Pan American Materials Congress: Advanced Biomaterials: Antibacterial and Nanostructured Materials
Sponsored by: Third Pan American Materials Congress Organizing Committee
Program Organizers: Carlos Elias, Instituto Militar de Engenharia; Wen Yang, University of California, San Diego

Thursday 8:30 AM
March 2, 2017
Room: Mission Hills
Location: Marriott Marquis Hotel

Session Chair: Xiaodong Li, University of Virginia; Pablo Zavattieri, Purdue University

8:30 AM  Cancelled
Carboxyl-functionalized Zinc Oxide Nanoparticles and Its Antiproliferative Effect in Cervical Cell Lines: Lisbeth Almeida-Ramón1; Mayra Alvarez-Lemus1; Erick De la Cruz Hernández1; Rosendo López-González1; Gilberto Torres-Torres1; Socorro Oros-Ruíz2; Patricia Quintana-Owen3; 1Juarez Autonomous University of Tabasco; 2Autonomous Metropolitan University-Iztapalapa; 3CINVESTAV-Merida
    Zinc oxide (ZnO) nanoparticles were prepared using zinc (II) acetylacetonate and ammonium or sodium hydroxide as catalyst. The materials were modified with acetic acid and ascorbic acid and later characterized by FTIR, SEM, DLS and Nitrogen adsorption. Particle sizes between 100-500 nm were obtained, and ammonia hydroxide directed to the formation of hexagonal nanotubes whereas nanorods were formed when sodium hydroxide was used. Cell viability was evaluated with mononuclear cells extracted from normal individuals using 10, 15 and 20 µg/mL of nanoparticles and no significant effect was observed since viability for all tested concentrations was above 90%. The nanoparticles were incubated for 48 h with HeLa and SiHa cells, XTT assay was performed and for Ascorbic-ZnO cell viability in HeLa cells decreased to 30% whereas Acetic-ZnO reached 20% in SiHa cell line. In order to elucidate the mechanism p53 expression, bax activation and apoptosis were also evaluated.

9:00 AM  
Investigation on Passive Film Structure and Antibacterial Property of 316L Stainless Steel by Cu-added Nitric Acid Passivation Treatment: Jin-Long Zhao1; Da-Ke Xu1; Xin-Rui Zhang1; Chunguang Yang1; Ke Yang1; 1Institute of Metal Research, Chinese Academy of Sciences
    Surface passivation using nitric acid solution is a traditional way to improve corrosion resistance of stainless steel. In this work, we added different concentration of Cu-bearing ion solution into nitric acid, and Cu deposition behavior was further investigated by adjusting different passivation parameters. Based on the point defect model, the nucleation mechanism of passive film, film thickness, the diffusivity and density of the defects within the passive film were characterized by using the current-time transient, EIS and Mott-Schottky analysis. XPS was employed to analyze the chemical composition and valance distribution of Cu-bearing passive film. Antibacterial performance testing was performed by live-dead cell staining method. The biocompatibility test was also used to evaluate the biosafety of passivated 316L stainless steels. This work would help in building the corresponding relation of passive film structure and antibacterial property as well as to clarify the antibacterial mechanism of Cu ion in stainless steel.

9:20 AM  
An Experimental Study on 304L Cu-bearing Antibacterial Stainless Steel for Its Integrated Performance Optimization as a Versatile Biomaterial: M. Babar Shahzad1; Tong Xi1; Chunguang Yang1; Ke Yang1; 1Institute of Metal Research, Chinese Academy of Sciences
    The novel concept of antibacterial metals has been in spotlight in recent years, owing to unimpeded efforts to overcome certain barriers to pave its way from laboratory scope to diverse commercial applications. Bio-functioning of 304L stainless steel (SS) concept rely on its alloying with copper element and appropriate heat treatment to endow it superb antibacterial property. We devised a systemic experimental optimization for Cu-bearing 304L SS to optimize Cu-content, aging temperature and aging time to integrate its intrinsic metallic properties, corrosion resistance and antibacterial performance. A range of techniques were employed for experimental characterization, while in-depth analysis and discussion is provided to find the role and effects of Cu-content, aging temperature and time on Cu-precipitation behavior, Cu ion-release, corrosion properties and antibacterial mechanism to refine the integrated performance of Cu-bearing 304L SS. These results would provide a profound base for design and applications of 304L SS as a functional biomaterial.

9:40 AM  
Effects of Dialium Guineense Based Zinc Nanoparticle Material on the Inhibition of Microbes Inducing Microbiologically Influenced Corrosion: Joshua Okeniyi1; Gbadebo John1; Taiwo Owoeye1; Elizabeth Okeniyi1; Deborah Akinlabu1; Olugbenga Taiwo1; Olufisayo Awotoye1; Ojo Ige1; Yemisi Obafemi1; 1Covenant University, Ota, Nigeria
    This paper investigates the effects of Dialium guineense based zinc nanoparticle material on the inhibition of microbes inducing microbiologically influenced corrosion (MIC) in metals. Extract of leaf from the natural plant were used as precursor for zinc nanoparticle material, which was characterized by scanning electron microscopy and energy dispersive spectroscopy (SEM+EDS) instrument. Sensitivity of the developed zinc bio-nanoparticle material from this on different strains of microbes that are known to induce microbiological influenced corrosion, in metallic materials, was then studied and compared with that obtained from a commercial antibiotic employed as control. Results showed that the biomaterial based nanoparticle exhibited inhibited growth of the studied different MIC inducing microbes. Zones of inhibition, the sensitivity measure of the biosynthesized material against the microbial strains either surpassed or compared well with the zones of inhibition from the commercial antibiotic (control). These results engender implication on the prospects of the zinc bio-nanoparticle usages in corrosion inhibition and protection system for metals in microbial corrosion influencing environment.

