Copper as an alternative antimicrobial coating for implants - An in vitro study

Periprosthetic infection (PPI) is a devastating complication in joint replacement surgery. On the background of an aging population, the number of joint replacements and associated complications is expected to increase. The capability for biofilm formation and the increasing resistance of different microbes to antibiotics have complicated the treatment of PPI, requiring the need for the development of alternative treatment options. The bactericidal effect of the naturally occurring amino alcohol sphingosine has already been reported. In our study, we demonstrate the antimicrobial efficacy of sphingosine on three different strains of biofilm producing Staphylococcus epidermidis, representing one of the most frequent microbes involved in PPI. In an in vitro analysis, sphingosine’s capability for prevention and treatment of biofilm-contamination on different common orthopedic implant surfaces was tested. Coating titanium implant samples with sphingosine not only prevented implant contamination but also revealed a significant reduction of biofilm formation on the implant surfaces by 99.942%. When testing the antimicrobial efficacy of sphingosine on sessile biofilm-grown Staphylococcus epidermidis, sphingosine solution was capable to eliminate 99.999% of the bacteria on the different implant surfaces, i.e., titanium, steel, and polymethylmethacrylate. This study provides evidence on the antimicrobial efficacy of sphingosine for both planktonic and sessile biofilm-grown Staphylococcus epidermidis on contaminated orthopedic implants. Sphingosine may provide an effective and cheap treatment option for prevention and reduction of infections in joint replacement surgery.Key messages• Here we established a novel technology for prevention of implant colonization by sphingosine-coating of orthopedic implant materials.• Sphingosine-coating of orthopedic implants prevented bacterial colonization and significantly reduced biofilm formation on implant surfaces by 99.942%.• Moreover, sphingosine solution was capable to eliminate 99.999% of sessile biofilm-grown Staphylococcus epidermidis on different orthopedic implant surfaces.

Metal ion release from TiN coated CoCrMo orthopedic implant material

The successful application of a nanostructured biomaterial as an implant is strongly determined by the nanotopography size triggering the ideal cell response. Here, nanoporous topography on 304L stainless steel substrates was engineered to identify the nanotopography size causing a transition in the cellular characteristics, and accordingly, the design of nanostructured stainless steel surface as orthopedic implants is proposed. A variety of nanopore diameters ranging from 100 to 220 nm were fabricated by one-step electrolysis process and collectively referred to as artificial microenvironments. Control over the nanopore diameter was achieved by varying bias voltage. MG63 osteoblasts were cultured on the nanoporous surfaces for different days. Immunofluorescence (IF) and scanning electron microscopy (SEM) were performed to compare the modulation in cell morphologies and characteristics. Osteoblasts displayed differential growth parameters and distinct transition in cell behavior after nanopore reached a certain diameter. Nanopores with 100-nm diameter promoted cell growth, focal adhesions, cell area, viability, vinculin-stained area, calcium mineralization, and alkaline phosphatase activity. The ability of these nanoporous substrates to differentially modulate the cell behavior and assist in identifying the transition step will be beneficial to biomedical engineers to develop superior implant geometries, triggering an ideal cell response at the cell-nanotopography interface.

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We have synthesized two-dimensional carbon nanoparticles by oxidative unfolding of C60 fullerene and demonstrated that the selective sensitivity of this material to the presence of Cu2+ and Pb2+, resulting in variations of the fluorescence intensity and optical absorbance, is related to nanoparticle aggregation processes. This mechanism occurs through coordination of the metal ions and, above a certain ion concentration, leads to precipitation of the carbon material that reduces the metal content in solution. The effect has been characterized by optical measurements while Atomic Absorption Spectroscopy have been carried out for a precise assessment of the real ion concentration in solution.We have synthesized two-dimensional carbon nanoparticles by oxidative unfolding of C60 fullerene and demonstrated that the selective sensitivity of this material to the presence of Cu2+ and Pb2+, resulting in variations of the fluorescence intensity and optical absorbance, is related to nanoparticle aggregation processes. This mechanism occurs through coordination of the metal ions and, above a certain ion concentration, leads to precipitation of the carbon material that reduces the metal content in solution. The effect has been characterized by optical measurements while Atomic Absorption Spectroscopy have been carried out for a precise assessment of the real ion concentration in solution.

Implant is widely used to correct deformation, to stabilize fracture site, and promote bone healing in several orthopaedic surgeries. The use of implant is usually having a higher risk of developing infection. Although the use of antibiotic prophylaxis and antimicrobial impregnated biomaterial are used in cases of surgeries. But, the emerging superbugs which resistant to antibiotics, biofilms formation, and chronic immune suppressing diseases and lifestyles are challenging issues to make good osteosynthesis. Author use orthopaedic implant related infection to explain about the infection associated with the use of orthopaedic implants. This article attempts to discuss about infection associated with orthopaedic implant surgeries and treatment possible to treat the infection during implant placement.

