Prasad, Shalini

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Shalini Prasad is the Cecil H. and Ida Green Professor in Systems Biology Science and Professor of Bioengineering. Dr. Prasad is also the leader of the Department of Bioengineering and the Director of the Biomedical Microdevices and Nanotechnology Lab. Her research is multi-disciplinary and "includes the engineering of multi-functional nanomaterials for designing portable devices and platforms for cellular and molecular diagnostics." The goal is to improve devices for faster, more affordable and accurate diagnosis of cancer, neurodegenerative diseases, and cardiovascular diseases.Learn more about Dr. Prasad on her Endowed Professorships and Chairs, Department of Bioengineering Faculty page and her laboratory website.

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Recent Submissions

Now showing 1 - 12 of 12
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    Enzymatic Low Volume Passive Sweat Based Assays for Multi-Biomarker Detection
    (MDPI, 2019-01-16) Bhide, Ashlesha; Cheeran, Sarah; Muthukumar, Sriram; Prasad, Shalini; Bhide, Ashlesha; Cheeran, Sarah; Prasad, Shalini
    Simultaneous detection of correlated multi-biomarkers on a single low-cost platform in ultra-low fluid volumes with robustness is in growing demand for the development of wearable diagnostics. A non-faradaic biosensor for the simultaneous detection of alcohol, glucose, and lactate utilizing low volumes (1-5 μL) of sweat is demonstrated. Biosensing is implemented using nanotextured ZnO films integrated on a flexible porous membrane to achieve enhanced sensor performance. The ZnO sensing region is functionalized with enzymes specific for the detection of alcohol, glucose, and lactate in the ranges encompassing their physiologically relevant levels. A non-faradaic chronoamperometry technique is used to measure the current changes associated with interactions of the target biomarkers with their specific enzyme. The specificity performance of the biosensing platform was established in the presence of cortisol as the non-specific molecule. Biosensing performance of the platform in a continuous mode performed over a 1.5-h duration showed a stable current response to cumulative lifestyle biomarker concentrations with capability to distinguish reliably between low, mid, and high concentration ranges of alcohol (0.1, 25, 100 mg/dL), glucose (0.1, 10, 50 mg/dL), and lactate (1, 50, 100 mM). The low detection limits and a broader dynamic range for the lifestyle biomarker detection are quantified in this research demonstrating its suitability for translation into a wearable device.
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    Ultrasensitive and Rapid-Response Sensor for the Electrochemical Detection of Antibiotic Residues within Meat Samples
    (American Chemical Society) Stevenson, Hunter S.; Shetty, Shubrath S.; Thomas, Noel J.; Dhamu, Vidram N.; Bhide, Ashlesha; Prasad, Shalini; 0000-0002-2404-3801 (Prasad, S); Stevenson, Hunter S.; Shetty, Shubrath S.; Thomas, Noel J.; Dhamu, Vidram N.; Bhide, Ashlesha; Prasad, Shalini
    Antimicrobial use in livestock has emerged as a pressing global issue because of the rise of antimicrobial-resistant bacteria. Regulatory authorities across the globe have taken steps to discourage the misuse of these antibiotics by banning or limiting the use of medically important antibiotics in food animals. However, to ensure that food animals are not being administered antibiotics inappropriately, there is a need for a reliable, raid-response biosensor that can detect the presence of these antibiotic residuals in meat products. We have developed an affinity-based electrochemical biosensor for the label-free detection of ceftiofur residues in meat samples. The sensor uses a self-assembled immunoassay to target the ceftiofur biomarker by employing electrochemical impedance spectroscopy to probe the interfacial capacitive changes as ceftiofur binds to the sensor surface. We have demonstrated a platform that can detect ceftiofur within 15 min of introducing the sample at concentrations down to 0.01 ng/mL in 1× phosphate-buffered saline and 10 ng/mL in 220 mg ground turkey meat samples. © 2019 American Chemical Society.
