NASA SBIR abstracts of 1990 phase 1 projects

The research objectives of the 280 projects placed under contract in the National Aeronautics and Space Administration (NASA) 1990 Small Business Innovation Research (SBIR) Phase 1 program are described. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses in response to NASA's 1990 SBIR Phase 1 Program Solicitation. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 280, in order of its appearance in the body of the report. The document also includes Appendixes to provide additional information about the SBIR program and permit cross-reference in the 1990 Phase 1 projects by company name, location by state, principal investigator, NASA field center responsible for management of each project, and NASA contract number

3D Cell Printed Tissue Analogues: A New Platform for Theranostics

Stem cell theranostics has received much attention for noninvasively monitoring and tracing transplanted therapeutic stem cells through imaging agents and imaging modalities. Despite the excellent regenerative capability of stem cells, their efficacy has been limited due to low cellular retention, low survival rate, and low engraftment after implantation. Three-dimensional (3D) cell printing provides stem cells with the similar architecture and microenvironment of the native tissue and facilitates the generation of a 3D tissue-like construct that exhibits remarkable regenerative capacity and functionality as well as enhanced cell viability. Thus, 3D cell printing can overcome the current concerns of stem cell therapy by delivering the 3D construct to the damaged site. Despite the advantages of 3D cell printing, the in vivo and in vitro tracking and monitoring of the performance of 3D cell printed tissue in a noninvasive and real-time manner have not been thoroughly studied. In this review, we explore the recent progress in 3D cell technology and its applications. Finally, we investigate their potential limitations and suggest future perspectives on 3D cell printing and stem cell theranostics.116Nsciescopu

Cell Compatible Electrospun Poly(vinyl alcohol) Fibers for Tissue Regeneration

Poly(vinyl alcohol) (PVA) is a well known biocompatible synthetic polymer. PVA is not cell compatible due to its high hydrophilicity. As prepared by electrospinning in the form of nanofibers, it is unstable in aqueous environments including cell culture media. For tissue regeneration applications, this study demonstrates the use of PVA scaffold utilizing electrospun nanofibers with aqueous stability and cell compatibility toward creating biomaterial-tissue hybrid based medical devices. Two different approaches: heat treatment and ion beam treatment were developed to improve aqueous stability and promote cell compatibility for PVA fibers. Using a thermal annealing method at elevated temperatures, the fibers became stable in water. This observation correlated closely to the change in the crystallinity of PVA. Elastic moduli of individual fibers were determined using a multi-points bending approach by atomic force microscopy. Elastic moduli of as-spun PVA fibers were determined to be a function of fiber diameter and humidity. Significant changes in the elastic modulus of the modified PVA fibers were also observed. To improve the cell compatibility, low energy N+ and He+ ion beams were used to introduce amine and carbonyl functional groups. Cell compatibility was assessed in vitro using primary human skin fibroblasts (hsF). Confocal microscopy confirmed the adhesion and proliferation of hsF on both the random and aligned PVA fibers after the ion beam treatment, while cells failed to adhere to the untreated fibers. Cell morphology was observed to align and elongate along the fiber axis on aligned PVA fibers. After 10 days of proliferation, cells were found to form confluent layers and even multiple layers on the N+treated fibers. Cell proliferation depends on ion species, ion dose and fiber alignment. With the two post-processing treatments, PVA fibrous scaffold showed the potential to become biomaterial-tissue hybrid based medical devices for tissue regeneration applications

Emulsion Inks: A New Class of Materials for 3D Printing Porous Tissue Engineered Grafts

Tissue grafts are often crucial in restoring function and promoting healing after traumatic injury. Many synthetic materials have been developed, but these often suffer from inadequate tissue integration, limited biodegradability, and mechanical mismatch with the target tissue. Recent advances in 3D printing technologies have enabled the fabrication of custom-fit scaffolds that resemble native tissue. Although these scaffolds can more closely mimic defect shape, new inks are needed to provide tunable control over multiple levels of scaffold structure and function. To address these limitations, we have developed an extensible system for printing complex tissue engineered scaffolds by creating emulsion templated inks. These emulsion inks exhibit tunable pore sizes, modulus, and strength. Formulation of inks with viscous, reactive macromers results in extruded material that holds its shape after extrusion and polymerizes rapidly upon exposure to UV light. New methodology was developed to permit the rational design of emulsion inks based on rheological and cure properties, and these inks were able to successfully create high fidelity scaffolds with customizable, hierarchical porosity. Emulsion inks are compatible with nearly any hydrophobic macromer allowing development of inks with limitless chemical and material properties. Next, a hybrid printing system was developed for extrusion of thermoplastic PCL and PLA along with emulsion inks to provide mechanical reinforcement. Scaffolds without reinforcement exhibited an increase in permeability with a decrease in infill density, with detriment to their modulus and strength. Mechanical reinforcement with PLA, however, resulted in a significant increase in modulus and strength in all cases. The creation of novel emulsion inks from existing biomaterial systems opens the door to the creation of scaffolds with a wide range of physical and chemical properties. Finally, this system was extended to oil-in-water emulsions, termed hydrocolloid inks, to facilitate printing of hydrogels. Due to their low viscosity, high fidelity printing of hydrogels has typically been limited to SLA methods. SFF printing of hydrogel scaffolds frequently relies on thickeners and additives, but we have refined the rheological properties without modification of the hydrogel makeup by emulsifying with innocuous mineral oil. These 3D printed hydrogel scaffolds represent some of the highest fidelity reproductions of complex anatomical geometries in the literature to date. Additionally, this system provides a methodology for creating hydrocolloid inks from nearly any hydrogel biomaterial. In summary, we have developed a library of porous materials that can be used to improve tissue regeneration. Furthermore, the emulsion structure-property relationships explored here can be used in designing future emulsion inks. A combinatorial approach of tuning the ink and fabrication system allows for creation of complex scaffolds with improved biomimicry, allowing for a new generation of hierarchically porous tissue engineered constructs

