Biodegradable Materials for Medical Applications II: Polymers and Ceramics
Sponsored by: TMS Functional Materials Division, TMS: Biomaterials Committee
Program Organizers: Jaroslaw Drelich, Michigan Technological University; Ehsan Mostaed, Michigan Technological University; Malgorzata Sikora-Jasinska, Michigan Technological University; Jan-Marten Seitz, Syntellix AG; Petra Maier, University of Applied Sciences Stralsund; Norbert Hort, Helmholtz-Zentrum Hereon; Huinan Liu, University Of California Riverside
Tuesday 8:30 AM
February 25, 2020
Room: Vista
Location: Marriott Marquis Hotel
Session Chair: Huinan Liu, University of California at Riverside; Jaroslaw Drelich, Michigan Technological University
8:30 AM Keynote
Fixing Broken Hearts:
Biodegradable Cardiovascular Implants: Subbu Venkatraman1; 1Nanyang Technological University
Implants are used for both opening up and closing cardiovascular vessels or defects. A stent is used for reopening clogged arteries, while an occluder is employed for patching up a defect or hole. Historically, such implants have been made of biostable materials; however, the implants are not needed after performing their intended function, and can be a liability when present permanently. This highlights the need for biodegradable versions of these devices. In our laboratory, we have developed fully-resorbable stents for ureteric, tracheal and peripheral vasculature/ coronary artery applications. I will describe the materials evaluated and the state of its development.Our experience with the resorbable stent led to other cardiovascular applications such as closure of atrial septal defects (ASD) or patent foramen ovale (PFO). For this application (temporary occlusion), two major designs were developed and tested, and will be described in terms of their performance in vitro and in vivo.
9:05 AM
3D-printed Nanocomposites for Bone Repair: Chaoxing Zhang1; Catherine Seo2; Changlu Xu2; Jiajia Lin2; Edgar Villafana2; Hector Jimenez2; Huinan Liu2; 1University of California at Riverside ; 2University of California at Riverside
Biodegradable polyesters such as polycaprolactone (PCL) have been actively studied as tissue engineering scaffolds for decades. The composite scaffolds that consist of polyesters and nano-ceramic phases such as hydroxyapatite (HA), have shown improved mechanical strength and bioactivity. However, infections and unwanted inflammation still occur. Incorporation of nano-sized magnesium oxide (MgO) as an additional phase to PCL/HA can induce antibacterial properties and further improve bioactivity. In this study, PCL-based nanocomposite scaffolds with 0-20 wt.% of HA and 0-1 wt.% MgO were 3D-printed and characterized. To evaluate the cytocompatibility of each scaffold in vitro, a direct cell culture study with bone marrow-derived stem cells (BMSCs) was completed and analyzed. Two triphasic nanocomposites, PCL with 9 wt.% HA and 1 wt.% MgO and PCL with 19 wt.% HA and 1 wt.% MgO showed the best cell adhesion and proliferation, offering promising results for serving as 3D scaffolds for bone regeneration.
9:25 AM
Corrosion Products of Zinc Implant Degradation Suppress Neointimal Hyperplasia: Roger Guillory1; Timothy Kolesar1; Jaroslaw Drelich1; Jeremy Goldman1; 1Michigan Technological University
Zinc-based materials are emerging as promising degradable metals for arterial stenting. While most in vivo investigations of degradable materials focus on implant degradation behavior and macro tissue responses, few have explored the interactions between intracellular signaling molecules and corrosion products. Here, we investigate the role of the Zn2+ ion in mediating recently reported suppressive effects against smooth muscle cells (SMCs). Cross sections of zinc implants within the abdominal aorta were probed for markers of apoptosis within the neointima. An increase in active caspase-3 and TUNEL signal were found relative to platinum control wires, along with a reduction in SMC coverage. The work demonstrates a caspase-3 dependent intracellular signaling mechanism of SMC apoptosis stimulated by Zn2+. These findings suggest that Zn2+ ions released from degrading zinc implants may impart suppressive effects against neointimal growth, similar to the action of synthetic drugs incorporated into a polymer surface on drug eluting stents (DES).
