Biomedical Engineering and Bioengineering Commons^™

A 3d Bioprinted Hydrogel Microfluidic Device For Screening Applications, Anant Bhusal

Theses and Dissertations

The microfluidic enabled the integration of engineered miniaturized tissue models for drug screening. Conventional polydimethylsiloxane or plastic-based devices require multiple fabrication steps, which are challenging. We developed a 3D bioprinting approach to create prototypes of hydrogel-based multi-material microfluidic devices integrated with microtissue models. The approach utilizes poly(ethylene glycol) diacrylate and gelatin-methacryloyl to create microfluidic chips using multi-material bioprinting capacity with a high resolution of 15µm on x-y and 50µm on the z-axis and post-printing viability of >90%. We demonstrated easy regulation of stiffness from 24±5 kPa to 1,180±9 kPa and burst pressure from 16±1kPa to 256±19 kPa in the chip …

Longitudinal Oxygen Imaging In 3d (Bio)Printed Models, Ryan Curtis O'Connell

Graduate Theses, Dissertations, and Problem Reports

Electron paramagnetic resonance (EPR), and its molecular imaging modality, is a powerful tool to noninvasively map various biological and chemical markers within objects of interest. Reliable data acquisition is a major impeding factor for longitudinal hands-off measurements. Measurements are especially challenging in biomedical applications, as live objects are not static. Frequent changes occur that require constant fine recalibration of the EPR detection system, called the resonator. To enable longitudinal imaging, a technology permitting automatic digital control of resonator coupling, tuning, and EPR data acquisition was developed. Automation was achieved through the utilization of a microcontroller and digital peripheral components such …

Structural Health Monitoring Of Bioprinted Materials, Kathryn H. Mcintosh

Honors College Theses

Bioprinting is a new method that utilizes additive manufacturing to construct organs, tissues, and other biostructures. This method presents endless possibilities - less reliance on organ donors (according to the Health Resources and Services Administration, 17 people die each day waiting for an organ transplant in the U.S.), more transplant opportunities, and the ability to save significantly more lives. While bioprinting has opened a new frontier in the biomedical field, there may be some research issues that need to be addressed. For example, numerous researchers have focused on creating novel approaches to print complicated geometries. However, the structural integrity or …

Applied Machine Learning In Extrusion-Based Bioprinting, Shuyu Tian

Theses and Dissertations

Optimization of extrusion-based bioprinting (EBB) parameters have been systematically conducted through experimentation. However, the process is time and resource-intensive and not easily translatable across different laboratories. A machine learning (ML) approach to EBB parameter optimization can accelerate this process for laboratories across the field through training using data collected from published literature. In this work, regression-based and classification-based ML models were investigated for their abilities to predict printing outcomes of cell viability and filament diameter for cell-containing alginate and gelatin composite hydrogels. Regression-based models were investigated for their ability to predict suitable extrusion pressure given desired cell viability when keeping …

Development Of Novel Inks And Approaches For Printing Tissues And Organs, Shen Ji

Dissertations

Tissue engineering is a multidisciplinary field that investigates and develops new methods to repair, regenerate and replace damaged tissues and organs, or to develop biomaterial platforms as in vitro models. Tissue engineering approaches require the fabrication of scaffolds using biomaterials or fabrication of living tissues using cells. As the demands of customized, implantable tissue/organs are increasing and becoming more urgent, conventional scaffold fabrication approaches are difficult to meet the requirements, especially for complex large-scale tissue fabrication. In this regard, three-dimensional (3D) printing attracted more interest over the past decades due to its unrivaled ability to fabricate highly customized tissues or …

Bioprinted In Vitro Model Of Human Glioblastoma, Rachel Lauren Schwartz

Theses and Dissertations

Glioblastoma multiform (GBM) is one of the most aggressive forms of primary brain tumors. GBM is fast progressing and resistant to treatment, resulting in a low survival rate. Conventional 2-dimensional tissue culture models cannot fully replicate the complexities of cancer lesions that contain multiple cell types and structures (e.g. vessels composed of endothelial cells, cancer cells, normal cells, etc.) as well as an intricate scaffold of proteins comprising the extracellular matrix (ECM). In addition, animal models cannot translate into the clinical disease in patients. Thus, this study has developed a bioprintable organ-on-a-chip (OOAC) model that mimics the important ECM factors …

