Spark plasma sintering synthesis of porous nanocrystalline titanium alloys for biomedical applications

The reason for the extended use of titanium and its alloys as implant biomaterials stems from their lower elastic modulus, their superior biocompatibility and improved corrosion resistance compared to the more conventional stainless steel and cobalt-based alloys [Niinomi, M., Hattori, T., Niwa, S., 2004. Material characteristics and biocompatibility of low rigidity titanium alloys for biomedical applications. In: Jaszemski, M.J., Trantolo, D.J., Lewandrowski, K.U., Hasirci, V., Altobelli, D.E., Wise, D.L. (Eds.), Biomaterials in Orthopedics. Marcel Dekker Inc., New York, pp. 41-62]. Nanostructured titanium-based biomaterials with tailored porosity are important for cell-adhesion, viability, differentiation and growth. Newer technologies like foaming or low-density core processing were recently used for the surface modification of titanium alloy implant bodies to stimulate bone in-growth and improve osseointegration and cell-adhesion, which in turn play a key role in the acceptance of the implants. We here report preliminary results concerning the synthesis of mesoporous titanium alloy bodies by spark plasma sintering. Nanocrystalline cp Ti, Ti-6Al-4V, Ti-Al-V-Cr and Ti-Mn-V-Cr-Al alloy powders were prepared by high-energy wet-milling and sintered to either full-density (cp Ti, Ti-Al-V) or uniform porous (Ti-Al-V-Cr, Ti-Mn-V-Cr-Al) bulk specimens by field-assisted spark plasma sintering (FAST/SPS). Cellular interactions with the porous titanium alloy surfaces were tested with osteoblast-like human MG-63 cells. Cell morphology was investigated by scanning electron microscopy (SEM). The SEM analysis results were correlated with the alloy chemistry and the topographic features of the surface, namely porosity and roughness.     

Inactivation of spores by nonthermal plasmas

Bacterial and fungal spore contamination in different industries has a greater economic impact. Because of the remarkable resistance of spores to most physical and chemical microbicidal agents, their inactivation need special attention during sterilization processes. Heat and chemical sporicides are not always well suited for different sterilization/decontamination applications and carries inherent risks. In recent years, novel nonthermal agents including nonthermal plasmas are emerging as effective sporicides against a broad spectrum of bacterial and fungal spores. The present review discusses various aspects related to the inactivation of spores using nonthermal plasmas. Different types of both low pressure plasmas (e.g., capacitively coupled plasma and microwave plasma) and atmospheric pressure plasmas (e.g., dielectric barrier discharges, corona discharges, arc discharges, radio-frequency-driven plasma jet) have been successfully applied to destroy spores of economic significance. Plasma agents contributing to sporicidal activity and their mode of action in inactivation are discussed. In addition, information on factors that affect the sporicidal action of nonthermal plasmas is included.     

Metallic ion content and damage to the DNA in oral mucosa cells of children with fixed orthodontic appliances

Although the metal devices used in orthodontic treatments are manufactured highly resistance to corrosion, they may still suffer some localized corrosion resulting from the oral cavity conditions. The corrosion causes the release of metals from the alloys used for their manufacture. In this report, we evaluated the in vivo metal ions release of three alloys (stainless steel, titanium and nickel-free) usually used in the orthodontics treatments and its genotoxicity. We applied to 15 patients, between 12 and 16 years, 4 tubes and 20 brackets. Samples from oral mucosa were taken before the treatment and 30 days later. The concentration of the titanium, chromium, manganese, cobalt, nickel, molybdenum and iron were detected using inductively coupled plasma mass spectrometry (ICP-MS). The genotoxicity was measured with a comet assay (Olive moment). The oral mucosa cells in contact with the stainless steel alloy displayed the greatest titanium and manganese concentrations and those in contact with the nickel-free alloy presented the greatest concentration of chromium and iron. Both alloys, stainless steel and nickel-free, induced a higher DNA damage in the oral mucosa cells than the titanium alloy, in which the Olive moment was similar to controls. Based on the results of our study, we can conclude that titanium brackets and tubes are the most biocompatible of the three alloys.     

