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Study of the use of polymers with higher conductivity like polypyrrole, and polyaniline in the electrochemical insulin sensors can overcome the drawbacks arising from the ongoing use of non-conductive polymer membrane. Conductive polymer membranes maintain the positive properties of polymers, like improved stability, reproducibility, and even increase the current response of the prepared sensor toward insulin oxidation. Three different screen-printed electrodes modified with polyaniline, polypyrrole, or chitosan with electrochemically deposited nickel nanoparticles ensuring insulin oxidation were prepared. The electrode morphology was examined via SEM with EDX analysis. Also, the electroactive surface area and stability were determined by voltammetric methods. Based on the results, the SPCEs modified by polypyrrole and nickel nanoparticles were determined as the most appropriate for the insulin determination. The NiNPs-PPy-SPCE exhibited a linear range (500 nM–5 µM), a low-down limit of detection (38 nM), high sensitivity (3.98 µA/µM), and excellent result from insulin determination in real samples (human blood serum). The results confirmed the high potential of developed sensor for future research focused on detection of insulin via electrochemistry methods in clinical samples. Graphical Abstract: [Figure not available: see fulltext.] © 2023, The Author(s)., RP/CPS/2022/005; European Commission, EC: CZ.02.2.69/0.0/0.0/18_053/0017879; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Agentúra na Podporu Výskumu a Vývoja, APVV

Porous degradable metallic biomaterials are attracting considerable attention as promising bone implant materials. Recently, the interest in developing new biomaterials with enhanced performance stimulates the widespread development of fabricating techniques for porous metals. In this work, the recent progress and novel trends on preparation methods of metallic foams for biomedicine were systematically reviewed. The common synthesis methods for porous Mg, Fe, Zn, and their alloys intended for orthopedic applications are comprehensively discussed and compared. The advantages and disadvantages of relevant manufacturing strategies are evaluated. While the modern techniques enable fabrication of complex porous structures and customized shapes, the cost-effective and easy controllable approach are major benefits of traditional methods. Main structural characteristics and properties of biomaterials fabricated using different routes are also presented. Furthermore, the future research directions and current challenges are mentioned. The ambition of this review article is to provide useful guidelines for researchers to choose suitable manufacturing technique to prepare materials with desired structural topology and mechanical, and degradation properties.

Zn-Fe alloys have been extensively investigated in this study with a view to their application as biodegradable bone implants. Biogenic element zinc is a very appropriate metal because of the ideal degradation rate compared to those of Mg and Fe. Studied alloys were made by compressing metallic powders in a content ratio of 100% Zn, Zn-1% Fe, Zn-2% Fe, Zn-5% Fe and Zn-10% Fe and sintering at 350 ​°C for 1 ​h. Prepared samples were examined by optical microscopy, SEM and XRD. Corrosion behavior, mechanical testing and hemocompatibility were observed subsequently. The electrochemical performance of such materials was studied in the simulated body fluids. The enhanced corrosion rate was observed for all samples after iron addition due to the micro-galvanic effect between the pure Zn and Zn11Fe intermetallic phase. The corrosion rate of the Zn-5% Fe alloyed sample was more than 20-times higher (2.89 mmpy) compared to the pure Zn. However, alloying with more than 5 ​wt % of iron diminished the mechanical performance of the material. Therefore, the performed mechanical and hemocompatibility tests showed acceptable biocompatibility of zinc and Zn-1% Fe and Zn-2% Fe samples.

In a coronary angioplasty or orthopaedic surgery, metallic implants are often used to provide mechanical support to the healing tissues. In some situations, this support is really needed only temporarily. After tissue recovery, the implant no longer provides any benefits and can trigger adverse reactions. An optimal solution might be the short-term implants which are able to decompose in situ and can be readily excreted from the body. Iron-based materials are promising candidates for application in biodegradable devices. For the successful application, the ability to control the material’s corrosion rate is important. In this contribution, the corrosion of iron-iron oxide composites is investigated. In order to obtain such materials, iron-oxide granules were incompletely reduced, compacted and sintered. Materials consisting of a pure iron and iron oxides were obtained. Specimens from as-sintered materials and materials reduced once again after sintering were prepared. Potentiodynamic polarization testing in Hanks’ solution indicated that specimens underwent a galvanic corrosion, where the release of ferrous ions from iron surfaces represents the anodic reaction and the oxygen reduction on surfaces of both iron and iron oxides represents the cathodic reaction. Changes in the content of oxides resulted in anticipated shifts in corrosion potential and apparent corrosion current density.

