Matching Items (22)
Description
Cardiac tissue engineering is an emerging field that has the potential to regenerate and repair damaged cardiac tissues after myocardial infarction. Numerous studies have introduced hydrogel-based cardiac tissue constructs featuring suitable microenvironments for cell growth along with precise surface topographies for directed cell organization. Despite significant progress, previously developed cardiac tissue constructs have suffered from electrically insulated matrices and low cell retention. To address these drawbacks, we fabricated micropatterned hybrid hydrogel constructs (uniaxial microgrooves with 50 µm with) using a photocrosslinkable gelatin methacrylate (GelMA) hydrogel incorporated with gold nanorods (GNRs). The electrical impedance results revealed a lower impedance in the GelMA-GNR constructs versus the pure GelMA constructs. Superior electrical conductivity of GelMA-GNR hydrogels (due to incorporation of GNRs) enabled the hybrid tissue constructs to be externally stimulated using a pulse generator. Furthermore, GelMA-GNR tissue hydrogels were tested to investigate the biological characteristics of cultured cardiomyocytes. The F-actin fiber analysis results (area coverage and alignment indices) revealed higher directed (uniaxial) cytoskeleton organization of cardiac cells cultured on the GelMA-GNR hydrogel constructs in comparison to pure GelMA. Considerable increase in the coverage area of cardiac-specific markers (sarcomeric α-actinin and connexin 43) were observed on the GelMA-GNR hybrid constructs compared to pure GelMA hydrogels. Despite substantial dissimilarities in cell organization, both pure GelMA and hybrid GelMA-GNR hydrogel constructs provided a suitable microenvironment for synchronous beating of cardiomyocytes.
ContributorsMoore, Nathan Allen (Author) / Nikkhah, Mehdi (Thesis director) / Smith, Barbara (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Patch-clamp electrophysiology is the current gold-standard technique for obtaining high-resolution recordings of neuronal activity in vivo. However, robotic technologies recently developed to automate these labor-intensive and low-throughput experiments are limited to superficial regions of the brain or lack cell type specific-targeting (Kodandaramaiah et al., 2012; Suk et al., 2017; Annecchino et al., 2017) . In this work, a new approach for automatically navigating patch-clamp micropipette electrodes using fluorescence feedback collected at the electrode aperture was developed and validated in vitro. In future efforts, an internal excitation source will be integrated into the system to enable micropipette navigation at any electrode-accessible depth and the system will be tested in vivo using fluorescence feedback from cell type-specific labels.
ContributorsHowell, Madeleine R. (Author) / Smith, Barbara (Thesis director) / Anderson, Trent (Committee member) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Mycobacterium tuberculosis is the primary bacteria responsible for tuberculosis, one of the most dangerous diseases, and top causes of death worldwide, as identified by the World Health Organization in a 2018 report. Diagnostic tools currently exist for identifying those who carry active or latent versions of the infection including chest radiographs, a Mantoux tuberculin skin test, or an acid-fast bacilli smear of sputum samples. These methods are standard in the medical community of high income countries, but pose challenges for lower-income regions of the world as well as vulnerable populations. The need for a rapid, inexpensive, and non-invasive method of tuberculosis detection is evident by the ten million that contracted and 1.6 million that died from TB in 2017 alone. In our study, we used a previously developed nanoplasmon-enhanced scattering technology combined with dark field microscopy in order to investigate the potential for a blood-based TB detection assay. Twenty-eight capture antibodies were screened using cell culture exosomes and human serum samples to identify candidates for a TB-derived exosome biomarker. Four antibodies demonstrated potential for distinguishing negative controls from positive controls in this study: anti-AG85, anti-AG85B, anti-SodA, anti-Ald. These capture antibodies displayed significant differences (p<0.05) for both cell culture exosomes and human serum samples on more than one occasion. The work is significant in its ability to distinguish potential capture antibody targets, and future experimentation may yield a technology ready for clinical settings to address the gap in current TB detection methods.