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    Screen Printed Graphene Oxide Textile Biosensor for Applications in Inexpensive and Wearable Point-Of-Exposure Detection of Influenza for At-Risk Populations
    (Electrochemical Society Inc.) Kinnamon, David S.; Krishnan, Siddharth; Brosler, Samantha; Sun, Evan; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); 0000-0002-2404-3801 (Prasad, S); Kinnamon, David S.; Krishnan, Siddharth; Brosler, Samantha; Sun, Evan; Prasad, Shalini
    A textile screen-printed biosensor was developed using silver conductive electrodes and graphene oxide transduction film built upon both nanoporous polyamide and consumer utility textiles for the detection of environmental exposure to influenza A virus. An affinity assay was constructed upon the graphene oxide layer to introduce influenza protein-specific antibodies to the sensor surface. Validation of fabrication reproducibility and stability, as well as affinity assay stability, was conducted using electrochemical impedance spectroscopy. The textile sensor was utilized for the detection of influenza A in biofluid analog buffer. Its linear dynamic range was from 10 ng/mL to 10 µg/mL with a limit of detection of 10 ng/mL, spanning both pre- and post-symptomatic ranges. The sensor can be integrated into common textiles and worn by at-risk populations to detect exposure to the virus before symptoms manifest. If integrated with Internet-of-Things reporting platforms, this sensor could have the ability to predict potential influenza outbreaks before broad symptoms manifest, reducing the physical and economic burden of the disease. © The Author(s) 2018.
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    CLASP (Continuous Lifestyle Awareness Through Sweat Platform): A Novel Sensor for Simultaneous Detection of Alcohol and Glucose from Passive Perspired Sweat
    (Elsevier Ltd) Bhide, Ashlesha; Muthukumar, S.; Prasad, Shalini; Bhide, Ashlesha; Prasad, Shalini
    Wearable- IOT based low- cost platforms can enable dynamic lifestyle monitoring through enabling promising and exciting opportunities for wellness and chronic- disease management in personalized environments. Diabetic and pre- diabetic populations can modulate their alcohol intake by tracking their glycemic content continuously to prevent health risks through these platforms. We demonstrate the first technological proof of a combinatorial biosensor for continuous, dynamic monitoring of alcohol and glucose in ultra- low volumes (1–5 µL) of passive perspired sweat towards developing a wearable- IOT based platform. Non-invasive biosensing in sweat is achieved by a unique gold- zinc oxide (ZnO) thin film electrode stack fabricated on a flexible substrate suitable for wearable applications. The active ZnO sensing region is immobilized with enzyme complexes specific for the detection of alcohol and glucose through non- faradaic electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). Biomolecular interactions occurring at the electrode- sweat interface are represented by the impedance and capacitive current changes in response to charge modulations arising in the double layer. We also report the detection of alcohol concentrations of 0.01–100 mg/dl and glucose concentrations of 0.01–50 mg/dl present in synthetic sweat and perspired human sweat. The limit of detection obtained for alcohol and glucose was found to be 0.1 mg/dl in perspired human sweat. Cross- reactivity studies revealed that glucose and alcohol did not show any signal response to cross- reactive molecules. Furthermore, the stable temporal response of the combinatorial biosensor on continuous exposure to passive perspired human sweat spiked with alcohol and glucose over a 120-min duration was demonstrated. © 2018 Elsevier B.V.
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    Simultaneous Lancet-Free Monitoring of Alcohol and Glucose from Low-Volumes of Perspired Human Sweat
    Bhide, Ashlesha; Muthukumar, Sriram; Saini, Amreek; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); 0000-0002-2404-3801 (Prasad, S); Bhide, Ashlesha; Saini, Amreek; Prasad, Shalini
    A lancet-free, label-free biosensor for simultaneous detection of sweat glucose and alcohol was demonstrated using zinc oxide thin films integrated into a nanoporous flexible electrode system. Sensing was achieved from perspired human sweat at low volumes (1-3μL), comparable to ambient conditions without external stimulation. Zinc oxide thin film electrodes were surface functionalized with alcohol oxidase enzyme and with glucose oxidase enzyme towards developing an affinity biosensor specific to the physiological relevant range of alcohol comprising of 0-2 drinks (0-50mg/dl) and physiologically relevant range of glucose ranging from hypo- to hyper-glycaemia (50- 130mg/dl) in perspired human sweat. Sensing was achieved by measuring impedance changes associated with alcohol and glucose binding onto the sensor interface using electrochemical impedance spectroscopy with a dynamic range from 0.01-200mg/dl and a limit of detection of 0.01mg/dl for alcohol in human sweat. Sensor calibration in synthetic sweat containing interferents (25-200mg/dl) and comparison using regression and Bland-Altman analysis of sweat sensor performance was done with BACtrack. Combinatorial detection of glucose and ethanol in perspired human sweat and comparison of sweat sensor performance with Accu-Chek blood glucose monitoring system that we expect would be relevant for pre-diabetics and diabetics for monitoring their glucose levels and alcohol consumption.
