Baicalein-modified hydroxyapatite nanoparticles and coatings with antibacterial and antioxidant properties

Abstract

Aseptic loosening and bacterial infections are the two main causes of failure for metallic implants used for joint replacement. A coating that is both bioactive and possesses antimicrobial properties may address such shortcomings and improve the performance of the implant. We have sought to study the properties of combining hydroxyapatite-based nanoparticles or coatings with baicalein, a plant-extracted molecule with both antibacterial and antioxidant properties. (B-type) carbonated hydroxyapatite nanoparticles prepared by a chemical wet method could subsequently adsorbed by soaking in a baicalein solution. The amount of adsorbed baicalein was determined to be 63 mg.g -1 by thermogravimetric measurements. In a second approach, baicalein was adsorbed on a biomimetic calciumdeficient hydroxyapatite planar coating (12 m thick) deposited on Ti6Al4V alloy from an aqueous solution of calcium, phosphate, sodium and magnesium salts. Soaking of the hydroxyapatite coated on titanium alloy in a baicalein solution induced partial dissolution/remodeling of the upper surface of the coating. However, the observed remodeling of the surface was much more pronounced in the presence of a baicalein solution, compared to pure water. The presence of adsorbed baicalein on the HAp layer, although it could not be precisely quantified, was assessed by XPS and fluorescence analysis. Planar coatings exhibited significant antibacterial properties against Staphylococcus epidermidis. Baicaleinmodified nanoparticles exhibited significant antioxidant properties. These results illustrate the potential of hydroxyapatite used as a carrier for natural biologically-active molecules and also discuss the challenges associated with their applications as antibacterial agents.

Nanodelivery of the Gramicidin Peptide for Enhancing Antimicrobial Activity

“…The bactericidal activity of free GraS and L‐GraS was studied on Gram‐positive ( Staphylococcus aureus ) bacteria. For this, S. aureus (ATCC 29 213, Departamento de Microbiología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires) was grown overnight at 37 °C in LB medium (yeast extract (Britania), 5 g L −1 ; tryptone (Britania), 10 g L −1 ; and NaCl (Cicarelli), 10 g L −1 ; pH = 7) and diluted a hundred times obtaining a concentration of 1 × 10 [ 4 ] Colony Forming Units (CFU) mL −1 . A certain amount of the bacterial culture (100 µL) was mixed with different concentrations of GraS or L‐GraS in LB and incubated at 37 °C for 24 h. After this, the MIC was determined by measuring turbidity of the samples and MBC was evaluated by seeding 20 µL of the samples on agar Petri dishes and evaluating the bacterial growth of S. aureus after 24 h through the colony forming units method (CFU).…”

“…For cellular viability experiments, 1 × 10 [ 4 ] cells mL −1 in DMEM were mixed with different concentrations of GraS dissolved in ethanol 10% and aqueous L‐GraS and kept at 37 °C in a humidified 5% CO 2 air atmosphere. The medium containing GraS or L‐GraS was removed after 24 h and cell metabolic activity was measured by the colorimetric 3‐(4,5‐dimethyl‐thiazol‐2‐yl)‐2,5‐diphenyl‐tetrazolium bromide (MTT) assay.…”

“…In the last years, nanotechnology has been increasingly used for the development of new nanomaterials to deliver therapeutic cargos for the treatment of wound infections as they seemed to have better impact and more efficient results than conventional therapies. [ 2–5 ] Most of the therapeutic approaches based on the use of drug delivery systems are strategically design to administrate poor soluble therapeutics molecules or improve “old” drugs, [ 6,7 ] rather than developing and distributing new drugs that is expensive and time‐consuming process. The main advantage of using drug delivery systems relies on their ability to enhance the effectiveness of existent therapeutic agents, protect them from degradation, and improve their stability and biocompatibility, as well as targeting infection sites, improve their accumulation and control their release, reducing in this way their undesirable side effects.…”

Metal Nanozymes: New Horizons in Cellular Homeostasis Regulation

“…There are numerous reports and reviews concerning the oxidative stress-related mechanisms and effects induced by metallic nanoparticles. At the same time, there are several strategies to overcome this: not always desired property of nanoparticles or even giving nanoparticles the antioxidant properties [49,50]. There are attempts to achieve this by combining, quenching, or coating nanoparticles with classic chain-breaking antioxidants, such as tocopherols (vitamin E) [51], flavonoids [52,53], ascorbate (vitamin C [54,55]), aromatic amines [56], and nitroxides [57].…”

Synthesis of hybrid polyphenol/hydroxyapatite nanomaterials: adsorption vs. in situ incorporation

“…For instance, antibiotics such as gentamicin or tobramycin but also polyphenols, as extracts or single molecules, have been adsorbed on hydroxyapatite nanoparticles or coatings. 36,[43][44][45][46][47][48] The adsorption of bisphosphonates, such as alendronate, tiludronate or risendronate, 24,49 on hydroxyapatite nanoparticles was described, adding osteogenic properties to the materials.…”