Fetal Bovine Serum Solution Research Articles

Behavior of the Coefficient of Friction of Textured Tibial Inserts of Total Knee Replacements under the Conditions Prescribed by ISO 14243-3:2014

This work investigates the effect of surface texturing on the coefficient of friction (COF) of tibial inserts (TIs), of total knee replacements (TKRs), using a servomechanical knee simulator operating under the conditions prescribed by ISO 14243-3:2014, which requires strict control of flexion/extension (FE), anterior/posterior displacement (AP), inward/outward rotation (IOR) movements, and load variation. Tests were carried out lubricating with fetal bovine serum solution with a protein concentration of 20 g/L at 37 ± 2 °C. TIs were manufactured by fused deposition modeling (FDM) using polylactic acid (PLA) because of the advantages associated with rapid prototyping and customization. The acquired COF data were analyzed using statistical parametric mapping (SPM) to determine how the surface of the TIs affects the COF, identifying ranges where significant differences occurred. Textured surfaces led to significant reductions in COF during the swing phase of the walking cycle.

Cultivation, Identification, and Parameter Optimization of Chicken Embryo Fibroblast (CEF) in Primary Culture

Chicken eggs have frequently been used as research models for pathogenic disease processes and human research biology. The inflammatory responses and immune suppressions significantly influence the growth of chicken embryo fibroblasts’s (CEFs) growth. In the current study, CEFs were isolated, grown and effect of temperature, serum, incubation, and viral growth were examined. An inverted microscope confirmed morphological features and spindle shape CEFs. It was revealed that 37 ºC temperature, 24-48 h incubation time, and 10% fetal bovine serum (FBS) solution are best optimal conditions for cultivation of CEFs. Viral growth was more prominent with an increase in incubation time span. Haemagglutination (HA) and haemagglutination inhibition (HI) assays confirmed 1024 virus counts and 6 titer of blood. The current study is a contribution to the literature that could be explored to model a platform for the development of viral vaccines by using CEFs cultures.

Nanomolar concentrations of the photodynamic compound TLD-1433 effectively inactivate numerous human pathogenic viruses

The anti-viral properties of a small (≈1 kDa), novel Ru(II) photo dynamic compound (PDC), referred to as TLD-1433 (Ruvidar™), are presented. TLD-1433 had previously been demonstrated to exert strong anti-bacterial and anti-cancer properties. We evaluated the capacity of TLD-1433 to inactivate several human pathogenic viruses. TLD-1433 that was not photo-activated was capable of effectively inactivating 50 % of influenza H1N1 virus (ID50) at a concentration of 117 nM. After photo-activation, the ID50 was reduced to <10 nM. The dose of photo-activated TLD-1433 needed to reduce H1N1 infectivity >99 % (ID99) was approximately 170 nM. Similarly, the ID99 of photo-activated TLD-1433 was determined to range from about 20 to 120 nM for other tested enveloped viruses; specifically, a human coronavirus, herpes simplex virus, the poxvirus Vaccinia virus, and Zika virus. TLD-1433 also inactivated two tested non-enveloped viruses; specifically, adenovirus type 5 and mammalian orthoreovirus, but at considerably higher concentrations. Analyses of TLD-1433-treated membranes suggested that lipid peroxidation was a major contributor to enveloped virus inactivation. TLD-1433-mediated virus inactivation was temperature-dependent, with approximately 10-fold more efficient virucidal activity when viruses were treated at 37 °C than when treated at room temperature (∼22 °C). The presence of fetal bovine serum and virus solution turbidity reduced TLD-1433-mediated virucidal efficiency. Immunoblots of TLD-1433-treated human coronavirus indicated the treated spike protein remained particle-associated.

The Simultaneous Detection of Dopamine and Uric Acid In Vivo Based on a 3D Reduced Graphene Oxide-MXene Composite Electrode.