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    A New Paradigm in Sweat Based Wearable Diagnostics Biosensors using Room Temperature Ionic Liquids (RTILs)
    (Springer Nature, 2018-05-07) Munjie, Rujuta D.; Muthukumar, Sriram; Jagannath, Badrinath; Prasad, Shalini; Erik Jonsson School of Engineering and Computer Science; Munjie, Rujuta D.; Jagannath, Badrinath; Prasad, Shalini
    Successful commercialization of wearable diagnostic sensors necessitates stability in detection of analytes over prolonged and continuous exposure to sweat. Challenges are primarily in ensuring target disease specific small analytes (i.e. metabolites, proteins, etc.) stability in complex sweat buffer with varying pH levels and composition over time. We present a facile approach to address these challenges using RTILs with antibody functionalized sensors on nanoporous, flexible polymer membranes. Temporal studies were performed using both infrared spectroscopic, dynamic light scattering, and impedimetric spectroscopy to demonstrate stability in detection of analytes, Interleukin-6 (IL-6) and Cortisol, from human sweat in RTILs. Temporal stability in sensor performance was performed as follows: (a) detection of target analytes after 0, 24, 48, 96, and 168 hours post-antibody sensor functionalization; and (b) continuous detection of target analytes post-antibody sensor functionalization. Limit of detection of IL-6 in human sweat was 0.2 pg/mL for 0–24 hours and 2 pg/mL for 24–48 hours post-antibody sensor functionalization. Continuous detection of IL-6 over 0.2–200 pg/mL in human sweat was demonstrated for a period of 10 hours post-antibody sensor functionalization. Furthermore, combinatorial detection of IL-6 and Cortisol in human sweat was established with minimal cross-talk for 0–48 hours post-antibody sensor functionalization.
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    Use of Dicationic Ionic Liquids as a Novel Liquid Platform for Dielectrophoretic Cell Manipulation
    (Royal Society of Chemistry) Taruvai Kalyana Kumar, Rajeshwari; De Mello Gindri, Izabelle.; Kinnamon, David; Rodrigues, Daniele C.; Frizzo, C. P.; Prasad, Shalini; 0000-0002-2404-3801 (Prasad, S); Taruvai Kalyana Kumar, Rajeshwari; De Mello Gindri, Izabelle; Kinnamon, David; Rodrigues, Daniele C.; Prasad, Shalini
    Separation, characterization and analysis of target cells demonstrate critical cues for diagnosis and monitoring of chronic diseases. Electrokinetic cell separation methods have been previously established to have greater efficiency when compared to traditional flow cytometry methods. Ionic liquids show promise in the design of conductive buffers with required electrical properties suitable for electrokinetic manipulation of cells with an enhanced signal to noise ratio (SNR). The goal of this project is to design and test tailored ionic liquid compositions with the hypothesis that dielectrophoretic forces are enhanced on cells while creating an environment for retaining cell integrity. We analysed two uniquely synthesized methylimidazolium based ionic liquids with a low toxicity as conductive suspension buffers for cell separation. These dicationic ionic liquids possess slight electrical and structural differences with high thermal stability. The two ionic liquids were tested for cytotoxicity and their ability to enhance SNR. We validated our hypothesis using osteosarcoma cells Saos-2 and MC3T3-E1 osteoblast cells. The tests were compared against commonly used dielectrophoretic sucrose-isotonic solution. The effects of electrical neutrality, charged particle effects, free charge screening due to ionic liquids from cells were studied using a single-shell model. Effects of ionic liquid and isotonic medium on electrokinetic signal from cells were studied through dielectrophoretic force profiles as a function of non-linear displacement of cells in the two ionic liquids and control media. We observed significant differences in electrokinetic responses between healthy and cancerous cells and steady increase in signal magnitude resulting in enhanced SNR using ILs when compared against sucrose buffer.
