“…For this reason, probably for the Cu70 powder (which has the largest particle size of all tested), the highest cell survival rate is observed for the highest concentration. On the other side, the possible cytotoxicity of copper nanoparticles was reported several times [ 68 , 72 , 73 , 74 , 75 ], even if it depends on the amount and size of particles. In the case of samples of cement without additives, and cement with nanoparticles of Ni and AgCu, adhering bacteria were observed on their surface after 6 months.…”
Section: Discussionmentioning
confidence: 99%
“…In the case of this additive, studies of the powders themselves in contact with mammalian cells demonstrated that all metallic nanoparticles had a certain effect on the vitality of cells, and the addition of Ni reduced the vitality of Saos-2 cells to the smallest extent [ 76 , 77 ]. All these phenomena may be related to both the toxic effect of metal ions (regardless of whether they attack the cell membrane or make adhesion of bacteria easier or do not prevent it), apparently higher for copper than for silver and size of the nanoparticle, more dangerous at smaller dimensions [ 72 , 75 ].…”
Cemented arthroplasty is a common process to fix prostheses when a patient becomes older and his/her bone quality deteriorates. The applied cements are biocompatible, can transfer loads, and dampen vibrations, but do not provide antibacterial protection. The present work is aimed at the development of cement with antibacterial effectivity achieved with the implementation of nanoparticles of different metals. The powders of Ag, Cu with particles size in a range of 10–30 nm (Cu10) and 70–100 nm (Cu70), AgCu, and Ni were added to PMMA cement. Their influence on compression strength, wettability, and antibacterial properties of cement was assessed. The surface topography of samples was examined with biological and scanning electron microscopy. The mechanical properties were determined by compression tests. A contact angle was observed with a goniometer. The biological tests included an assessment of cytotoxicity (XTT test on human cells Saos-2 line) and bacteria viability exposure (6 months). The cements with Ag and Cu nanopowders were free of bacteria. For AgCu and Ni nanoparticles, the bacterial solution became denser over time and, after 6 months, the bacteria clustered into conglomerates, creating a biofilm. All metal powders in their native form in direct contact reduce the number of eukaryotic cells. Cell viability is the least limited by Ag and Cu particles of smaller size. All samples demonstrated hydrophobic nature in the wettability test. The mechanical strength was not significantly affected by the additions of metal powders. The nanometal particles incorporated in PMMA-based bone cement can introduce long-term resistance against bacteria, not resulting in any serious deterioration of compression strength.
“…For this reason, probably for the Cu70 powder (which has the largest particle size of all tested), the highest cell survival rate is observed for the highest concentration. On the other side, the possible cytotoxicity of copper nanoparticles was reported several times [ 68 , 72 , 73 , 74 , 75 ], even if it depends on the amount and size of particles. In the case of samples of cement without additives, and cement with nanoparticles of Ni and AgCu, adhering bacteria were observed on their surface after 6 months.…”
Section: Discussionmentioning
confidence: 99%
“…In the case of this additive, studies of the powders themselves in contact with mammalian cells demonstrated that all metallic nanoparticles had a certain effect on the vitality of cells, and the addition of Ni reduced the vitality of Saos-2 cells to the smallest extent [ 76 , 77 ]. All these phenomena may be related to both the toxic effect of metal ions (regardless of whether they attack the cell membrane or make adhesion of bacteria easier or do not prevent it), apparently higher for copper than for silver and size of the nanoparticle, more dangerous at smaller dimensions [ 72 , 75 ].…”
Cemented arthroplasty is a common process to fix prostheses when a patient becomes older and his/her bone quality deteriorates. The applied cements are biocompatible, can transfer loads, and dampen vibrations, but do not provide antibacterial protection. The present work is aimed at the development of cement with antibacterial effectivity achieved with the implementation of nanoparticles of different metals. The powders of Ag, Cu with particles size in a range of 10–30 nm (Cu10) and 70–100 nm (Cu70), AgCu, and Ni were added to PMMA cement. Their influence on compression strength, wettability, and antibacterial properties of cement was assessed. The surface topography of samples was examined with biological and scanning electron microscopy. The mechanical properties were determined by compression tests. A contact angle was observed with a goniometer. The biological tests included an assessment of cytotoxicity (XTT test on human cells Saos-2 line) and bacteria viability exposure (6 months). The cements with Ag and Cu nanopowders were free of bacteria. For AgCu and Ni nanoparticles, the bacterial solution became denser over time and, after 6 months, the bacteria clustered into conglomerates, creating a biofilm. All metal powders in their native form in direct contact reduce the number of eukaryotic cells. Cell viability is the least limited by Ag and Cu particles of smaller size. All samples demonstrated hydrophobic nature in the wettability test. The mechanical strength was not significantly affected by the additions of metal powders. The nanometal particles incorporated in PMMA-based bone cement can introduce long-term resistance against bacteria, not resulting in any serious deterioration of compression strength.