Dopamine (DA) and uric acid (UA) are essential for many physiological processes in the human body. Abnormal levels of DA and UA can lead to multiple diseases, such as Parkinson's disease and gout. In this work, a three-dimensional reduced graphene oxide-MXene (3D rGO-Ti3C2) composite electrode was prepared using a simple one-step hydrothermal reduction process, which could separate the oxidation potentials of DA and UA, enabling the simultaneous detection of DA and UA. The 3D rGO-Ti3C2 electrode exhibited excellent electrocatalytic activity towards both DA and UA. In 0.01 M PBS solution, the linear range of DA was 0.5-500 µM with a sensitivity of 0.74 µA·µM-1·cm-2 and a detection limit of 0.056 µM (S/N = 3), while the linear range of UA was 0.5-60 µM and 80-450 µM, with sensitivity of 2.96 and 0.81 µA·µM-1·cm-2, respectively, and a detection limit of 0.086 µM (S/N = 3). In 10% fetal bovine serum (FBS) solution, the linear range of DA was 0.5-500 µM with a sensitivity of 0.41 µA·µM-1·cm-2 and a detection limit of 0.091 µM (S/N = 3). The linear range of UA was 2-500 µM with a sensitivity of 0.11 µA·µM-1·cm-2 and a detection limit of 0.6 µM (S/N = 3). The modified electrode exhibited advantages such as high sensitivity, a strong anti-interference capability, and good repeatability. Furthermore, the modified electrode was successfully used for DA measurement in vivo. This could present a simple reliable route for neurotransmitter detection in neuroscience.

A Ratiometric Fluorescent Sensor Based on Chelation-Enhanced Fluorescence of Carbon Dots for Zinc Ion Detection

Zinc ion, one of the most important transition metal ions in living organisms, plays a crucial role in the homeostasis of the organism. The disorder of zinc is associated with many major diseases. It is highly desirable to develop selective and sensitive methods for the real-time detection of zinc ions. In this work, double-emitting fluorescent carbon dots (CDs) are prepared by a solvothermal method using glutathione, L-aspartic acid, and formamide as the raw materials. The carbon dots specifically recognize zine ions and produce a decrease in fluorescence intensity at 684 nm and an increase at 649 nm, leading to a ratiometric fluorescent sensor for zinc detection. Through surface modification and spectral analysis, the surface groups including carboxyl, carbonyl, hydroxyl, and amino groups, and C=N in heterocycles of CDs are revealed to synergistically coordinate Zn2+, inducing the structural changes in the emission site. The CDs can afford a low limit of detection of ~5 nM for Zn2+ detection with good linearity in the range of 0.02–5 μM, showing good selectivity as well. The results from real samples including fetal bovine serum, milk powder, and zinc gluconate oral solution indicated the good applicability of the CDs in the determination of Zn2+.

Development of Zn-2Cu-xMn/Mg Alloys for Orthopedic Applications: Mechanical Performance to In Vitro Degradation under Different Physiological Environments.

Zinc (Zn) and its alloys are considered futuristic biodegradable materials for their acceptable mechanical properties, suitable corrosion rate, and good biocompatibility. In this study, we report newly developed biodegradable Zn-2Cu-xMn/Mg (x = 0, 0.1, and 0.5) alloys, aiming to achieve good mechanical strength with excellent elongation, desirable wear resistance, and suitable corrosion rate. The effect of Mn/Mg addition on the structural, mechanical, wear, and degradation behaviors of the Zn-2Cu-xMn/Mg alloys was thoroughly investigated. Degradation and tribological behaviors of the alloys were explored in the presence of simulated body fluid (SBF), Dulbecco's modified Eagle medium (DMEM), and DMEM with a 10% fetal bovine serum (FBS) solution. Alloy elements and hot rolling improve their mechanical properties significantly due to precipitation hardening, grain refinement, and solid solution strengthening owing to the formation of MnZn13 and Mg2Zn11 phases. Among all the alloys, the Zn-2Cu-0.5Mn alloy achieved the highest ultimate tensile strength (UTS) of ∼405 MPa and yield strength (YS) of ∼293 MPa with an excellent elongation of ∼51%. The corrosion behavior of the alloys as determined by a potentiodynamic polarization study under different solutions follows the sequence Zn-2Cu < Zn-2Cu-0.5Mn < Zn-2Cu-0.1Mn < Zn-2Cu-0.1Mg < Zn-2Cu-0.5Mg. The corrosion rate by immersion testing for 30 and 90 days also follows the same sequence. The corrosion rate in different solutions follows the order SBF > DMEM + 10%FBS > DMEM. The addition of Mn/Mg also improves the wear resistance and slows the wear rate under wet conditions. The bending test results also indicate the highest bending strength of ∼375 MPa for the Zn-2Cu-0.5Mn alloy, among all the alloys. The bending and tensile strengths deteriorate continuously after the immersion for 30 and 90 days in the solution of SBF, DMEM, and DMEM + 10%FBS. Therefore, the Zn-2Cu-xMn/Mg (x = 0.1 and 0.5) alloys can be considered potential biodegradable implant materials.

