Universidade Federal do Ceará
PPGEQ – Programa de Pós-graduação em Engenharia Química

Hybrid materials are widely used due to it’s their unique properties that have provided advance in science. The hybrid produced with the combination of bacterial cellulose (BC) and hydroxyapatite (CaHA) has been shown to be a promising material, especially for bone repair. The insertion of strontium (Sr) in CB/CaHA matrices was chosen due to its similar properties to calcium, with a similar action in the human body related to the bone formation mechanisms. In this context, this study aims to obtain hybrid materials containing bacterial cellulose and/or hydroxyapatite doped with strontium ions, using three different synthesis routes. The first route is the formation of a hybrid material CB/HA, where hydroxyapatite is formed by calcium phosphate (CaHA), followed by batch adsorption of Sr ions, generating the hybrid (CB/CaHA/Sr). In the second route synthesis the hybrid is formed using apatite strontium (SrAp), by CB immersion cycles on dibasic sodium phosphate solution and strontium chloride solution, forming the hybrid (CB/SrAp). The synthesis third route consists of strontium insertion into the culture medium, which leads the formation of a hybrid CB/Sr by co- condensation. The three biomaterials produced were evaluated and compared, related to the amount of metal adsorbed and to the elution process. The higher amount of Sr adsorbed in the biomaterials for each route was in the following order: CB/SrAp > CB/CaHA/Sr > CB/Sr, 237,31; 29,91; 26,25 mg of Sr per g material, respectively. The CB/CaHA/Sr presented the lowest adsorbed amount and earler Sr release, with around 80% of Sr desorbed after 26h. The equilibrium adsorption data were described using the Langmuir model. Some parameters were investigated (temperature and pH) in the adsorption process. The Sr release by the other two materials (CB/Sr and CB/SrAp) were around 50% and 16% of the total Sr amount after 26 h, respectively. During production of CB/Sr it was observed that when compared to a BC control sample (produced without the addition of strontium) in the culture medium, there was a yield loss in terms of cellulose mass, suggesting that Sr causes a decrease in production of CB, it is corroborated by the decrease in sugar consumption by the bacteria. The materials were characterized through FTIR, SEM, BET, TGA, determination of porosity and swelling degree in order to elucidate the morphology and the interaction metal/biopolimer. From these results we can concluded that biomaterials produced are able to adsorb/desorb Sr ions, showing a different profile for each material, involving either chemisorption and physisorption mechanisms.