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Among applications of ceramics in technological context, hydroxyapatite (HAp) stands out in the scientific community due to chemical biocompatibility and molecular similarity with the structures of bone and dental tissues. Such features are in addition to its antimicrobial properties. This work aimed firstly to synthesize hydroxyapatite by two different routes: hydrothermal (HD HAp) and co-precipitation (CP HAp), and secondly to verify the antimicrobial properties of these materials through direct contact tests against Staphylococcus aureus (SA10) and Escherichia coli (EC7) bacteria. These materials were characterized by XRD, Raman, and TEM. Antimicrobial tests showed inhibitory efficacy of 97.0% and 9.5% of CP HAp for SA10 and EC7, respectively. The HD HAp showed inhibitory effect of 95.0% and 0.0% for SA10 and EC7, respectively. The inhibitory effect of the tested materials against Staphylococcus aureus may be related to the HAp hydrophilicity.

Polymeric blends composed of conducting polypyrrole chains dispersed in a matrix of polyvinylalcohol containing ferric chloride represent a class of materials whose electrical behavior is intermediary between those of insulating and conducting polymers. To investigate the transport and polarization characteristics of these films we examine in this work their dielectric relaxation spectrum in the frequency domain. A relaxation in frequency identified in the resistance–reactance diagram is followed as a function of the relative concentration of the two polymers, as different types of dopants are used to promote the conducting behavior of polypyrrole. We also analyze the change in the relative dc and ac contributions to the total conductivity of the samples as the amount of incorporated polypyrrole is increased.