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    A Wearable Biochemical Sensor for Monitoring Alcohol Consumption Lifestyle Through Ethyl Glucuronide (EtG) Detection in Human Sweat
    (Nature Publishing Group) Panneer Selvam, Anjan; Muthukumar, Sriram; Kamakoti, Vikramshankar; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); 0000-0002-2404-3801 (Prasad, S); Panneer Selvam, Anjan; Kamakoti, Vikramshankar; Prasad, Shalini
    We demonstrate for the first time a wearable biochemical sensor for monitoring alcohol consumption through the detection and quantification of a metabolite of ethanol, ethyl glucuronide (EtG). We designed and fabricated two co-planar sensors with gold and zinc oxide as sensing electrodes. We also designed a LED based reporting for the presence of EtG in the human sweat samples. The sensor functions on affinity based immunoassay principles whereby monoclonal antibodies for EtG were immobilized on the electrodes using thiol based chemistry. Detection of EtG from human sweat was achieved through chemiresistive sensing mechanism. In this method, an AC voltage was applied across the two coplanar electrodes and the impedance across the sensor electrodes was measured and calibrated for physiologically relevant doses of EtG in human sweat. EtG detection over a dose concentration of 0.001-100  μg/L was demonstrated on both glass and polyimide substrates. Detection sensitivity was lower at 1 μg/L with gold electrodes as compared to ZnO, which had detection sensitivity of 0.001 μg/L. Based on the detection range the wearable sensor has the ability to detect alcohol consumption of up to 11 standard drinks in the US over a period of 4 to 9 hours.;
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    Flexible Nanoporous Tunable Electrical Double Layer Biosensors for Sweat Diagnostics
    Munje, Rujuta D.; Muthukumar, Sriram; Selvam, Anjan Panneer; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); Munje, Rujuta D.; Selvam, Anjan Panneer; Prasad, Shalini
    An ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10–200 ng/mL.
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    A Novel Approach for Electrical Tuning of Nano-Textured Zinc Oxide Surfaces for Ultra-Sensitive Troponin-t Detection
    (The Royal Society of Chemistry) Munje, Ruijuta D.; Jacobs, Michael; Muthukumar, S.; Quadri, Bilal; Shanmugam, Nandhinee Radha; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); Munje, Ruijuta D.; Jacobs, Michael; Quadri, Bilal; Shanmugam, Nandhinee Radha; Prasad, Shalini
    We have developed a label-free, non-faradaic, electrochemical sensor for ultra-sensitive detection of a cardiac biomarker, troponin-T by utilizing the stoichiometric surface compositions of nanotextured zinc oxide (ZnO) thin films. In this study, we show how the performance of a nanotextured zinc oxide based non-faradaic biosensor is modulated by differences in the fabrication parameters of the metal oxide thin film as well as the choice of cross-linkers. Two cross-linking molecules, dithiobis succinimidyl propionate and 3-aminopropyl triethoxysilane, demonstrate significantly different binding chemistries with zinc oxide. The non-faradaic electrochemical behaviour of the sensor due to the two linkers is compared by analyzing the troponin-T dose response using electrochemical impedance spectroscopy (EIS). The sensor performance associated with both linkers is compared based on the dynamic range and limit of detection. The sensor utilizing zinc surface terminations demonstrated a wider dynamic range between the two linkers. This range extended from 26% to 54% in phosphate buffered saline and from 21% to 65% in human serum, for a concentration range from 10 fg mL⁻¹ to 1 ng mL⁻¹ of troponin-T. The limit of detection was found to be at 10 fg mL⁻¹ and has potential utility in the development of point-of-care (POC) diagnostics for cardiovascular diseases. Fluorescence quantification analysis was also performed to further validate the specificity of the linker binding to the ZnO films. An ultrasensitive troponin-T biosensor can be designed by leveraging the zinc termination based surface chemistry for selective protein immobilization.
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    Nanochannel-Based Electrochemical Sensor for the Detection of Pharmaceutical Contaminants in Water
    Nagaraj, V. J.; Jacobs, Michael; Vattipalli, K. M.; Annam, V. P.; Prasad, Shalini
    Effective real-time monitoring is the key to understanding and tackling the issue of pharmaceutical contamination of water. This research demonstrates the utility of an alumina nanochannel-based electrochemical sensor platform for the detection of ibuprofen in water derived from various sources. Our results indicate that the sensor is highly sensitive with a limit of detection at 0.25 pg mL⁻¹. The novel sensor described here has potential for application as a simple, rapid, inexpensive and highly reliable method for real-time environmental water quality assessment.
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    An Electrochemical Sensor for the Detection of Antibiotic Contaminants in Water
    Jacobs, Michael; Nagaraj, V. J.; Mertz, T.; Selvam, Anjan Panneer; Ngo, T.; Prasad, Shalini
    A nanochannel-based electrochemical sensor for the detection of trace amounts of erythromycin has been developed. The sensor is capable of specifically detecting erythromycin, at a sensitivity of 0.001 parts per trillion, in various water samples and has potential utility in the assessment of environmental water quality.

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