consisted of tricalcium phosphate (TCP, Ca(3)(PO(4))(2)), hydroxyapatite (HA, Ca(10)(PO(4))(6)(OH)(2)) and hydroxyapatite-doped with magnesium (HA with 4% of Mg and trace amount of (Ca,Mg)(3)(PO(4))(2)) were ablated using ArF excimer laser (lambda=193 nm). The using of different targets enabled to determine the influence of target composition on the nature of deposited layers. The obtained deposits were characterized by means of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction method (XRD). The obtained Fourier spectras revealed differences in terms of intensity of spectral bands of different layers. The analysis from XRD showed that Mg-doped HA layer has crystalline structure and TCP and HA layers composition is characterized by amorphous nature.

Bacterial colonisation of bioceramic surfaces

Abstract Hydroxyapatite (HAp – Ca10(PO4)6(OH)2) and tricalcium phosphate (TCP – Ca3(PO4)2) are bioceramic materials of special interest with regards to bone surgery, in particular the repair of bone tissue defects. These materials are highly biocompatible with bone and soft tissue; they are bioactive, osteoconductive and resistant to sterilisation processes. In comparison with other biomaterials, particularly metallic materials, bioceramic surfaces exhibit high resistance to bacterial colonisation. This is currently considered to be one of the most important issues concerning materials used in medicine, due to the fact that bacterial biofilm is difficult to combat or remove and can be responsible for recurrent infections. The aim of the present study was to evaluate bacterial colonisation on the surface of different calcium phosphate based materials.

Comparative in vitro study of calcium phosphate ceramics for their potency as scaffolds for tissue engineering

BACKGROUND Calcium phosphate ceramics have been widely considered as scaffolds for bone tissue engineering. Selection of the best support for cultured cells, crucial for tissue engineered systems, is still required. OBJECTIVE We examined three types of calcium phosphate compounds: α-tricalcium phosphate - the most soluble one, carbonate hydroxyapatite - chemically the most similar to the bone mineral and biphasic calcium phosphate - with the best in vivo biocompatibility in order to select the best support for osteoblastic cells for tissue engineered systems. METHODS Human osteoblasts were tested in direct contact with both dense samples and 3D scaffolds in either static or dynamic culture. Cell viability, cell spreading, osteogenic cell capacity, and extracellular matrix production were examined. RESULTS The obtained data indicate that biphasic calcium phosphate is the optimal cell-supporting material. In addition, dynamic culture improved cell distribution in the scaffolds, enhanced production of the extracellular matrix and promoted cells osteogenic capacity. CONCLUSIONS Biphasic calcium phosphate should be recommended as the most suitable matrix for osteogenic cells expansion and differentiation in tissue engineered systems.

Effects of Mg Additives on Properties of Mg-Doped Hydroxyapatite Ceramics

In the studies undoped HA and HA modified with 0.3; 0.6; 0.9; 1.8 wt % of Mg were prepared by the wet method. Introduction of magnesium into HA structure influenced its thermal stability as well as phase composition, sinterability, microstructure, flexural strength and chemical stability of the obtained calcium-phosphate ceramics. The presence of magnesium promoted the decomposition of HA to βTCP above 800°C. Beyond a certain limit (0.9 wt %), Mg ions caused formation of MgO in Mg-HA ceramics. Chemical stability of Mg modified HA below 0.9 wt % Mg under in vitro conditions was similar to that of the undoped hydroxyapatite. Biological studies showed that the number of cells cultured on the surface of HA samples with 1.8 wt % Mg additive, probably due to the MgO content, was lower than on the pure HA ceramics.

Drug Release from Hydroxyapatite Implants with Different Microstructure and Phase Composition

The goal of our studies has been to determine under in vitro conditions the amount and rate of pentoxifylline release from the samples of modified hydroxyapatite [HAp-Ca10(PO4)6(OH)2] implants in the form of microporous blocks (heterogeneous system) as well as from hydroxyapatitegypsum pellets (homogeneous system). For the preparation of microporous hydroxapatite ceramics additives of calcium metaphosphate Ca(PO3)2 (5 and 10 wt. %) or hydrated magnesium orthophosphate Mg3(PO4)2·8H2O (10 wt. %) were used as modifiers. In the case of drug release from heterogeneous carriers, cylinders filled with 50 mg of PTX were used. In the homogeneous system the pellets made of HAp and CaSO4·1/2H2O powders with homogeneously incorporated of 50 mg PTX were applied. It has been shown that the process of drug release from multifunctional ceramic implants depends to a significant degree on the microstructure of the materials, and the type of carrier system (heterogeneous or homogeneous).

XRD Studies on Transformation of Calcium-Deficient Apatite to β and α TCP in Dynamic and Technological Conditions

Calcium phosphates (CaPs): hydroxyapatite (HA) and TCP are common biomaterials used in orthopedic, dental and maxillofacial surgery as bone fillers and also as drug carriers. Studies of the β→α TCP transformation and formation of mono-, bi- or three-phase CaPs materials: βTCP-αTCP-HA are of principal importance. Stability of calcium phosphate ceramics depends on many factors. Our dynamic studies by high temperature XRD measurements showed that monoclinic αTCP was a considerably stable phase after its creation completed at 1200°C. Different phase composition was obtained in technological conditions.