Polymer-coated metals may act as biodegradable orthopedic implants with adjustable corrosion rates. Metallic surfaces represent a dynamic system with specific interactions occurring after the material is implanted into the human body. An additional layer, in the form of polymeric thin film, changes the nature of this metal-body fluids interface. Moreover, the interaction between polymer and metal itself can differ for various systems. Iron-based material modified with a thin layer of polyethyleneimine (PEI) coating was prepared and studied as potential absorbable implant. Computational methods were employed to study the interaction between the metallic surface and polymer functional monomer units at atomic levels. Various spectroscopical and optical methods (SEM, AFM, Confocal, and Raman spectroscopy) were also used to characterize prepared material. Electrochemical measurements have been chosen to study the polymer adsorption process onto the iron surface and corrosion behavior which is greatly influenced by the PEI presence. The adsorption mechanism of PEI onto iron was proposed alongside the evaluation of Fe and Fe-PEI degradation behavior studied using the impedance method. Bonding via amino -NH2 group of PEI onto Fe and enhanced corrosion rate of coated samples were observed and confirmed.

Coating of the biodegradable metals represents an effective way of modification of their properties. Insufficient biological, mechanical, or degradation performance of pure metals may be enhanced when the proper type of organic polymer coating is used. In our previous work, the significant effect of the polyethyleneimine (PEI) coating not only on the rate but also on the type of corrosion was discovered. To bring a comprehensive overview of the Fe-PEI system performance, iron-based biodegradable scaffolds with polyethyleneimine coating were studied and their cytocompatibility and hemocompatibility, and mechanical properties were evaluated and discussed in this work. Electrochemical impedance spectroscopy (EIS) measurements were conducted for further study of material behavior. Biological analyses (MTS assay, fluorescent imaging, hemocompatibility tests) showed better cell proliferation on the surface of Fe-PEI samples but not sufficient overall cytocompatibility. Good anti-platelet adhesion properties but higher hemolysis when compared to the pure iron was also observed for the coated samples. Mechanical properties of the prepared Fe-PEI material were enhanced after coating. These findings suggest that the Fe-PEI may be an interesting potential biomaterial after further composition optimization resulting in lower cytotoxicity and better hemocompatibility.

Biodegradable metallic implants are materials that serve as a temporary implants and scaffolds. They degrade directly in vivo and therefore eliminate need for secondary surgical intervention. They are often made of metals such as magnesium, iron, zinc and can be modified by coating with the inorganic or polymeric layer. In this work iron-based biomaterial was prepared and modified with polymeric (polyethyleneimine, PEI) layer. Its degradation behavior was studied under conditions of simulated body fluids at 37 ± 0.2 °C in the form of static immersion tests. It has been shown that the surface modification caused an acceleration of degradation of the material and also had an influence on the corrosion mechanism.

Biodegradable materials have attracted a great attention in material engineering and medical community in the last decade. In certain cases, degradable implants may overcome the disadvantages of permanent devices. Any biodegradable material for medical use should support the healing process of a diseased tissue or organ and after that degrade slowly in the human body. In orthopaedic applications, biodegradable implants should allow a gradual load transfer to the healing bone as the materials degrade. Iron and iron based alloys have been identified as appropriate materials for the temporary replacement of bones, since they combine high strength at medium corrosion rates. The main goal of this work is evaluation of the in vitro biocompatibility of open cell iron foams with polyethylene glycol (PEG) coating layer for bone repair applications. Based on results of in vitro cytotoxicity studies it was found that the coating of sintered cellular iron samples with PEG layer led to a desired improvement of biocompatibility.

