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Effect Of Passivation And Surface Treatment Of A Laser Powder Bed Fusion Biomedical Titanium Alloy On Corrosion Resistance And Protein Adsorption, Saman Nikpour, Jeffrey Henderson, Sina Matin, Heng-Yong Nie, Jonas Hedberg, Vahid Dehnavi, Yara Hosein, David Holdsworth, Mark Biesinger, Yolanda Hedberg

Chemistry Publications

The biomedical titanium alloy Ti6Al4V has excellent corrosion resistance and biocompatibility and is, therefore, widely used in orthopedic and orthodontic implants. Biomedical implants are increasingly fabricated by additive manufacturing, such as laser powder bed fusion (LPBF). These manufacturing protocols often include sandblasting, surface finish, and passivation. This study aims to investigate the effect of different surface finishes and the commonly used ASTM F86-13 nitric acid passivation for LPBF Ti6Al4V on its corrosion resistance, metal release, and surface changes in benign (bovine serum albumin in a pH 7.4 buffer) and harsh (hydrochloric acid at pH 1.5) solutions using various electrochemical and …

A Bio-Tribocorrosion Comparison Between Additively Manufactured And Forged Ti6al4v Parts, Sina Matin, Sahar Toorandaz, Saman Nikpour, Hamidreza Abdolvand, Eshan Toyserkani, Yolanda S. Hedberg

Chemistry Publications

Ti6Al4V has been used widely as a biomedical alloy and is increasingly manufactured by additive manufacturing due to customized shapes. As implant material, it is frequently exposed to both friction and corrosive environments. This study investigates the effect of the fabrication process (laser powder bed fusion and forging) on the tribocorrosion behavior of Ti6Al4V in various environments including diluted hydrochloric acid to simulate the acidic environment in a crevice (HCl), phosphate-buffered saline (pH 7.3) with 10 g/L bovine serum albumin (PBS+BSA), and PBS+BSA with 30 mM H2O2. While the presence of BSA hindered the repassivation (reforming of the protective passive …

Corrosion Of Implant Materials In The Human Body, Maedeh Barzmehri

Corrosion Research

This paper extensively examines the complex problem of implant corrosion occurring within the human body. The corrosion of implants gives rise to substantial challenges, encompassing compromised implant durability, patient safety concerns, and potential adverse impacts on the long-term functionality of the medical device. The study's primary objectives include offering a concise overview of the various corrosion mechanisms that impact a range of implant materials and outlining health complications linked to the byproducts of implant corrosion. Furthermore, it delves into a cost analysis specific to hip or knee revision arthroplasty, which has become a prevalent scenario in implant failure cases on …

In Vitro Corrosion And Biocompatibility Behavior Of Cocrmo Alloy Manufactured By Laser Powder Bed Fusion Parallel And Perpendicular To The Build Direction, Masoud Atapour, Saber Sanaei, Zheng Wei, Mohammadali Sheikholeslam, Jeffrey D. Henderson, Ubong Eduok, Yara K. Hosein, David W. Holdsworth, Yolanda S. Hedberg, Hamid Reza Ghorbani

Chemistry Publications

Biomedical cobalt-chromium-molybdenum alloys (CoCrMo) are frequently used for orthopedic implant and dental materials exposed to mechanical stressors, such as wear and cyclic load. Due to the high demand for customizable implant shapes, these alloys are increasingly manufactured by additive manufacturing methods such as laser powder bed fusion (LPBF). LPBF results in different microstructures and surface roughness as a function of the building direction. This study investigated the corrosion resistance, bioactivity, biocompatibility, and microstructure of LPBF CoCrMo (low carbon content, heat-treated) in the XY (perpendicular) and XZ (parallel) plane of the building direction for as-printed (as-received) and abraded surfaces. A distinct …

Metal Release From A Biomedical Cocrmo Alloy In Mixed Protein Solutions Under Static And Sliding Conditions: Effects Of Protein Aggregation And Metal Precipitation, Zheng Wei, Valentine Romanovski, Luimar Filho, Cecilia Persson, Yolanda S. Hedberg

Chemistry Publications

Biomedical materials made of cobalt-chromium-molybdenum (CoCrMo) alloys are commonly used in artificial prostheses and dental implants, which are exposed to friction and load. The release of Co, Cr, and Mo from these surfaces is governed by physical and chemical processes. The extent of measured metal release from biomedical CoCrMo alloys into mixed protein solutions may be influenced by protein aggregation and metal precipitation effects. Metal release from, and the surface composition of, a CoCrMo alloy was investigated in physiological relevant solutions (phosphate buffered saline, PBS, with varying concentrations of fibrinogen from bovine plasma and/or bovine serum albumin) at pH 7.3 …

Patch Testing With Aluminium Finn Chambers Could Give False-Positive Reactions In Patients With Contact Allergy To Aluminium, Lisbeth Rosholm Comstedt, Jakob Dahlin, Magnus Bruze, Yolanda S. Hedberg, Mihály Matura, Cecilia Svedman

Chemistry Publications

Background

Earlier laboratory studies have shown that sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride trigger the release of aluminium (Al) from Finn Chambers (FC).