ContributorsWalls, Robert (Author) / Hu, Tony (Thesis director) / Fan, Jia (Committee member) / School of Molecular Sciences (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
The optimization of a blood-based assay for diagnosing tuberculosis which has been developed and validated in Dr. Hu’s lab, at Arizona State University, is important for ensuring its successful translation to a resource-limited setting of the developing world. Tuberculosis is most prevalent in the developing world with Sub-Saharan Africa having the highest cases of HIV/TB coinfections. The implementation of a blood-based assay for diagnosing Tuberculosis in the sub-Saharan would significantly improve the diagnosis and treatment monitoring of tuberculosis thereby managing or eliminating the pandemic altogether. The World Health Organization has called for robust diagnostic technologies that would resolve the shortfalls of the current technologies which include GeneXpert, X-ray, and smear microscopy. The blood-based diagnostic methodology heavily relies on Mass-spectrometry, a technology which could be entirely novel and expensive to implement in most laboratories in the Sub-Saharan. Despite virtual challenges in implementing the technology, the assay has demonstrated high specificity and sensitivity to HIV/TB coinfected patients and children in comparison to the available TB diagnostic assays. This study endorses the Blood-based Mass Spectrometry assay as one of the promising technologies to effectively improve the diagnosis of TB. The performance of the assay on detecting TB antigens was tested using different methods and materials. In the end, the use of DBS and miniaturized mass spectrometers have been discussed as possible routes for translating the assay to the developing world
ContributorsTwaibu, Jaffalie (Author) / Hu, Tony (Thesis director) / Shu, Qingbo (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Over the past 20 years, the fields of synthetic biology and synthetic biosystems engineering have grown into mature disciplines, leading to significant breakthroughs in cancer research, diagnostics, cell-based medicines, biochemical production, etc. Application of mathematical modelling to biological and biochemical systems have not only given great insight into how these systems function, but also have lent enough predictive power to aid in the forward-engineering of synthetic constructs. However, progress has been impeded by several modes of context-dependence unique to biological and biochemical systems that are not seen in traditional engineering disciplines, resulting in the need for lengthy design-build-test cycles before functional prototypes are generated.In this work, two of these universal modes of context dependence – resource competition and growth feedback –their effects on synthetic gene circuits and potential control mechanisms, are studied and characterized. Results demonstrate that a novel competitive control architecture can be utilized to mitigate the effects of winner-take-all resource competition (a form of context dependence where distinct gene modules influence each other by competing over a shared pool of transcriptional/translational resources) in synthetic gene circuits and restore circuits to their intended function. Application of the fluctuation-dissipation theorem and rigorous stochastic simulations demonstrate that realistic resource constraints present in cells at the transcriptional and translational levels influence noise in gene circuits in a nonmonotonic fashion, either increasing or decreasing noise depending on the transcriptional/translational capacity.
Growth feedback on the other hand links circuit function to cellular growth rate via increased protein dilution rate during exponential growth phase. This in turn can result in the collapse of bistable gene circuits as the accelerated dilution rate forces switches in a high stable state to fall to a low stable state. Mathematical modelling and experimental data demonstrate that application of repressive links can insulate sensitive parts of gene circuits against growth-fluctuations and can in turn increase the robustness of multistable circuits in growth contexts.
The results presented in this work aid in the accumulation of understanding of biological and biochemical context dependence, and corresponding control strategies and design principles engineers can utilize to mitigate these effects.
ContributorsStone, Austin (Author) / Tian, Xiao-jun (Thesis advisor) / Wang, Xiao (Committee member) / Smith, Barbara (Committee member) / Kuang, Yang (Committee member) / Cheng, Albert (Committee member) / Arizona State University (Publisher)
Created2023
Description
Safety and efficacy of neuromodulation are influenced by abiotic factors like failure of implants, biotic factors like tissue damage, and molecular and cellular mechanisms of neuromodulation. Accelerated lifetime test (ALT) predict lifetime of implants by accelerating failure modes in controlled bench-top conditions. Current ALT models do not capture failure modes involving biological mechanisms. First part of this dissertation is focused on developing ALTs for predicting failure of chronically implanted tungsten stimulation electrodes. Three factors used in ALT are temperature, H2O2 concentration, and amount of charge delivered through electrode to develop a predictive model of lifetime for stimulation electrodes. Second part of this dissertation is focused on developing a novel method for evaluating tissue response to implants and electrical stimulation. Current methods to evaluate tissue damage in the brain require invasive and terminal procedures that have poor clinical translation. I report a novel non-invasive method that sampled peripheral blood monocytes (PBMCs) and used enzyme-linked immunoassay (ELISA) to assess level of glial fibrillary acidic protein (GFAP) expression and fluorescence-activated cell sorting (FACS) to quantify number of GFAP expressing PBMCs. Using this method, I was able to detect and quantify GFAP expression in PBMCs. However, there was no statistically significant difference in GFAP expression between stimulatory and non-stimulatory implants. Final part of this dissertation assessed molecular and cellular mechanisms of non-invasive ultrasound neuromodulation approach. Unlike electrical stimulation, cellular mechanisms of ultrasound-based neuromodulation are not fully known. Final part of this dissertation assessed role of mechanosensitive ion channels and neuronal nitric oxide production in cell cultures under ultrasound excitation. I used fluorescent imaging to quantify expression of nitric oxide in neuronal cell cultures in response to ultrasound stimulation. Results from these experiments indicate that neuronal nitric oxide production increased in response to ultrasound stimulation compared to control and decreased when mechanosensitive ion channels were suppressed. Two novel methods developed in this dissertation enable assessment of lifetime and safety of neuromodulation techniques that use electrical stimulation through implants. The final part of this dissertation concludes that non-invasive ultrasound neuromodulation may be mediated through neuronal nitric oxide even in absence of activation of mechanosensitive ion channels.
