Enhanced Antioxidant Ability of PEG-Coated Ce0.5Zr0.5O2-Based Nanofluids for Scavenging Hydroxyl Radicals.

The antioxidant therapy to preserve residual hearing is relatively recent, and the search for effective antioxidants is still ongoing. Though nanoceria has shown promising radical-scavenging capability, improving its antioxidant ability and the dispersion stability of its nanofluid, which is critical to the desired site, i.e., cochlea, still remains a major challenge. The objective of the present work is to study the radical-scavenging capability of poly(ethylene glycol) (PEG)-coated CeO2 and Ce0.5Zr0.5O2 nanoparticles in water and the biologically relevant fluid (PBS buffer). Nanoparticles in the size range of 4.0-9.0 nm are synthesized using the coprecipitation method and characterized using suitable techniques. The scavenging and dispersion stability of the synthesized nanofluid are analyzed using a UV-vis spectrophotometer. It is found that the addition of PEG during the synthesis process promoted the generation of finer nanoparticles with a narrow size distribution and the doping of zirconium produced a large number of defects in the crystallite structure. The PEG coating over the nanoparticles improved the dispersion stability of nanofluids without affecting their surface reactivity, and it is found to be 94 and 80% in water and PBS, respectively, at 500 µM and 60 min, which is maintained till 90 min. The highest scavenging of hydroxyl radicals by PEG-coated Ce0.5Zr0.5O2 is found to be 60%, which is significantly superior to that of CeO2. The scavenging capability is found to be increased with the concentration of nanoparticles, showing the best scavenging activity at 190 and 150 µM for PEG-coated CeO2 and Ce0.5Zr0.5O2, respectively, and the scavenging in water is at par with that of PBS, indicating that these nanoparticles are suitable to be used in sites where a biologically relevant fluid is present, e.g., the cochlea. It is proposed that PEG-coated Ce0.5Zr0.5O2 having an average size of ∼ 4 nm can be a potential antioxidant in relevant biomedical applications.

Rehabilitation evaluation of the newly developed polymeric based passive polycentric knee joint.

Objective: The lower limb amputation is one of the major concerns for the amputee's daily life and the trans-femoral (TF) amputation is being paid a lot of attention because of its functional requirement in flexion-extension motion. Though significant progress has been made for the development of high end prosthetic knee joint, the affordability of the same is still a great concern. Thus, a passive polycentric knee joint was developed and the health related quality of life (HRQL) before and after the fixation of the prosthesis, and performance of the same were studied.Design: After 6 months of fixation, the HRQL and performance of the prosthetic device were evaluated.Results: The HRQL after the fixation was found to be increased, where the improvement on the physical and mental score was found to be 49 and 46%, respectively, in comparison with pre-fixation stage. The global score (G) for the prosthetic function was found to be 63, which confirmed the increased performance of the prosthesis.Conclusions: The improved HRQL and G of prosthetic performance confirmed the enhanced performance of the prosthesis. It is concluded that the developed passive polycentric knee joint could be explored in large scale for the TF amputees.Implications for rehabilitationThe above knee (AK) amputation is a surgical interference that severs the thigh segment between the knee and hip joints.The above knee prosthesis consists of a socket, knee joint, pylon and foot.The artificial prosthetic knee joint imitates the functions of human knee to achieve the flexion-extension motion of the above knee amputee.The satisfaction of the amputees with the usage of the existing artificial prosthetic knee joint is still a concern. Hence, a passive prosthetic knee joint was developed and its effect on the quality of life of trans-femoral amputee was evaluated using health related quality of life (HRQL) before and after the fixation of the prosthesisThe HRQL after the fixation was found to be increased in comparison with pre-fixation stage.The global score for the prosthetic function was also found to be increased which confirmed the increased performance of the prosthesis.It is anticipated that the developed knee joint is expected to make huge impact due to its function, performance and affordability.

Rapid Manufacturable Ventilator for Respiratory Emergencies of COVID-19 Disease.

