The influence of silver, copper and zinc ions on the properties of bioceramic materials based on calcium phosphate

[Ž. M. Radovanović]

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Hemija i hemijska tehnologija / Chemistry and chemical technology

Kalcijum-fosfati čine neorganski deo kostiju i zuba sisara. Ova dobro poznata činjenica je ohrabrila istraživače da tokom prethodnih godina primene sintetisani kalcijum-hidroksiapatit (HAp, Ca10(PO4)6(OH)2) i kalcijum-fosfat (TCP, Ca3(PO4)2), α- i β-TCP faze, kao implantne materijale. Njihova sličnost sa neorganskim delom kostiju je potvrđena, a posebno je istaknuta njihova biokompatibilnost i osteokonduktivnost i dodatno bioaktivnost HAp-a i bioresorpcija TCP-a. Dvofazne forme (BCP): HAp/β-TCP i HAp/α-TCP, kao i trifazna forma HAp/β-TCP/α-TCP, pokazale su se kao bolji biomaterijali nego pojedinačne faze i posebno su interesantne za dalja istraživanja. U cilju dobijanja biomaterijala sa antimikrobnim efektom, prahovi HAp-a dopirani jonima Ag+, Cu2+ ili Zn2+ su sintetisani hidrotermalnom metodom pri čemu je odnos Ca/P iznosio 1,67. U sintezama molski udeo dopanata iznosio je 0,2, odnosno 0,4 mol% sa ciljem da se dobiju prahovi sa dobrom antimikrobnom aktivnošću uz očuvanje biokompatibilnosti. Dopirani prahovi HAp-a su kalcinisani na 1200 °C tokom 2 h sa namerom da se ispita uticaj dopiranja na stvaranje dvofaznih prahova HAp/α-TCP, kao i antimikrobna aktivnost i biokompatibilnost tako dobijenih prahova. Za analizu svih prahova, nedopiranih i dopiranih HAp i HAp/α-TCP, korišćeni su visokorezolucioni skenirajući elektronski mikroskop (FESEM), rendgenska difrakcija (XRD), infracrvena spektroskopija sa Furijeovom transformacijom (FTIR), atomska apsorpciona spektroskopija (AAS) i energetska disperziona spektroskopija (EDS). Termička analiza sintetisanih prahova je sprovedena u cilju određivanja faznih transformacija tokom zagrevanja do 1200 °C. Antibakterijska aktivnost prahova ispitana je u in vitro uslovima u odnosu na mikroorganizme: Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) i Candida albicans (C. albicans). Svi prahovi su pokazali dobru antimikrobnu aktivnost, s tim da su prahovi dopiranih HAp/α-TCP dali malo bolje rezultate u odnosu na sve patogene mikroorganizme nego dopirani HAp prahovi. In vitro testovi biokompatibilnosti, kolorimetrijski test sa tetrazolijum solima (MTT) i test odbacivanja boje (DET), su korišćeni da bi se procenila biokompatibilnost dopiranih HAp/α-TCP prahova sa MRC-5 humanim fibroblastnim ćelijama. Ovi testovi su potvrdili da dati prahovi nemaju citotoksični efekat. Posebno dobru biokompatibilnost su pokazali prahovi HAp/α-TCP dopirani nižim udelom jona Ag+, Cu2+ i Zn2+. Na osnovu testova antimikrobne aktivnosti i biokompatibilnosti zaključeno je da su dopirani HAp/α-TCP prahovi obećavajući materijal za korišćenje u rekonstruktivnoj hirurgiji kostiju...

Calcium phosphates constitute the inorganic part of bones and teeth of mammals. This fact is well known and has encouraged researchers to apply hydroxyapatite (HAp, Ca10(PO4)6(OH)2) and tricalcium phosphate (TCP, Ca3(PO4)2), both α- and β-TCP, over the past years as implant materials. Their similarity to the inorganic part of hard tissues has been confirmed, highlighting their biocompatibility and osteoconductivity and, in addition, the bioactivity of HAp and the bioresorbability of TCP. The biphasic forms (BCP): HAp/β-TCP and HAp/α-TCP and the triphasic form HAp/β-TCP/α-TCP, which were proved to be even better biomaterial than single phases, are of particular interest. Hydroxyapatite (HAp) powders doped with Ag+, Cu2+ or Zn2+ were synthesized by a hydrothermal method, at a Ca/P ratio of 1.67, in order to obtain biomaterial with an antimicrobial effect. The synthesis was performed with two contents of dopant (0.2 or 0.4 mol %) by considering both the antimicrobial activities and biocompatibility of the powders. The doped HAp was annealed at 1200 °C for 2 h with the intention of investigating the influence of doping on the creation of biphasic HAp/α-TCP and determining the antimicrobial activity and biocompatibility of the obtained biphasic powders. Analyses of all powders, undoped and doped HAp and HAp/α-TCP, were performed by Field emission scanning electron microscopy (FESEM), X-Ray diffraction (XRD), Atomic absorption spectroscopy (AAS) and Energy-dispersive X-Ray spectroscopy (EDS). Thermal analysis of the synthesized powders was performed to evaluate the phase transformations during heating up to 1200 °C. The in vitro antibacterial activities of the powders were evaluated against the pathogenic microorganisms: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. All powders showed good antimicrobial activity but generally the powders of doped HAp/α-TCP demonstrated better results against all pathogenic microorganisms than the powders of doped HAp. In vitro biocompatibility tests, MTT and DET, were used to evaluate the biocompatibility of doped HAp/α-TCP with MRC-5 human fibroblast cells. These tests confirmed that the powders did not have a cytotoxic effect. The HAp/α-TCP powders doped with the lower content of Ag+, Cu2+ and Zn2+ ions showed especially good biocompatibility. The antimicrobial and biocompatibility tests recommend the doped HAp/α-TCP as promising material for use in reconstructive surgery of bones...

hidroksiapatit, dopiranje, kalcijum-fosfat, antimikrobna aktivnost, biokompatibilnost, sinterovanje, biokeramika, skafoldi, mehanička svojstva

hydroxyapatite, doping, calcium phosphate, antimicrobial activity, biocompatibility, sintering, bioceramics, scaffold, mechanical properties

66.018:666.3.04(043.3)

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