9 results on '"Monika Schechinger"'
Search Results
2. A SERS approach for rapid detection of microRNA-17 in the picomolar range
- Author
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Mahua Choudhury, Monika Schechinger, Samuel Mabbott, Gerard L. Coté, and Haley L. Marks
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Silver ,Metal Nanoparticles ,Nanotechnology ,02 engineering and technology ,Spectrum Analysis, Raman ,01 natural sciences ,Biochemistry ,Rapid detection ,Analytical Chemistry ,Functionalized nanoparticles ,Pre-Eclampsia ,Limit of Detection ,Pregnancy ,microRNA ,Electrochemistry ,Animals ,Environmental Chemistry ,Spectroscopy ,Epigenetic biomarkers ,Chemistry ,010401 analytical chemistry ,Early disease ,Nucleic Acid Hybridization ,DNA ,Surface-enhanced Raman spectroscopy ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,MicroRNAs ,Biomarker (medicine) ,Cattle ,Female ,Spectrum analysis ,DNA Probes ,0210 nano-technology ,Biomarkers - Abstract
Epigenetic biomarkers are powerful tools for early disease detection and are particularly useful for elusive conditions like preeclampsia. Predicting preeclampsia at an early stage is one of the most important goals of maternal-fetal medicine. To this end, recent studies have identified microRNAs-such as microRNA-17-as early biomarkers for preeclampsia. Yet clinical applications are lagging, owing in part to the sensing challenges presented by the biomarkers' small size and complex environment. Surface enhanced Raman spectroscopy (SERS) is an emergent optical technique that is recognized for its potential to overcome these challenges. In this study, DNA functionalized nanoparticles were designed as probes to capture and quantify miRNA-17 in solution. SERS was used to determine the presence and concentration of miRNA-17 based on the formation of plasmonic nanoparticle aggregates. The miRNA-17 assay was tested at concentrations of 1 pM to 1 nM in both PBS and a representative complex biological sample. In both situations the assay was unaffected by non-complementary microRNA samples. These results demonstrate SERS's specificity and sensitivity for a new biomarker (miRNA-17) that may ultimately be used in a detection platform for early diagnosis of preeclampsia.
- Published
- 2019
3. Development of a paper microfluidic surface enhanced Raman scattering assay for cardiac troponin I
- Author
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Monika Schechinger, Allison Holderby, Gerard L. Coté, John C. Dean, and Dandan Tu
- Subjects
Analyte ,symbols.namesake ,Cardiac troponin ,Chemistry ,Aptamer ,Troponin I ,Microfluidics ,symbols ,Surface-enhanced Raman spectroscopy ,Sensing system ,Raman scattering ,Biomedical engineering - Abstract
The accurate and rapid diagnosis of myocardial infarction (MI) is essential to implement timely and definitive treatment to the patient. Cardiac Troponin I (cTnI) has been widely used as a biomarker for early diagnosis of MI. Point-of-care (POC) testing is favored because it can provide timely results when the patient is first encountered (e.g. ambulance, clinic, or emergency department). However, the clinical cut-off of cTnI for diagnosis of MI is in the pico- to femtomolar range (i.e. 0.01-0.1 ng/ml). Thus, a sensitive sensing system is needed to quantitively measure cTnI at the POC. Surface-enhanced Raman spectroscopy (SERS) is a sensitive optical technique that can be used to measure trace analytes in a sample. Moreover, paper-based sensing systems have demonstrated potential as a platform to implement assays, especially at the POC. This research describes the development of a paper-based SERS assay for detection of cTnI in the physiological relevant range. Aptamer is used in the assay for recognizing the cTnI in a sample. SERS is used to sensitively transduce the sensing signal from the assay. A handheld Raman spectrometer is used to measure the SERS signal. By measuring the change in the SERS signal, the concentration of target molecule is quantitatively determined. Moreover, spectral processing techniques are used to evaluate their effect on signal-to-noise ratio as well as sensitivity of the assay. Results showed the designed sensing system can be used to measure cTnI (0-0.5 ng/mL) in standard buffer solutions.