Influenza like pandemics are a severe threat to any established health care system as many thousands of patients would need emergency ventilator support during the acute respiratory failure stage, and this quickly overloads the existing facilities. The present article addresses the design and development of a human breathing assist machine (ventilator) prototype for use by qualified medical professionals in the emergency room, as well as in other locations, where a regular ventilator machine cannot be made available. The ventilator has been designed using readily available locally sourced materials, which can be assembled in a short time. This ensures the minimum required features to ventilate a patient in emergency conditions. The popular crank-rocker mechanism has been used to meet some of the vital design requirements of the emergency ventilator. The size of the links has been chosen to maintain a fixed inspiratory-to-expiratory (I:E) time ratio of 1:2. The kinematic linkage design has been kept modular by introducing a feature to adjust the location of the rocker tip to control the tidal volume from 100 ml to 600 ml of oxygenated air per breath. A virtual CAD model, based on the above-mentioned linkage design, has been designed to assess the variation of the position and velocity with time. Finally, a working prototype has been made, and it was observed that the I:E time ratio of 1:2 was achieved satisfactorily.

Performance enhancement of epoxy based sandwich composites using multiwalled carbon nanotubes for the application of sockets in trans-femoral amputees.

A socket plays a vital role in giving the comfort to the amputees. However, the accumulation of heat inside the socket and its weight led to increase their metabolic cost. Hence, an attempt was made to increase the performance of the epoxy based sandwich composites to be used for the socket by reinforcing multiwalled carbon nanotubes (MWCNT), which was varied from 0.1 to 0.5wt%. It was homogeneously dispersed in epoxy to obtain the desired properties, where the enhancement of thermal conductivity, compressive strength and modulus of epoxy was observed to be 76.7%, 62.6% and 20.2%, respectively at 0.3wt% of MWCNT concentration beyond which the mechanical properties were found to be decreased. Hence, the epoxy, E-glass plain fabric, 2-10 layers of stockinet and 0.3wt% of MWCNT were used to prepare the sandwich composites. The flexural strength and thermal conductivity of 0.3wt% of MWCNT reinforced sandwich composites were found to be improved by 11.38±1.5% and 29.8±1.3% for the 4-10 layers and up to 10 layers of stockinet, respectively compared to unreinforced sandwich composites, which helped to reduce the weight of the socket and decrease the heat accumulation inside the socket. Thus, it is suggested to be explored for the application of socket in trans-femoral amputees to increase their comfort level by decreasing the metabolic cost.

Mechanical characterization and validation of poly (methyl methacrylate)/multi walled carbon nanotube composite for the polycentric knee joint.

Trans femoral amputation is one of the most uncomfortable surgeries in patient׳s life, where the prosthesis consisting of a socket, knee joint, pylon and foot is used to do the walking activities. The artificial prosthetic knee joint imitates the functions of human knee to achieve the flexion-extension for the above knee amputee. The objective of present work is to develop a light weight composite material for the knee joint to reduce the metabolic cost of an amputee. Hence, an attempt was made to study the mechanical properties of multi walled carbon nanotubes (MWCNT) reinforced Poly (methyl methacrylate) (PMMA) prepared through melt mixing technique and optimize the concentration of reinforcement. The PMMA nanocomposites were prepared by reinforcing 0, 0.1, 0.2, 0.25, 0.3 and 0.4 wt% of MWCNT using injection moulding machine via twin screw extruder. It is observed that the tensile and flexural strength of PMMA, which were studied as per ASTM D638 and D790, respectively, were increased by 32.9% and 26.3% till 0.25 wt% reinforcement of MWCNT. The experimental results of strength and modulus were compared with theoretical prediction, where a good correlation was noted. It is concluded that the mechanical properties of PMMA were found to be increased to maximum at 0.25 wt% reinforcement of MWCNT, where the Pukanszky model and modified Halpin-Tsai model are suggested to predict the strength and modulus, respectively, of the PMMA/MWCNT composite, which can be opted as a suitable materiel for the development of polycentric knee joint.

Restricting the ageing degradation of the mechanical properties of gamma irradiated UHMWPE using MWCNTs.

