Next Generation Biomaterials: Metallic, Polymeric, and Ceramic Biomaterials
Sponsored by: MS&T Organization
Program Organizers: R. Narayan, UNC/NCSU Joint Department of Biomedical Engineering; Kalpana Katti, North Dakota State University; Kajal Mallick, University of Warwick; Vilupanur Ravi, California State Polytechnic University, Pomona; Varshni Singh, Louisiana State University
Tuesday 2:00 PM
October 18, 2011
Room: C215
Location: Greater Columbus Convention Center
Session Chair: Vilupanur Ravi , California State Polytechnic University, Pomona ; Rajarshi Banerjee , University of North Texas
2:00 PM Invited
Laser Processed Tantalum: Mechanical, In vitro Wear and Biological Properties: Amit Bandyopadhyay1; Vamsi Balla1; Susmita Bose1; 1Washington State University
Metallic biomaterials currently in use for load-bearing orthopedic applications are bioinert. Recent in vitro and in vivo studies demonstrated that Ta is a promising metal that is bioactive, but its applications have been limited by processing challenges. We report how to process Ta to create net shape porous and dense structures as well as coatings using Laser Engineered Net Shaping (LENS). Porous Ta samples with relative densities between 45 to 73% have been successfully fabricated and characterized for their mechanical properties. In vitro cell materials interactions, using human osteoblast cell line showed six times better biocompatibity than Ti, and comparable to that of HA. In vitro linear reciprocating wear tests on Ta coatings showed one order of magnitude less wear rate compared to Ti. Our results demonstrate that Ta coatings can potentially minimize the early-stage bone-implant interface due to their high wear resistance and toughness compared to popular HA coatings.
2:20 PM Invited
Stability of Boron-Containing Titanium Alloys in Saline and Related Bioreceptor Studies: Vilupanur Ravi1; Shaun Rogers1; Mehnaz Malek1; Daniel Surmenian1; Isaac Priddy1; Ryan Urak1; Steve Alas1; Suresh Divi2; Sesh Tamirisakandala3; Daniel Miracle4; 1California State Polytechnic University, Pomona; 2Titanium Metals Corporation (TIMET); 3FMW Composite Systems Inc; 4Air Force Research Laboratory
Durable bio-implants that can withstand the rigors of the physiological environment and applied mechanical stresses are of continuing interest to the biomaterials community. Titanium alloys are preferred candidates for structural implants. In this talk, we will discuss a new class of titanium alloys with boron additions that significantly increase the specific strength of the base alloys. The effect of boron on mechanical properties and the corrosion behavior of these alloys will be discussed. Open circuit potential and cyclic polarization measurements to determine the corrosion resistance of Ti-6Al-4V-B and Ti-B alloys in 0.9 wt% sodium chloride (saline) solutions will be presented. A mechanism for the corrosion behavior will be discussed and the role of the titanium boride, TiB, phase pointed out. Immune response studies for this system will be touched upon as well.
2:40 PM Invited
Next-Generation Rotary Endodontic Instruments Fabricated from Special NiTi Alloy: William Brantley1; Jie Liu1; William Clark1; Masahiro Iijima2; Libor Kovarik1; Fengyuan Zheng1; Scott Schricker1; Satish Alapati3; John Nusstein1; 1The Ohio State University; 2School of Dentistry, Health Sciences University of Hokkaido; 3University of Illinois at Chicago
Background: Next-generation rotary endodontic instruments with improved clinical performance are being fabricated from special superelastic NiTi wire (termed M-Wire) that has a nanoscale martensitic structure. In this presentation we report etched microstructures, Vickers hardness measurements, and SEM observations of as-manufactured and clinically-used GTŪ Series X™ rotary instruments, with comparisons to rotary instruments fabricated from conventional dental superelastic NiTi alloy. Results: The next-generation NiTi instruments have significantly higher Vickers hardness and much less evidence of clinical wear compared to conventional NiTi instruments. Etched microstructures show a martensitic structure, which is consistent with our previously reported STEM observations. Differential scanning calorimetric analyses have shown that the manufactured instruments have similar phase transformation behavior to starting M-Wire blanks. Conclusions: The properties and clinical performance of the next-generation NiTi rotary instruments arise from their special martensitic structure. More TEM studies are needed to elucidate details of this complex microstructure and effects of clinical use.