Technique and equipment of physical vapor deposition (PVD) thin films on ceramic powders for thermal spraying technologies are developed. Alumina powders coated metal thin films were used for plasma spraying. Deposition of two-layer films on the powder particles was carried out. The first layer was titanium and the second layer was aluminum or copper. The titanium as adhesively-active element capable of wet alumina is necessary for increase the adhesion strength vacuum films. Effect of PVD process conditions on the concentration of titanium, aluminum and copper ions in the metallic plasma flow was studied. Suggested are the relationships allowing determination of time, required to attain the preset temperature on the powder particle surface and to produce a metallic film of the required thickness.

Surface modification of titanium-based orthopedic implants has been investigated over the last decades to promote better bone-to-implant association, osseointegration, and fracture healing. Yet, post-surgical failure of coated orthopedic implants occurs due to poor adhesive strength, fatigue failure, high wear rate of coated materials, low biocompatibility, limited osseointegration, and stress-shielding effect. Therefore, there is an unmet clinical need to develop a smart coating strategy. Herein, we have created an electrospun nanofibrous coating for Ti-implants using piezoelectric Polyvinylidene fluoride (PVDF) polymer reinforced with osteoconductive nanofiller Zinc oxide (ZnO). We have found that by varying the ZnO content from 0.5 to 2.0 wt.% in the PVDF matrix, we can modulate the electrospun coating's mechanical, thermal, physicochemical stability, and piezoelectric characteristics. Our results proved that PVDF-ZnO nanofibrous coatings exhibit almost ~3-4 fold increase in the piezoelectric d33 coefficient as well as output voltage, compared to pure PVDF using Piezo-responsive Force Microscopy (PFM). Furthermore, electrically poled piezoelectric PVDF-ZnO nanofibers also demonstrated a significant increment (~5-fold) in collagen deposition, hydroxyapatite formation, and improved bio- and hemo-compatibility compared to unpoled nanofibers. Furthermore, through the invitro experiments, we have confirmed that the piezoelectric PVDF-ZnO nanofibrous activates calcium-calmodulin mediated cellular pathway to induce cell adhesion, proliferation, and cell spreading in the osteoblast cells. Nonetheless, using the biomimetic mechanical bioreactor, we have investigated the piezoelectricity-mediated increased focal adhesion and enhanced F-actin production under the physiologically relevant (i.e., 1%) mechanical strain in bone cells. Moreover, the current study elucidates the piezoelectric-based smart, multifunctional coating strategies for developing an osteoconductive implant.

Physical vapor deposition (PVD) coating is a versatile and well-liked method for depositing thin films of materials onto surfaces in a range of industries. Due to their numerous functional and aesthetic benefits, PVD coatings are beneficial in several applications, from electronics and optics to automotive and medical equipment. PVD coating technology dramatically improves the effectiveness and quality of medical implants. PVD-coated medical implants improve osseointegration, lower wear and friction, increase corrosion resistance, and have antibacterial properties, which lead to better patient outcomes, fewer complications, and overall higher quality of life for people who need implantable medical devices. The essential concepts of PVD coating and the numerous deposition techniques and materials used are covered at the study's outset. The specific uses of PVD-coated medical implants are then highlighted, including those for orthopedic and dental implants and cardiovascular and neurosurgical devices. The review also emphasizes the critical contribution of PVD coatings to reducing wear and friction, improving corrosion resistance, augmenting biocompatibility, enhancing osseointegration, and aesthetic appeal. The challenges and prospects of PVD coating technologies were further addressed in this article. This review is invaluable for academics, doctors, and businesspeople interested in the beneficial combination of PVD coating and medical implantology.

Candida biofilm is difficult to control due to the poor penetration and unspecificity of antifungal drugs against the microorganisms associated with this structure. Nanoparticles have been investigated for their antimicrobial potential. In this context, the present study evaluated the antibiofilm activity of silver nanoparticle colloids (AgNPs) against candida isolated from the oral cavity. AgNPs were prepared in two different ethanolic syntheses - without and with ammonium hydroxide: AgNP-1 and AgNP-2, respectively. AgNPs were characterized by atomic absorption spectroscopy (AAS), UV-visible (UV-vis) absorption electron spectroscopy, zeta potential, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Subsequently, they were evaluated against biofilm formation by clinical isolates of Candida albicans and Candida krusei by determining the minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and minimum biofilm formation inhibitory concentration (MBIC50). AgNPs inhibited biofilm formation of tested C. albicans and C. krusei and showed antibiofilm activity at subinhibitory concentrations against all yeasts. AgNP-1 inhibited biofilm formation at concentrations between 7.55 and 60.46 µg/mL and AgNP-2 between 7.71 and 30.80 µg/mL. The characterization of AgNP showed that AgNP-1 and AgNP-2 differ mainly in size and dispersion, with AgNP-2 being monodisperse, indicating that these characteristics could be related to the activity against the formation of C. albicans and C. krusei biofilm, and the silver nanoparticles may represent innovative and complementary alternatives to the available antifungal arsenal.

