8 results on '"Emad L. Izake"'
Search Results
2. Label-free identification of Erythropoietin isoforms by surface enhanced Raman spectroscopy
- Author
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Emad L. Izake, Waleed A. Hassanain, and Frederick L. Theiss
- Subjects
Gene isoform ,chemistry.chemical_classification ,Chromatography ,Chemistry ,Biomolecule ,Reproducibility of Results ,Substrate (chemistry) ,Surface-enhanced Raman spectroscopy ,Spectrum Analysis, Raman ,Recombinant Proteins ,Analytical Chemistry ,law.invention ,Extractor ,law ,Erythropoietin ,Recombinant DNA ,medicine ,Humans ,Protein Isoforms ,Label free ,medicine.drug - Abstract
We present a sensitive label-free surface enhanced Raman spectroscopy (SERS) method for the discrimination between the recombinant and endogenous human Erythropoietin (EPO) isoforms. The proposed methodology comprises a lectin-functionalised extractor chip for the extraction of the recombinant human EPO (rhuEPO) and the endogenous EPO (enEPO) from blood plasma. The disulfide bond molecular structure of the purified isoforms was modified to chemisorb the biomolecules onto a SERS substrate in a unified orientation, thus maximizing the reproducibility and sensitivity of the SERS measurements. The acquired SERS spectra of the EPO isoforms showed diagnostic Raman bands that allowed for the discrimination between rhuEPO and enEPO. The method was also used for the SERS quantification of rhuEPO and enEPO down to 0.1 pM and 0.5 pM, respectively. The SERS determination of the protein isoforms was cross validated against ELISA. The new SERS method has strong potential for the rapid screening of rhuEPO doping in athletes and for the therapeutic drug monitoring of rhuEPO treatment in cancer patients.
- Published
- 2022
3. Utilizing the thiol chemistry of biomolecules for the rapid determination of anti-TNF-α drug in blood
- Author
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Godwin A. Ayoko, Saiqa Muneer, Nazrul Islam, and Emad L. Izake
- Subjects
Anti-Inflammatory Agents ,02 engineering and technology ,Biosensing Techniques ,Spectrum Analysis, Raman ,01 natural sciences ,Analytical Chemistry ,Nanomaterials ,symbols.namesake ,medicine ,Molecule ,Sulfhydryl Compounds ,chemistry.chemical_classification ,Chromatography ,medicine.diagnostic_test ,Tumor Necrosis Factor-alpha ,Biomolecule ,010401 analytical chemistry ,Adalimumab ,Substrate (chemistry) ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Nanostructures ,chemistry ,Therapeutic drug monitoring ,Thiol ,symbols ,Gold ,0210 nano-technology ,Raman spectroscopy ,Biosensor ,Copper - Abstract
The detection of anti-TNF-α drugs require rapid, selective and sensitive biosensors that can be easily utilised at the point of care. Herein, we demonstrate a new biosensing approach that employs target-specific nanomaterial and label free surface-enhanced Raman spectroscopy (SERS) for the selective extraction and rapid determination of Adalimumab (ADB) in human blood plasma. The new method utilises the tumour necrosis factor (TNF-α) for the fabrication of a target-specific nanomaterial for extraction of ADB. The method also uses the thiol chemistry of the purified antibody drug for its chemisorption onto a gold-coated copper oxide substrate. A handheld Raman spectrophotometer is used for the determination of ADB by label free SERS. The limits of quantification (LOQ) and detection (LOD) of the purified and reduced drug by SERS were 0.10 fM and 0.03 fM respectively. ELISA was used for the cross validation of the SERS quantification of ADB where a 98.8% agreement was found between the two methods. Many proteins have disulfide bonds in their molecular structure. Therefore, the demonstrated biosensing approach can be extended for the rapid screening of other proteins and antibody drugs by developing target-specific extractor nanomaterial and utilizing the disulfide bond structure of the purified biomolecules for their label free SERS detection.