ContributorsVoziyanov, Vladislav (Author) / Muthuswamy, Jitendran (Thesis advisor) / Smith, Barbara (Committee member) / Greger, Bradley (Committee member) / Abbas, James (Committee member) / Okandan, Murat (Committee member) / Arizona State University (Publisher)
Created2022
Description
Advancing the understanding and treatment of many neurological disorders can be achieved by improving methods of neuronal detection at increased depth in the mammalian brain. Different cell subtypes cannot be detected using non-invasive techniques beyond 1 mm from cortical surface, in the context of targeting particular cell types in vivo (Wang, 2012). These limitations in the depth of imaging and targeting are due to optical scattering (Ntziachristos, 2010). In order to overcome these restrictions, longer wavelength fluorescent proteins have been utilized by researchers to see tagged cells at depth. Optical techniques such as two-photon and confocal microscopy have been used in combination with fluorescent proteins to expand depth, but are still limited by the penetration depth of light due to optical scattering (Lee, 2015). This research aims to build on other detection methods, such as the photoacoustic effect and automated fluorescence-guided electrophysiology, to overcome this limitation.
ContributorsAridi, Christina (Author) / Smith, Barbara (Thesis director) / Marschall, Ethan (Committee member) / Barrett, The Honors College (Contributor) / Watts College of Public Service & Community Solut (Contributor) / Harrington Bioengineering Program (Contributor)
Created2023-05
Description
Growing interest in using volatile organic compounds (VOCs) as markers of biological function and health has highlighted the need for a standardized method to analyze gas metabolites released by biological organisms. Non-destructive VOC collection techniques have emerged, allowing researchers to study diseases over time without compromising the sample. However, continuous sampling is often not performed, and previous systems have not undergone rigorous testing. To overcome current limitations, we developed a gas flow-based device and tested it for consistent headspace sweeping, cell viability and morphology, and detection accuracy. The results showed that the device offers a high degree of reproducibility, and our modeling shows that laminar flow conditions are maintained at experimental gas flow rates, ensuring consistent headspace sweeping. Furthermore, our modular design allowed us to adjust the temperature and input gas, allowing us to maintain a favorable environment for cell culture. Isotopic labeling and heavy VOC production confirmed that the system achieves sufficient sensitivity and reproducibility to monitor metabolic changes across time. This comprehensive evaluation demonstrates that our flow-based device has great potential in further research and subsequent clinical applications.
ContributorsAmbrose, Benjamin (Author) / Smith, Barbara (Thesis director) / Eshima, Jarrett (Committee member) / Barrett, The Honors College (Contributor) / Department of Physics (Contributor)
Created2023-05
Description
Breast cancer can be imaged at greater depths using photoacoustic imaging to differentiate between cancerous and non-cancerous tissue. Current photoacoustic modalities struggle to display images in real-time because of the required image reconstruction. In this work, we aim to create a real-time photoacoustic imaging system where the photoacoustic effect is detected through changes in index of refraction. To reach this aim, two methods are applied to visualize the acoustic waves including Schlieren optics and differential interference contrast microscopy. This combined approach provides a new tool for the widespread application in clinical settings.
ContributorsSmetanick, Derek (Author) / Burgett, Joshua (Co-author) / Smith, Barbara (Thesis director) / Muthuswamy, Jitendran (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor) / School of Life Sciences (Contributor)
Created2022-05
Description
Tumor resectioning is a primary method for cancer treatment but is limited by the inability of surgeons to differentiate tissue, which results in the unnecessary removal of healthy tissue. One method that is uniquely suited to circumvent this issue is photoacoustic imaging. However, this technique lacks real time imaging capabilities which are critical for surgical applications. This work explores the development of a real-time optical imaging tool that utilizes optical detection of an acoustic signal. Determining healthy vs unhealthy tissue will enable improved clinical patient outcomes.
ContributorsBurgett, Joshua (Author) / Smith, Barbara (Thesis director) / Takahashi, Timothy (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2022-05