Antimicrobial properties of the Ag, Cu Nanoparticle System

ABSTRACT: Microbes, including bacteria and fungi, easily form stable biofilms on many surfaces. Such biofilms have high resistance to antibiotics, and cause nosocomial and postoperative infections. The antimicrobial and antiviral behaviors of Ag and Cu nanoparticles (NPs) are well known, and possible mechanisms for their actions, such as released ions, reactive oxygen species (ROS), contact killing, the immunostimulatory effect, and others have been proposed. Ag and Cu NPs, and their derivative NPs, have different antimicrobial capacities and cytotoxicities. Factors, such as size, shape and surface treatment, influence their antimicrobial activities. The biomedical application of antimicrobial Ag and Cu NPs involves coating onto substrates, including textiles, polymers, ceramics, and metals. Because Ag and Cu are immiscible, synthetic AgCu nanoalloys have different microstructures, which impact tHeir antimicrobial effects. When mixed, the Combination of Ag and Cu NPs act synergistically, offering substantially enhanced antimicrobial behavior. However, when alloyed in Ag–Cu NPs, the antimicrobial behavior is even more enhanced. The reason for this enhancement is unclear. Here, we discuss these results and the possible behavior mechanisms that underlie them

Natural Coral as a Biomaterial Revisited

ABSTRACT: This paper first describes the state of the art of natural coral. The biocompatibility of different coral species has been reviewed and it has been consistently observed that apart from an initial transient inflammation, the coral shows no signs of intolerance in the short, medium, and long term. Immune rejection of coral implants was not found in any tissue examined. Other studies have shown that coral does not cause uncontrolled calcification of soft tissue and those implants placed under the periosteum are constantly resorbed and replaced by autogenous bone. The available studies show that the coral is not cytotoxic and that it allows cell growth. Thirdly, porosity and gradient of porosity in ceramics is explained based on far from equilibrium thermodynamics. It is known that the bone cross-section from cancellous to cortical bone is non-uniform in porosity and in pore size. Thus, it is hypothesized that a damaged bone containing both cancellous and cortical bone can be better replaced by a graded/gradient porous implant based on the idea of a biomimetic approach. The purpose of this article is to review and summarize all the pertinent work that has been published on natural coral as a bone graft during the last twenty years including in vitro, animal, and clinical human studies. In addition, as an illustration, we report the clinical experience of one of us using coral. It is a case study of complex femoral fracture (Table 1) where the essential role of vascularization and stabilization of the fracture site are underlined. The results are supported with more than 300 other femoral fractures treated using the same modus operandi. Finally, this paper overviews the ecological and ethical concerns around the use of corals as well as discussing briefly about recent impacts of nano-pollutants

BIOMECHANICAL STUDY ON CADAVER KNEE FOR THE EVALUATION OF CRUCIATE KNEE LIGAMENT RECONSTRUCTIONS

INTRODUCTION: Ruptures of the anterior and posterior cruciate knee ligament (ACL and PCL), alone or combined, are some of the most frequent joint injuries, especially in sports. The long-term unsatisfactory results and lack of systematic evaluation of surgical reconstructions have led us to undergo an evaluation on cadaver knees. MATERIAL AND METHOD: A preliminary study was performed on one cadaver knee. The femur was fixed on a holder and magnetic sensors “BirdsTM” were attached to the tibia and the femur, which tracked the knee’s movement. A threedimensional knee analyzer GENI(1) was used to calculate kinematic parameters (tibial internal and external rotation and ab/adduction), as well as ligament combined deformation (elongation / bending / torsion) during knee flexion. This experiment was performed on an intact knee and a knee where the PCL has been cut and reconstructed using a synthetic Trevia ligament. Finally the knee was dissected to produce a combined postero-lateral instability and reconstructed with and without postero-lateral corner reconstruction. The effect of different reconstruction methods on kinematics and ligament deformation were compared. RESULTS AND DISCUSSION: Kinematic parameters changed significantly when PCl and postero-lateral corner were dissected. The reconstruction of the PCL alone, using an “Over-the-Bottom” method described by Krudwig(2), shifted the curves back to the initial situation and decreased the variability of the movement. Ligament deformation was 3 mm elongation, 50o femoral flexion and 90o torsion. These values are in accordance with material properties and should lead to good long-term biofunctionnality. CONCLUSION: This study proposes an in vitro protocol for a better understanding of the clinical success or failure of different procedures. Preliminary results showed that the system and the protocol setup are sensitive to changes in kinematics following posterior cruciate ligament dissection and reconstruction. Experiments are performed at this time on several cadaver knees, in order to compare different reconstruction methods. REFERENCES: Sati, M. et al. (1997). Computer Assisted Knee Surgery: Diagnostics and Planning of Knee Surgery. Computer Aided Surgery 2, 108-123. Krudwig, W. (1997). In L'H. Yahia (Ed.), Ligaments and Ligamentoplasties. Heidelberg: Springer Verlag