In Vivo Corrosion Resistance of Ca-P Coating on AZ60 Magnesium Alloy

Magnesium-based alloys are frequently reported as potential biodegradable orthopedic implant materials. Controlling the degradation rate and mechanical integrity of magnesium alloys in the physiological environment is the key to their applications. In this study, calcium phosphate (Ca-P) coating was prepared on AZ60 magnesium alloy using phosphating technology. AZ60 samples were immersed in a phosphating solution at 37 ± 2 °C for 30 min, and the solution pH was adjusted to 2.6 to 2.8 by adding NaOH solution. Then, the samples were dried in an attemperator at 60 °C. The degradation behavior was studied in vivo using Ca-P coated and uncoated magnesium alloys. Samples of these two different materials were implanted into rabbit femora, and the corrosion resistances were evaluated after 1, 2, and 3 months. The Ca-P coated samples corroded slower than the uncoated samples with prolonged time. Significant differences (p < 0.05) in mass losses and corrosion rates between uncoated samples and Ca-P coated samples were observed by micro-computed tomography. The results indicate that the Ca-P coating could slow down the degradation of magnesium alloy in vivo.     

Examination of the molecular nature of low-molecular-mass chromium(III) ions in isolated osteoarthritic knee-joint synovial fluid

High field (1)H NMR spectroscopy demonstrated that equilibration of added Cr(III) ions in osteoarthritic knee-joint synovial fluid (SF) resulted in its complexation by a range of biomolecules, the relative efficacies of these complexants/chelators being threonine approximately alanine>glycine>glutamine>citrate>histidine approximately phenylalanine approximately tyrosine>valine approximately isoleucine approximately leucine>glutamate>lactate approximately acetate approximately formate approximately pyruvate, this order reflecting the ability of these ligands to compete for the available Cr(III) in terms of (1) thermodynamic equilibrium constants for the formation of their complexes and (2) their SF concentrations. The significance of these observations with regard to the in vivo corrosion of chromium-containing metal alloy joint prostheses (e.g., CoCr alloys) is discussed.     

Comparative analysis of corrosion resistance between beta titanium and Ti-6Al-4V alloys: A systematic review

BackgroundThe knowledge of the electrochemical property (corrosion resistance) of beta titanium alloys compared to Ti-6Al-4 V for implants is relevant because of the potential cytotoxic effects that the released ions could cause to long-term health.ObjectivesThe objective of this systematic review was to seek information on the electrochemical properties (corrosion resistance) of beta titanium alloys compared to Ti-6Al-4 V since the awareness of the electrochemical behavior of the implant surface in the medium is essential for the best indication of the alloys or compositional changes, which may promote benefits to bone-implant interaction in all areas that this procedure is required.MethodsThe PubMed, LILACS, COCHRANE Library, and Science Direct databases were electronically searched for the terms: dental implants AND beta-titanium AND Ti-6Al-4 V AND electrochemical technics. The inclusion criteria were research articles that studied beta-titanium compared to Ti-6Al-4 V using electrochemical techniques in electrolytes of chemical composition similar to body fluid, published in English, between 2000 and 2020. Articles that did not compare the corrosion resistance of these alloys in electrolytes similar to body fluids were excluded.ResultsA total of 189 articles were restored and selected by title and/or abstract according to the inclusion and exclusion criteria, which resulted in 15 articles that were reduced to 8 after read in full. The studies in vitro evaluated the corrosion resistance in electrolytes Hank, Ringer, SBF, and 0.9 % NaCl, between beta titanium alloys, obtained by arc fusion or bars stock, and Ti-6Al-4 V, for dental or biomedical implants submitted to surface treatments by heat treatment, plasma electrolytic oxidation (PEO), alkaline treatment, and thermomechanical.ConclusionThe evaluated literature allowed to determine that 1) The oxides Nb₂O ₅, Ta₂O _5, and ZrO₂ have higher stability and protection quality than that of TiO₂ modified by the oxides of Al and V; 2) A higher modulus of elasticity of the Ti-6Al-4 V alloy favors protection against corrosion by maintaining a thicker and more firmly adhered oxide layer; 3) The increase in the thickness of the Ti alloys superficial layer contributes to the improvement of the corrosion resistance.     

