ScholarWorks@UMassAmherst
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Recent Submissions
Publication CIE Newsletter - 2006(Center for International Education, UMass Amherst, 2006-12)Publication Graphene-Based Nanomaterials for Advancing Biosensing and Biocontrol(2024-09)The development of techniques for detecting and regulating biomolecules and cells is crucial in clinical diagnostics and biological research. Elevated by significant advancements in materials science, electronics, and optics, the methodologies for detecting and modulating biomolecules and cells have achieved remarkable enhancements in sensitivity, specificity and reliability. However, combining all the necessary properties for electrode materials—including high transparency, high conductivity, biocompatibility, chemical stability, low impedance, and low cost— into a single material system remains a challenge for achieving high-performance biosensing and biocontrol. By synthesizing graphene-based nanomaterials with exceptional properties and applying them to interface with biological systems, this dissertation addresses this challenge and demonstrates advancements in biological sensing and control. For protein analysis, I utilize monolayer graphene microelectrodes in microfluidic devices for electrokinetic focusing and sensing of proteins. The electrolysis stability of graphene electrodes is >103× improved compared to typical microfabricated inert-metal microelectrodes. The reliable pH gradient between a pair of biased graphene microelectrodes enables the separation and concentration of specific proteins into narrow band (~100 micrometers) within minutes. The high optical transparency of graphene allows for label-free detection of the proteins at same processing position with sensitivity ~100× higher than those of the state-of-the-art label-free sensors. For cell action potential measurement, I synthesized whisker-like multiwalled carbon nanotubes on monolayer graphene surface via chemical vapor deposition using nanoparticle catalysts. The carbon nanotubes and substrate graphene share the same fermi level, and the hybrid material retains electrical mobility comparable to that of bare graphene. The carbon-nanotube structures enhance capacitive and resistive by 80× and 7×, respectively, serving as the primary transducing pathway and improving the signal-to-noise ratio for detecting extracellular cardiomyocytic action potentials by 2.5×. Furthermore, the enhancement of electric field at the carbon-nanotube structures enables low-bias (~4 V) nano-electroporation and the recording of intracellular action potentials. Future research in this area includes utilizing isoelectric focusing to analyze viruses and bacteria in our devices, and developing controllable capture and release systems to detect target molecules. Additionally, we aim to measure intracellular action potentials of neurons and investigate gene delivery to cancer cells using our CNT-graphene-based devices.Publication Impact of Fish Oil Intake and Hyperthermia Therapy on Metabolic Health(2024-09)Aging is a major contributor to decreased metabolic rate, underscoring the need to develop effective strategies to combat this decline. Interventions that combine lifestyle adjustments with dietary strategies could be particularly effective in reducing the risks of metabolic dysfunction. Hyperthermia/heat treatment (HT) is a therapeutic practice that has been demonstrated to provide a variety of metabolic benefits. Fish oil (FO) is a potent dietary intervention that promotes metabolic health. However, whether HT could promote metabolic health by combating aging-associated metabolic slowdown and the combinational effect of FO and HT have not yet been evaluated. The first aim was to investigate the impact of HT on aging-associated metabolic dysfunction and to determine the underlying molecular mechanisms, including potential associations with gut microbiota. Next, we also aimed to unravel the synergistic effect of HT and FO supplementation on aging-related obesity and metabolic dysfunction in both aged female mice and ovariectomized (OVX) mice. Our overarching hypothesis was that HT and FO synergistically improve metabolic health by promoting energy expenditure and improving insulin sensitivity and inflammation response in aging and menopause. Our findings indicate that daily HT at 40-41℃ for 30 min showed no tissue damage and significantly reduced lactate dehydrogenase (LDH) levels in older females, indicating a decline in aging-mediated tissue damage. HT effectively countered weight gain induced by a high-fat diet in both aged female and ovariectomized mice. Furthermore, HT demonstrated significant improvements in 1) insulin sensitivity and insulin signaling in inguinal white adipose tissue (iWAT), 2) reduced lipid accumulation in the liver and brown fat, and 3) increased fatty acid beta-oxidation in the liver and iWAT. An increase in the expression of transient receptor potential vanilloid 1 (TRPV1) and genes associated with Ca2+/ATP-pump on the plasma membrane and endoplasmic reticulum (ER) suggests that HT triggers ATP-consuming futile calcium cycling. These findings were confirmed in human brown adipocytes. HT alone notably lowered core body temperature (~0.5℃) across all diets, leading to a reduced Firmicutes to Bacteroidetes ratio and significant changes in gut microbiome diversity and composition. Additionally, microbiota genera Tuzzerella, Defluviitaleaceae_UCG-011, Alistipes, and Enterorhabdus were significantly correlated with liver, brown adipose tissue weights, and core body temperature. The combination of HT and FO