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Innovative and improved antimicrobial agents by nanotechnology are developed to control and mitigation of resistant microorganisms. Nanoparticles of metals or oxide metals be able to be toxic to bacteria, demonstrating biocidal behaviors at low concentrations. The integration of silver nanoparticles in ceramic matrices has enhanced the antimicrobial performance, resulting in the search for new composites with improved bactericidal properties. The aim of this study was to prepare and characterize hydroxyapatite-silver nanocomposite and evaluate its antimicrobial properties against various Gram-positive and negative bacteria related to drug-resistance infections. Hydroxyapatite nanopowders were produced by sol-gel and silver nanoparticles were synthesized by reduction of Ag+ions with the simple addition of gallic acid. Hydroxyapatite-silver composite (HAp-AgNPs) was prepared by adsorption of AgNPs at several concentrations. The results of UV–visible spectroscopy, dynamic light scattering, and transmission scanning electron microscopy revealed the existence of AgNPs with diameters around 6 nm. Scanning electron microscopy and energy dispersive X-ray spectroscopy corroborated the presence of silver disseminated over the surface of hydroxyapatite nanopowders. All HAp-AgNPs composites demonstrated excellent antibacterial effect even at lower silver concentration. HAp-AgNPs composites have a higher possibility for medical applications focused no the control of microorganisms with drug-resistance.

The search for adsorbent materials with a certain chemical inertness, mechanical resistance, and high adsorption capacity, as is the case with alumina, is carried out with structural or surface modifications with the addition of additives or metallic salts. This research shows the synthesis, characterization, phase evolution and Cd(II) adsorbent capacity of α-Al2O3/Ba-β-Al2O3 spheres obtained from α-Al2O3 nanopowders by the ion encapsulation method. The formation of the Ba-β-Al2O3 phase is manifested at 1500 °C according to the infrared spectrum by the appearance of bands corresponding to AlO4 bonds and the appearance of peaks corresponding to Ba-O bonds in Raman spectroscopy. XRD determined the presence of BaO·Al2O3 at 1000 °C and the formation of Ba-β-Al2O3 at 1600 °C. Scanning electron microscopy revealed the presence of spherical grains corresponding to α-Al2O3 and hexagonal plates corresponding to β-Al2O3 in the spheres treated at 1600 °C. The spheres obtained have dimensions of 4.65 ± 0.30 mm in diameter, weight of 43 ± 2 mg and a surface area of 0.66 m2/g. According to the curve of pH vs. zeta potential, the spheres have an acid character and a negative surface charge of −30 mV at pH 5. Through adsorption studies, an adsorbent capacity of Cd(II) of 59.97 mg/g (87 ppm Cd(II)) was determined at pH 5, and the data were fitted to the pseudo first order, pseudo second order and Freundlich models, with correlation factors of 0.993, 0.987 and 0.998, respectively.

Researchers are currently looking for materials that are stable, functional, aesthetic, and biocompatible without infections. Therefore, there is a great interest in obtaining a material that has a balance between aesthetic, biological, mechanical, and functional factors, which can be used as an infection control material. The addition of hydroxyapatite to alumina make highly bioactive scaffolds with mechanical strength. Biomedical applications require antibacterial properties; therefore, this idea leads to great interest in the development of new synthetic routes of ceramic biomaterials that allow the release of nanoparticles or metal ions. This investigation presents the obtention of alumina-hydroxyapatite spheres doped with silver nanoparticles with antibacterial effect against various Gram-positive and negative bacteria related to drug-resistance infections. The microstructural and spectroscopic studies demonstrate that the spheres exhibit a homogeneous structure and crystal hydroxyapatite and silver nanoparticles are observed on the surface. The antimicrobial susceptibility was verified with the agar diffusion and turbidimetry methods in Gram-negative ( Escherichia coli and Pseudomonas aeruginosa) and Gram-positive ( Staphylococcus aureus and Bacillus subtilis) bacteria. All bacteria used were susceptible to the alumina-hydroxyapatite-silver spheres even at lower silver concentration. The composites have a higher possibility for medical applications focused on the control of drug-resistance microorganisms.

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