- Published
- 2020
4. Detection of cardiovascular disease associated miR-29a using paper-based microfluidics and surface enhanced Raman scattering
- Author
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Charles R. Mace, Gerard L. Coté, Karen Faulds, Monika Schechinger, Syrena C. Fernandes, Duncan Graham, and Samuel Mabbott
- Subjects
Paper ,Point-of-care testing ,Microfluidics ,Myocardial Infarction ,Metal Nanoparticles ,Spectrum Analysis, Raman ,Biochemistry ,Analytical Chemistry ,Qualitative feedback ,symbols.namesake ,Limit of Detection ,Electrochemistry ,Rosaniline Dyes ,Environmental Chemistry ,Humans ,QD ,Spectroscopy ,Detection limit ,Reproducibility ,Spectrometer ,Paper based ,MicroRNAs ,Point-of-Care Testing ,symbols ,Gold ,Raman scattering ,Biomedical engineering - Abstract
The development of viable point-of-care diagnostic formats is integral to achieving better patient care and improved outcomes. The need for robust and low-cost tests is especially important in under-resourced and rural settings. Perhaps the greatest challenge is ensuring that an untrained individual is capable of operating and interpreting the test, out with a care facility. Here we present a paper-based diagnostic device capable of sensing miR-29a using both colorimetric and surface enhanced Raman scattering (SERS) analysis. Rather, than carry out the two types of analyses in tandem, we envisage that the colorimetric output is easy enough to be interpreted by the untrained-individual administering the test to provide them with qualitative feedback. If deemed positive, the test can be further validated at a centralized care facility using a handheld-Raman spectrometer to provide a semi-quantitative result. Detection of miR-29a, a microRNA associated with myocardial infarction, was achieved at a level of pg μL-1 through the combination of three-dimensional paper-based microfluidics, colorimetric detection, and surface enhanced Raman scattering (SERS) analysis. RGB analysis of the colorimetric output generated from samples containing miR-29a at different concentrations (18-360 pg μL-1) showed differentiation from the control sample, however significant repeat variability indicated that it could not be used for quantifying miR-29a levels. However, the SERS analysis exhibited greater reproducibility at varying concentrations, achieving an LoD of 47 pg μL-1. The union of the paper-based device and the two analysis methods resulted in the production of a sensitive, reproducible and facile, point of care test (POCT), which paves the way for future implementation in the diagnosis of a range of diseases.
- Published
- 2019
5. Surface enhanced Raman spectroscopy (SERS) for in vitro diagnostic testing at the point of care
- Author
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Gerard L. Coté, Javier T. Garza, Monika Schechinger, Andrea K. Locke, and Haley L. Marks
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Physics ,QC1-999 ,010401 analytical chemistry ,optical biosensing ,Nanotechnology ,02 engineering and technology ,Surface-enhanced Raman spectroscopy ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,In vitro diagnostic ,point of care ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Nanomaterials ,surface enhanced raman spectroscopy ,Electrical and Electronic Engineering ,0210 nano-technology ,Biotechnology ,Point of care - Abstract
Point-of-care (POC) device development is a growing field that aims to develop low-cost, rapid, sensitivein-vitrodiagnostic testing platforms that are portable, self-contained, and can be used anywhere – from modern clinics to remote and low resource areas. In this review, surface enhanced Raman spectroscopy (SERS) is discussed as a solution to facilitating the translation of bioanalytical sensing to the POC. The potential for SERS to meet the widely accepted “ASSURED” (Affordable, Sensitive, Specific, User-friendly, Rapid, Equipment-free, and Deliverable) criterion provided by the World Health Organization is discussed based on recent advances in SERSin vitroassay development. As SERS provides attractive characteristics for multiplexed sensing at low concentration limits with a high degree of specificity, it holds great promise for enhancing current efforts in rapid diagnostic testing. In outlining the progression of SERS techniques over the past years combined with recent developments in smart nanomaterials, high-throughput microfluidics, and low-cost paper diagnostics, an extensive number of new possibilities show potential for translating SERS biosensors to the POC.