- Published
- 2019
4. An electrochemical biosensor for the rapid detection of erythropoietin in blood
- Author
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Godwin A. Ayoko, Arumugam Sivanesan, Waleed A. Hassanain, and Emad L. Izake
- Subjects
Time Factors ,02 engineering and technology ,Biosensing Techniques ,Electrochemistry ,01 natural sciences ,Analytical Chemistry ,Limit of Detection ,Desorption ,Blood plasma ,medicine ,Electrochemical biosensor ,Humans ,Electrodes ,Erythropoietin ,Chromatography ,Chemistry ,010401 analytical chemistry ,Reproducibility of Results ,Chronoamperometry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Electrode ,Differential pulse voltammetry ,Gold ,0210 nano-technology ,Blood Chemical Analysis ,medicine.drug - Abstract
A label free electrochemical detection method for the rapid detection of recombinant human erythropoietin (rhuEPO) has been developed. In this method, we modified the rhuEPO structure for its direct sensing without using a complex signal amplification strategy. The protein was selectively extracted from blood plasma sample using target-specific magnetic beads. After releasing rhuEPO from the magnetic beads, its disulfide bonds were electrochemically reduced and the protein was spontaneously assembled onto a nanostructured gold electrode via Au-S bonds formation. For electrochemical quantification, the reduced protein was desorbed from the electrode surface using differential pulse voltammetry (DPV). The desorption current was proportional to the concentration of rhuEPO in the range 1 pM – 1000 pM. By cross-validating against ELISA, we found a 104.85 ± 3.35% agreement between the results obtained using the electrochemical biosensor and ELISA. Therefore the developed method has a strong potential for the sensitive detection of rhuEPO doping in sports as well as its rapid screening and pathology labs.
- Published
- 2018
5. Rapid detection of TNT in aqueous media by selective label free surface enhanced Raman spectroscopy
- Author
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Arniza Khairani Mohd Jamil, Peter M. Fredericks, Emad L. Izake, and Arumugam Sivanesan
- Subjects
Aqueous solution ,Analytical chemistry ,Picric acid ,Surface-enhanced Raman spectroscopy ,Meisenheimer complex ,Analytical Chemistry ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,Absorption band ,Colloidal gold ,symbols ,Moiety ,Raman spectroscopy ,Nuclear chemistry - Abstract
We report rapid and ultra-sensitive detection system for 2,4,6-trinitrotoluene (TNT) using unmodified gold nanoparticles and surface-enhanced Raman spectroscopy (SERS). First, Meisenheimer complex has been formed in aqueous solution between TNT and cysteamine in less than 15 min of mixing. The complex formation is confirmed by the development of a pink colour and a new UV-vis absorption band around 520 nm. Second, the developed Meisenheimer complex is spontaneously self-assembled onto unmodified gold nanoparticles through a stable Au-S bond between the cysteamine moiety and the gold surface. The developed mono layer of cysteamine-TNT is then screened by SERS to detect and quantify TNT. Our experimental results demonstrate that the SERS-based assay provide an ultra-sensitive approach for the detection of TNT down to 22.7 ng/L. The unambiguous fingerprint identification of TNT by SERS represents a key advantage for our proposed method. The new method provides high selectivity towards TNT over 2,4 DNT and picric acid. Therefore it satisfies the practical requirements for the rapid screening of TNT in real life samples where the interim 24-h average allowable concentration of TNT in waste water is 0.04 mg/L.
- Published
- 2015
6. Deep Raman spectroscopy for the non-invasive standoff detection of concealed chemical threat agents
- Author
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Biju Cletus, Shankaran Sundarajoo, Esa Jaatinen, Peter M. Fredericks, Emad L. Izake, and William J. Olds
- Subjects
Time Factors ,Explosive material ,Opacity ,Analytical chemistry ,Signal-To-Noise Ratio ,Spectrum Analysis, Raman ,Nitroparaffins ,Analytical Chemistry ,symbols.namesake ,Optics ,Explosive Agents ,Interference (communication) ,Humans ,Chemical Warfare Agents ,Surface layer ,Nitrates ,business.industry ,Chemistry ,Lasers ,Spatially offset Raman spectroscopy ,Picosecond ,symbols ,Barium Sulfate ,business ,Raman spectroscopy ,Methane ,Excitation - Abstract
Deep Raman spectroscopy has been utilized for the standoff detection of concealed chemical threat agents from a distance of 15 meters under real life background illumination conditions. By using combined time and space resolved measurements, various explosive precursors hidden in opaque plastic containers were identified non-invasively. Our results confirm that combined time and space resolved Raman spectroscopy leads to higher selectivity towards the sub-layer over the surface layer as well as enhanced rejection of fluorescence from the container surface when compared to standoff spatially offset Raman spectroscopy. Raman spectra that have minimal interference from the packaging material and good signal-to-noise ratio were acquired within 5 seconds of measurement time. A new combined time and space resolved Raman spectrometer has been designed with nanosecond laser excitation and gated detection, making it of lower cost and complexity than picosecond-based laboratory systems.