Simultaneous detection and imaging of two specific miRNAs using DNA tetrahedron-based catalytic hairpin assembly

Improving the accuracy, sensitivity and speed of intracellular miRNA imaging is essential for early diagnosis of cancer. To achieve this goal, we herein present a strategy for imaging two distinct miRNAs by DNA tetrahedron-based catalytic hairpin assembly (DCHA). Two nanoprobes, DTH-13 and DTH-24, were prepared by one-pot synthesis. The resultant structures were DNA tetrahedrons functionalized with two sets of CHA hairpins, which respectively responded to miR-21 and miR-155. Using these structured DNA nanoparticles as the carriers, the probes could easily enter living cells. The presence of miR-21 or miR-155 could trigger CHA between DTH-13 and DTH-24, leading to independent fluorescence signals of FAM and Cy3. In this system, the sensitivity and kinetics were significantly enhanced owing to the strategy of DCHA. The sensing performance of our method was thoroughly investigated in buffers, fetal bovine serum (FBS) solutions, living cells, and clinical tissue samples. The results validated the potential of DTH nanoprobes as a diagnostic tool for early stages of cancer.

Application of a Dual-Probe Coloading Nanodetection System in the Process Monitoring and Efficacy Assessment of Photodynamic Therapy: An In Vitro Study.

The oxygen-consuming property of photodynamic therapy (PDT) affects its effects and aggravates tumor hypoxia, thus upregulating the vascular endothelial growth factor (VEGF) to exacerbate tumor metastasis and lead to treatment failure. Therefore, it is necessary to monitor the dynamic changes in the factors related to PDT and tumor development trends in real time, thus helping to improve PDT efficiency. This study fabricated a fluorescent probe, TPE-2HPro, and a fluorescein-labeled aptamer probe, FAM-AptamerVEGF, to detect hydrogen peroxide (H2O2) and VEGF through the photoinduced electron-transfer effect and the specific affinity of the aptamer to VEGF, respectively. The two probes were loaded into the inner pores and absorbed on the surface of polydopamine coating-wrapped mesoporous silica nanoparticles (MSN@PDA) to construct the dual-probe-loaded system, MSNTH@PDAApt, which was kept stable in fetal bovine serum (FBS) solution and achieved pH-responsive release behavior, thus helping to increase the accumulation of the two probes in tumor cells. The dichloroacetic acid-mediated in vitro antitumor tests showed that the changing trends of H2O2 and VEGF levels were consistent with the results of related mechanism studies and could be monitored by MSNTH@PDAApt. The in vitro chlorin e6 (Ce6)-mediated PDT treatment demonstrated that when the illumination condition was 650 nm, 50 mW/cm2 for 10 min, cells were more inclined to metastasis and invasion rather than death due to a substantial increase in VEGF expression at the low Ce6 concentrations. With the increase of the Ce6 concentration, the growth of the H2O2 level gradually exceeded that of VEGF, and the reactive oxygen species (ROS)-mediated cell death dominated when the Ce6 concentration was about 2 times its IC50 values. Besides, hypoxia also affected the H2O2 and VEGF changes. These results demonstrated that MSNTH@PDAApt could precisely monitor and assess the tumor development trends during PDT treatment, thus helping improve the treatment effect.