Preliminary in vitro experiments revealed that wollastonite (CaSiO3) is a potentially highly bioactive material that forms a hyroxyapatite (HA) surface layer on exposure to simulated body fluid with an ion concentration, pH and temperature virtually identical with those of human blood plasma. The formation of the HA layer is an essential requirement for an artificial material to be used as bioactive bone substitute. This finding opens up a wide field for biomedical applications of wollastonite. Biomaterials used as implants in the human body require strict control of trace elements and of the toxic species specified in American Society for Testing and Materials F-1185-88 (As, Cd, Hg and Pb) in ceramic hydroxyapatite for surgical implantation. In this work, two types of pseudowollastonite, the high temperature form of wollastonite, were analysed by using cold vapour atomic absorption spectrometry and hydride generation atomic absorption spectrometry, in order to determine the elements stated in the above-mentioned norm, and inductively coupled plasma atomic emission spectrometry to establish the SiO2/CaO ratio of the two materials and analyse for all other impurities introduced by the raw materials and by the processes of synthesis, sintering and grinding. Barium and Mg were especially prominent in raw materials, and Zr, Y, Mg, W, Co and Ni come mainly from the processing.

Contamination at the surface of the insulator becomes a serious problem. Especially for the tropical area, humidity and rainfall play an important role in wetness by the water at the insulator surface, which result in the presence of contaminant and leakage current flowing at the surface. This leakage current will generate heat which occurs at the surface of an insulator. This ultimately leads to flashover. This paper presents the influence of contaminants to leakage current and formation of electrical tracking at the surface of epoxy resin compound wit silicon rubber. The test was based on IPT method with NH4Cl as contaminants. The industrial and coastal contaminants are used to explain the effect of contaminant at surface tracking process. The flow rate of contaminant was 0.3 ml/min. The 3.5 kV AC high voltage 50 Hz was applied to the top electrodes. It is found that industrial contamination resulting in the smallest surface leakage current is 327.6 mA. Also it is found that coastal contaminant showed the severest damage at surface of test sample. Therefore, special treatment of the sample is needed under these conditions so that the material performance can be improved, especially against the electrical tracking.

The effects of fire retardants paint on combustion properties of fir (Abies bornmulleriana M.) were examined. For this purpose, fire retardants paint were applied on the surface of test sample according to company’s suggestions. The combustion test was performed according to the ASTM-E 69 standard. The mass reduction, release of gasses (CO, NO, O 2 ), and temperature differences of samples were determined for each 30 seconds during combustion. It was observed that the highest mass reduction occurred in fir wood with fire retardant paint.

In this contribution we present a new method detecting changes in the composite material's acoustic behavior by analyzing disturbed coincidence conditions on plate-like test samples. The coincidence condition for an undamaged GFRP test sample has been experimentally identified using Schlieren measurements. Disturbances of this condition follow from a disturbed acoustic behavior of the test sample which is an indicator for local damages in the region inspected. An experimental probe has been realized consisting of two piezoceramic elements adhered to the nonparallel sides of an isosceles trapezoidal body made of silicone. The base angles of the trapezoidal body have been chosen such that the incident wave meets pre-measured condition of coincidence. The receiving element receives the geometric reflection of the acoustic wave scattered at the test sample's surface which corresponds to the non-coupled part of the incident wave as send by the sending element. Analyzing the transfer function or impulse response of the electro-acoustic system (transmitter, scattering at test sample, receiver), it is possible to detect local disturbances with respect to Cramer's coincidence rule. Thus, it is possible to realize a very simple probe for local ultrasonic nondestructive testing of composite materials (as well as non-composite material) which can be integrated in a small practical device and is good for small size inspection areas.

Machined surface quality and integrity affect the corrosion performance of AZ31 magnesium composites. These novel materials are preferred for temporary orthopedic and vascular implants. In this paper, the drilling performance of AZ31-magnesium reinforced with hollow alumina microsphere syntactic foam under LN2 cryogenic, dry, and Almag® Oil is presented. Cutting tests were conducted using TiAlN physical vapor deposition (PVD) coated multilayer carbide and K10 uncoated carbide twist drills. AZ31 magnesium matrices were reinforced with hollow alumina ceramic microspheres with varying volume fractions (5%, 10%, 15%) and average bubble sizes. Experimental results showed that the drilling thrust forces increased by 250% with increasing feed rate (0.05 to 0.6 mm/tooth) and 46% with the increasing volume fraction of alumina microspheres (5% to 15%). Cryogenic machining generated 45% higher thrust forces compared to dry and wet machining. The higher the volume fraction and the finer the average size of hollow microspheres, the higher were the thrust forces. Cryogenic machining (0.42 µm) produced a 75% improvement in surface roughness (Ra) values compared to wet machining (1.84 µm) with minimal subsurface machining-induced defects. Surface quality deteriorated by 129% with an increasing volume fraction of alumina microspheres (0.61 µm to 1.4 µm). Burr height reduction of 53% was achieved with cryogenic machining (60 µm) compared to dry machining (130 µm). Overall, compared to dry and wet machining methods, cryogenic drilling can be employed for the machining of AZ31 magnesium syntactic foams to achieve good surface quality and integrity.