Property degradation of the medical grade polymers after gamma irradiation is the primary concern that limits longevity of them. Though the conventional antioxidant material helps to reduce the degradation but it limits the degree of crosslinking of the polymer. The objective of the present work is to study the influence of multi walled carbon nanotubes (MWCNTs) on restricting the degradation of mechanical properties of medical grade ultra high molecular weight polyethylene (UHMWPE) after its irradiation. UHMWPE was reinforced by chemically treated MWCNTs at different concentrations such as 0.5, 1.0, 1.5, and 2.0 wt%. The test samples were then subjected to Co6° gamma irradiation with an integral dose of 25, 50, 75 and 100 kGy in air. The mechanical properties of irradiated samples were evaluated within 10 days, 60 and 120 days after irradiation. It was observed that the mechanical properties of virgin UHMWPE and nanocomposites were enhanced immediately after irradiation but they were found to be reduced at later stages. It was also observed that the presence of MWCNTs limited the ageing degradation of the mechanical properties of UHMWPE. Raman spectroscopic and TEM studies confirmed the formation of irradiation induced defects on the MWCNTs. Electron spin resonance studies showed that the relative radical intensity of virgin UHWMPE was reduced significantly with an increase of MWCNTs concentration confirming the radical scavenging ability of them. It is concluded that MWCNTs restricted the ageing degradation of irradiated UHMWPE.

Assessment of bulk and surface properties of medical grade UHMWPE based nanocomposites using Nanoindentation and microtensile testing.

A thrust on the enhancement of the mechanical properties of ultra high molecular weight polyethylene (UHMWPE) to enhance its longevity has taken a new direction with the advent of nanomaterials and carbon nanotubes. In the present work, UHMWPE was reinforced by chemically treated multi walled carbon nanotubes (MWCNTs) at different concentrations such as 0.5, 1.0, 1.5, 2.0, 2.5 and 5 wt%. The mechanical properties of nanocomposites were studied using a Nanoindentation technique and micro-tensile testing. It is observed that the toughness, ultimate stress, fracture strain, and yield stress of medical grade UHMWPE were enhanced by 176, 93, 70, and 44%, respectively at an optimum concentration of 2 wt% MWCNTs reinforcement. The mechanism for the enhancement of mechanical properties was confirmed by the micro-Raman and calorimetric technique. The reduction of the mechanical properties of nanocomposites beyond optimum concentration of MWCNTs was confirmed by the rheological studies. The generation of microvoids on the nanocomposites was verified by the scanning electron microscopy technique. Nanoindentation characteristics revealed that the surface hardness of UHMWPE was increased by 75% by the reinforcement of 2 wt% of MWCNTs. The Young's modulus obtained at the surface of nanocomposites was observed to be 9.8% higher than that of surface layer removed sample for 2 wt% nanocomposite. It is concluded that the presence of MWCNTs enhanced the mechanical properties and surface properties of medical grade UHMWPE.

The use of Taguchi technique to optimize the compression moulding cycle to process acetabular cup components.

Taguchi technique is a powerful method of solving engineering problems in order to improve the performance of a process and to enhance the productivity. The methodology for the design of the experiment is proposed in order to find the best parameters for better experimental results with less number of experiments as possible. In this study, Taguchi technique was applied to optimize the compression moulding cycle for processing the Acetabular cup prototype. For the design of the experiments, three main factors such as processing temperature, pressure and the time of compaction were identified which directly influence the quality of the final product. For each factor three levels were considered and an orthogonal array L9 was associated. With the L9 orthogonal array, a total of 9 trial experiments have been performed and the optimum parameters were identified. An experimental test was performed in order to validate the founded conditions. The optimized conditions encountered were: processing temperature of 160 degrees C, processing pressure of 1000 psi and the compaction time of 90 s. With these optimized parameters, the acetabular cup prototypes were processed for nanocomposites having ultra-high molecular weight (UHMWPE) reinforced with different volume fractions of carbon nanotubes (CNTs) in the range of 0.2 to 2.0 vol.%.

In vitro studies of multiwalled carbon nanotube/ultrahigh molecular weight polyethylene nanocomposites with osteoblast-like MG63 cells.