9:45 AM
Synthesis of Absorable and Non-absorbable Sutures for Surgical Incisions and Wounds: Muhammad Shoaib Butt1; 1National University of Science and Technology
Nosocomial infection is surgical site infections (SSIs) mainly caused due to infected suture materials used in medical implants. SSIs remain the third most common hospital acquired infection with a rate of 2-5% of patients undergoing surgery which is challenge to a worldwide. To solve (SSIs) we focus on the development of novel natural anti-inflammatory based polymeric composite films and antimicrobial suture coatings. A synthetic, biocompatible and biodegradable polymer will combined with a natural herb to exploit its antibacterial and anti-inflammatory properties. The properties of these two materials will be combined together to get long term impact such as wound healing and prevention of surgical site infections.The synthetic polymer and the natural herb extract will be mixed in various ratios to produce polymer based films. The films will be screened for antibacterial and antifungal activity against bacterial (E. coli, P. aeruginosa) and fungal strains (Aspergillus flavus and Aspergillus tubingensis).
10:05 AM Break
10:20 AM
Ceramic Composites as Bone Tissue Scaffolds: Caitlin Guzzo1; John Nychka1; 1University of Alberta
Broken or diseased bone tissue requires a multitude of repair strategies ranging from allografts to bone substitutes. Herein we describe a manufacturing process to create all-ceramic porous scaffolds for bone tissue repair in the absence of traditional consolidation techniques for ceramics—a technique that has potential for in situ use in operating rooms, or in field hospitals. The room temperature and pressure process utilizes a reaction with a liquid ceramic precursor to form a silicate-glass binder phase to consolidate bioactive glass frit particles. Herein, characterization and mechanical response of the composite scaffolds is reviewed with respect to design specifications required in biomedical implant materials, such as: formability, structural integrity, porosity, load-bearing capability, and bioactivity.
10:40 AM
Biocompatibility Study of Luminescent Hydroxyapatite: Fabian Martinez1; Ekaterina Novitskaya1; Manuel Herrera2; Karla Juarez-Moreno2; Olivia Graeve1; 1University of California, San Diego; 2Universidad Nacional Autónoma de México
We present a biocompatibility study of hydroxyapatite doped with rare-earth elements, including Eu2+, Eu3+, Ce3+, Tb3+, and Yb2+, and a cathodoluminescence study of the chemical decomposition of the hydroxyapatites in the presence of simulated body fluid. Before assay studies, the hydroxyapatite powders were analyzed by X-ray diffraction and spectral cathodoluminescence, confirming that the dopants are present in the powders in amounts of a few atomic percent and they do not modify the equilibrium phase of hydroxyapatite. For the biocompatibility study, cytotoxicity assay and hemolysis assay were performed. The cytotoxicity assay of murine pre-osteoblast cells and the hemolysis assay demonstrate that the doped hydroxyapatite does not interfere on the proliferation of the cells, and does not induce the destruction of erythrocytes, respectively. Cathodoluminescence shows that the emission of the dopants decreases in a linear manner when they are immersed in simulated body fluid for different periods of time.
11:00 AM
Low Pressure and Atmospheric Plasma-based Surface Modifications for Biodegradable Materials and Implants: Leticia de Andrade Marin1; Samira Ravanbakhsh1; Sofia Gambaro1; Andranik Sarkissian2; Carlo Paternoster1; Diego Mantovani1; 1Research Center Laval University; 2Plasmionique Inc.
Over the last 50 years, biomaterials, prostheses and implants saved and prolonged the life of millions of humans around the globe. Today, biodegradable materials allow industrials, scientists, and clinicians design new temporary devices for patient benefits that one decade ago was simply unimaginable. However, controlling the surface behavior is an effective method to modulate degradation, target biological properties, and improving radiopacity for thinner devices. For example, short reactions such as cell adhesion and migration are known to be mainly affected by chemical composition, roughness and wettability of the material surface. Plasma techniques are an advantageous method to modify surfaces of complex devices such as tiny medical implants. They offer several advantages as a surface modification technique without affecting the overall sample thickness and allowing the treatment of complex shape samples. This presentation aims to discuss results obtained by surface characterization techniques of a Fe-Mn-based surfaces modified by different plasma-based processes.