- Published
- 2012
7. Ultra sensitive label free surface enhanced Raman spectroscopy method for the detection of biomolecules
- Author
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William B. Lott, Godwin A. Ayoko, Emad L. Izake, Martin N. Sillence, and Juanita Hughes
- Subjects
Analyte ,Surface Properties ,Analytical chemistry ,Nanoparticle ,Metal Nanoparticles ,Biosensing Techniques ,Photochemistry ,Spectrum Analysis, Raman ,Analytical Chemistry ,symbols.namesake ,Mice ,Nanosensor ,Caffeine ,Molecule ,Animals ,Humans ,Erythropoietin ,chemistry.chemical_classification ,Biomolecule ,Antibodies, Monoclonal ,Surface-enhanced Raman spectroscopy ,Silicon Dioxide ,chemistry ,Colloidal gold ,symbols ,Gold ,Raman spectroscopy - Abstract
We present a proof of concept for a novel nanosensor for the detection of ultra-trace amounts of bio-active molecules in complex matrices. The nanosensor is comprised of gold nanoparticles with an ultra-thin silica shell and antibody surface attachment, which allows for the immobilization and direct detection of bio-active molecules by surface enhanced Raman spectroscopy (SERS) without requiring a Raman label. The ultra-thin passive layer (~1.3 nm thickness) prevents competing molecules from binding non-selectively to the gold surface without compromising the signal enhancement. The antibodies attached on the surface of the nanoparticles selectively bind to the target molecule with high affinity. The interaction between the nanosensor and the target analyte result in conformational rearrangements of the antibody binding sites, leading to significant changes in the surface enhanced Raman spectra of the nanoparticles when compared to the spectra of the un-reacted nanoparticles. Nanosensors of this design targeting the bio-active compounds erythropoietin and caffeine were able to detect ultra-trace amounts the analyte to the lower quantification limits of 3.5 × 10(-13)M and 1 × 10(-9)M, respectively.
- Published
- 2014
8. Standoff Raman spectrometry for the non-invasive detection of explosives precursors in highly fluorescing packaging
- Author
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Shankaran Sundarajoo, Biju Cletus, William J. Olds, Esa Jaatinen, Peter M. Fredericks, and Emad L. Izake
- Subjects
Spectrometer ,Explosive material ,Chemistry ,Spatially offset Raman spectroscopy ,Non invasive ,Analytical chemistry ,Signal-To-Noise Ratio ,Mass spectrometry ,Laser ,Spectrum Analysis, Raman ,Transmission Raman spectroscopy ,Fluorescence ,Analytical Chemistry ,law.invention ,symbols.namesake ,Explosive Agents ,law ,symbols ,Humans ,Physics::Atomic Physics ,Raman spectroscopy ,Algorithms ,Drug Packaging - Abstract
Noninvasive standoff deep Raman spectroscopy has been utilised for the detection of explosives precursors in highly fluorescing packaging from 15 m. To our knowledge this is the first time standoff deep Raman spectroscopy of concealed substances in highly fluorescing coloured packaging is demonstrated. Time-resolved Raman spectroscopy, spatially offset Raman spectroscopy and time-resolved spatially offset Raman spectroscopy have been compared to identify their selectivity towards the deep layers of a sample. The selectivity of time-resolved Raman spectroscopy towards the concealed chemical substances was found to be comparable to that of spatially offset Raman spectroscopy. However, time-resolved Raman spectroscopy did not require precise translation of the laser excitation beam onto the surface of the interrogated packaging as in the case of spatially offset Raman spectroscopy. Our results confirm that standoff time-resolved spatially offset Raman spectroscopy has significantly higher selectivity towards the deep layers of a sample when compared to the other deep Raman spectroscopy modes. The developed spectrometer was capable of detecting the concealed substances within 5 s of data acquisition. By using time-resolved spatially Raman spectroscopy, a Raman spectrum that is representative of the content alone was acquired without the use of sophisticated algorithms to eliminate the spectral contributions of the packaging material within the acquired spectrum as in the case of time-resolved Raman spectroscopy and spatially offset Raman spectroscopy.
- Published
- 2012
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