Carbon nanotube mesh bucky paper capsules
health medicine and biotechnology
Carbon nanotube mesh bucky paper capsules (TOP2-195)
Making Mesh Buckypaper Capsules for Transplantation of Cells and Implantation of Medical Devices
Overview
NASA has developed an innovative method for fabricating containers (biocapsules) made of biocompatible mesh for holding living cells and tissues, to facilitate transplantation into the body, for a wide range of high-impact medical applications. The biocompatible mesh (buckypaper) is made of carbon nanotubes (CNTs), and the containers are fabricated by depositing the nanotubes onto pre-formed molds, in order to achieve the desired shape and size of the biocapsule. Various forms are possible, including hollow tubes, closed cylinders, and more complex shapes, determined by the configuration of the mold. The biocompatibility of the capsule makes it possible to implant a variety of cells into a host, even cells that would otherwise be considered foreign, such as cells from unmatched donors, specially engineered cells, and even non-human cells. Because the capsule pores are too small for the cells to pass through, the cells stay inside the capsule, where they are protected from the host immune system.
The Technology
Fabrication of the biocapsule is accomplished by the use of a perforated mold, which allows CNTs in suspension or solution to be deposited by vacuum filtration. Other methods of creating a pressure differential between the outside of the mold and the inside of the mold can be used to drive the CNT deposition process. The mesh builds up gradually, over the course of minutes, so the thickness of the mesh can be controlled by the time of deposition. The fabrication procedure results in a mesh that is held together entirely by entanglement and non-covalent interaction between the CNTs. Filtration of CNTs onto the surface of a mold as the method of biocapsule fabrication is superior to other methods of fabrication that require assembly from multiple pieces of buckypaper, since these methods require seams in order to create a closed container. Seams result in weakness of the biocapsule and can result in leakage of the transplanted cells outside the container, which defeats the immune-shielding function of the biocapsule. The perforated mold/filtration method makes biocapsule manufacture more efficient, and makes possible a wider range of shapes of the biocapsule, to facilitate transplantation into a wider range of sites in the body. The perforated mold/filtration method also allows small beads to be incorporated into the wall of the biocapsule. Small beads, functionalized with bioactive materials, may be used to maintain the health or enhance the function of the cells inside the biocapsule, or may be used to enhance biocompatibility. The pores of the biocapsule permit gas exchange (oxygen, carbon dioxide), as well as free diffusion of metabolites, proteins and other cell products, which keep the cells healthy, and may provide useful therapeutics. Tissue or tissue fragments, and micro or nanoscale medical devices can also be placed inside the biocapsule to facilitate their implantation into the body.
Benefits
- Provides potentially more variation in the range of shapes
- Ability to form structures comprised of multiple layers
- No suture or other ligature material is needed
- The system can be sealed up to provide for large-scale reproduction
Applications
- Nanobiotechnology
- Nanomedicine
- Molecular nanotechnology
- Biomolecular computing
- Medical devices
Similar Results
Holey Carbon Allotropes
This invention is for scalable methods that allows preparation of bulk quantities of holey nanocarbons with holes ranging from a few to over 100 nm in diameter. The first method uses metal particles as a catalyst (silver, copper, e.g.) and offers a wider range of hole diameter. The second method is free of catalysts altogether and offers more rapid processing in a single step with minimal product work-up requirements and does not require solvents, catalysts, flammable gases, additional chemical agents, or electrolysis. The process requires only commercially available materials and standard laboratory equipment; and, it is scalable. Properties that can be controlled include: surface area, pore volume, mechanical properties, electrical conductivity, and thermal conductivity.
3D Construction of Biologically Derived Materials
Once genes for a desired material type, delivery mode, control method and affinity have been chosen, assembling the genetic components and creating the cell lines can be done with well-established synthetic biology techniques. A 3D microdeposition system is used to make a 3D array of these cells in a precise, microstructure pattern and shape.
The engineered cells are suspended in a printable 'ink'. The 3D microdeposition system deposits minute droplets of the cells onto a substrates surface in a designed print pattern. Additional printer passes thicken the material. The cell array is fed nutrients and reagents to activate the engineered genes within the cells to create and deposit the desired molecules. These molecules form the designed new material. If desired, the cells may be removed by flushing. The end product is thus a 3D composite microstructure comprising the novel material.
This innovation provides a fast, controlled production of natural, synthetic, and novel biomaterials with minimum resource overhead and reduced pre- and post-processing requirements.
Sucrose Treated Carbon Nanotube and Graphene Yarns and Woven Sheets
Various aerospace and terrestrial applications require lightweight materials with very high mechanical properties. Carbon nanotubes and graphene sheets have been found to be such materials. In addition, they have been found to have excellent electrical and thermal transport properties. However, retaining the excellent nanoscale properties, particularly mechanical and thermal transport, in bulk materials has proven to be challenging. In order for the nanotubes to be used in applications, they must be spun into yarn(s), sheet(s), and other macroscopic forms introducing relatively weak tube-to-tube and inter-bundle bonds. Also, the nanotubes tend to be entangled, and they therefore do not all contribute in load bearing. Weak coupling at tube and bundle interfaces also leads to mechanical and thermal transport that are much lower than would be expected from the nanoscale carbon nanotube or graphene properties.
This invention is for consolidated carbon nanotube or graphene yarns and woven sheets via the formation of a carbon binder formed from the dehydration of sucrose. The resulting materials are lightweight and possess a high specific modulus and/or strength on the macro-scale. Sucrose is relatively inexpensive and readily available, leading to a cost-effective route for achieving bulk nanotube/graphene based multifunctional material formats.
Conductive Polymer/Carbon Nanotube Structural Materials and Methods for Making Same
Carbon nanotubes (CNTs) show promise for multifunctional materials for a range of applications due to their outstanding combination of mechanical, electrical and thermal properties. However, these promising mechanical properties have not translated well to CNT nanocomposites fabricated by conventional methods due to the weak load transfer between tubes or tube bundles.
In this invention, the carbon nanotube forms such as sheets and yarns were modified by in-situ polymerization with polyaniline, a -conjugated conductive polymer. The resulting CNT nanocomposites were subsequently post-processed to improve mechanical properties by hot pressing and carbonization. A significant improvement of mechanical properties of the polyaniline/carbon nanotube nanocomposites was achieved through a combination of stretching, polymerization, hot pressing, and carbonization.
Dispersion of Carbon Nanotubes in Polymers
The technology portfolio spans several methods for dispersion and processing of CNTs in polymer resins and composites. CNT/resin systems with high dispersion and long-term stability are provided by three general approaches. One method relies on mechanical dispersion by sonication simultaneous with partial polymerization to increase the resin viscosity to maintain dispersion and enable further polymer processing of the CNT blend into films and other articles. Another approach relies on what is termed donor acceptor bonding, which essentially is a dipole bond created on the CNT/resin interface to maintain dispersion and stability of the CNT/resin blend. This dispersion method also provides advantages in mechanical properties of processed composites due to the interface characteristics. A range of polymer types can be used, including polymethyl methacrylate, polyimide, polyethylene, and others.
An additional dry blending approach provides advantages for a variety of
thermoplastic and thermoset systems. Use of ball mill mixing achieves effective
blending and dispersion of the CNT, even at high loadings. Further processing steps
using injection molding or similar melt processing methods have yielded CNT/
polymer composites with a range of useful electronic, optical, and mechanical
properties.
