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Browsing by Subject "Biosensing Techniques"
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Item Highly specific plasmonic biosensors for ultrasensitive microRNA detection in plasma from pancreatic cancer patients(American Chemical Society, 2014-12-10) Joshi, Gayatri K.; Deitz-McElyea, Samantha; Johnson, Merrell; Mali, Sonali; Korc, Murray; Sardar, Rajesh; Department of Chemistry & Chemical Biology, School of ScienceMicroRNAs (miRs) are small noncoding RNAs that regulate mRNA stability and/or translation. Because of their release into the circulation and their remarkable stability, miR levels in plasma and other biological fluids can serve as diagnostic and prognostic disease biomarkers. However, quantifying miRs in the circulation is challenging due to issues with sensitivity and specificity. This Letter describes for the first time the design and characterization of a regenerative, solid-state localized surface plasmon resonance (LSPR) sensor based on highly sensitive nanostructures (gold nanoprisms) that obviates the need for labels or amplification of the miRs. Our direct hybridization approach has enabled the detection of subfemtomolar concentration of miR-X (X = 21 and 10b) in human plasma in pancreatic cancer patients. Our LSPR-based measurements showed that the miR levels measured directly in patient plasma were at least 2-fold higher than following RNA extraction and quantification by reverse transcriptase-polymerase chain reaction. Through LSPR-based measurements we have shown nearly 4-fold higher concentrations of miR-10b than miR-21 in plasma of pancreatic cancer patients. We propose that our highly sensitive and selective detection approach for assaying miRs in plasma can be applied to many cancer types and disease states and should allow a rational approach for testing the utility of miRs as markers for early disease diagnosis and prognosis, which could allow for the design of effective individualized therapeutic approaches.Item Monitoring focal adhesion kinase phosphorylation dynamics in live cells(Royal Society of Chemistry, 2017-07-24) Damayanti, Nur P.; Buno, Kevin; Narayanan, Nagarajan; Harbin, Sherry L Voytik; Deng, Meng; Irudayaraj, Joseph M.K.; Medicine, School of MedicineFocal adhesion kinase (FAK) is a cytoplasmic non-receptor tyrosine kinase essential for a diverse set of cellular functions. Current methods for monitoring FAK activity in response to an extracellular stimulus lack spatiotemporal resolution and/or the ability to perform multiplex detection. Here we report on a novel approach to monitor the real-time kinase phosphorylation activity of FAK in live single cells by fluorescence lifetime imaging.Item Printed Graphene Electrochemical Biosensors Fabricated by Inkjet Maskless Lithography for Rapid and Sensitive Detection of Organophosphates(ACS, 2018-04-04) Hondred, John A.; Breger, Joyce C.; Alves, Nathan J.; Trammell, Scott A.; Walper, Scott A.; Medintz, Igor L.; Claussen, Jonathan C.; Emergency Medicine, School of MedicineSolution phase printing of graphene-based electrodes has recently become an attractive low-cost, scalable manufacturing technique to create in-field electrochemical biosensors. Here, we report a graphene-based electrode developed via inkjet maskless lithography (IML) for the direct and rapid monitoring of triple-O linked phosphonate organophosphates (OPs); these constitute the active compounds found in chemical warfare agents and pesticides that exhibit acute toxicity as well as long-term pollution to soils and waterways. The IML-printed graphene electrode is nano/microstructured with a 1000 mW benchtop laser engraver and electrochemically deposited platinum nanoparticles (dia. ∼25 nm) to improve its electrical conductivity (sheet resistance decreased from ∼10 000 to 100 Ω/sq), surface area, and electroactive nature for subsequent enzyme functionalization and biosensing. The enzyme phosphotriesterase (PTE) was conjugated to the electrode surface via glutaraldehyde cross-linking. The resulting biosensor was able to rapidly measure (5 s response time) the insecticide paraoxon (a model OP) with a low detection limit (3 nM), and high sensitivity (370 nA/μM) with negligible interference from similar nerve agents. Moreover, the biosensor exhibited high reusability (average of 0.3% decrease in sensitivity per sensing event), stability (90% anodic current signal retention over 1000 s), longevity (70% retained sensitivity after 8 weeks), and the ability to selectively sense OP in actual soil and water samples. Hence, this work presents a scalable printed graphene manufacturing technique that can be used to create OP biosensors that are suitable for in-field applications as well as, more generally, for low-cost biosensor test strips that could be incorporated into wearable or disposable sensing paradigms.Item Wearable biosensors have the potential to monitor physiological changes associated with opioid overdose among people who use drugs: A proof-of-concept study in a real-world setting(Elsevier, 2021-12-01) Roth, Alexis M.; Tran, Nguyen K.; Cocchiaro, Ben; Mitchell, Allison K.; Schwartz, David G.; Hensel, Devon J.; Ataiants, Janna; Brenner, Jacob; Yahav, Inbal; Lankenau, Stephen E.INTRODUCTION: Wearable biosensors have the potential to monitor physiological change associated with opioid overdose among people who use drugs. METHODS: We enrolled 16 individuals who reported ≥ 4 daily opioid use events within the previous 30 day. Each was assigned a wearable biosensor that measured respiratory rate (RR) and actigraphy every 15 s for 5 days and also completed a daily interview assessing drug use. We describe the volume of RR data collected, how it varied by participant characteristics and drug use over time using repeated measures one-way ANOVA, episodes of acute respiratory depression (≤5 breaths/minute), and self-reported overdose experiences. RESULTS: We captured 1626.4 h of RR data, an average of 21.7 daily hours/participant over follow-up. Individuals with longer injection careers and those engaging in polydrug use captured significantly fewer total hours of respiratory data over follow-up compared to those with shorter injections careers (94.7 vs. 119.9 h, p = 0.04) and injecting fentanyl exclusively (98.7 vs. 119.5 h, p = 0.008), respectively. There were 385 drug use events reported over follow-up. There were no episodes of acute respiratory depression which corresponded with participant reports of overdose experiences. DISCUSSION: Our preliminary findings suggest that using a wearable biosensor to monitor physiological changes associated with opioid use was feasible. However, more sensitive biosensors that facilitate triangulation of multiple physiological data points and larger studies of longer duration are needed.