Biocompatible DCPD Coating Formed on AZ91D Magnesium Alloy by Chemical Deposition and Its Corrosion Behaviors in SBF

Bioactive calcium phosphate coatings were prepared on AZ91D magnesium alloy in phosphating solution in order to im- prove the corrosion resistance of the magnesium alloy in Simulated Body Fluid （SBF）. The surface morphologies and compo- sitions of the calcium phosphate coatings deposited in the phosphating bath with different compositions were investigated by Scanning Electron Microscopy （SEM） with Energy Dispersive Spectrometer （EDS） and X-ray Diffraction （XRD）. Results showed that the calcium phosphate coating was mainly composed of dicalcium phosphate dihydrate （CaHPO4o2H20, DCPD）, with Ca/P ratio of approximately 1 ： 1. The corrosion resistance was evaluated by acid drop, electrochemical polarization, elec- trochemical impedance spectroscopy and immersion tests. The dense and uniform calcium phosphate coating obtained from the optimal phosphating bath can greatly decrease the corrosion rate and hydrogen evolution rate of AZ91D magnesium alloy in SBE     

Thermal Disinfection Validation: The Relationship Between A0 and Microbial Reduction

Validating a thermal disinfection process for the processing of medical devices using moist heat via direct temperature monitoring is a conservative approach and has been established as the A₀ method. Traditional use of disinfection challenge microorganisms and testing techniques, although widely used and applicable for chemical disinfection studies, do not provide as robust a challenge for testing the efficacy of a thermal disinfection process. Considerable research has been established in the literature to demonstrate the relationship between the thermal resistance of microorganisms to inactivation and the A₀ method formula. The A₀ method, therefore, should be used as the preferred method for validating a thermal disinfection process using moist heat.

Disinfection, which is defined as reducing the number of viable microorganisms on a product to a level previously specified as appropriate for its intended further handling or use, can be achieved thermally by the action of moist heat.1 Thermal disinfection during the processing of medical devices, typically performed in a washer-disinfector, is widely used for two purposes. The first is for reducing product bioburden (disinfection) either as a terminal step (e.g., for noncritical or semicritical devices) or prior to packaging and sterilization (e.g., for critical devices) in preparation for patient use. The second is to render the devices safe for handling for central service professionals during inspection and packaging.2,3 Thermal disinfection requirements therefore should consider the potential levels of microbial contamination on reusable devices after use, the desired level of reduction to render those devices safe for handling and for their intended purpose, and the reliability of the disinfection process to consistently achieve that endpoint.The microbial load on device types after patient use has been established in the literature and can vary depending on the typical clinical use of the device. For example, critical (surgical) devices, on average, have demonstrated relatively low levels of viable microorganisms (bioburden level <10² colony-forming units [CFU]/cm²).4 However, these same studies have shown the concentration of other testing analytes (e.g., protein, total organic carbon, hemoglobin) to be more noteworthy. Although the data indicate that residual clinical soil (e.g., human secretions, blood, tissue) can harbor microorganisms, the incoming product bioburden levels are far below the microbial populations challenged during an overkill sterilization process (e.g., moist heat or gaseous processes).Conservative sterilization processes have been demonstrated to achieve at least a 12-log₁₀ reduction of microorganisms with a known higher resistance versus typical bioburden.3,5 Cleaning, which is defined as the removal of contamination from an item to the extent necessary for its further processing and its intended subsequent use, is an important step to render the device ready for sterilization and will further reduce the levels of microorganisms prior to sterilization. Therefore, with critical devices, adequate cleaning followed by sterilization is the minimum requirement to ensure the device is safe for patient use.It is not likely that, for the intended use of the device, a disinfection process is strictly necessary as an intermediate step prior to sterilization. A benefit may exist to having an interim disinfection step to render the device safe for handling during inspection and packaging for sterilization. For example, the expectation in the Occupational Safety and Health Administration''s Bloodborne Pathogens standard 29 CFR 1910.1030 is that an employer will minimize the occupational exposure to bloodborne pathogens.Thermal disinfection has been used by sterile processing departments as a universal precaution to reduce the risk of exposure to processing personnel postcleaning. Although routine thermal disinfection at less than 100°C (212°F) may not be effective in deactivating all types of microorganisms (e.g., certain types of bacteria spores), it is a reliable and consistent disinfection process. As the temperature increases above a certain point (typically ≥70°C or 158°F), so does the activity against microorganisms, with variable intrinsic and acquired resistance mechanisms to heat.3 Thermal disinfection therefore will provide processing personnel with a minimized risk of bloodborne pathogens exposure.In other situations, the microbiological load can be much higher (e.g., with flexible endoscopes used in the gastrointestinal system6) or more variable (e.g., with noncritical devices or surfaces depending on their use7). Where practical, thermal disinfection is still viewed as the preferred and more reliable method to render these devices safe for use due to its known efficacy against microbial pathogens.5 Chemical disinfection generally is only considered if thermal disinfection cannot be applied (e.g., due to thermo-sensitivity of device or surface materials).     

