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Browsing Research Publications/Outputs by browse.metadata.impactarea "Bio-photonics"
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Item Chemical sensor nanotechnology in pharmaceutical drug research(2022-08) Thobakgale, Setumo L; Ombinda-Lemboumba, Saturnin; Mthunzi-Kufa, PatienceThe increase in demand for pharmaceutical treatments due to pandemic-related illnesses has created a need for improved quality control in drug manufacturing. Understanding the physical, biological, and chemical properties of APIs is an important area of health-related research. As such, research into enhanced chemical sensing and analysis of pharmaceutical ingredients (APIs) for drug development, delivery and monitoring has become immensely popular in the nanotechnology space. Nanomaterial-based chemical sensors have been used to detect and analyze APIs related to the treatment of various illnesses pre and post administration. Furthermore, electrical and optical techniques are often coupled with nano-chemical sensors to produce data for various applications which relate to the efficiencies of the APIs. In this review, we focus on the latest nanotechnology applied to probing the chemical and biochemical properties of pharmaceutical drugs, placing specific interest on several types of nanomaterial-based chemical sensors, their characteristics, detection methods, and applications. This study offers insight into the progress in drug development and monitoring research for designing improved quality control methods for pharmaceutical and healthrelated research.Item The combination of low level laser therapy and efavirenz drastically reduces HIV infection in TZM-bl cells(2020-06) Lugongolo, Masixole Y; Manoto, Sello L; Ombinda-Lemboumba, Saturnin; Maaza, M; Mthunzi-Kufa, PatienceHuman immunodeficiency virus (HIV) infection remains a global health challenge despite the use of antiretroviral therapy, which has led to a significant decline in the mortality rates. Owing to the unavailability of an effective treatment to completely eradicate the virus, researchers continue to explore new methods. Low level laser therapy (LLLT) has been widely used to treat different medical conditions and involves the exposure of cells or tissues to low levels of red and near infrared light. The study aimed to determine the effect of combining two unrelated therapies on HIV infection in TZM-bl cells.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 Detection of mycobacterium tuberculosis using gold nanoparticles conjugated to TB antibodies(2021-03) Maphanga, Charles P; Manoto, Sello L; Ombinda-Lemboumba, Saturnin; Mthunzi-Kufa, PatienceIn recent years, conjugated nanoparticles have gained significant applications in diagnostics, particularly gold nanoparticles (AuNPs). When functionalized with antibodies, AuNPs can selectively interact with cells and biomolecules. The conjugation of biomolecules to AuNPs has been achieved using a variety of techniques, one such approach is the covalent coupling method used in the current study. Generally, in diagnostics, the conjugation of different moieties such as antibodies to the AuNPs widens their applications and provides them with new or enhanced properties. Due to their high specificity and diversity, antibodies are widely used to provide specificity and bioactivity to AuNPs, particularly for biosensor applications. Localized surface plasmon resonance (LSPR) has emerged as a leader among label-free biosensing techniques because it offers sensitive, robust, and rapid detection of biological analytes. Biomolecular adsorptions on AuNPs surface increases the dielectric constant and change the intensities and the wavelengths of the LSPR band associated with AuNPs. As a result, the adsorptions of biomolecules onto surfaces of this AuNPs can be monitored by measuring the absorption spectra of the AuNPs. In this study, TB antibodies were covalently conjugated to AuNPs and used to detect mycolic acid TB antigens at various concentrations. Characterization of the AuNPs was done using transmission electron microscopy (TEM) while the biomolecular interaction between TB antibodies and the antigen was measured using LSPR. From our findings, it was realised that the use of antibodyconjugated AuNPs enhanced the detection of the analyte even at low concentrations of the analyte.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 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 Exploring optical spectroscopic techniques and nanomaterials for virus detection(2020-08) Manoto, Sello L; El-Hussein, A; Malabi, Rudzani; Thobakgale, Setumo L; Ombinda-Lemboumba, Saturnin; Attia, YA; Kasem, MA; Mthunzi-Kufa, PatienceViral infections pose significant health challenges globally by affecting millions of people worldwide and consequently resulting in a negative impact on both socioeconomic development and health. Corona virus disease 2019 (COVID-19) is a clear example of how a virus can have a global impact in the society and has demonstrated the limitations of detection and diagnostic capabilities globally. Another virus which has posed serious threats to world health is the human immunodeficiency virus (HIV) which is a lentivirus of the retroviridae family responsible for causing acquired immunodeficiency