Browsing by Subject "biosensor"

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    Bottom-Up Fabrication of Plasmonic Nanoantenna-Based High-throughput Multiplexing Biosensors for Ultrasensitive Detection of microRNAs Directly from Cancer Patients’ Plasma
    (ACS, 2020) Masterson, Adrianna N.; Liyanage, Thakshila; Kaimakliotis, Hristos; Derami, Hamed Gholami; Deiss, Frédérique; Sardar, Rajesh; Chemistry and Chemical Biology, School of Science
    There is an unmet need in clinical point-of-care (POC) cancer diagnostics for early state disease detection, which would greatly increase patient survival rates. Currently available analytical techniques for early stage cancer diagnosis do not meet the requirements for POC of a clinical setting. They are unable to provide the high demand of multiplexing, high-throughput, and ultrasensitive detection of biomarkers directly from low volume patient samples (“liquid biopsy”). To overcome these current technological bottle-necks, herein we present, for the first time, a bottom-up fabrication strategy to develop plasmonic nanoantenna-based sensors that utilize the unique localized surface plasmon resonance (LSPR) properties of chemically synthesized gold nanostructures, gold triangular nanoprisms (Au TNPs), gold nanorods (Au NRs), and gold spherical nanoparticles (Au SNPs). Our Au TNPs, NRs, and SNPs display refractive index unit (RIU) sensitivities of 318, 225, and 135 nm/RIU respectively. Based on the RIU results, we developed plasmonic nanoantenna-based multiplexing and high-throughput biosensors for the ultrasensitive assay of microRNAs. MicroRNAs are directly linked with cancer development, progression, and metastasis, thus they hold promise as next generation biomarkers for cancer diagnosis and prognosis. The developed biosensors are capable of assaying five different types of microRNAs at an attomolar detection limit. These sets of microRNAs include both oncogenic and tumor suppressor microRNAs. To demonstrate the efficiency as a POC cancer diagnostic tool, we analyzed the plasma of 20-bladder cancer patients without any sample processing steps. Importantly, our liquid biopsy-based biosensing approach is capable of differentiating healthy from early (“non-metastatic”) and late (“metastatic”) stage cancer with a p value <0.0001. Further, receiver operating characteristic analysis shows that our biosensing approach is highly specific, with an area under the curve of 1.0. Additionally, our plasmonic nanoantenna-based biosensors are regenerative, allowing multiple measurements using the same biosensors, which is essential in low- and middle-income countries. Taken together, our multiplexing and high-throughput biosensors have the unmatched potential to advance POC diagnostics and meet global needs for early stage detection of cancer and other diseases (e.g., infectious, autoimmune, and neurogenerative diseases).
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    β-Cell Autophagy in the Pathogenesis of Type 1 Diabetes
    (2021-12) Muralidharan, Charanya; Linnemann, Amelia K.; Dong, Charlie X.; Sims, Emily K.; Kaplan, Mark H.
    Type 1 diabetes (T1D) is a multifactorial disease involving genetic and environmental factors. One of the factors implicated in disease pathogenesis is early life viral infection. A typical immune response to viral infection includes production of type 1 interferons (IFN), such as IFN-α, which can induce stress in the pancreatic β-cells. Reactive oxygen species (ROS) accumulation occurs after exposure to other inflammatory cytokines, causing oxidative stress that may be linked to T1D pathogenesis. Therefore, we hypothesized that IFN-α may also elicit β-cell ROS accumulation. Our in vivo and in vitro experiments with human islets showed rapid and heterogenous ROS accumulation with IFN-α. Although T1D is characterized by autoimmune destruction of β-cells, some cells survive this persistent attack. We hypothesized that survival/ death of β-cells could be attributed to the ability to effectively mitigate ROS accumulation. One mechanism to mitigate ROS is autophagy, which degrades and recycles cellular components to promote cellular homeostasis. We observed an impairment in autophagy in β-cells of donors with T1D as well as in islets of diabetic non-obese diabetic (NOD) mouse model of autoimmune diabetes. Autophagic flux was also impaired in diabetic NOD mouse islets, further confirming impairment of autophagy. Interestingly, we observed an induction of autophagy after acute treatment with IFN-α both in vitro and in vivo, suggesting compensatory upregulation of autophagy to restore homeostasis. Similarly, we observed an increase in autophagosomes and telolysosomes in β-cells of normoglycemic autoantibody positive organ donors compared to nondiabetic organ donors. Together, these data implicate a defect in the final degradation step of autophagy involving lysosomes. Therefore, we analyzed the activity and expression of lysosomal cysteine protease Cathepsin H (CTSH, a T1D susceptibility locus), and found both to be increased in islets of pre-diabetic NOD mice. Together, these data support compensatory hyperactivation of lysosomal enzymes prior to overt diabetes, potentially to rid the cell of ROS and degradation-resistant oxidized proteins and lipids. We also observed that C57Bl/6J mice lacking a key autophagy enzyme, ATG7, in their β-cells, spontaneously developed hyperglycemia. Collectively, these data highlight the importance of -phagic degradation process in the pathogenesis of T1D.