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Browsing Conference Publications by browse.metadata.impactarea "Bio-photonics"
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Item Detection and quantification of iodine in biological fluids using photonic-based systems: UV-Vis and Transmission spectroscopy(2024-01) Mcotshana, Zenande KS; Thwala, Nomcebo L; Ombinda-Lemboumba, Saturnin; Ramokolo, Lesiba R; Lugongolo, Masixole Y; Van Steen, E; Mthunzi-Kufa, PatienceIodine is a crucial trace element that occurs in minute amounts in nature and is necessary for the development of bones, thyroid function, and several metabolic processes. Iodine deficiency, also known as hypothyroidism, affects millions of individuals worldwide, and an overabundance of iodine in the body is known as hyperthyroidism. The early identification of iodine with high sensitivity and selectivity is crucial for physiological impact since the abnormalities caused by iodine disorder can increase the frequency of mortality and mental impairments. This work aims to detect iodine using UV-Vis and Transmission spectroscopy and utilizing selenium nanoparticles as a probe. Selenium nanoparticles (SeNPs) were synthesized by ND: YAG laser method and characterized by Dynamic light scattering (DLS), and High-resolution transmission electron microscopy (HRTEM), while the conjugation of iodine to SeNPs was confirmed by Ultraviolet-visible (UV-vis) spectroscopy. For iodine detection, UV-Vis and Transmission spectroscopy were used and compared and the synthesized colloidal and spherical selenium nanoparticles were utilized as a probe to detect iodine. The absorption peaks and a red shift for SeNPs changed upon the reaction with iodine and this shift may allow for the estimation of iodine concentration. The two methods will enable the detection and monitoring of iodine at different concentrations in the body thus preventing the onset of iodine-related diseases.Item Examining HIV infected cells using optical trapping and Raman spectroscopy(2021-09) Lugongolo, Masixole Y; Ombinda-Lemboumba, Saturnin; Manoto, Sello L; Mthunzi-Kufa, PatienceManipulation of biological cells using optical trapping is a non-invasive approach in which individual living cells are examined without causing any damage because there is no direct mechanical contact with cells. Optical trapping uses a tightly focused laser beam emitted through a high numerical aperture microscope objective lens to hold microscopic particles. When using this technique, there is minimal chances of exposing cells to contamination and optically handled cells can still be utilised in downstream sterile experiments whenever necessary. In this study, optical trapping is used to trap HIV infected cells, which are then analysed by Raman spectroscopy. Raman spectroscopy as an analytical technique provides specific chemical/molecular details about a sample based on the fundamental vibrational modes of the chemicals. By combining these two light-based technologies, HIV infected TZM-bl cells were distinguished from the uninfected cells as they exhibited different molecular fingerprints. The acquired results both confirm and provide more detail to the findings of the previous study where transmission spectroscopy was used to differentiate between HIV infected and uninfected cells. This current study shows how the two cell populations differ according to the chemical/molecular composition and distribution. These results present valuable information that would be essential in the development of a label-free HIV point of care diagnostic device.Item Gelatine-based biosensor for molecular screening of aspirin and paracetamol via surface enhanced Raman spectroscopy(2020-02) Thobakgale, Setumo L; Manoto, Sello L; Ombinda-Lemboumba, Saturnin; Mthunzi-Kufa, PatiencePolypeptide gelatine has been used extensively in microbiology to enhance cellular adhesion and growth. Likewise, fabrication of biochemical sensors using a variety of organic material and nanomaterials is a growing research area particularly in experiments involving single molecular screening. Both fields of study exploit the various interactions that occur at molecular level such as charge-charge binding, hydrogen bonding and van Der Waals forces. In this work, a thin film gelatine based biosensor, containing amino acids such as glycine, proline and hydroxy-proline was synthesized on glass slides using the self-assembly method. Further -adaption involved coating gold nanoparticles onto the substrate to enhance chemical binding and improve signal intensity and sensitivity. Pharmaceutical drugs aspirin and paracetamol were used as analytes to explore the qualitative and quantitative capabilities of the sensor