Surface Functionalization Via Photoinitiated Radical Polymerization For Rare Cell Isolation And Mechanical Protection, Calvin Frank Cahall

Theses and Dissertations--Chemical and Materials Engineering

Surface functionalization of living cells for cell therapeutics has gained substantial momentum in the last two decades. From encapsulating islets of Langerhans, to cell laden gels for tissue scaffolds, to individual cell encapsulation in thin hydrogels, to surface adhesives and inert surface camouflage, modification of living cell surfaces has a wide array of important applications. Here we use hydrogel encapsulation of individual cells as a mode of protection from mechanical forces for high throughput cell printing, and chemical stimuli for the isolation of rare cells in blood.

In the first study, we review methods of surface functionalization and establish a …

3d Bioprinting A Pcl/13-93b3 Glass Composite And Its Potential Use As A Bio-Ink, Caroline Blair Murphy

Masters Theses

"A major limitation of using synthetic scaffolds in tissue engineering is little growth of incorporated cells in the interior of the scaffold, resulting in insufficient angiogenesis in the scaffold interior. Recently, cells have been 3D bioprinted concurrently with biomaterials to produce a cellularized, bioactive, angiogenic 3D environment. This thesis describes a novel solvent-extrusion method for printing polycaprolactone (PCL)/bioactive borate glass composite as a biomaterial for a cell-laden scaffold.

Bioactive borate glass was added to a mixture of PCL and organic solvent to make an extrudable paste, creating scaffolds measuring 10×10×1 mm³ in overall dimensions with pore sizes ranging from …

Development Of A Fluidic Mixing Nozzle For 3d Bioprinting, Will Hoggatt

Open Access Theses

3D bioprinting is a relatively new and very promising field that uses conventional 3D printing techniques and adapts them to print biological materials that are suited for use with cells. These bioprinters can be used to print cells encapsulated within biological "ink" (bio-ink) to create and customize complex three-dimensional tissues and organs. Our work has focused on developing a new bioprinter nozzle that addresses critical gaps with present-day bioprinters, namely, the lack of standardized, physiologically-relevant biomaterials, and their one nozzle per composition printing capacity. These shortcomings preclude printing a range of cellular and biomaterial compositions (including gradients of cells and …

Biophysical Characterization And Theoretical Analysis Of Molecular Mechanisms Underlying Cell Interactions With Poly(N-Isopropylacrylamide) Hydrogels, Michael C. Cross

USF Tampa Graduate Theses and Dissertations

So-called, “Dynamic biomaterials” comprised of stimuli-responsive hydrogels are useful in a wide variety of biomedical applications including tissue engineering, drug delivery, and biomedical implants. More than 150,000 peer-reviewed articles (as of 2016) have been published on these materials, and more specifically, over 100,000 of these are on the most widely studied, poly(N-isopropylacrylamide). This thermoresponsive polymer in a crosslinked hydrogel network undergoes a large volume phase transition (𝑉/𝑉₀ ~ 10 − 100) within a small temperature range (𝑇 ~ 1 − 3𝐾) making it particularly useful for tissue engineering applications because of the ability to control the topographical configuration of …

Fabrication Of Tissue Precursors Induced By Shape-Changing Hydrogels, Olukemi O. Akintewe

USF Tampa Graduate Theses and Dissertations

Scaffold based tissue reconstruction inherently limits regenerative capacity due to inflammatory response and limited cell migration. In contrast, scaffold-free methods promise formation of functional tissues with both reduced adverse host reactions and enhanced integration. Cell-sheet engineering is a well-known bottom-up tissue engineering approach that allows the release of intact cell sheet from a temperature responsive polymer such as poly-N-isopropylacrylamide (pNIPAAm). pNIPAAm is an ideal template for culturing cell sheets because it undergoes a sharp volume-phase transition owing to the hydrophilic and hydrophobic interaction around its lower critical solution temperature (LCST) of 32°C, a temperature close to physiological temperature. Compared to …