- Published
- 2017
6. Nanoengineered capsules for selective SERS analysis of biological samples
- Author
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Gerard L. Coté, Michael J. McShane, Andrea K. Locke, Monika Schechinger, and Yil-Hwan You
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Rhodamine 6G ,chemistry.chemical_compound ,Analyte ,Plasmonic nanoparticles ,chemistry ,Colloidal gold ,Aptamer ,Biophysics ,Nanoparticle ,Small molecule ,Polyelectrolyte - Abstract
Metal nanoparticles conjugated with DNA oligomers have been intensively studied for a variety of applications, including optical diagnostics. Assays based on aggregation of DNA-coated particles in proportion to the concentration of target analyte have not been widely adopted for clinical analysis, however, largely due to the nonspecific responses observed in complex biofluids. While sample pre-preparation such as dialysis is helpful to enable selective sensing, here we sought to prove that assay encapsulation in hollow microcapsules could remove this requirement and thereby facilitate more rapid analysis on complex samples. Gold nanoparticle-based assays were incorporated into capsules comprising polyelectrolyte multilayer (PEMs), and the response to small molecule targets and larger proteins were compared. Gold nanoparticles were able to selectively sense small Raman dyes (Rhodamine 6G) in the presence of large protein molecules (BSA) when encapsulated. A ratiometric based microRNA-17 sensing assay exhibited drastic reduction in response after encapsulation, with statistically-significant relative Raman intensity changes only at a microRNA-17 concentration of 10 nM compared to a range of 0-500 nM for the corresponding solution-phase response.
- Published
- 2018
7. Optimization of surface enhanced Raman scattering (SERS) assay for the transition from benchtop to handheld Raman systems
- Author
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Haley L. Marks, Gerard L. Coté, Andrea K. Locke, Mahua Choudhury, and Monika Schechinger
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Fluorophore ,Materials science ,Nanotechnology ,02 engineering and technology ,Surface-enhanced Raman spectroscopy ,Chromophore ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Small molecule ,0104 chemical sciences ,law.invention ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,law ,symbols ,0210 nano-technology ,Raman spectroscopy ,Raman scattering ,Plasmon - Abstract
Human biomarkers are indicative of the body’s relative state prior to the onset of disease, and sometimes before symptoms present. While blood biomarker detection has achieved considerable success in laboratory settings, its clinical application is lagging and commercial point-of-care devices are rare. A physician’s ability to detect biomarkers such as microRNA-17, a potential epigenetic indicator of preeclampsia in pregnant woman, could enable early diagnosis and preventive intervention as early as the 1st trimester. One detection approach employing DNA-functionalized nanoparticles to detect microRNA-17, in conjunction with surface-enhanced Raman spectroscopy (SERS), has shown promise but is hindered, in part, by the use of large and expensive benchtop Raman microscopes. However, recent strides have been made in developing portable Raman systems for field applications. Characteristics of the SERS assay responsible for strengthening the assay’s plasmonic response were explored, whilst comparing the results from both benchtop and portable Raman systems. The Raman spectra and intensity of three different types of photoactive molecules were compared as potential Raman reporter molecules: chromophores, fluorophores, and highly polarizable small molecules. Furthermore, the plasmonic characteristics governing the formation of SERS colloidal nanoparticle assemblies in response to DNA/miRNA hybridization were investigated. There were significant variations in the SERS enhancement in response to microRNA-17 using our assay depending on the excitation lasers at wavelengths of 532 nm and 785 nm, depending on which of the three different Raman systems were used (benchtop, portable, and handheld), and depending on which of the three different Raman reporters (chromophore, fluorophore, or Raman active molecule) were used. Analysis of data obtained did indicate that signal enhancement was better for the chromophore (MGITC) and Raman active molecule (DTNB) than it was for the fluorophore (TRITC) and that, although it is possible to obtain enhancements when using excitation lasers that do not directly coincide with the optical properties of the Raman reporter molecule, clearly the enhancements are more significant when it reaches to the characteristic wavelengths of those molecules.
