Development of biodegradable metallic implants : influence of surface modification on the rate of decomposition and biocompatibility : doctoral thesis

Razvoj biorazgradivih metalnih implantata izazovan je zadatak jer od materijala zahtjeva da u potpunosti ispuni inženjerske, kemijske i medicinske zahtjeve. Magnezij i njegove legure dobri su potencijalni materijali za izradu biorazgradivih implantata. Njihovom primjenom smanjuje se mogućnost pojave induciranog stresa. Problem koji je potrebno riješiti je brza korozija Mg i Mg legura koja uzrokuje gubitak mehaničkog integriteta, prije zacjeljivanja tkiva. Funkcionalizacija površine Mg implantata provedena je kako bi se nastali produkti dekompozicije mogli izlučiti iz organizma ne narušavajući njegovu biokompatibilnost. Površine Mg i Mg legure modificirane su samoorganizirajućim organskim i bioaktivnim keramičkim filmovima. Najvažniji čimbenik u dizajniranju biorazgradivih metalnih implantata bila je: (i) in situ analiza aktivne interfazne granice metal/fiziološka otopina i (ii) karakterizacija modificiranih površina površinsko-analitičkim metodama. S fundamentalnog i aplikativnog stajališta provedena istraživanja značajna su za razumijevanje procesa koji se zbivaju na granici faza biorazgradivi metalni implantat/realni biookoliš.Development of biodegradable metallic implants is a complex task, because it combines engineering, chemical and medical requests of materials. Mg and Mg alloys are the potential biodegradable implant materials. Similar mechanical properties of Mg and bone can reduce the appearance of the induced stress. However, Mg and Mg-alloy in body fluids corrode rapidly, causing loss of mechanical integrity, before the tissues have sufficient time to heal. The aim of this work was functionalization of Mg implants, so that the resulting products of the decomposition can extract from the body without compromising its biocompatibility. Mg and Mg alloy surfaces were modified with self-assembled organic films and bioactive ceramic films. The most important factor in designing biodegradable metallic implants was: (i) in situ analysis of the active metal/physiological solution interphase and (ii) characterization of the modified surface with surface-analytical methods. From the fundamental and applicative point of view, performed research is relevant to the understanding of the processes that occur at the biodegradable metal implant/real bioenvironment interface

Copper(II) Coordination Compound with 2-Oxonicotinate: Synthesis, Spectroscopic and Electrochemical Studies

Metal organic frameworks (MOFs) are gaining interest for technological purposes due to their intriguing open structure properties such as ion exchange, catalytic properties and application as sensors. To prepare coordination compounds with desired properties, the choice of organic ligand is crucial. This work demonstrates the hydrothermal synthesis of a copper(II) coordination compound with 2-hydroxynicotinic acid. Characterization was based on elemental analyses, ESI-MS, MALDI-TOFMS, FT-IR spectra, thermogravimetric analysis (TGA), and cyclic voltammetry. Electrochemical characterization of the compound prepared was also carried out to find a sensitive and simple method to improve the determination of biologically active thiol substances. From the rectangular voltammetry results, a linear response between 0.2 and 20 μM was obtained with an estimated detection limit of 0.09 μM

Scientific Research Activities of the Department of General and Inorganic Chemistry in the Period 2010–2020

Od utemeljenja Zavoda, akademske godine 1961./62., njegova znanstveno-istraživačka djelatnost bila je usmjerena na elektrokemijska istraživanja metala, pojavu pasiviteta i inhibiciju korozije. Kasnije, ponajprije primjenom elektrokemijskih metoda, proučavaju se fenomeni na granici faza metal│anodni sloj│elektrolitna otopina koji su od značaja za kemijske izvore struje i poluvodičke sustave. Tijekom posljednjih deset godina istraživanja se usmjeravaju u dva smjera: i) ispitivanje utjecaja legirajućih elemenata na dizajn otpornih materijala i biofunkcionalizacija površine biorazgradljivih i biokompatibilnih metalnih implantata; ii) modifikaciju elektroda i njihovih površina u svrhu razvoja novih elektroanalitičkih metoda za određivanje teških metala i biomolekula. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.Since the establishment of the Department of General and Inorganic Chemistry in 1961, at the Faculty of Chemistry and Technology, University of Split, its scientific interest and investigations were focused toward electrochemical research. Consequently, electrochemistry became the backbone of the scientific research and development of the Department. In the last 10 years, scientific interest has been focused on the influence of alloying elements on design of corrosion resistance materials, as well as biofunctionalisation of biodegradable and biocompatible metal-based implants. In addition, development of various electroanalytical methods based on modified electrodes as sensing part of sensors, have been in focus in the recent period. The developed sensors were used for determination of heavy metals or biomolecules. This work is licensed under a Creative Commons Attribution 4.0 International License