Objectives

To investigate whether aluminium realease from FC could influence the diagnostic outcome of patch testing with FC.

Method

A retrospective analysis of patch test results from 2010 to 2019 was performed. A two-sided Fisher's exact test was used to calculate any overrepresentation of contact allergy to Al among patients with positive reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride.

Results

A total of 5446 patients had been tested …

Ph-Sensitive Chitosan Nanoparticles For Salivary Protein Delivery, Yi Zhu, Lina M. Marin, Yizhi Xiao, Elizabeth R. Gillies, Walter L. Siqueira

Chemistry Publications

Salivary proteins such as histatins (HTNs) have demonstrated critical biological functions directly related to tooth homeostasis and prevention of dental caries. However, HTNs are susceptible to the high proteolytic activities in the oral environment. Therefore, pH-sensitive chitosan nanoparti-cles (CNs) have been proposed as potential carriers to protect proteins from enzymatic degradation at physiological salivary pH. Four different types of chitosan polymers were investigated and the optimal formulation had good batch to batch reproducibility, with an average hydrodynamic diame-ter of 144 ± 6 nm, a polydispersity index of 0.15 ± 0.04, and a zeta potential of 18 ± 4 mV at …

Gibbs Point Process Model For Young Star Clusters In M33, Dayi Li, Pauline Barmby

Physics and Astronomy Publications

We demonstrate the power of Gibbs point process models from the spatial statistics literature when applied to studies of resolved galaxies. We conduct a rigorous analysis of the spatial distributions of objects in the star formation complexes of M33, including giant molecular clouds (GMCs) and young stellar cluster candidates (YSCCs). We choose a hierarchical model structure from GMCs to YSCCs based on the natural formation hierarchy between them. This approach circumvents the limitations of the empirical two-point correlation function analysis by naturally accounting for the inhomogeneity present in the distribution of YSCCs. We also investigate the effects of GMCs' properties …

Tuning The Hydrophobic Cores Of Self-Immolative Polyglyoxylate Assemblies, Bo Fan, Rebecca E. Yardley, John F. Trant, Aneta Borecki, Elizabeth R. Gillies

Chemistry Publications

Polyglyoxylates are a recently-introduced class of self-immolative polymers, that depolymerize to small molecules upon the cleavage of a stimuli-responsive end-cap from the polymer terminus. The incorporation of different pendant ester groups or other aldehyde monomers offers the potential to tune the polymer properties, but this remains largely unexplored. With the goal of tuning the self-assembly and drug-loading properties of polyglyoxylate block copolymers, we explored the polymerization and copolymerization of n-butyl glyoxylate, L-menthyl glyoxylate, and chloral with ethyl glyoxylate to form UV light-responsive polyglyoxylates. The resulting polymers were coupled to poly(ethylene glycol) to afford amphiphilic block copolymers. Self-assembly of the …

Limiting The Impact Of Destructive Analytical Techniques Through Sequential Microspatial Sampling Of The Enamel From Single Teeth, Alexis E. Dolphin, Mathew A. Teeter, Christine D. White, Fred J. Longstaffe

Earth Sciences Publications

A fundamental research concern within contemporary bioarchaeology is the sensitive balance between the preservation of human remains and the use of destructive techniques to collect information. Here we describe one example of how multiple microspatial destructive/semi-destructive techniques may be carried out in sequence using only the enamel of a single tooth. With careful planning of both sample preparation strategies and sequencing of sampling methods, it is possible to produce multiple datasets, and yet to retain material for future analyses.

In this case, enamel from the teeth of 27 individuals who lived during the early medieval period (AD 1170-1198) in Bergen, …

Taxonomy, Location Of Origin, And Health Status Of Proboscideans From Western Canada Investigated Using Stable Isotope Analysis, Jessica Z. Metcalfe, Fred Longstaffe, Christopher N. Jass, Grant D. Zazula, Grant Keddie

Earth Sciences Publications

We investigated the application of stable isotope analysis of proboscidean remains (collagen in bone/dentin/cementum and structural carbonate in enamel bioapatite) for genus-level identification of isolated specimens, assessment of geographic origins, and testing for nutritional stress. Mammoths (Mammuthus sp.) tended to have higher δ¹⁵N_col and lower δ¹³C_col than mastodons (Mammut americanum), but differences were not significant in every location. Determining the genus of isolated specimens may be possible for locations and time periods with good isotopic baselines, but environmental changes can confound interpretations. For example, an Alberta proboscidean with a δ¹⁵N …