syndrome (AIDS). Even though there has been a significant progress in the HIV biosensing over the past years, there is still a great need for the development of point of care (POC) biosensors that are affordable, robust, portable, easy to use and sensitive enough to provide accurate results to enable clinical decision making. The aim of this study was to present a proof of concept for detecting HIV-1 pseudoviruses by using anti-HIV1 gp41 antibodies as capturing antibodies. In our study, glass substrates were treated with a uniform layer of silane in order to immobilize HIV gp41 antibodies on their surfaces. Thereafter, the HIV pseudovirus was added to the treated substrates followed by addition of anti-HIV gp41 antibodies conjugated to selenium nanoparticle (SeNPs) and gold nanoclusters (AuNCs). The conjugation of SeNPs and AuNCs to anti-HIV gp41 antibodies was characterized using UV–vis spectroscopy, transmission electron microscopy (TEM) and zeta potential while the surface morphology was characterized by fluorescence microscopy, atomic force microscopy (AFM) and Raman spectroscopy. The UV–vis and zeta potential results showed that there was successful conjugation of SeNPs and AuNCs to anti-HIV gp41 antibodies and fluorescence microscopy showed that antibodies immobilized on glass substrates were able to capture intact HIV pseudoviruses. Furthermore, AFM also confirmed the capturing HIV pseudoviruses and we were able to differentiate between substrates with and without the HIV pseudoviruses. Raman spectroscopy confirmed the presence of biomolecules related to HIV and therefore this system has potential in HIV biosensing applications.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 Label-free detection of mutations in the HIV genome using a surface plasmon resonance biosensor(2021-03) Lugongolo, Masixole Y; Manoto, Sello L; Maphanga, Charles P; Ombinda-Lemboumba, Saturnin; Thobakgale, Setumo L; Mthunzi-Kufa, PatienceSurface plasmon resonance (SPR) biosensors are optical materials that measure changes in the refractive index as they monitor non-covalent molecular interactions in real time. These utilise a label free analytical approach, which does not require dyes to produce a visible signal. In this study SPR was assessed for the detection of DNA hybridization between complementary DNA sequences within the pol gene of the human immunodeficiency virus (HIV) genome. HIV mutates rapidly due to its error prone reverse transcriptase enzyme. Some of these mutations make the virus to be resistant to antiretroviral drugs used to treat HIV infected individuals, rendering the drugs ineffective. In order to assess whether an infected individual expresses any drug resistant mutations, different bio-assays must be performed. However, these tests are expensive and require sophisticated equipment, which might be unavailable in resource limited settings. In a quest to simplify these tests so that they can be used in resource limited settings and reduce costs associated with HIV drug resistance testing, SPR capabilities were explored in this study. This was achieved by amplifying a 174 bp region of the HIV-1 pol gene using polymerase chain reaction (PCR). The detection was based on the hybridization between the PCR amplified DNA sequence and a biotinylated oligonucleotide probe immobilized onto an SPR sensor chip made of a gold coated slide. The acquired results indicated that the SPR-sensor-chip used was able to recognize changes in different wells and thereby able to differentiate between a sample with DNA hybridization and the one without. Based on these findings, this approach has potential to detect HIV drug resistance mutations with high efficiency in less time, at lower cost.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 enhanced raman spectroscopy on polymer-graphene oxide scaffolds for drug screening applications(2020-05) Thobakgale, Setumo L; Manoto, Sello L; Ombinda-Lemboumba, Saturnin; Mthunzi-Kufa, PatienceSurface enhanced Raman spectroscopy (SERS) has evolved to be a powerful analytical tool for investigating molecular properties of various types of samples. Literature has shown SERS capabilities in both qualitative and quantitative analysis of biomolecules like proteins and DNA as well as single molecules like antiretroviral medication. Central to its application is the synthesis and use of sensing platforms that enhance signal intensity, sensitivity and detection limits. The most popular approach to make such platforms is through fabricating thin film substrates using a combination of polymers and nanomaterials. In this work, we use the self-assembly method to synthesize graphene oxide based scaffolds in a layer-by-layer fashion and characterize them using SERS. The results show a clear difference in Raman spectral fingerprint for the different layers during the self-assembly steps. Lastly, the intensity ratio between the D and G bands of the graphene layer were calculated to measure the layer thickness which was found to be 0.65, this was comparable to thin layer scaffolds reported in literature. Future work will involve the use of atomic force microscopy to confirm surface morphology and layer thickness, followed by screening of antiretroviral medication.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.