“…Another concern regarding weakly-bonded particles is the risk of their loosening after implantation which could pose health problems from ion release in other parts of the body. High concentrations of powder particles (>1x10 5 particles/mL) are known to affect cell viability indicating the need to minimise the quantity of surface-sintered particles [ 71 ]. Figure 12.…”
Current intervertebral fusion devices present multiple complication risks such as a lack of fixation, device migration and subsidence. An emerging solution to these problems is the use of additively manufactured lattice structures that are mechanically compliant and permeable to fluids, thus promoting osseointegration and reducing complication risks. Strut-based diamond and sheet-based gyroid lattice configurations having a pore diameter of 750 µm and levels of porosity of 60, 70 and 80% are designed and manufactured from Ti-6Al-4V alloy using laser powder bed fusion. The resulting structures are CT–scanned, compression tested and subjected to fluid permeability evaluation. The stiffness of both structures (1.9–4.8 GPa) is comparable to that of bone, while their mechanical resistance (52–160 MPa) is greater than that of vertebrae (3–6 MPa), thus decreasing the risks of wither bone or implant failure. The fluid permeability (5–57 × 10
−9
m
2
) and surface-to-volume ratios (~3) of both lattice structures are close to those of vertebrae. This study shows that both types of lattice structures can be produced to suit the application specifications within certain limits imposed by physical and equipment-related constraints, providing potential solutions for reducing the complication rate of spinal devices by offering a better fixation through osseointegration.
“…Because many AM processes (such as EBM and SLM) employ metal powder in the 15-100 µm range, these sizes were selected. In particular, our previous study has found that powder particles in the range of 75-100 µm did not cause changes in the expression of in ammatory factors related to immune cells in vitro [24]. The samples will be referred to as 316L-S, 316L-M, CoCrMo-S, CoCrMo-M, CP-Ti-S, CP-Ti-M, Ti64-S, and Ti64-M, respectively.…”
Section: Preparation and Characterization Of Powder Particlesmentioning
confidence: 99%
“…In addition, the wear particles produced by metal implants during service can activate monocytes and macrophages in granuloma tissue, enhance osteoclast development and activity, inhibit osteoblast activity, and induce bone resorption [22,23]. In our previous studies, it was found that metallic 3D printing powders have more di culty triggering immunological responses than ions/wear particles because of their regular shape, size, and surface chemical composition [24].…”
Background
Residual powder is a defect in powder bed fusion-based additive manufacturing (3D printing), and it is difficult to completely remove it from as-printed materials. In addition, it is not necessary to apply 3D printed implants with residual powder in the clinic. The immunological response triggered by the residual powder is an important area of study in medical research.
Methods
To further understand the possible immunological reactions and hidden dangers caused by residual powders in vivo, this study compared the immunological reactions and osteolysis caused by typical powders for four implant materials: 316L stainless steel, CoCrMo, CP-Ti, and Ti-6Al-4V (particle size range of 15–45 µm), in a mouse skull model. Furthermore, the possible immunological responses and bone regeneration induced by the four 3D printed implants with residual powder in a rat femur model were compared.
Results
In the mouse skull model, it was found that the 316L-S, CoCrMo-S, and especially the 316L-M powders, upregulated the expression of pro-inflammatory factors, increased the ratio of RANKL/OPG, and activated more functional osteoclasts, resulting in more severe bone resorption compared with those in other groups. In the rat femur model, which is more suitable for clinical practice, there is no bone absorption in implants with residual powders, but they show good bone regeneration and integration ability because of their original roughness. The results indicate that the expressions of inflammatory cytokines in all experimental groups were the same as those in the control group, showing good biological safety.
Conclusions
The results answered some critical questions related to additively manufactured medical materials in vivo and indicated that as-printed implants may have great potential in future clinical applications.
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