Wear Performance of a Novel Silicon Nitride Ceramic for Biomedical Applications

Ceramic materials are sometimes used as bearing surfaces of joint implants due to their high wear resistance and biocompatibility. Silicon nitride (Si3N4) is one of the ceramics under investigation for such use, owing to its bacteriostatic properties and high wear resistance. Traditional Si3N4 is sintered using Al2O3 and Y2O3 as sintering aids. To improve the biocompatibility and bioactivity of Si3N4, new sintering aids (SrO, MgO, and SiO2) were used in this work. This substitution may however have substantial effects on the wear properties of the material. Hence, the aim of this study was to evaluate these effects. Multidirectional pin-on-disc wear tests against ultra-high molecular weight polyethylene pins were used to this end, running in fetal bovine serum solution at 37 °C for 2 million cycles. The surface roughness, phase composition, and surface morphology of the surfaces were investigated, together with the pH of the wear test lubricant and compared to a traditional Si3N4 composition. XRD and SEM results showed that the prepared ceramics were composed of α- and β-phase Si3N4. The surface roughness of the Si3N4 ceramic discs was in accordance with the biomedical standard, and the wear test results demonstrated that the new ceramics had a low wear factor and a comparable coefficient of friction to Si3N4 ceramics reported in previous work. However, the dissolution of the materials over time may be a concern for biotribological applications, such as long-term use or in other wear couples.

Dual-Responsive Amphiphilic P(DMAEMA-co-LMA-co-OEGMA) Terpolymer Nano-Assemblies in Aqueous Media.

This work reports on the synthesis and self-assembly of a novel series of dual-responsive poly[2-(dimethylamino)ethylmethacrylate-co-laurylmethacrylate-co-(oligoethyleneglycol)methacrylate], P(DMAEMA-co-LMA-co-OEGMA)statistical terpolymers in aqueous solutions. Five P(DMAEMA-co-LMA-co-OEGMA) amphiphilic terpolymers, having different content of the three monomers, were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The success of the synthesis was confirmed by the molecular characterization of the terpolymers via size exclusion chromatography (SEC) for the determination of molecular weights and the molecular weight distributions. By using nuclear magnetic resonance (1H-NMR) and Fourier-transform infrared (FTIR) spectroscopy, it was possible to determine the exact composition of the terpolymers. Dynamic light scattering (DLS) and fluorescence spectroscopy (FS) indicated the formation of P(DMAEMA-co-LMA-co-OEGMA) unimolecular or multichain aggregates in aqueous solutions, as a response to pH, temperature and ionic strength changes, with their dimensions being largely affected. The amphiphilic terpolymers were able to encapsulate the hydrophobic drug curcumin (CUR) and demonstrate stability to fetal bovine serum (FBS) solutions. These terpolymer aggregates were studied by DLS, FS and UV-Vis, and it was found that they may have been used as potential nanocarriers for drug delivery and bio-imaging applications.

Endogenous Stimuli-Responsive Autonomous Separation of Dual-Targeting DNA Guided Missile from Nanospacecraft for Intelligent Targeted Cancer Therapy.