Structural and Electrochemical Studies of Cobalt(II) and Nickel(II) Coordination Polymers with 6-Oxonicotinate and 4,4′-Bipyridine

The 6-oxonicotinate (6-Onic) salts of a one-dimensional cationic cobalt(II) or nickel(II) coordination polymers with 4,40 -bipyridine (4,40 -bpy), namely {[Co(4,40 -bpy)(H2O)4 ](6-Onic)2 ·2H2O}n (1) and {[Ni(4,40 -bpy)(H2O)4 ](6-Onic)2 ·2H2O}n (2), were prepared hydrothermally by reactions of cobalt(II) nitrate hexahydrate or nickel(II) nitrate hexahydrate, respectively, 6-hydroxynicotinic acid and 4,40 -bipyridine in a mixture of ethanol and water. In the hydrogen-bonded frameworks of 1 and 2, the one-dimensional polymeric chains of {[M(4,40 -bpy)(H2O)4 ] 2+}n (M = Co, Ni), the 6-oxonicotinate anions and the lattice water molecules were assembled via strong intermolecular O–H···O and N–H···O hydrogen bonds and π–π interactions, leading to the formation of the representative hydrogen-bond ring motifs: trimeric R 2 3 (10) motif, the centrosymmetric tetrameric R 2 4 (8) and R 2 4 (12) motifs and the pentameric R 4 5 (12) motif. The isostructural coordination polymers 1 and 2 exhibited a different electrochemical behavior, as observed by cyclic voltammetry, which can be attributed to the nature of the metal ions (cobalt(II) vs. nickel(II))

Correction: Škugor Rončević, I.; et al. Effective and Environmentally Friendly Nickel Coating on the Magnesium Alloy. Metals 2016, 6, 316

The following changes have been made to the published manuscript “Effective and Environmentally Friendly Nickel Coating on the Magnesium Alloy [...

Effective and Environmentally Friendly Nickel Coating on the Magnesium Alloy

The low density and good mechanical properties make magnesium and its alloys attractive construction materials in the electronics, automotive, and aerospace industry, together with application in medicine due to their biocompatibility. Magnesium AZ91D alloy is an alloy with a high content of aluminum, whose mechanical properties overshadow the low corrosion resistance caused by the composition of the alloy and the existence of two phases: α magnesium matrix and β magnesium aluminum intermetallic compound. To improve the corrosion resistance, it is necessary to find an effective protection method for the alloy surface. Knowing and predicting electrochemical processes is an essential for the design and optimization of protective coatings on magnesium and its alloys. In this work, the formations of nickel protective coatings on the magnesium AZ91D alloy surface by electrodeposition and chemical deposition, are presented. For this purpose, environmentally friendly electrolytes were used. The corrosion resistance of the protected alloy was determined in chloride medium using appropriate electrochemical techniques. Characterization of the surface was performed with highly sophisticated surface-analytical methods

The Preparation, Morphological Characterization and Possible Electroanalytical Application of a Hydroxyapatite-Modified Glassy Carbon Electrode

By simple modification of a GC electrode with biofunctional material, hydroxyapatite (HAp), an efficient electroanalytical tool, was designed and constructed. Modification of the GC surface includes two steps in synthesis: electrochemical deposition and chemical conversion. The properties, structure, and morphology of a nanosized material formed on a surface and absorbability were studied by electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy and scanning electron microscopy with energy-dispersive spectroscopy analysis. Numerous methods in this work confirmed that the developed method for controlled HAp deposition results in a HAp open structure and uniform morphology, which is capable of the selective absorption of the target species. The main goal of this study was the possibility of using a HAp-modified electrode for the fast screening of copper, cadmium, and lead content in honey and sugar samples. The electrochemical behavior and potential of the electroanalytical determination of heavy metals using the HAp/GC electrode were studied using cyclic voltammetry and square wave anodic stripping voltammetry. The HAp/GC electrode exhibited great performance in the determination of heavy metals, based on the reduction of target metals, because of the high absorbability of the HAp film and the electroanalytical properties of GC. A linear response between 10 and 1000 μg/L for Cu and Pb and 1 and 100 μg/L for Cd, with an estimated detection limit of 2.0, 10.0, and 0.9 μg/L, respectively, was obtained