showed a more substantial improvement in metabolic health and insulin sensitivity. Additionally, FO supplementation significantly increased the abundance of [Eubacterium]_coprostanoligenes_group, a genus known for reducing cholesterol absorption and associated with lower plasma lipids and body weight. HT and FO intake correlated with a decrease in Alistipes, which are usually present with obesity and inflammation conditions. In the OVX mice, Colidextribacter and Muribaculaceae showed increased abundance in the HT group compared to the CON group. FO combined with HT increased the abundance of the microbial genera [Eubacterium]_coprostanoligenes_group, Bacteroides, and Incertae_Sedis, which negatively correlated with core body temperature. HT, FO, or the combination of HT and FO, did not have a similar effect in OVX mice compared to the aged female mice, suggesting a potential effect of the absence of estrogen on the microbiota. Overall, the findings of this dissertation demonstrate that HT and FO supplementation, independently and in combination, significantly enhance metabolic health by improving insulin sensitivity, promoting thermogenic energy expenditure, and modulating gut microbiota diversity and composition. The combinational effects of HT and FO are more potent in aged female mice compared to the OVX mouse model of menopause.Publication Controlling Reactivity and Triggerability Using Intramolecular and Ad Hoc Electrostatic Interactions(2024-09)Electrostatic interactions play a vital role in natural design principles. An extraordinary amount of impact of such interactions also can be observed in evolutionary biology. The profound impact of these interactive forces underscores their pivotal role, yet there remains ample scope to develop our grasp of the bases that regulate and manipulate these interactions. Enriched intellectual capacity regarding electrostatic interactions will enable their more sophisticated and effective application across diverse platforms, unlocking new avenues and innovations. This dissertation reviews charge-based interactions at the molecular level and presents three perspectives on their fundamental and practical applications. The dissertation focuses on three key aspects i) studying intramolecular electrostatic interactions in tertiary amine-based zwitterionic structures, showing how these interactions affect reaction kinetics and nanostructure formation ii) developing hybrid lipid-polymer nanoparticles for RNA delivery using a ‘de-cationizable’ non-viral design, highlighting the separate roles of encapsulation and intracellular trafficking in optimizing delivery vectors. It also creates a unique opportunity to impose targeted delivery capabilities for selective treatment of excruciating diseases like triple-negative breast cancer, using a two-factor authentication approach for enhanced selectivity and efficacy. iii) Additionally, the dissertation explores improving electroporation in T-cells with anionic polymers attached to targeting antibodies, aimed at enhancing targeted cell therapies. Finally, this thesis summarizes these findings and discusses prospects, emphasizing the multifaceted roles of electrostatic interactions in biomedical research.Publication Critical Minerals and the Green Transition(2024-09)One major issue in the global green transition—i.e. in advancing a viable global climate stabilization path—is the massive increase in demand for electric vehicles (EVs). The growing demand for EVs in turn, generates a commensurate demand increase for the minerals needed to operate the batteries that power EVs. These minerals critical for the operation of EV batteries include lithium, cobalt, and nickel. This dissertation examines a range of questions resulting from the ongoing huge expansion in the global demand for these three critical minerals. The first chapter builds from the International Energy Agency’s (IEA) framework to estimate the requirements for lithium, cobalt, and nickel used in electric vehicle batteries in the IEA’s Net Zero Emissions by 2050 scenario. According to my analysis, demand for these minerals will far outstrip the estimates of supply under current industry conditions, thereby creating a demand-supply gap for these minerals. The chapter reviews alternative approaches to closing this gap. The second chapter explores the factors that have enabled China to dominate at present the global production and supply chain of critical minerals. I argue that the most basic explanation is that China developed effective industrial policies from the 1980s onward to create capacity for supplying the global economy with EVs and the batteries that power them. Among other resources, I draw here on Chinese government documents and data on state funding for innovation. Using mergers and acquisitions data, I also document various ways through which Chinese corporations have secured critical mineral supply chains. The third chapter documents the impact of critical mineral mining on a selected set of mineral-rich economies, in particular, Chile, Indonesia, and Congo. I utilize data on social conflicts that have resulted from mining operations in these economies to understand the impact of mining on conditions for mine workers and communities. I also explore ways through which state ownership and distribution of resources can provide net benefits to local communities. Such benefits do not result when mining operations are controlled by private multinational corporations along with governments that align themselves primarily with the interests of the multinationals.
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