Delivery of Alpha-Ketoglutarate from Hyaluronic Acid Hydrogels for Bone Repair Applications

Description
Bone loss affects millions of people every year posing a major public health problem. Currently, autograft and allograft bones are the only options for treating bone loss. Although, they pose many limitations including donor availability, immunogenicity risks, and the potential

Bone loss affects millions of people every year posing a major public health problem. Currently, autograft and allograft bones are the only options for treating bone loss. Although, they pose many limitations including donor availability, immunogenicity risks, and the potential to carry a risk of disease and/or infection transmission to name a few. Therefore, there is a pressing clinical need to create a novel treatment that will promote bone repair. Alpha-ketoglutarate (aKG) was investigated as it plays an important role in cellular energy metabolism as a key intermediate in the Krebs cycle. It has been shown to stimulate the production of collagen in the bone repair process. However, controlling the release of aKG is important in being able to control where and how much new bone growth is stimulated. To address this aKG was delivered via a hyaluronic acid hydrogel and its release was controlled via the degradation of poly(alpha-ketoglutarate) microparticles (paKG MPs). paKG MPs were synthesized and characterized based on size, shape, and uniformity. The release of aKG from paKG MPs was evaluated, as well as the addition of paKG MPs into norbornene functionalized hyaluronic acid and maleimide functionalized hyaluronic acid hydrogels. Initial cell work was also done to grow osteoblasts for future work. It was found that paKG MPs were of the desired size and shape. The release of aKG from the paKG MPs was found to be sustained. The addition of paKG MPs in norbornene functionalized hyaluronic acid (NorHA) was found to be ineffective due to the opaqueness of the MPs. Maleimide functionalized hyaluronic acid (MaHA) hydrogels were chosen as an alternative delivery system for this reason. Future tests will be done on the addition of paKG MPs into MaHA hydrogels. Osteoblasts were also successfully grown and will be used in future studies.
Date Created
2024-05
Agent

Structure-property-function Relationships for Segmented Ionenes

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Description
There are limited analyses of the properties of segmented ionenes on the influence of the type, structure, content of soft/hard segments, and type of counterions through direct comparisons, which are needed for a diverse set of applications. This dissertation research

There are limited analyses of the properties of segmented ionenes on the influence of the type, structure, content of soft/hard segments, and type of counterions through direct comparisons, which are needed for a diverse set of applications. This dissertation research focuses on resolving the gaps in the structure-property-function relationship of segmented ionenes. First, the synthesis of novel segmented ionenes using step-growth polymerization via the Menshutkin reaction of ditertiary amines and alkyl dihalides was performed with PEG soft segment with three different content of soft/hard segments, 25, 50, and 75 wt%, and two different hard segments, linear aliphatic and heterocyclic aliphatic hard segments. The content of the soft segment influenced the degree of phase separation and ionic aggregation which affected the thermomechanical properties of segmented ionenes. In addition, the crystallization of the soft segment influenced the mechanical properties of the ionenes. Second, the effect of the type of the soft segment was investigated by analyzing the novel PTMO-based segmented ionenes possessing three different content of soft/hard segments, as well as two different hard segments. The heterocyclic aliphatic hard segment provided a better degree of phase separation compared to the linear aliphatic hard segment irrespective of the type of soft segment, PEG, or PTMO. Moreover, the type and content of hard segments not only affected the thermal and mechanical properties but also the morphology of the segmented ionenes significantly that even inducing an ordered morphology. Third, the counter-anion metathesis was performed with PEG- and PTMO-based segmented ionenes possessing two structurally different hard segments to investigate the effect of the type of counter-anions with a direct comparison of the type of soft and hard segments. The type of counterion significantly influenced the thermomechanical properties of the segmented ionenes, and the degree of phase separation of different types of counter-anions was dependent on the type of soft and hard segments. The results of this dissertation provide fundamental insights into the correlations between each factor that influences the properties of the segmented ionenes and enable the design of segmented ionenes for a diverse range of applications.
Date Created
2023
Agent

Investigating the Potential of F16BP-poly(I:C) Microparticle Associated CAR Therapies

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Description
Adoptive cell therapies such as chimeric antigen receptor (CAR) modified immune cells are revolutionizing cancer treatment. These innovative immunotherapies have a promising outlook for liquid cancers, but lack robustness against solid tumors due to complex variables introduced by the tumor

