Conference Publications

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Browsing Conference Publications by browse.metadata.impactarea "Biophotonics"

Now showing 1 - 4 of 4
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    Biosensing multidrug-resistant TB genes using SPR
    (2024-01) Chauke, Sipho H; Ombinda-Lemboumba, Saturnin; Dube, FS; Mthunzi-Kufa, Patience
    Tuberculosis (TB) is one of the most prevalent infectious diseases globally. Although it is curable, several factors, such as the inappropriate use of treatment drugs lead to drug-resistant strains of TB. The burden of infection is disproportionately high in low-income and resource-limited settings. Furthermore, this disparity is exacerbated in patients with already compromised immune systems. Therefore, early detection and treatment of TB play an important role in reducing the spread and progression to drug-resistant disease forms. There are currently a few rapid multi-drug resistant TB diagnostic tests available, however, 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 resistance to the TB drug, isoniazid. We therefore, aim to use a custom-built surface plasmon resonance (SPR) 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 gold-coated glass sensor chip 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 specificity and sensitivity of the capture probes to the target DNA were investigated using the gold-coated glass sensor chip on the SPR setup. The changes in the resonance angle dip indicated the hybridization of the target DNA and the capture probe. The results from this study will contribute to the optimization of an optical-based biosensor detecting drug-resistant mutations.
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    Detection of viral pathogens using optical photonic techniques with the aid of selenium nanoparticles
    (2024-01) Mcotshana, Zenande KS; Thwala, Nomcebo L; Ombinda-Lemboumba, Saturnin; Ramokolo, Lesiba R; Thobakgale, Setumo L; Lugongolo, Masixole Y; Van Steen, E; Mthunzi-Kufa, Patience
    Viral infections such as HIV and SARS-CoV-2 have significantly increased morbidity in humans and resulted in a significant number of fatalities globally, hence early detection is crucial, particularly at a point-of-care (POC) setting to prevent the spread of these diseases. Localized surface plasmon resonance (LSPR) and green light-based Transmission spectroscopy techniques were used in this study to assess real-time molecular interactions between virus-spiked and non-spiked samples. The current study focuses on integrating selenium nanoparticles (SeNPs) with different optical photonic techniques for enhanced detection of HIV. Selenium nanoparticles were synthesized and functionalized with antibodies specific to HIV. Before and after bioconjugation with viral secondary antibodies, the SeNPs were characterized using Ultraviolet–visible (UV-Vis) spectroscopy, Dynamic light scattering (DLS), High-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy, to elucidate their properties and confirm the presence of functional groups. After that, the NPs were integrated with plasmonic systems and used for the enhanced detection of HIV in comparison to traditional LSPR and Transmission spectroscopy. Colloidal selenium nanoparticles were successfully synthesized, using ND: YAG laser. The orange-colored, spherically shaped nanoparticles were evenly distributed and easily resuspended. Anti-HIV antibodies conjugated to SeNPs were added after HIV-specific antibodies were successfully immobilized on a glass slide substrate to react with HIV pseudovirus. The pseudovirus was effectively identified by the use of Transmission Spectroscopy and LSPR techniques. The two optical techniques for HIV detection were more sensitive after integrating selenium nanoparticles, as compared to the conventional Transmission spectroscopy and LSPR methods. This improved and highly sensitive approach may be utilized to identify viral infections early, thus combating the spread of infectious diseases.
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    The efficiency of surface plasmon resonance in measuring human immunodeficiency virus concentrations
    (2024-01) Lugongolo, Masoxile Y; Ombinda-Lemboumba, Saturnin; Nomcebo Thwala, Nomcebo L; Tjale, Mabotse A; Mcoy, Michael P; Mthunzi-Kufa, Patience
    Surface plasmon resonance is a label free optical detection technique, which responds to refractive index variations that are induced by molecular binding incidents or binding affinities. This occurrence takes place when electrons on a thin metal film are excited by the light directed at an incident angle and travel parallel to the film. The angle of incidence that triggers surface plasmon resonance is linked to the refractive index of the material and even an insignificant change in the refractive index will be detected due to the sensitivity of the method. Because of its sensitivity, this technique is used as a real-time analytical approach that can be used for many different applications such as investigating the antibody-antigen affinity. In this study, surface plasmon resonance and localized surface plasmon resonance were investigated for their efficiency in detecting human immunodeficiency virus concentrations. This was achieved by functionalizing gold coated slides using an antibody against the surface protein of the human immunodeficiency virus. To the functionalized gold coated surface, different viral concentrations were added. The samples were then analyzed on home-built surface plasmon resonance and localized surface plasmon resonance biosensing systems. The results showed that the systems detected differences in viral concentrations as demonstrated by resonance curve shifts and varying transmission intensities. These findings will used towards the development of an optical biosensor to be used at point of care system for the detection of viral load in resource limited settings.
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    Quantification of viral particles using a photonic crystal biosensor
    (2024-03) Lugongolo, Masixole Y; Ombinda-Lemboumba, Saturnin; Maphanga, Charles P; Mcoyi, Phumulani M; El-Hussein, A; Mthunzi-Kufa, Patience
    The quantification of human immunodeficiency virus at point of care remains a challenge in resource limited settings. The incorporation of nanotechnology and label free optical biosensing has unlocked promising opportunities in the development of diagnostic tools for infectious diseases. Optical biosensors offer a rapid and sensitive optical method for various biological materials such as cells, biomolecules, and viruses by monitoring the dielectric permittivity changes at the interface of a transducer substrate and the analyte. This work focuses on exploring photonic crystal biosensor efficiency and sensitivity for viral load measurement. Photonic crystal biosensors are a unique class of biosensors that allow for label free analysis as they can control and confine light propagation due to the photonic bandgap. Silane treated photonic crystal was functionalized with anti-HIV-gp120 antibody before the addition of various concentrations of HIV pseudovirus. The samples were analyzed on a custom build transmission spectroscopy that used white light as a light source. The results showed a red shift at different virus concentrations, which demonstrates that photonic crystal biosensors are sensitive enough to detect differences in virus concentrations. Therefore, photonic crystals have a potential in the development of photonic crystal-based biosensors for viral load detection.