Background: The presence of skin problems in patients using external lower limb prosthesis is recurrent. This has generated the need to develop interfaces for prosthesis with the ability to control microbial growth. Silver nanoparticles (AgNPs) have been implemented in the development of biomaterials because of their high antimicrobial activity. This article discusses the development of an AgNP-containing polymer composite with antimicrobial activity for developing prosthetic liners. Methods: AgNPs were synthesized using a photochemical method and certain physicochemical properties were characterized. Furthermore, the antimicrobial activity of AgNPs against Staphylococcus aureus ATCC 25923 and methicillin-resistant Staphylococcus aureus (MRSA), was assessed on the basis of their minimum inhibitory concentrations (MICs). AgNPs were incorporated into a silicon elastomer to assess certain physicomechanical properties, antimicrobial activity and cytotoxic effect of the material. Results: The maximum antimicrobial activity of the material against Staphylococcus aureus ATCC 25923 and MRSA was 41.58% ±2.97% at AgNP concentration of 32.98 μg/mL and 14.85% ±5.94% at AgNP concentration of 16.49 μg/mL, respectively. Additionally, the material exhibited tensile yield strength, rupture tensile strength, and tensile modulus of elasticity of 0.70-1.10 MPa, 0.71-1.06 MPa, and 0.20-0.30 MPa, respectively. The mechanical characteristics of the material were within the acceptable range for use in external lower limb prosthetic and orthotic interfaces. Conclusions: It was possible to incorporate the AgNPs in a silicone elastomer, finding that the composite developed presented antimicrobial activity against Staphylococcus aureus ATCC 25923 and MRSA when compared to non-AgNP material samples.

Depth sensing indentation study was conducted in a Fischerscope H100V machine, equipped with a Vickers indenter with a tip roundness of approximately 1330 nm. Tests were carried out on soda-lime glass, fused silica, sapphire, aluminum (1100 alloy), high alloyed steel, titanium and copper. The widely used iterative method of Oliver and Pharr was unsuccessful in the attempts to analyze machine compliance and indenter area function. Therefore, an alternative procedure was adopted. The alternative procedure is based on the ratio between maximum load and unload stiffness squared, Pm/Su². It was found that this procedure, which is not iterative, gives good results. A careful study of the Pm/Su² ratio, lead us to conclude that the Fischercope machine has a low compliance which depends on the sample mounting. This low compliance in conjunction with the recent discovery of the dependence of beta factor on the tip roundness/maximum depth ratio, which appears in the relation between contact stiffness and contact area, explains why the iterative method does not converge. However, variations in beta and machine compliance produces deviation on the hardness and elastic modulus lower that 6% with respect to expected values for the materials and the machine studied in this work

RESUMENEl cuidado del medioambiente y el uso responsable de los recursos, ha promovido investigaciones con diferentes biopolímeros que permitan el desarrollo de nuevos materiales que puedan ser empleados en empaques para alimentos. Entre estos biopolímeros se encuentra la fibroína de seda (FS), que representa cerca del 70% de la fibra de seda y puede ser obtenida a partir de capullos de primera calidad o de los desperdicios generados en la producción serícola. En el desarrollo de empaques de alimentos con FS, se pueden dar dos alternativas de producción, una en la que la FS puede ser funcionalizada por otros componentes, y otra en la que se incluye la FS como componente funcional modificando otros biopolímeros. La FS puede conferirle al material de empaque ciertas propiedades, como: aumento de la permeabilidad de oxígeno, resistencia a la rotura y una mayor velocidad de degradación del biopolímero. Este artículo se centra en cuatro temas principales: empaques, biopolímeros en empaques, FS y finalmente, la FS en empaques para alimentos.Palabras clave: Empaques, Materiales poliméricos, Biopolímeros, Fibroína de seda, Biomateriales. ABSTRACTEnvironmental protection and responsible use of resources, have promoted research of different biopolymers allowing to develop biodegradable materials which can be used in food packaging. Among these biopolymers is silk fibroin (SF), this protein represents nearly 70% of the silk fiber and it can be obtained from high quality cocoons or from waste generated in the silk industry. In the development of food packaging with SF, there are two possible alternative of production, one in what the SF can be functionalized by other components and another in which, the FS is included as functional component modifying other biopolymers. In the case of food packaging, the SF can concede desirable properties to the package such as an increase in oxygen permeability, more tensile strength and a higher biopolymer degradation rate. This paper is focused on four main topics: packaging, biopolymers in packaging, SF and finally, the SF in food packaging.

Background:The presence of skin problems in patients using external lower limb prosthesis is recurrent. This has generated the need to develop interfaces for prosthesis with the ability to control microbial growth. Silver nanoparticles (AgNPs) have been implemented in the development of biomaterials because of their high antimicrobial activity. This article discusses the development of an AgNP-containing polymer composite with antimicrobial activity for developing prosthetic liners. Methods:AgNPs were synthesized using a photochemical method and certain physicochemical properties were characterized. Furthermore, the antimicrobial activity of AgNPs against Staphylococcus aureus ATCC 25923 and, methicillin-resistant Staphylococcus aureus (MRSA), was assessed on the basis of their minimum inhibitory concentrations (MICs). AgNPs were incorporated into a silicon elastomer to assess antimicrobial activity and certain mechanical properties of the material. Results: The maximum antimicrobial activity of the material against Staphylococcus aureus ATCC 25923 and MRSA was 41.58 % ± 2.97 % at an AgNP concentration of 32.98 μg/mL and 14.85 % ± 5.94 % at an AgNP concentration of 16.49 μg/mL, respectively. Additionally, the material exhibited tensile yield strength, rupture tensile strength, and tensile modulus of elasticity of 0.70 - 1.10, 0.71–1.06, and 0.20 - 0.30 MPa, respectively. The mechanical characteristics of the material were within the acceptable range for use in external lower limb prosthetic and orthotic interfaces. Conclusions:It was possible to incorporate the AgNPs in a silicone elastomer, finding that the composite developed presented antimicrobial activity against Staphylococcus aureus ATCC 25923 and MRSA when compared to non-AgNP material samples.