ABSTRACT
Thin films of transition metal oxides and oxynitrides have proven highly effective in protecting stainless steels against corrosion in both chemically aggressive environments and biological fluids. In the present work, cerium zirconium oxynitride thin films were deposited to enhance the corrosion resistance of surgical-grade stainless steel to be used in osteosynthesis processes. Two techniques were employed: co-sputtering and radiofrequency (RF) sputtering, and the morphology and corrosion efficiency of the coatings deposited by each technique were evaluated. X-ray diffraction, X-ray photoelectron spectroscopy and field emission transmission electron microscopy were used to characterize the morphological and chemical structure, respectively. Additionally, the corrosion resistance of the oxynitride-coated surgical grade stainless steel system (ZrCeOxNy-AISI 316L) was assessed using Hank's solution as the corrosive electrolyte, to determine its resistance to corrosion in biological media. The results show that ZrCeOxNy coatings increase the corrosion resistance of surgical grade stainless steel by two orders of magnitude and that the Ce(III)/Ce(IV) equilibrium decreases the corrosion rate, thereby increasing the durability of the steel in a biological environment. The results show that Ce coatings increase the corrosion resistance of surgical grade stainless steel by two orders of magnitude and that the Ce(III)/Ce(IV) equilibrium decreases the corrosion rate, thereby increasing the durability of the steel in a biological environment.
ABSTRACT
BACKGROUND: Chronic periodontitis is a multifactorial infectious disease, where multiple bacteria, such as Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum are implicated. The main purpose of researching natural products is to find substances or compounds with antimicrobial activity. AIM: The objective of this work was to determine antimicrobial activity from extracts and obtained fractions from Piper marginatum Jacq and Ilex guayusa Loes on P. gingivalis ATCC 33277, F. nucleatum ATCC 25586, and P. intermedia ATCC 25611. METHODS: Total ethanol extracts were obtained from both plants. Fractions were obtained from total ethanol extracts with amberlite as a stationary phase employing hexane, acetone, and ethanol-water as solvents. Qualitative and quantitative phytochemical characterization was performed on total ethanol extracts from both plants. Antimicrobial activity from total ethanol extracts and fractions from both plants were evaluated on P. gingivalis ATCC 33277, F. nucleatum ATCC 25586, and P. intermedia ATCC by the well diffusion method with Wilkins-Chalgren agar. RESULTS: Piper marginatum Jacq total ethanol extract presented antimicrobial activity against all three bacteria, whereas Ilex guayusa Loes was only efficient against P. gingivalis ATCC 33277 and P. intermedia ATCC 25611, with inhibition halos from 9.3 to 30 mm. Ilex guayusa Loes obtained fractions presented antimicrobial activity against all three microorganisms evaluated, with inhibition halos ranging from 9.7 to 18.7 mm. In regards to Piper marginatum Jacq fractions, inhibition halos were between 8.3 and 19 mm, against all three microorganisms evaluated; only hexane fraction did not present antimicrobial activity against F. nucleatum ATCC 25586. CONCLUSION: Piper marginatum Jacq and Ilex guayusa Loes total ethanol extracts and fractions presented outstanding antimicrobial activity against P. gingivalis ATCC 33277, P. intermedia ATCC 25611, and F. nucleatum ATCC 25586.