Carbon nanotubes are highly versatile materials; new applications using them are continuously being developed. Special attention is being dedicated to the possible use of multiwalled carbon nanotubes in biomaterials contacting with bone. However, carbon nanotubes are also controversial in regards to effects exerted on living organisms. Carbon nanotubes can be used to improve the tribological properties of polymer/composite materials. Ultrahigh molecular weight polyethylene (UHMWPE) is a polymer widely used in orthopedic applications that imply wear and particle generation. We describe here the response of human osteoblast-like MG63 cells after 6 days of culture in contact with artificially generated particles from both UHMWPE polymer and multiwalled carbon nanotubes (MWCNT)/UHMWPE nanocomposites. This novel composite has superior wear behavior, having thus the potential to reduce the number of revision hip arthroplasty surgeries required by wear failure of acetabular cups and diminish particle-induced osteolysis. The results of an in vitro study of viability and proliferation and interleukin-6 (IL-6) production suggest good cytocompatibility, similar to that of conventional UHMWPE (WST-1 assay results are reported as percentage of control +/- SD: UHMWPE = 96.19 +/- 7.92, MWCNT/UHMWPE = 97.92 +/- 8.29%; total protein: control = 139.73 +/- 10.78, UHMWPE = 137.07 +/- 6.17, MWCNT/UHMWPE = 163.29 +/- 11.81 microg/mL; IL-6: control = 90.93 +/- 10.30, UHMWPE = 92.52 +/- 11.02, MWCNT/UHMWPE = 108.99 +/- 9.90 pg/mL). Standard cell culture conditions were considered as control. These results, especially the absence of significant elevation in the osteolysis inductor IL-6 values, reinforce the potential of this superior wear-resistant composite for future orthopedic applications, when compared to traditional UHMWPE.

In vitro studies of multiwalled carbon nanotube/ultrahigh molecular weight polyethylene nanocomposites with osteoblast-like MG63 cells

Carbon nanotubes are highly versatile materials; new applications using them are continuously being developed. Special attention is being dedicated to the possible use of multiwalled carbon nanotubes in biomaterials contacting with bone. However, carbon nanotubes are also controversial in regards to effects exerted on living organisms. Carbon nanotubes can be used to improve the tribological properties of polymer/composite materials. Ultrahigh molecular weight polyethylene (UHMWPE) is a polymer widely used in orthopedic applications that imply wear and particle generation. We describe here the response of human osteoblast-like MG63 cells after 6 days of culture in contact with artificially generated particles from both UHMWPE polymer and multiwalled carbon nanotubes (MWCNT)/UHMWPE nanocomposites. This novel composite has superior wear behavior, having thus the potential to reduce the number of revision hip arthroplasty surgeries required by wear failure of acetabular cups and diminish particle-induced osteolysis. The results of an in vitro study of viability and proliferation and interleukin-6 (IL-6) production suggest good cytocompatibility, similar to that of conventional UHMWPE (WST-1 assay results are reported as percentage of control ± SD: UHMWPE = 96.19 ± 7.92, MWCNT/UHMWPE = 97.92 ± 8.29 percent; total protein: control = 139.73 ± 10.78, UHMWPE = 137.07 ± 6.17, MWCNT/UHMWPE = 163.29 ± 11.81 µg/mL; IL-6: control = 90.93 ± 10.30, UHMWPE = 92.52 ± 11.02, MWCNT/UHMWPE = 108.99 ± 9.90 pg/mL). Standard cell culture conditions were considered as control. These results, especially the absence of significant elevation in the osteolysis inductor IL-6 values, reinforce the potential of this superior wear-resistant composite for future orthopedic applications, when compared to traditional UHMWPE.

Dynamic mechanical analysis of multi-walled carbon nanotube/HDPE composites.

Since the discovery of carbon nanotubes (CNTs), their remarkable properties make them ideal candidates to reinforce in advanced composites. In this attempt, an enhancement of mechanical properties of high density polyethylene (HDPE) by adding 1 wt% of CNTs is studied using Dynamic mechanical and Thermal analyzer (DMTA). The chemically treated and functionalized CNTs were homogeneously dispersed with HDPE and the test samples were made using injection molding machine. Using DMTA, storage modulus (E'), loss modulus (E") and damping factor (tan delta) of the sample under oscillating load were studied as a function of frequency of oscillation and temperatures. The storage modulus decreases with an increase of temperature and increases by adding CNTs in the composites where the reinforcing effect of CNT is confirmed. It is concluded that the large scale polymer relaxations in the composites are effectively restrained by the presence of CNTs and thus the mechanical properties of nanocomposites increase. The transition frequency of loss modulus is observed at 1 Hz. The loss modulus decreases with an increase of temperature at below 1 Hz but opposite trend was observed at above 1 Hz. The shift factor could be predicted from Williams-Landel-Ferry (WLF) model which has good agreement with experimental results.