Most conventional chemotherapeutics indiscriminately kill both cancerous and healthy cells and cause toxic side effects, limiting the maximum tolerated dose and thereby compromising therapeutic efficacy. To address this challenge, here dual-targeting intelligent DNA guided missile (GM)-integrated nanospacecraft (NSC) (abbreviated as GM-NSC) is demonstrated for staged chemotherapeutic drug delivery exclusively into cancer cells and then mitochondria (not into healthy cells). GM-NSC is essentially a core/shell nanocomposite composed of gold nanoparticles (AuNPs) surrounded by a high-density multilayer DNA crown that is self-assembled from DNA tetrahedral units (DNA Tetra) in a highly ordered manner. Each tetrahedral structural unit is equipped with three functional components: a cancer cell-targeting aptamer pointing toward the outside environment, a hidden mitochondria-targeting triphenylphosphonium (TPP), and an explosive bolt (E-bolt). GM-NSC can remain intact in fetal bovine serum solution over 12 h and has 53-fold improved systemic stability. Each GM-NSC accommodates 1250 anticancer doxorubicin (Dox), achieving a 48-63-fold improved drug payload capacity. When systemically administrated into a tumor-bearing xenograft murine model, Dox-loaded GM-NSC enters into tumor sites with 18-fold improved specificity followed by autonomous separation of GMs from the NSC core and specific mitochondrial accumulation due to the explosion of E-bolt upon stimuli of endogenous miRNAs. About 80% of Dox uptaken is transferred into mitochondria and induces mitochondria-mediated apoptosis. As a result, the growth of malignant tumor is almost 100% inhibited without detectable toxicity to healthy tissues. Due to the desirable systemic stability, good biocompatibility, high cargo loading capability, satisfactory in vivo biodistribution, and therapeutic efficacy without adverse effects, intelligible GM-NSC is expected to become an alternative drug delivery system for precision cancer therapy.

Preliminary tribological results of a new total temporary hip joint prosthesis spacer

Temporary antibiotic-loaded cement spacers are widely used for treating chronic periprosthetic hip infections. The aim of this study is to evaluate the short-term tribological performance of ultra-high-molecular-weight polyethylene (UHMWPE) and (60Co) gamma-irradiated cross-linked UHMWPE (XLPE) self-mated systems as frictional pairs for temporary total hip spacers. A three-axial hip joint simulator, FIME II, was used to test the UHMWPE and XLPE self-mated systems under variable load profiles. A fetal bovine serum solution was used as a lubricant. After simulation tests, wear measurements of damaged coupled surfaces were made with a coordinate measuring machine. Finally, surfaces were characterized with scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and nanoindentation tests. The mass loss test results for UHMWPE were 11.91 ± 3.43 mg for the cups and 4.57 ± 0.92 mg for the heads. Whereas, the results for XLPE showed a significant reduction, with mean mass loss values of 6.59 ± 0.14 mg for the cups and 2.82 ± 0.59 mg for the heads, suggesting the viability of the self-mated XLPE contact pair for a temporary total hip spacer.

Structure, mechanical properties and tribological behavior of sp2-C:Ti/sp3-C:Ti multilayer films deposited by magnetron sputtering

Amorphous carbon (a-C), one of the most studied carbon-based films, has been widely applied in the filed of artificial joints due to its excellent mechanical and tribological properties and high corrosion resistance. However, low adhesive strength and poor fatigue resistance are fatal shortcomings of this kind of films. In this study, carbon (sp2-C:Ti/sp3-C:Ti) nano-multilayer films (MFs) with sequential sp3-rich and sp2-rich layers were deposited on Ti6Al4V and c-Si substrate by DC magnetron sputtering. X-ray diffraction, scanning electron microscopy, the X-ray photoelectron spectroscopy and the transmission electron microscopy were used to characterize the composition, structure and morphologies of the MFs. In the sp2-C:Ti/sp3-C:Ti MFs, the sp3-C rich layer and the sp2-C rich layer exhibit amorphous features and onion-like structure, respectively. Moreover, the layered structure is continuous in a relatively clear region but with a rough layer interface. The mechanical and the scratch behaviors were elaborately characterized by nanoindentation and scratch tests. The results revealed that the sp2-C:Ti/sp3-C:Ti MFs possess hardness of 21.9 GPa and excellent scratch behavior at sputtering bias voltage −220 V, which are significantly better than single-layer films. Furthermore, the adhesion and tribological behaviors of the sp2-C:Ti/sp3-C:Ti MFs were obtained by Rockwell and ball-on-disk tribometer tests. It was found that the sp2-C:Ti/sp3-C:Ti MFs synthesized under a sputtering bias of −220 V not only exhibit relatively low coefficient of friction (only 0.11) in humid air, but also present lower coefficient of friction (0.085) and wear rate (7.5 × 10−17m3N−1 m−1) of Si3N4 balls in Fetal bovine serum (FBS) solution. In conclusion, the critical loads and wear resistance of the sp2-C:Ti/sp3-C:Ti-MFs were effected by the sputtering bias and the mechanical properties of the MFs. And when sputtering bias is −220 V, the sp2-C:Ti/sp3-C:Ti MFs exhibited the improved mechanical properties, the lowest coefficient of friction (CoF) and the highest wear resistance.