Adoptive cell therapies such as chimeric antigen receptor (CAR) modified immune cells are revolutionizing cancer treatment. These innovative immunotherapies have a promising outlook for liquid cancers, but lack robustness against solid tumors due to complex variables introduced by the tumor microenvironment (TME). Additionally, existing CAR-T cell treatments are commonly accompanied by toxic side effects. However, by grafting a CAR construct onto macrophages, a professional phagocytic innate cell which are actively recruited by solid tumors, the efficacy of this treatment is hoped to be extended beyond hematological malignancies. Moreover, the introduction of energy metabolite-based polymers (EMPs) to provide a sustained release of activating F16BP-poly(I:C) microparticles could address the toxicity complications that arise from CAR treatments. It was determined that PLGA-F16BP-poly(I:C) microparticles allow for CAR-macrophage activation in vitro, though not in a sustained manner. Moreover, F16BP-poly(I:C) microparticles were better geared toward reducing cytokine related toxicity in vitro, with in vivo results remaining inconclusive. These findings suggest prioritization between macrophage activation or cytokine storm reduction would be required at this time, though additional future studies to explore variables such as CAR-macrophage sensitivity and the positive control could help refine this immunotherapy.
Date Created
2023
Agent

A Quantitative Study on the Effect of Rotation Rate on Radiation Heat Transfer in a Rotary Drum

Description

Rotary drums are used to manufacture pharmaceuticals, cement, food, and other particulate products because of their high heat and mass transfer rates. These processes are governed by particle parameters, such as particle size, particle distribution, and shape, and operating parameters,

Rotary drums are used to manufacture pharmaceuticals, cement, food, and other particulate products because of their high heat and mass transfer rates. These processes are governed by particle parameters, such as particle size, particle distribution, and shape, and operating parameters, such as rotation rate and fill level. Enormous energy savings are possible with further research in rotary drums due to potential increases in operating efficiency. This study investigates the drum rotation rate on particle bed temperature at temperatures above 500 °C to see the role that radiation heat transfer plays in this process. 2 mm silica beads and a stainless steel rotary drum were used at a fill level of 25% with rotation rates from 2-10 rpm. A new setup and procedure were developed using heating coils and an IR camera to reach high temperatures. The inner drum wall temperature exceeded the outer drum wall temperature because the steel transmitted more heat into the drum at higher temperatures. Although it was unclear whether the heat transfer rate was affected by the increasing rotation rate, the highest final average particle temperature was obtained at 5 rpm. The particle bed temperature distribution narrowed as the rotation rate increased because, at higher rotation rates, more particles are in contact with the drum wall than at lower rotation rates.

Date Created
2023-05
Agent

The Development of a Microgel/Hydrogel Composite System for TBI Treatment

Description

Traumatic brain injury (TBI), a neurological condition that negatively affects neural capabilities, occurs when a blunt trauma impacts the head. Following the initial injury that immediately impacts neural cell function and survival, a series of secondary injury events lead to

Traumatic brain injury (TBI), a neurological condition that negatively affects neural capabilities, occurs when a blunt trauma impacts the head. Following the initial injury that immediately impacts neural cell function and survival, a series of secondary injury events lead to substantial sustained inflammation for weeks to years post-injury. To develop TBI treatments that may stimulate regenerative processes, a novel drug delivery system that efficiently delivers the appropriate drug/payload to injured tissue is crucial. Hyaluronic acid (HA) hydrogels are attractive when developing a biomaterial for tissue reparation and regeneration. HA is a natural polymer with physicochemical properties that can be tuned to match the properties of the extracellular matrix (ECM) of the many tissues including the central nervous system (CNS). Here, the project objective was to develop a HA hydrogel system for local delivery of a biological payload; this objective was completed by employing a composite system with two parts. The first part is an injectable, shear-thinning bulk hydrogel, and the second is microgels for loading biological payloads. The bulk hydrogel was composed of cyclodextrin modified HA (Cd-HA) and adamantane modified HA (Ad-HA) that give rise to guest-host interactions that facilitate physical crosslinking. The microgel, composed of norbornene-HA (Nor-HA) and sulfated-HA, crosslink via chemical crosslinks upon activation of a UV photoinitiator. The sulfated-HA microgels facilitate loading of biological payloads by mimicking heparin binding sites via the conjugated sulfated group. Neuregulin I, an epidermal growth factor with neuroprotective properties, is one such protein with a heparin binding domain that may be retained in the sulfated-HA microgels. Specifically, the project focused on mechanical testing of this composite microgel/hydrogel system and also developing protein affinity assays.