- Published
- 2017
8. Aptamer conjugated silver nanoparticles for the detection of interleukin 6
- Author
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Haley L. Marks, Duncan Graham, George W. Jackson, Gerard L. Coté, Nicole Norwood, Andrea K. Locke, Monika Schechinger, Vo-Dinh, Tuan, Lakowicz, Joseph R., Ho, Ho-Pui A., and Ray, Krishanu
- Subjects
Plasmonic nanoparticles ,010405 organic chemistry ,Chemistry ,Aptamer ,Nanoparticle ,Nanotechnology ,Surface-enhanced Raman spectroscopy ,010402 general chemistry ,01 natural sciences ,Silver nanoparticle ,0104 chemical sciences ,QC350 ,Dynamic light scattering ,TA164 ,Target protein ,Biosensor - Abstract
The controlled assembly of plasmonic nanoparticles by a molecular binding event has emerged as a simple yet sensitive methodology for protein detection. Metallic nanoparticles (NPs) coated with functionalized aptamers can be utilized as biosensors by monitoring changes in particle optical properties, such as the LSPR shift and enhancement of the SERS spectra, in the presence of a target protein. Herein we test this method using two modified aptamers selected for the protein biomarker interleukin 6, an indicator of the dengue fever virus and other diseases including certain types of cancers, diabetes, and even arthritis. IL6 works by inducing an immunological response within the body that can be either anti-inflammatory or pro-inflammatory. The results show that the average hydrodynamic diameter of the NPs as measured by Dynamic Light Scattering was ∼42 nm. After conjugation of the aptamers, the peak absorbance of the AgNPs shifted from 404 to 408 nm indicating a surface modification of the NPs due to the presence of the aptamer. Lastly, preliminary results were obtained showing an increase in SERS intensity occurs when the IL-6 protein was introduced to the conjugate solution but the assay will still need to be optimized in order for it to be able to monitor varying concentration changes within and across the desired range.
- Published
- 2016
9. Development of a miRNA surface-enhanced Raman scattering assay using benchtop and handheld Raman systems
- Author
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Haley L. Marks, Mahua Choudhury, Andrea K. Locke, Monika Schechinger, and Gerard L. Coté
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Materials science ,Microscope ,Fluorophore ,Biomedical Engineering ,Nanotechnology ,02 engineering and technology ,Spectrum Analysis, Raman ,010402 general chemistry ,01 natural sciences ,law.invention ,Biomaterials ,symbols.namesake ,chemistry.chemical_compound ,Isothiocyanates ,law ,Rosaniline Dyes ,Coloring Agents ,Plasmon ,DNA ,Surface-enhanced Raman spectroscopy ,021001 nanoscience & nanotechnology ,Small molecule ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,MicroRNAs ,chemistry ,Point-of-Care Testing ,symbols ,Nanoparticles ,Raman microscope ,0210 nano-technology ,Raman spectroscopy ,Raman scattering - Abstract
DNA-functionalized nanoparticles, when paired with surface-enhanced Raman spectroscopy (SERS), can rapidly detect microRNA. However, widespread use of this approach is hindered by drawbacks associated with large and expensive benchtop Raman microscopes. MicroRNA-17 (miRNA-17) has emerged as a potential epigenetic indicator of preeclampsia, a condition that occurs during pregnancy. Biomarker detection using an SERS point-of-care device could enable prompt diagnosis and prevention as early as the first trimester. Recently, strides have been made in developing portable Raman systems for field applications. An SERS assay for miRNA-17 was assessed and translated from traditional benchtop Raman microscopes to a handheld system. Three different photoactive molecules were compared as potential Raman reporter molecules: a chromophore, malachite green isothiocyanate (MGITC), a fluorophore, tetramethylrhodamine isothiocyanate, and a polarizable small molecule 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB). For the benchtop Raman microscope, the DTNB-labeled assay yielded the greatest sensitivity under 532-nm laser excitation, but the MGITC-labeled assay prevailed at 785 nm. Conversely, DTNB was preferable for the miniaturized 785-nm Raman system. This comparison showed significant SERS enhancement variation in response to 1-nM miRNA-17, implying that the sensitivity of the assay may be more heavily dependent on the excitation wavelength, instrumentation, and Raman reporter chosen than on the plasmonic coupling from DNA/miRNA-mediated nanoparticle assemblies.
- Published
- 2018
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