Development and Optimization of Electrochemical Method for Determination of Vitamin C

The focus of this work was to develop a simple electrochemical method for the determination of vitamin C (VitC) by using a specially constructed microelectrode made from pyrolytic graphite sheet (PGS). A procedure for quantifying VitC in a real sample was established. VitC shows a single quasi-reversible reaction. The method was optimized, and analytical determination was performed by using cyclic voltammetry and square wave voltammetry for electroanalytical purposes. The obtained results show a linear response of the PGS electrode in a wide concentrations range. For the lower concentration range, 0.18–7.04 µg L−1, the sensitivity is 11.7 µAcm−2/mgL−1, while for the higher concentration range, 10.6–70.4 µg L−1, the sensitivity is 134 µAcm−2/mgL−1, preserving the linearity of 0.998 and 0.999. The second objective was to determine the effect of the addition of five different types of “green” biowaste on plant growth, VitC content, and antioxidant activity in arugula (Eruca sativa L.) using the developed method. After three weeks of cultivation, small differences in growth and large differences in certain nutritional characteristics were observed. The addition of black coffee makes the soil slightly alkaline and causes a significant increase in VitC content and antioxidant activity

Voltammetric Electrochemical Behavior of Carbon Paste Electrode Containing Intrinsic Silver for Determination of Cysteine

In this paper, the electrochemical behavior of cysteine is described, using carbon paste electrodes (CPEs) modified with ternary silver-copper sulfide containing intrinsic silver at two pH values (pH 3 and 5). Experiments have revealed that presence of cysteine has a large impact on the electrochemical behavior of modified CPEs. Observed phenomena take place in solution, as well as at the surface of the modified CPEs, and can be applied for electroanalytical purposes. Based on the electrochemical behavior observed in the examined system, differential pulse voltammetry (DPV) was selected as an electroanalytical method for determination of cysteine. The effects of the various parameters on the electroanalytical signal, such as the amount of electroactive material, electroanalytical parameters, pH etc., were investigated using differential pulse voltammograms. The results indicated that electrochemical signal characterized with well-defined cathodic peak at 0.055 V vs. Ag/AgCl (3 M) in acetic buffer solution at pH 5 can be used for indirect electrochemical determination of cysteine. The optimization procedure revealed that the most sensitive and stabile electrode was that containing 5% modifier. The DPV response of the electrode, in the presence of cysteine, showed two different linear concentration ranges of 0.1 to 2.5 μM, and 5.6 to 28 μM. The explanation of the origin of two linear ranges is proposed. The lower concentration range was characterized by remarkable sensitivity of the 11.78 μA μM−1, owing to the chosen indirect method of determination. The calculated limit of detection (LOD), as well as limit of quantification (LOQ) were 0.032 and 0.081 μM, respectively. The influence of interfering agents on the electroanalytical response was examined, and low or no interference on the DPVs was observed. The proposed method was validated and applied for the determination of cysteine in pharmaceutical preparations with satisfactory recoveries in the range of 97 to 101.7%

Effective and Environmentally Friendly Nickel Coating on the Magnesium Alloy

The low density and good mechanical properties make magnesium and its alloys attractive construction materials in the electronics, automotive, and aerospace industry, together with application in medicine due to their biocompatibility. Magnesium AZ91D alloy is an alloy with a high content of aluminum, whose mechanical properties overshadow the low corrosion resistance caused by the composition of the alloy and the existence of two phases: α magnesium matrix and β magnesium aluminum intermetallic compound. To improve the corrosion resistance, it is necessary to find an effective protection method for the alloy surface. Knowing and predicting electrochemical processes is an essential for the design and optimization of protective coatings on magnesium and its alloys. In this work, the formations of nickel protective coatings on the magnesium AZ91D alloy surface by electrodeposition and chemical deposition, are presented. For this purpose, environmentally friendly electrolytes were used. The corrosion resistance of the protected alloy was determined in chloride medium using appropriate electrochemical techniques. Characterization of the surface was performed with highly sophisticated surface-analytical methods