Date Created
2023-05
Agent

Recycling of HDPE

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Description
High-Density polyethylene (HDPE) is the most used polymer on earth. Since it is used in such large quantities, it has become the most extensively produced polymer on the planet. Unfortunately, the rate of reusing or recycling HDPE is far behind

High-Density polyethylene (HDPE) is the most used polymer on earth. Since it is used in such large quantities, it has become the most extensively produced polymer on the planet. Unfortunately, the rate of reusing or recycling HDPE is far behind the rate of production leading to plastic pollution. Most of this waste plastic ends up in landfills or incineration to recover energy. Plastic production consumes a lot of energy and is associated with CO2 emissions. This method of disposing plastic only adds to the environmental pollution rather than improving it. Primary reasons for low recycling rate appear to be more political and financial. In the US, the rate of recycling was less than 10% whereas Japan showed a recycling rate of more than 80%. The other aspect of low recycling is financial. In order to make recycling a financially viable process, efforts have to be made to streamline the process of waste collection, segregation and technically feasible process. This study focusses on the technical aspect of the issue. Even though efforts have been made to recycle HDPE, none of the processes have been recycle HDPE with financial viability, recovering full value of plastic, minimum CO2 emissions and minimum change in properties of the polymer. This study focusses on effective recycling of HDPE with minimum change in its properties. Dissolution has been used to dissolve the polymer selectively and then reprecipitating the polymer using a non-solvent to obtain the polymer grains. This is followed by mixing additives to the polymer grains to minimize degradation of the polymer during the extrusion process. The polymer is then extruded in an extruder beyond its melting temperature. This process is repeated for 5 cycles. After each cycle, the polymer is tested for its properties using the Tensile Testing, Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Dynamic Mechanicalii Analysis (DMA). It was observed that the rheological properties of the polymer were maintained after the 5th recycle whereas the mechanical properties deteriorated after the 2nd recycle. Also, increase in carbonyl index was observed after 5th recycle.
Date Created
2022
Agent

3D printed Bioactive Scaffolds for Tissue Repair and Drug Delivery

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Description
Combining 3D bio-printing and drug delivery are promising techniques tofabricate scaffolds with well controlled and patient-specific structures for tissue engineering. In this study, silk derivatives of bioink were developed consisting of silk fibroin and gelatin then 3D printed into scaffolds. The scaffolds

Combining 3D bio-printing and drug delivery are promising techniques tofabricate scaffolds with well controlled and patient-specific structures for tissue engineering. In this study, silk derivatives of bioink were developed consisting of silk fibroin and gelatin then 3D printed into scaffolds. The scaffolds would be evaluated for small molecule release, cell growth, degradation, and morphology. Preparations and design of the scaffolds are major parts of engineering and tissue engineering. Scaffolds are designed to mimic extracellular matrix by providing structural support as well as promoting cell attachment and proliferation with minimum inflammation while degrading at a controlled rate. Scaffolds offers new potentials in medicine by aiding in the preparation of personalized and controlled release therapeutic systems.
Date Created
2022
Agent

High-Frequency Ultrasound Analysis of Soft Material Characterization

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Description
Ultrasound has become one of the most popular non-destructive characterization tools for soft materials. Compared to conventional ultrasound imaging, quantitative ultrasound has the potential of analyzing detailed microstructural variation through spectral analysis. Because of having a better axial and lateral

Ultrasound has become one of the most popular non-destructive characterization tools for soft materials. Compared to conventional ultrasound imaging, quantitative ultrasound has the potential of analyzing detailed microstructural variation through spectral analysis. Because of having a better axial and lateral resolution, and high attenuation coefficient, quantitative high-frequency ultrasound analysis (HFUA) is a very effective tool for small-scale penetration depth application. One of the QUS parameters, peak density had recently shown a promising response with the variation in the soft material microstructure. Acoustic scattering is arguably the most important factor behind different parametric responses in ultrasound spectra. Therefore, to evaluate peak density, acoustic scattering at different frequency levels was investigated. Analytical, computational, and experimental analysis was conducted to observe both single and multiple scattering in different microstructural setups. It was observed that peak density was an effective tool to express different levels of acoustic scattering that occurred through microstructural variation. The feasibility of the peak density parameter was further evaluated in ultrasound C-scan imaging. The study was also extended to detect the relative position of the imaged structure in the direction of wave propagation. For this purpose, a derivative parameter of peak density named mean peak to valley distance (MPVD) was developed to address the limitations of peak density. The study was then focused on detecting soft tissue malignancy. The histology-based computational study of HFUA was conducted to detect various breast tumor (soft tissue) grades. It was observed that both peak density and MPVD parameters could identify tumor grades at a certain level. Finally, the study was focused on evaluating the feasibility of ultrasound parameters to detect asymptotic breast carcinoma i.e., ductal carcinoma in situ (DCIS) in the surgical margin of the breast tumor. In that computational study, breast pathologies were modeled by including all the phases of DCIS. From the similar analysis mentioned above, it was understood that both peak density and MPVD parameters could detect various breast pathologies like ductal hyperplasia, DCIS, and calcification during intraoperative margin analysis. Furthermore, the spectral features of the frequency spectrums from various pathologies also provided significant information to identify them conclusively.
Date Created
2022
Agent