Experimental characterization of flow conditions in 2- and 20-L bioreactors with wave-induced motion

Quantifying the influence of flow conditions on cell viability is essential for a successful control of cell growth and cell damage in major biotechnological applications, such as in recombinant protein and antibody production or vaccine manufacturing. In the last decade, new bioreactor types have been developed. In particular, bioreactors with wave‐induced motion show interesting properties (e.g., disposable bags suitable for cGMP manufacturing, no requirement for cleaning and sterilization of cultivation vessels, and fast setup of new production lines) and are considered in this study. As an additional advantage, it is expected that cultivations in such bioreactors result in lower shear stress compared with conventional stirred tanks. As a consequence, cell damage would be reduced as cell viability is highly sensitive to hydrodynamic conditions. To check these assumptions, an experimental setup was developed to measure the most important flow parameters (liquid surface level, liquid velocity, and liquid and wall shear stress) in two cellbag sizes (2 and 20 L) of Wave Bioreactors®. The measurements confirm in particular low shear stress values in both cellbags, indicating favorable hydrodynamic conditions for cell cultivation. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011     

Biotransformation of lignin: Mechanisms,applications and future work

As one of the most abundant polymers in biosphere, lignin has attracted extensive attention as a kind of promising feedstock for biofuel and bio-based products. However, the utilization of lignin presents various challenges in that its complex composition and structure and high resistance to degradation. Lignin conversion through biological platform harnesses the catalytic power of microorganisms to decompose complex lignin molecules and obtain value-added products through biosynthesis. Given the heterogeneity of lignin, various microbial metabolic pathways are involved in lignin bioconversion processes, which has been characterized in extensive research work. With different types of lignin substrates (e.g., model compounds, technical lignin, and lignocellulosic biomass), several bacterial and fungal species have been proved to own lignin-degrading abilities and accumulate microbial products (e.g., lipid and polyhydroxyalkanoates), while the lignin conversion efficiencies are still relatively low. Genetic and metabolic strategies have been developed to enhance lignin biodegradation by reprogramming microbial metabolism, and diverse products, such as vanillin and dicarboxylic acids were also produced from lignin. This article aims at presenting a comprehensive review on lignin bioconversion including lignin degradation mechanisms, metabolic pathways, and applications for the production of value-added bioproducts. Advanced techniques on genetic and metabolic engineering are also covered in the recent development of biological platforms for lignin utilization. To conclude this article, the existing challenges for efficient lignin bioprocessing are analyzed and possible directions for future work are proposed.     

Surface Modification of Biodegradable Mg-4Zn Alloy Using PMEDM: An Experimental Investigation,Optimization and Corrosion Analysis

ObjectivesMagnesium alloys are the potential candidate for metallic implants due to their excellent mechanical characteristics, biodegradable nature, and properties similar to human bone. However, a high degradation rate is primary obstacle in implementing these alloys as biodegradable orthopedic implants. Powder-mixed electric discharge machining (PMEDM) is an emerging method of surface modification of metallic alloys that can be implemented to improve the corrosion resistance of Mg alloys. Therefore, PMEDM using zirconium (Zr) and manganese (Mn) powder particles has been proposed to modify the surface characteristics of Mg-4Zn alloy.Materials and MethodsIn the present work, Zr and Mn powders have been used in varying concentrations during PMEDM of Mg-4Zn alloy. Experiments were conducted as per mixed design L18 orthogonal array (OA). Taguchi and Grey Relational Analysis (GRA) have been used to optimize the process parameters. Analysis of response characteristics, namely material removal rate (MRR), surface roughness (SR), and thickness of the alloyed layer (TAL), has been carried out at different values of input variables (like powder additives (P_a), powder concentration (C_p), peak current (I_p), pulse on time (T_on) and duty cycle (DC)). The corrosion analysis was carried out by immersing the specimen (machined at an optimized setting) in simulated body fluid (SBF).ResultsIt is observed from the analysis that C_p, I_p, and T_on play a pivotal role in evaluating response characteristics. The favorable setting suggested by the gray approach is P_a: Zr; C_p: 2 g/l; I_p: 4A; T_on: 50 μs; DC: 80%, while responses at this setting are confirmed by confirmation experiments with MRR: 32.14 mm³/min; SR: 5.578 μm and TAL: 8.28 μm. The immersion test signifies that the corrosion rate (CR) of PMEDMed sample (3.20 mm/year) is 40.74% lesser than the corrosion rate of polished sample (5.40 mm/year).ConclusionZr powder shows better performance in terms of higher MRR, lower SR and higher TAL as compared to Mn powder during the PMEDM process. The corroded surface of polished sample exhibited larger size micro pits and cracks than the machined sample, which concluded that surface modification of MZ-4Zn alloy via PMEDM is a powerful tool to enhance its corrosion resistance.     