Powder metallurgy is one of the most prevalent ways for metallic degradable materials preparation. Knowledge of the properties of initial powders used during this procedure is therefore of great importance. Two different metals, iron and zinc, were selected and studied in this paper due to their promising properties in the field of biodegradable implants. Raw powders were studied using scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDX). Powders (Fe, Zn and Fe-Zn in a weight ratio of 1:1) were then compressed at the pressure of 545 MPa to the form of pellets with a diameter of 1.7 cm. Surface morphology and degradation behavior in the Hanks´ solution were studied and evaluated. Electrochemical polarization tests along with the static immersion tests carried out for 21 days were employed for corrosion behavior characterization. The highest corrosion rate was observed for pure Zn powder followed by the Fe-Zn and Fe, respectively. A mixed Fe-Zn sample showed similar properties as pure zinc with no signs of iron degradation after 21 days due to the effect of galvanic protection secured by the zinc acting as a sacrificial anode.

Degradable metallic biomaterials represent a new concept of bioactive biomaterials used for implants with temporary function. They should support the tissue healing process for a certain period and should progressively degrade thereafter. Degradable metallic materials could potentially replace the corrosion-resistant metals currently used for orthopaedic, cardiovascular, and paediatric implants. The interest in the study of degradable metallic biomaterials has dramatically increased in the last decade. This article reviews the current achievements in the design of biodegradable iron-based materials for orthopaedic load-bearing applications. It introduces a broad overview of the different alloying elements, coating materials, and processing methods used to improve the corrosion behaviour, mechanical properties, and biocompatibility of iron implant materials for temporary hard tissue scaffolds. An emphasis is set on Mn and Zn as the most promising alloying elements for Fe as well as on innovative calcium phosphate-based ceramic and polymeric coatings. In addition, the novel iron–ceramic composite biomaterials for orthopaedic implants are mentioned. Finally, recent challenges and future development direction for iron-based materials are proposed.

Research in the field of biodegradable metallic scaffolds has advanced during the last decades. Resorbable implants based on iron have become an attractive alternative to the temporary devices made of inert metals. Overcoming an insufficient corrosion rate of pure iron, though, still remains a problem. In our work, we have prepared iron foams and coated them with three different concentrations of polyethyleneimine (PEI) to increase their corrosion rates. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy were used for characterization of the polymer coating. The corrosion behavior of the powder-metallurgically prepared samples was evaluated electrochemically using an anodic polarization method. A 12 weeks long in vitro degradation study in Hanks&rsquo, solution at 37 &deg, C was also performed. Surface morphology, corrosion behavior, and degradation rates of the open-cell foams were studied and discussed. The use of PEI coating led to an increase in the corrosion rates of the cellular material. The sample with the highest concentration of PEI film showed the most rapid corrosion in the environment of simulated body fluids.

At present biodegradable implants received increased attention due to their use in various fields of medicine. This work is dedicated to testing of biodegradable materials which could be used as bone implants. The samples were prepared from the carbonyl iron powder by replication method and surface polymer film was produced through sol-gel process. Corrosion testing was carried out under static conditions during 12 weeks in Hank’s solution. The quantity of corrosion products increased with prolonging time of static test as it can be concluded from the results of EDX analysis. The degradation of open cell materials with polyethylene glycol coating layer was faster compared to uncoated Fe sample. Also the mass losses were higher for samples with PEG coating. The polymer coating brought about the desired increase in degradation rate of porous iron material.

Advances in biomedicine and development of modern technologies in the last century have fostered the improvement in human longevity and well-being. This progress simultaneously initiated the need for novel biomaterials. Recently, degradable metallic biomaterials have attracted serious attention in scientific and clinical research owing to their utilization in some specific applications. This work investigates the effect of the polyethylene glycol (PEG) coating of open-cell iron and phosphorus/iron foams on their microstructure and corrosion properties. The addition of phosphorus causes a slight increase in pore size and the deposition of a polymer coating results in a smoothened surface and a moderate decrease in pore diameter. The PEG coating leads to an increase in corrosion rates in both foams and potentially a more desirable product.

Significant progress was achieved presently in the development of metallic foam-like materials improved by biocompatible coatings. Material properties of the iron, magnesium, zinc, and their alloys are promising for their uses in medical applications, especially for orthopedic and bone tissue purposes. Current processing technologies and a variety of modifications of the surface and composition facilitate the design of adjusted medical devices with desirable mechanical, morphological, and functional properties. This article reviews the recent progress in the design of advanced degradable metallic biomaterials perfected by different coatings: polymer, inorganic ceramic, and metallic. Appropriate coating of metallic foams could improve the biocompatibility, osteogenesis, and bone tissue-bonding properties. In this paper, a comprehensive review of different coating types used for the enhancement of one or several properties of biodegradable porous implants is given. An outline of the conventional preparation methods of metallic foams and a brief overview of different alloys for medical applications are also provided. In addition, current challenges and future research directions of processing and surface modifications of biodegradable metallic foams for medical applications are suggested.