Corrosion Behaviour of Ti\u201334Nb\u201325Zr Alloy Fabricated by Spark Plasma Sintering

Titanium alloys are often used in orthopaedic applications owing to their superior mechanical properties and corrosion resistance. Passive corrosion or material degradation process such as wear has been reported due to the release of titanium and other alloying elements into the surrounding tissue. It is therefore important to study the corrosion behaviour of the alloy in biomedical environments. A sub-micron grain-structured Ti–34Nb–25Zr (TNZ) alloy was fabricated via mechanical alloying (MA) of elementary powders followed by spark plasma sintering (SPS). The electrochemical behaviour of TNZ alloy was investigated at 37 °C for 4 h in three different solutions; the Hank’s, the 0.9 wt% NaCl and the eagle minimum essential medium + 10% fetal bovine serum (E-MEM + 10%FBS) solutions. The results show Ecorr values for TNZ alloy in Hank’s, 0.9 wt% NaCl and E-MEM + 10%FBS solutions were about − 202 mV, − 251 mV and − 171 mV, respectively. The measured icorr values were ~ 1.66 nA/cm2 in hank’s solution, which is lower than that in 0.9 wt% NaCl (~ 4.20 nA/cm2) and E-MEM + 10% FBS solution (~ 3.19 nA/cm2). TNZ exhibits good corrosion resistance in all the solutions.

The sensitive detection of ATP and ADA based on turn-on fluorescent copper/silver nanoclusters.

A simple turn-on fluorescence strategy is proposed for the detection of ATP based on DNA-stabilized copper/silver nanoclusters (DNA-Cu/Ag NCs). The fluorescence intensity of DNA-Cu/Ag NCs increases significantly in the presence of ATP, because the specific interaction between ATP and its aptamer causes two darkish Cu/Ag NCs to be situated at the 5' and 3' termini close to each other. A limit of detection (LOD) of 7.0μM is found, in a linear range of 2-18mM, and the proposed sensor is simple, sensitive, and selective. Additionally, the DNA-Cu/Ag NCs/ATP system is further developed into a sensor for ADA detection and demonstrates a linear response to ADA from 5 to 50U/L with a LOD of 5U/L. The proposed method is also shown to be successful in detecting ATP and ADA in a solution of fetal bovine serum.

The microstructure, bio-tribological properties, and biocompatibility of titanium surfaces with graded zirconium incorporation in amorphous carbon bioceramic composite films

One type of carbon-based bioceramic composite film, zirconium (Zr) incorporated amorphous carbon (Zr/a-C) gradient multilayer films (GMFs), is deposited on titanium (Ti) alloys by magnetron sputtering to attain superior biocompatibility and mechanical and bio-tribological properties. The morphologies and structure of Zr/a-C GMFs were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). XRD and SEM and TEM analysis confirmed the gradient multilayer nature of the film, and the presence of nanostructured fcc-ZrC at the Zr/C layer interface for Zr content of 6.3 at.%. XPS analyses confirmed elevated sp2 bond content as a result of incorporating the Zr interlayer in the a-C matrix. The tribological properties of Zr/a-C GMFs were defined using a tribometer with a fetal bovine serum (FBS) solution, in which all Zr/a-C GMFs exhibited improved wear resistance, compared to the pure a-C film and Ti alloy. Additionally, Zr/a-C GMFs exhibited the lowest friction coefficient (COF) at 0.114, and a wear rate of 1.47–1.56 × 10−6 mm3/Nm, compared to pure a-C films and Ti alloy. Phase composition and the superior mechanical properties of GMFs were determined as crucial factors contributing to the enhanced wear resistance and low COF in Zr/a-C GMFs. Furthermore, osteoblast cell viability and proliferation on GMF films were tested in cultures, and results indicated that Zr/a-C GMFs have better biocompatibility, compared to Ti alloy. Cell adhesion experiments also demonstrated the excellent biocompatibility and functional reliability of composite biofilms for potential application in bone implants.