Effect of Tricalcium Magnesium Silicate Coating on the Electrochemical and Biological Behavior of Ti-6Al-4V Alloys

In the current study, a sol-gel-synthesized tricalcium magnesium silicate powder was coated on Ti-6Al-4V alloys using plasma spray method. Composition of feed powder was evaluated by X-ray diffraction technique before and after the coating process. Scanning electron microscopy and atomic force microscopy were used to study the morphology of coated substrates. The corrosion behaviors of bare and coated Ti-6Al-4V alloys were examined using potentiodynamic polarization test and electrochemical impedance spectroscopy in stimulated body fluids. Moreover, bare and coated Ti-6Al-4V alloys were characterized in vitro by culturing osteoblast and mesenchymal stem cells for several days. Results demonstrated a meaningful improvement in the corrosion resistance of Ti-6Al-4V alloys coated with tricalcium magnesium silicate compared with the bare counterparts, by showing a decrease in corrosion current density from 1.84 μA/cm² to 0.31 μA/cm². Furthermore, the coating substantially improved the bioactivity of Ti-6Al-4Valloys. Our study on corrosion behavior and biological response of Ti-6Al-4V alloy coated by tricalcium magnesium silicate proved that the coating has considerably enhanced safety and applicability of Ti-6Al-4V alloys, suggesting its potential use in permanent implants and artificial joints.     

Nuclear corrosion monitoring—

Nuclear corrosion technique has been developed for the assay of various heavy metals released through corrosion and abrasion into electrolytes from various biomaterials like amalgams, chromium— cobalt and gold alloys, steel, and titanium. Application of the technique in measurement of selective release rates under static or dynamic conditions, i.e., during cyclic loading, is discussed. The elements chromium, cobalt, copper, gold, iron, mercury, molybdenum, silver, titanium, and zinc have been quantitatively assessed. In vivo corrosion measurements are further included. By combining the present nuclear tracer technique with ESCA technique, knowledge about reaction mechanisms occurring at the interface solid/liquid is obtained. Exposure of humans to various heavy metals from biomaterials, e.g., dental materials, can be estimated using the NCM technique. The technique also has a potential for selective release measurements of several nuclides possessing suitable radioanalytical properties from other types of alloys immersed in various liquid environments.     

Evaluation of the speciation status of aluminium(III) ions in isolated osteoarthritic knee-joint synovial fluid

High field 1H NMR spectroscopy demonstrated that the equilibration of added Al(III) ions in osteoarthritic (OA) knee-joint synovial fluid (SF) resulted in its complexation by citrate and, to a much lesser extent, tyrosine and histidine. The ability of these ligands, together with inorganic phosphate, to compete for the available Al(III) in terms of (1) thermodynamic equilibrium constants for the formation of their complexes and (2) their SF concentrations was probed through the use of computer speciation calculations, which considered low-molecular-mass binary and ternary Al(III) species, the predominant Al(III) plasma transport protein transferrin, and also relevant hydrolysis and precipitation processes. It was found that, at relatively low added Al(III) concentrations, citrate species were more favoured, whilst phosphate species became dominant at higher levels. The significance of these findings with regard to the in vivo corrosion of aluminium-containing metal alloy joint prostheses (e.g., TiAlV alloys) is discussed.     

Influence of Bio-Lubricants on the Tribological Properties of Ti6Al4V Alloy

Titanium alloy is one of the best materials for biomedical applications due to its superior biocompatibility, outstanding corrosion resistance, and low elastic modulus. However, the friction and wear behaviors of titanium alloys were sensitive to the environment including lubrication. In order to clarify the wear mechanism of titanium alloy under different lubrications including deionized water, physiological saline and bovine serum, the friction and wear tests were performed between Ti6Al4V plates and Si₃N₄ ball on a universal multi-functional tester. The friction and the wear rate of titanium alloy were measured under dry friction and three different lubrication conditions. The worn surfaces were examined by scanning electron microscopy. The results revealed that under the dry friction, the wear resistance of titanium alloy was the worst since the wear mechanism was mainly the combination of abrasive wear and oxidation wear. It was also found that Ti6Al4V alloy had low friction coefficient and wear rate under three lubrication conditions, and its wear mechanism was adhesive wear.     