Advanced Applications of Rapid Prototyping Technology in Modern Engineering

Rapid prototyping (RP) technology has been widely known and appreciated due to its flexible and customized manufacturing capabilities. The widely studied RP techniques include stereolithography apparatus (SLA), selective laser sintering (SLS), three-dimensional printing (3DP), fused deposition modeling (FDM), 3D plotting, solid ground curing (SGC), multiphase jet solidification (MJS), laminated object manufacturing (LOM). Different techniques are associated with different materials and/or processing principles and thus are devoted to specific applications. RP technology has no longer been only for prototype building rather has been extended for real industrial manufacturing solutions. Today, the RP technology has contributed to almost all engineering areas that include mechanical, materials, industrial, aerospace, electrical and most recently biomedical engineering. This book aims to present the advanced development of RP technologies in various engineering areas as the solutions to the real world engineering problems

Application of an acoustofluidic perfusion bioreactor for cartilage tissue engineering

Cartilage grafts generated using conventional static tissue engineering strategies are characterised by low cell viability, suboptimal hyaline cartilage formation and, critically, inferior mechanical competency, which limit their application for resurfacing articular cartilage defects. To address the limitations of conventional static cartilage bioengineering strategies and generate robust, scaffold-free neocartilage grafts of human articular chondrocytes, the present study utilised custom-built microfluidic perfusion bioreactors with integrated ultrasound standing wave traps. The system employed sweeping acoustic drive frequencies over the range of 890 to 910 kHz and continuous perfusion of the chondrogenic culture medium at a low-shear flow rate to promote the generation of three-dimensional agglomerates of human articular chondrocytes, and enhance cartilage formation by cells of the agglomerates via improved mechanical stimulation and mass transfer rates. Histological examination and assessment of micromechanical properties using indentation-type atomic force microscopy confirmed that the neocartilage grafts were analogous to native hyaline cartilage. Furthermore, in the ex vivo organ culture partial thickness cartilage defect model, implantation of the neocartilage grafts into defects for 16 weeks resulted in the formation of hyaline cartilage-like repair tissue that adhered to the host cartilage and contributed to significant improvements to the tissue architecture within the defects, compared to the empty defects. The study has demonstrated the first successful application of the acoustofluidic perfusion bioreactors to bioengineer scaffold-free neocartilage grafts of human articular chondrocytes that have the potential for subsequent use in second generation autologous chondrocyte implantation procedures for the repair of partial thickness cartilage defects

Ceramic Materials for 3D Printing of Biomimetic Bone Scaffolds – Current state–of–the–art & Future Perspectives

Ceramic bone implants have potential properties ideal for long-term implantation applications. On comparison with other materials, ceramic biomaterials have advantages such as biocompatibility, low cost, osteoconductivity, osteoinductivity, corrosion resistance, and can be made into various shapes with desired surface properties. Among transplantation surgeries, bone transplantation is the second largest in the globe after blood transfusion which is an indication for rising hope on the potential treatment options for bone. 3D printing is one of the most advanced fabrication techniques to create customized bone implants using materials such as ceramics and their composites. Developing bone scaffolds that precisely recapitulate the mechanical properties and other biological functions of bone remains a major challenge. However, extensive research on ceramic biomaterials have resulted in the successful 3D printing of complex bony designs with >50% porosity with cortical bone mechanical properties. This review critically analyses the use of various 3D printing techniques to fabricate ceramic bone scaffolds. Further, various natural and synthetic ceramic materials for producing customized ceramic implants are discussed along with potential clinical applications. Finally, a list of companies that offer customized 3D printed implants and the future on clinical translation of 3D printed ceramic bone implants are outlined

The Fabrication of Integrated Strain Sensors for “Smart” Implants using a Direct Write Additive Manufacturing Approach

Over the 1980’s, the introduction of Additive Manufacturing (AM) technologies has provided alternative methods for the fabrication of complex three-dimensional (3D) synthetic bone tissue implant scaffolds. However, implants are still unable to provide post surgery feedback. Implants often loosen due to mismatched mechanical properties of implant material and host bone. The aim of this PhD research is to fabricate an integrated strain gauge that is able to monitor implant strain for diagnosis of the bone healing process. The research work presents a method of fabricating electrical resistance strain gauge sensors using rapid and mask-less process by experimental development (design of experiment) using the nScrypt 3Dn-300 micro dispensing direct write (MDDW) system. Silver and carbon electrical resistance strain gauges were fabricated and characterised. Carbon resistive strain gauges with gauge factor values greater than 16 were measured using a proven cantilever bending arrangement. This represented a seven to eight fold increase in sensitivity over commercial gauges that would be glued to the implant materials. The strain sensor fabrication process was specifically developed for directly fabricating resistive strain sensor structures on synthetic bone implant surface (ceramic and titanium) without the use of glue and to provide feedback for medical diagnosis. The reported novel approach employed a biocompatible parylene C as a dielectric layer between the electric conductive titanium and the strain gauge. Work also showed that parylene C could be used as an encapsulation material over strain gauges fabricated on ceramic without modifying the performance of the strain gauge. It was found that the strain gauges fabricated on titanium had a gauge factor of 10.0±0.7 with a near linear response to a maximum of 200 micro strain applied. In addition, the encapsulated ceramic strain gauge produced a gauge factor of 9.8±0.6. Both reported strain gauges had a much greater sensitivity than that of standard commercially available resistive strain gauges