in molecular screening through surface enhanced Raman spectroscopy (SERS). The results showed a distinguishable qualitative difference between the Raman spectra of gelatine-drug (Gel-D) and gelatine-gold-drug (Gel-Au-D) fabricated sensors. Similarly in both Gel-D and Gel-Au-D, the peak areas of the functional groups found in both aspirin and paracetamol increased with drug concentration, yielding satisfactory calibration curves. The gelatine based biosensor thus holds potential as an in vitro sensing platform for screening of pharmaceutical drugs.Item Optical-biosensing of multidrug-resistant Tuberculosis (TB) genes(2024-01) Chauke, Sipho H; Ombinda-Lemboumba, Saturnin; Dube, FS; Mthunzi-Kufa, PatienceTuberculosis (TB) remains one of the most important infectious diseases globally, killing approximately 1.5 million people annually. The burden of infection is disproportionately high in low-income and resource-limited settings. This disparity is exacerbated by the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis (Mtb), the bacterium that causes TB. Early detection and treatment of TB remain key strategies to reduce the spread and disease progression to drug-resistant forms of TB. However, this is hampered by slow, insensitive diagnostic methods, particularly for the detection of drug-resistant forms and in patients with human immunodeficiency virus infection (HIV). There are currently several rapid TB diagnostics, but most are limited due to costs and accessibility. Several genes, such as catalase-peroxidase (katG) and enoyl reductase (inhA) genes, contain mutations that are responsible for drug resistance. One of the initial objectives of this study was to use an optical-based system to detect katG and inhA genes. Deoxyribonucleic acid (DNA) probes, specific for katG and inhA, were used as biorecognition elements to capture katG and inhA target DNA. The katG and inhA gene-specific DNA probes were immobilized on a coated glass substrate before the target DNA was introduced for detection. As a negative control, a mismatched probe, unspecific to both genes was used for confirmation of the absence of the two genes in the experimental setup. The optical setup was used for the analysis of the binding interactions occurring on the coated glass substrate. The specificity and sensitivity of the coated glass substrate successfully detected the binding interactions through the changes in the transmitted intensity. The transmitted intensity further indicated the kinetics associated with DNA hybridization occurring between the target DNA and the capture probe. This is the initial step to potentially detecting drug-resistant mutations using optical-based biosensors at a point-of-care setting.Item Surface plasmon resonance (SPR) based biosensor for mycobacterium tuberculosis diagnosis(2021-03) Maphanga, Charles P; Ombinda-Lemboumba, Saturnin; Manoto, Sello L; Mthunzi-Kufa, PatienceRecently, various nanomaterials have been used to develop nanotechnology-based rapid diagnostic tests. Due to their unique optical properties, gold nanoparticles (AuNPs) have been employed to design and develop modern biosensors for the rapid and real-time detection of various diseases or pathogen-specific biomolecules/markers, such as DNA, RNA, proteins, and whole cells. Optical biosensors offer great advantages over conventional analytical techniques. Specifically, they can provide multiple capabilities such as user-friendly operation, real-time analysis, rapid response, high sensitivity and specificity, portability, label-free detection and cost-effectiveness. As a result, this diagnostic approach possesses suitable features to develop point-of-care (POC) diagnostics and monitoring technologies. This study implemented the use of surface plasmon resonance (SPR) biosensing to monitor biomolecular interaction between biorecognition element covalently immobilized on a gold-coated glass substrate and an analyte. A custom-built Kretschmann configuration SPR optical biosensing setup was used to measure angle shift to monitor the biomolecular interaction events on the biosensing layer. To amplify the differences in SPR biosensing due to biomolecular binding events, AuNPs were used and successfully conjugated to the anti-TB antibodies and confirmed using ultraviolet–visible (UV-vis) spectroscopy. Mycolic acids were successfully immobilized on gold-coated substrates and were able to bind to the anti-TB antibodies that were introduced on the substrates, therefore enabling the detection of the captured anti-TB antibodies. As a result, mycolic acids have been realized to be efficient biomarkers to specifically react with anti-TB antibodies and produce a detectable signal for the purpose of TB diagnosis.