The effect of micro-pulsatile electrical and ultrasound stimulation on cellular biosynthetic activities such as cellular proliferation, endogenous nitrogen oxide and collagen synthesis

ABSTRACT: The skin barrier poses an ongoing challenge for the cosmetics industry. Its penetration, by non-invasive means, can readily be achieved with currents and ultrasound or radiofrequency devices through electroporation, sonophoresis, iontophoresis or cavitation. When several types of energy are applied simultaneously, we expect the effects to be magnified and all the more effective. Although the mechanism of action of each technology on the skin is not entirely controlled, and is even less so when multiple technologies are applied concurrently, some studies demonstrate that nitric oxide (NO) plays a pivotal role in skin wound-healing and regeneration. With regard to wound healing, one of the key functions of NO appears to be its permissive effect on keratinocyte and fibroblast proliferation, which helps promote wound re-epithelialization. The objective of the actual research is to gain an in-depth understanding of the mechanisms generated by NO through the application of a specific combination of technologies

Biomimetic Polymer Composites for Orthopedic Implants

Peer reviewed: NoNRC publication: Ye

Effect of ceria on the organization and bio-ability of anatase fullerene-like crystals

The nanostructure and the oxygen storage capacity against reactive oxygen species (ROS) are essential features to take into account during the design of a new material that will be used as the basis of novel therapeutic technologies. Here we evaluate the incorporation of nano-ceria, which has a demonstrated ability to scavenge free radicals under physiological conditions comparable to those observed for superoxide dismutase and catalase, to TiO2 crystalline assemblies. The material was planned to merge the scavenging properties of CeO2 on a specifically designed structured TiO2 substrate. The presence of Ce atoms has a clear influence in the materials' morphologies, distorting anatase crystal lattice and inducing the formation of fullerene-like structures. The cytotoxicity of the materials against L929 fibroblasts after 24 hours of cell culture was evaluated. Both structural and oxidative properties of the materials have a clear effect on fibroblast viability; in fact it was demonstrated that cellular proliferation can be modulated varying the Ce3+/Ti4+ molar ratio.Fil: Gravina, Noel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Ruso, Juan Manuel. Universidad de Santiago de Compostela; EspañaFil: Mbeh, Doris Antoinette. École Polytechnique De Montréal; CanadáFil: Yahia, L'Hocine. École Polytechnique De Montréal; CanadáFil: Merhi Yahye. University Of Montreal; CanadáFil: Sartuqui, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Messina, Paula Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentin

Washing effect on superparamagnetic iron oxide nanoparticles

Much recent research on nanoparticles has occurred in the biomedical area, particularly in the area of superparamagnetic iron oxide nanoparticles (SPIONs); one such area of research is in their use as magnetically directed prodrugs. It has been reported that nanoscale materials exhibit properties different from those of materials in bulk or on a macro scale [1]. Further, an understanding of the batch-to-batch reproducibility and uniformity of the SPION surface is essential to ensure safe biological applications, as noted in the accompanying article [2], because the surface is the first layer that affects the biological response of the human body. Here, we consider a comparison of the surface chemistries of a batch of SPIONs, before and after the supposedly gentle process of dialysis in water

Comparative study from a chemical perspective of two- and three-step disinfection techniques to control Clostridium difficile spores

ABSTRACT: Around the world, the presence of Clostridium difficile in hospital environments remains a great concern. To control the spread of this Gram-positive bacterium requires a better understanding of the various chemical interactions between the components of the bacterium and the surfaces to be cleaned. The objective of the present study was to compare, from a chemical perspective, two surface disinfection techniques and the use of two dilutions (1/20 and 1/10) of a 5% sodium hypochlorite solution. The following two cleaning-disinfection procedures were used: first, a two-step technique consisting of the use of a detergent-disinfectant (thirdgeneration quaternary ammonium) followed by 5% household sodium hypochlorite; and second, a three-step technique consisting of the above steps plus a water rinse step between the detergent-disinfectant step and the disinfection product step. The results of the study show that the three-step technique with a 1/10 dilution of 5% sodium hypochlorite solution creates a chemical environment that provides greater disinfection potential compared to the two-step technique

Biomimetic Polymer Composites for Orthopedic Implants

Peer reviewed: YesNRC publication: Ye