Universal Soldering of Lithium and Sodium Alloys on Various Substrates for Batteries

The high theoretical specific capacity of lithium (Li) metal and the nonflammability of solid‐state electrolytes (SSEs) make the solid‐state Li metal battery a promising option to develop safe batteries with high energy density. To make the switch from liquid to solid‐state electrolyte, the high interfacial resistance resulting from the poor solid–solid contacts between Li metal and SSEs needs to be addressed. Herein, a one‐step soldering technique to quickly coat molten Li onto different substrates including metals, ceramics, and polymers is presented. It is deduced that the surface energy and viscosity of the molten Li can be tuned by adding alloy elements, which improves the wettability against various substrates. When soldered onto the surface of garnet‐based SSEs, the Li alloys exhibit significantly improved contact, which leads to an interface resistance as low as ≈7 Ω cm². While cycling under high loads, the newly plated Li still maintains tight contact with the garnet surface and demonstrates excellent electrochemical stability. Several Li binary alloys as well as sodium (Na) binary alloys are successfully tested on various substrates to demonstrate the versatility of this soldering technique for potential battery applications.     

Characterization of methods for determining sterilization efficacy and reuse efficiency of oxygen biosensor multiwell plates

High-throughput screening (HTS) assays based upon fluorometric detection of oxygen consumption in microtiter plates were primarily developed for applications in drug discovery and ecotoxicology but have recently been adopted for use in microbial community-level physiological profiling assays (CLPP). The widespread use of oxygen biosensor systems for CLPP applications has, however, been hindered by the relatively high cost of oxygen biosensor reagent systems and limited access to microplate fluorometer instrumentation platforms. The ability to recycle and reuse oxygen biosensor system plates would expand their utilization for CLPP assays and other research applications in microbial ecology. Here, the efficacy and cost effectiveness of multiple procedures for sterilization of Oxygen Biosensor System (OBS; BD Biosciences) plates for reuse was evaluated. OBS plates were sterilized using ethylene oxide, ultraviolet radiation, and bleach treatments, then evaluated for biosensor response and plate life-cycle performance. Of the sterilization methods tested, ethylene oxide sterilization was most effective based on its low cost, high sterilization efficacy, and minimal impact upon OBS plate response.     

Characterization of methods for determining sterilization efficacy and reuse efficiency of oxygen biosensor multiwell plates

High-throughput screening (HTS) assays based upon fluorometric detection of oxygen consumption in microtiter plates were primarily developed for applications in drug discovery and ecotoxicology but have recently been adopted for use in microbial community-level physiological profiling assays (CLPP). The widespread use of oxygen biosensor systems for CLPP applications has, however, been hindered by the relatively high cost of oxygen biosensor reagent systems and limited access to microplate fluorometer instrumentation platforms. The ability to recycle and reuse oxygen biosensor system plates would expand their utilization for CLPP assays and other research applications in microbial ecology. Here, the efficacy and cost effectiveness of multiple procedures for sterilization of Oxygen Biosensor System™ (OBS; BD Biosciences) plates for reuse was evaluated. OBS plates were sterilized using ethylene oxide, ultraviolet radiation, and bleach treatments, then evaluated for biosensor response and plate life-cycle performance. Of the sterilization methods tested, ethylene oxide sterilization was most effective based on its low cost, high sterilization efficacy, and minimal impact upon OBS plate response.     

Corrosion protection of reusable surgical instruments

To understand the corrosion properties of surgical scissors, 416 stainless steel disks and custom electrodes were used as simulated surfaces under various conditions. These simulated surfaces were exposed to tap water and 400-ppm synthetic hard water as Ca2CO3 under different conditions. The samples were evaluated by various techniques for corrosion potential and the impact of environmental conditions on the integrity of the passive film. The electrodes were used to monitor the corrosion behavior by potentiodynamic polarization technique in water both in the presence and absence of a cleaning product. The surface topography of the 416 stainless steel disks was characterized by visual observations and scanning electron microscopy (SEM), and the surface chemistry of the passive film on the surface of the scissors was characterized by x-ray photoelectron spectroscopy (XPS). The results suggest that surgical instruments made from 416 stainless steel are not susceptible to uniform corrosion; however, they do undergo localized corrosion. The use of suitable cleaning products can offer protection against localized corrosion during the cleaning step. More importantly, the use of potentiodynamic polarization techniques allowed for a quick and convenient approach to evaluate the corrosion properties of surgical instruments under a variety of simulated-use environmental conditions.