3:00 PM Break
3:20 PM Invited
Surface Engineering Approaches for Beta Titanium Alloys Used in Orthopedic Implants (Invited): Peeyush Nandwana1; Soumya Nag1; Sameer Paital1; Thomas Scharf1; Narendra Dahotre1; Rajarshi Banerjee1; 1University of North Texas
Next generation beta-titanium alloys, and wear-resistant boride-reinforced metal-matrix composites coated with a lubricious zinc oxide layer, have been processed using the laser engineered net shaping (LENS™) process coupled with sputter deposition, and their microstructure and properties investigated. Furthermore, with the objective of improving the osseo-integration of these alloys into the femur, coatings based on Ca-P have also been laser deposited on these titanium alloys using a continuous wave Nd:YAG laser induced direct melting of hydroxyapatite (HA) precursor on a titanium alloy substrate. Detailed microstructural investigations (x-ray diffraction, SEM, TEM) revealed the presence of various phases such as HA, CaTiO3, Ca3(PO4)2, TiO2 (anatase) and TiO2 (rutile) as a result of the intermixing between the precursor and substrate material during laser processing. Improvement in vitro bioactivity and in vitro biocompatibility was observed for the laser processed samples as compared to the control samples.
3:40 PM
Biomedical Titanium Alloy with Ultralow Elastic Modulus and High Strength: Yulin Hao1; Shujun li1; Rui Yang1; 1Institute of metal research, chinese academy of sciences
Ti2448 (Ti-24Nb-4Zr-8Sn, wt. %) is a metastable β type titanium alloy developed recently in China for intention of biomedical applications. The alloy possesses good biomechanical compatibility of high strength and ultralow elastic modulus closing to hard tissue of human body as well as biochemical compatibility. Bone plates and spinal fixators made of the Ti2448 alloy have been finished clinical trial and applied for product permission to State Food and Drug Administration, P.R. China. Here reviews briefly the alloy design, peculiar nonlinear elastic and highly localized plastic deformation behavior, mechanical properties varying with processing and heat treatment as well as several kinds of surface modifications to improve bioactivity and the corresponding in-vitro cell tests. The positive effect of elastic matching on healing fractured bone also includes in the talk, as evidences by new bone formation of intramedullary nails implanted in New Zealand white rabbits and bone plates implanted in Beagle dogs.
4:00 PM
Alkoxysilane Mediated Generation of Gold Nanoparticles: Development of Novel Electrocatalytic Materials: Prem Pandey1; Dheeraj Chauhan1; 1Institute of Technology, Banaras Hindu University
A novel approach towards synthesis of gold nanoparticles (AuNps) is described using alkoxysilanes containing organic functionalities. This method involves reduction of metal salt with 3-Glycidoxypropyltrimethoxysilane. 3-Aminopropyltrimethoxysilane is utilized to stabilize the gold salt before the reduction step and to protect and prevent agglomeration of the gold sol after reduction and through gelation, drying and aging steps. Through this method well dispersed AuNps of uniform size were obtained. The Nps are characterized using UV-vis spectroscopy and Atomic force microscopy. The synthesized Nps are utilized in the preparation of thin sol-gel films encapsulating potassium ferricyanide as electron transfer mediator. Electrochemical characterization of these films revealed that the presence of Nps lead to dramatic improvement of electrochemistry of ferricyanide. Futhermore, these films were used to study the electrocatalysis of hydrogen peroxide. It was observed that the present sensor is highly sensitive and showed excellent response towards electrochemical reduction of hydrogen peroxide.