Designing Gradient Scaffolds for Complex Tissue Engineering

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Description
Tissues within the body enable proper function throughout an individual’s life. After severe injury or disease, many tissues do not fully heal without surgical intervention. The current surgical procedures aimed to repair tissues are not sufficient to fully restore functionality.

Tissues within the body enable proper function throughout an individual’s life. After severe injury or disease, many tissues do not fully heal without surgical intervention. The current surgical procedures aimed to repair tissues are not sufficient to fully restore functionality. To address these challenges, current research is seeking new tissue engineering approaches to promote tissue regeneration and functional recovery. Of particular interest, biomaterial scaffolds are designed to induce tissue regeneration by mimicking the biophysical and biochemical aspects of native tissue. While many scaffolds have been designed with homogenous properties, many tissues are heterogenous in nature. Thus, fabricating scaffolds that mimic these complex tissue properties is critical for inducing proper healing after injury. Within this dissertation, scaffolds were designed and fabricated to mimic the heterogenous properties of the following tissues: (1) the vocal fold, which is a complex 3D structure with spatially controlled mechanical properties; and (2) musculoskeletal tissue interfaces, which are fibrous tissues with highly organized gradients in structure and chemistry. A tri-layered hydrogel scaffold was fabricated through layer-by-layer stacking to mimic the mechanical structure of the vocal fold. Furthermore, magnetically-assisted electrospinning and thiol-norbornene photochemistry was used to fabricate fibrous scaffolds that mimic the structural and chemical organization of musculoskeletal interfacial tissues. The work presented in this dissertation further advances the tissue engineering field by using innovative techniques to design scaffolds that recapitulate the natural complexity of native tissues.
Date Created
2021
Agent

Light-Activated Biomaterials for Soft Tissue Sealing and Wound Repair

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Description
Sutures, staples, and tissue glues remain the primary means of tissue approximation and vessel ligation. Laser-activated tissue sealing is an alternative approach that conventionally employs light-absorbing chromophores and nanoparticles for converting near-infrared (NIR) laser to heat. The local increase in

Sutures, staples, and tissue glues remain the primary means of tissue approximation and vessel ligation. Laser-activated tissue sealing is an alternative approach that conventionally employs light-absorbing chromophores and nanoparticles for converting near-infrared (NIR) laser to heat. The local increase in temperature engenders interdigitation of sealant and tissue biomolecules, resulting in rapid tissue sealing. Light-activated sealants (LASE) were developed in which indocyanine green (ICG) dye is embedded within a biopolymer matrix (silk or chitosan) for incisional defect repair. Light-activated tissue-integrating sutures (LATIS) that synergize the benefits of conventional suturing and laser sealing were also fabricated and demonstrated higher efficacies for tissue biomechanical recovery and repair in a full-thickness, dorsal surgical incision model in mice compared to commercial sutures and cyanoacrylate skin glue. Localized delivery of modulators of tissue repair, including histamine and copper, from LASE and LATIS further improved healed skin strength. In addition to incisional wounds, histamine co-delivered with silk fibroin LASE films accelerated the closure of full thickness, splinted excisional wounds in immunocompetent BALB/c mice and genetically obese and diabetic db/db mice, resulting in faster closure than Tegaderm wound dressing. Immunohistochemistry analyses showed LASE-histamine treatment enhanced wound repair involving mechanisms of neoangiogenesis, myofibroblast activation, transient epidermal EMT, and also improve healed skin biomechanical strength which are hallmarks of improved healing outcomes. Benefit of temporal delivery was further investigated of a second therapeutic (growth factor nanoparticles) in modulating wound healing outcomes in both acute and diabetic wounds. The hypothesis of temporal delivery of second therapeutic around the ‘transition period’ in wounds further improved wound closure kinetics and biomechanical recovery of skin strength. Laser sealing and approximation, together with delivery of immunomodulatory mediators, can lead to faster healing and tissue repair, thus reducing wound dehiscence, preventing wounds moving towards chronicity and lowering incidence of surgical site infections, all of which can have significant impact in the clinic.
Date Created
2021
Agent