Cutaneous T-Cell Lymphoma (CTCL) Cell Line-Derived Extracellular Vesicles Contain HERV-W-Encoded Fusogenic Syncytin-1

Cutaneous T-Cell Lymphoma (CTCL) Cell Line-Derived Extracellular Vesicles Contain HERV-W-Encoded Fusogenic Syncytin-1

The Effect of Coating Density on Functional Properties of SiNx Coated Implants.

Ceramic coatings may be applied onto metallic components of joint replacements for improved wear and corrosion resistance as well as enhanced biocompatibility, especially for metal-sensitive patients. Silicon nitride (SiNx) coatings have recently been developed for this purpose. To achieve a high coating density, necessary to secure a long-term performance, is however challenging, especially for sputter deposited SiNx coatings, since these coatings are insulating. This study investigates the time-dependent performance of sputter-deposited SiNx based coatings for joint applications. SiNx coatings with a thickness in the range of 4.3–6.0 µm were deposited by reactive high power impulse magnetron sputtering onto flat discs as well as hip heads made of CoCrMo. SiNx compositional analysis by X-ray photoelectron spectroscopy showed N/Si ratios between 0.8 and 1.0. Immersion of the flat disks in fetal bovine serum solution over time as well as short-term wear tests against ultra-high molecular weight polyethylene (UHMWPE) discs showed that a high coating density is required to inhibit tribocorrosion. Coatings that performed best in terms of chemical stability were deposited using a higher target power and process heating.

Mapping the friction coefficient of AISI 316L on UHMWPE lubricated with bovine serum to study the effect of loading and entrainment at high values of sliding-to-rolling ratio

From an experimental point of view, determining the lubrication regime established between contact surfaces of joint prosthesis using the theory of elastohydrodynamic lubrication is rather impractical due to the intrinsic hindrances to measure the thickness of the lubricant film at the contact area. This claim is supported by the results obtained by experts using optical interferometry to perform such measurements using synovial like fluids. Similarly, research has shown that the complex rheology of the synovial fluid complicates the direct application of EHL theory and plays an important role in the lubrication mechanisms at work in prosthetic devices. Since the natural response of all tribological systems is the frictional force, rather than trying to measure the thickness of the lubricant film to determine the lubrication regime, we measured the effect of loading and entrainment on the friction coefficient at the contact point of an AISI 316L stainless steel sphere loaded against an ultra-high molecular weight polyethylene disc, lubricated with fetal bovine serum solution, at high values of sliding-to-rolling ratio. Applying statistical analysis, we obtained a best-fit model that shows a smooth transition from mixed to full-film lubrication regime

Isolation and detection of exosomes via AAO membrane and QCM measurement

Increasing evidence suggests that exosomes are secreted by the majority of cancer cells and present in myriad biological fluids. They have been recognized as a potential new class of biomarkers for disease prognosis and diagnosis. The isolation and quantification of exosomes are crucial in facilitating exosome research. This paper presents a filtration method to isolate exosomes via anodic aluminum oxide (AAO) membrane and to quantify them using a quartz crystal microbalance (QCM). The filtration chip was designed to have two nano-porous AAO membranes sandwiched in between PDMS layers. In this study, fetal bovine serum (FBS) was adopted as the analyte for exosomal bioassays. The experimental results show that AAO membrane has a hydrophilic surface able to sieve exosomes by gravity. The spectrophotometric measurement and the result of gel electrophoresis confirmed that most of proteins in FBS were removed, leaving pure and undamaged exosomes for further analyses. Then, QCM measurement of the filtered FBS solution can give a quantitative analysis of exosome concentration. The relationship between the exosome concentration and its corresponding QCM's frequency shift is linear and monotonic. QCM is still sensitive to measure low concentration of exosomes.