Bioresorbable biomaterials are expected to degrade or to be resorbed within the body at an appropriate degradation rate rather than removing the implant after fulfilling its function. Adsorption of proteins on the metal surface and its subsequent detachment can affect the degradation mechanism and induce health complications. The iron samples were produced from carbonyl iron powder by powder metallurgy and coated by thin layer of polyethyleneimine (PEI). The effect of both PEI coating and bovine serum albumin (BSA) interaction on corrosion resistance of iron biomaterials in Hanks’ solution was investigated. Adsorption of BSA onto Fe + PEI was more rapid in comparison to adsorption onto bare Fe due to the electrostatic nature of BSA adsorption to polymeric layer. The corrosion behavior of sintered samples in Hanks’ solution without and with protein was investigated. Alteration of degradation mechanism was observed in the presence of PEI and/or BSA. PEI was observed to avoid the pitting corrosion while presence of BSA resulted in surface-induced complexation. The extensive pitting with high extent of metal release was observed in the presence of PEI and BSA. The additional spectroscopic and microscopic methods were used to prove the suggested alteration of corrosion mechanism.

The increasing demand for improved implant biomaterials encourages their design and development. Degradable biomaterials have gained considerable attention especially in the past few decades. Metallic biomaterials are commonly applied in current medical practice to replace or repair diseased tissue. Structural materials with appropriate mechanical properties are required for load-bearing orthopedic applications. Moreover, biomaterials must fulfil the safety requirements and exhibit reasonable degradation rates to support the failing tissue and allow a gradual load transfer to the healing bone. Metal foams with open cell structure allow the transport of body fluids, growth of new tissues, improvement of degradation rate and reduction of the stress shielding phenomenon. In this work, iron open cell foams were fabricated by means of powder metallurgy processes. The hemocompatibility and mechanical properties of the porous iron materials without and with polyethylene glycol (PEG) coating were evaluated depending on the time of immersion in a simulated body fluid. It has been discovered, that PEG layer has increased the density and strength of iron foams. A mechanism of corrosion of iron foams with PEG coating layer was proposed. The suppression of hemolysis extension, platelet adhesion, and thrombus formation due to the polymer layer was observed as a result.

Iron-based substrates with polyethylene glycol coating were prepared as possible materials for biodegradable orthopedic implants. Biodegradable materials that provide mechanical support of the diseased tissue at the time of implanting and then disappear gradually during the healing process are sometimes favored instead of permanent implants. The implant degradation rate should match the time of the tissue regrowth. In this work, the degradation behavior of iron-based foams was studied electrochemically during immersion tests in Hanks&rsquo, solution. The corrosion rate of the polyethylene glycol-coated samples increased and the corrosion potential shifted to more negative values. This indicates an enhanced degradation rate as compared to the uncoated material, fulfilling the goal of being able to tune the degradation rate. It is the interfacial interaction between the hydrophilic polymer layer and the iron surface that is responsible for the enhanced oxidation rate of iron.

Electron ionization and time-of-flight mass spectrometry was used to investigate the phenol clusters (PhOH)n of different size from single molecule to large clusters: in coexpansion with He, the dimers n = 2 are mostly generated; in Ar, large species of n ≥ 10 also occur. Besides [(PhOH)n](+•) cluster ion series, hydrated phenol cluster ions [(PhOH)n·xH2O](+•) with up to x = 3 water molecules and dehydrated phenol clusters [(PhOH)n-H2O](+•) were observed. The hydrated phenol series exhibits minima and maxima that are interpreted as evidence for proton transfer between the hydrogen bonded cluster ions of cyclic structures. The proton transfer leads to a water generation within the clusters, and subsequent elimination of the diphenyl ether molecule(s) from the cluster yields the hydrated phenol cluster ions. Alternatively, a water molecule release yields a series of dehydrated phenols, among which the diphenyl ether ion [PhOPh](+•) (n = 2) constitutes the maximum.