10:00 AM  Cancelled
Evaluation of Doped SiO2-TiO2 Nanoparticles as Possible Agents in Photodynamic Therapy: Rosendo López González1; Mayra Alvarez Lemus1; Jose de la Rosa Vázquez2; Erick De la Cruz Hernández1; Dora Frías Marquez1; 1Juarez Autonomous University of Tabasco; 2ESIME
    In photodynamic therapy (PDT) most of the photosensitizers are classified as porphyrins and non-porphyrins but this trend has been changed year after year. The use of inorganic nanoparticles increase the possibility to find the ideal material for PDT. The nanostructured TiO2-SiO2 synthesized by the sol-gel method allows the modification of its physicochemical properties to enhance its reactivity under irradiation. The respective materials were characterized by spectroscopic, textural and structural techniques. In the present research is showed the photoreactivity of doped TiO2-SiO2 nanomaterials toward the degradation of pyrimidines (thymine and uracil) which are components in epithelial zones. The photodegradation results shown an effectively of 98% under low uv irradiation (2 mW/cm2). Additionally the nanomaterials were evaluated in destruction of B16F0 melanoma cells (mice) in combination effect of OH radicals and reactive oxygen species under different irradiation wavelengths (390, 450, 520 and 620 nm), results are presented.

10:20 AM Break

10:35 AM  Invited
Laser Based 3d Printing of Biomaterials: Roger Narayan1; 1UNC/NCSU Joint Department of Biomedical Engineering
    Laser-based techniques such as two photon polymerization, stereolithography, excimer laser-based direct writing and have been used to create structures with microscale and nanoscale features for medical applications. For example, two photon polymerization involves use of a femtosecond laser to selectively polymerize and harden photosensitive resins. Polymerization takes place at locations in the photosensitive resin where the excitation threshold of the photoinitiator is exceeded. 3d printing of structures containing nanoscale features is possible due to the fact that two photon absorption has a nonlinear relationship with incident light intensity. Two photon polymerization has been used to create structures out of photosensitive polymers, zirconium oxide hybrid materials, and organically-modified ceramic materials. Several types of medically-relevant surfaces, such as tissue engineering scaffolds, sensors, and drug delivery devices, have been prepared using two photon polymerization. In this talk, biological and functional evaluation of 3d-printed structures will be considered.

11:00 AM  Invited
Nature’s Multiscale Design and Additive Manufacturing: Xiaodong Li1; 1University of Virginia
    Recent discoveries in seashells unveil that nature uses multiscale design strategies to achieve exceptional mechanical properties which are still beyond the reach of many engineering materials. The multiscale hierarchical structure, ranging from micro lamellae down to nanoparticles, renders seashells multilevel strengthening and toughening mechanisms such as crack deflection, interlocking, lamellae’s deformability, biopolymer’s viscosity, nanoparticle rotation, deformation twining in nanoparticles, and amorphization, jointly contributing to seashell’s ultra-high mechanical robustness. To realize nature’s performance in engineering materials, we need to use nature’s multiscale design and manufacturing strategies. This talk will present several case studies in which nature’s multiscale design strategies and materials selection principles are applied through manufacturing.

11:25 AM  
Miniaturization of Medical Implants Made from Nanostructured Metals: Alexander Polyakov1; Irina Semenova2; Georgy Raab2; Evgeny Parfenov2; Ruslan Valiev1; 1Laboratory for Mechanics of Bulk Nanomaterials, Saint Petersburg State University; 2Ufa State Aviation Technical University
    Nanostructured metals (Ti and Ti alloys, stainless steels, Mg alloys) with enhanced static and fatigue strengths are promising materials for medical implants. The use of a combined severe plastic deformation (SPD) processing, including the new equal channel angular pressing (ECAP)-Conform technique leads to significant strengthening of metallic rods due to material nanostructuring. In particular, the use of nanoTi rods with enhanced strength and fatigue life have enabled the fabrication of implants with improved design for dentistry and orthopaedics. Miniaturized dental implants and nanoTi plates with reduced thickness were manufactured and successfully tested in clinical trials.

11:50 AM  
Mechanical Properties and Biocompatibility of Nanostructured Titanium: Carlos Elias1; Daniel Fernandes1; Jochen Roestel2; 1Instituto Militar de Engenharia; 2Conexao Sistemas e Protese
    The selection of materials for medical devices is based on their mechanical properties, chemical composition and biocompatibility. Currently, dental implant manufacturers use cp Ti (G2 and G4) and titanium alloys (G5). Ti G5 and cp Ti have limitations for this application, due the possibility of toxic ion release (Al and V) and lower mechanical strength of cpTi. The purpose of this work was to compare mechanical and clinical properties of a nanostructured cp Ti G4 (nanoTi) with those of available cp Ti G2, G4 and Ti G5 alloys. Tensile, compression, hardness and torque testing were performed. The results showed that nanoTi is stronger than Ti G2, G4 and G5. The clinical performances of Ti G4 and Ti Hard were similar. Ti G5 can be safely replaced by nanoTi without compromising the fracture resistance and biocompatibility, with the advantage of not releasing toxic ions.