Browsing by Author "Januarie, Kaylin Cleo"

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    L-Cysteine-Capped Indium Telluriselenide Quantum Dot Aptasensor for Interferon-Gamma TB Biomarker
    (University of the Western Cape, 2018) Januarie, Kaylin Cleo; Iwuoha, Emmanuel
    Tuberculosis (TB) is one of the major infectious diseases that affect the health of people all over the world. South Africa is one of the countries that account for most of the TB cases; it is the leading cause of death in South Africa and is known to be lethal when combined with HIV in patients. Various tests have been used to diagnose tuberculosis infected patients, but some of these tests give false positive results. Studies have shown that tuberculosis-related cytokines can serve as biological markers for the diagnosis of TB. Cytokines are signalling proteins secreted by immune cells and one such cytokine is interferon-gamma (IFN-?). Interferon-gamma is secreted by immune cells in response to various pathogens and has many physiological roles in the immune system and inflammatory stimuli. IFN-? was first detected using antibody-based immunosensing techniques but this approach is expensive, time consuming and has low stability, it is therefore vital that an alternative detection method for IFN-? be developed.
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    Recent advances in the detection of interferon‑gamma as a TB biomarker
    (Springer, 2021) Januarie, Kaylin Cleo; Uhuo, Onyinyechi V.; Iwuoha, Emmanuel
    Tuberculosis (TB) is one of the main infectious diseases worldwide and accounts for many deaths. It is caused by Mycobacterium tuberculosis usually afecting the lungs of patients. Early diagnosis and treatment are essential to control the TB epidemic. Interferon-gamma (IFN-γ) is a cytokine that plays a part in the body’s immune response when fghting infection. Current conventional antibody-based TB sensing techniques which are commonly used include enzyme-linked immunosorbent assay (ELISA) and interferon-gamma release assays (IGRAs). However, these methods have major drawbacks, such as being time-consuming, low sensitivity, and inability to distinguish between the diferent stages of the TB disease. Several electrochemical biosensor systems have been reported for the detection of interferon-gamma with high sensitivity and selectivity. Microfuidic techniques coupled with multiplex analysis in regular format and as lab-on-chip platforms have also been reported for the detection of IFN-γ. This article is a review of the techniques for detection of interferon-gamma as a TB disease biomarker. The objective is to provide a concise assessment of the available IFN-γ detection techniques (including conventional assays, biosensors, microfuidics, and multiplex analysis) and their ability to distinguish the diferent stages of the TB disease.
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    Trimetallic chalcogenide-sensitised interferon gamma aptasensor for tuberculosis
    (Elsevier Ltd, 2025) Uhuo, Onyinyechi Vivian; Januarie, Kaylin Cleo; Mokwebo, Kefilwe Vanessa
    Novel copper indium tin sulfide nanomaterial synthesized with chitosan capping agent.•IFN-γ TB biomarker aptasensor was fabricated using a χt-c-CITS sensing platform.•By aptamer surface density study, χt-c-CITS enhanced aptamer loading by 84.6 %.•χt-c-CITS increased aptasensor signal by 73.9 % and target detection by 85.7 %.•"Turn-on" assay format was achieved and monitored by capacitive charge measurements. Tuberculosis (TB) is a highly contagious disease whose eradication has become challenging due to the difficulty of early and real-time diagnosis, especially in developing countries. These challenges arise due to the time-consuming, expensive, complicated, and non-user-friendly nature of the current diagnostic techniques, making them difficult to use except by a highly trained medical laboratory specialist. Since biosensors offer a faster, simpler, and highly sensitive alternative to traditional methods, there is a growing interest in enhancing biosensor signals for efficient application. One such method of biosensor signal amplification is the use of nanostructured materials. In this work, we report the positive effect of tuning the properties of a substituted-kesterite nanomaterial, copper indium tin sulfide (CITS), using a chitosan capping agent, for efficient signal amplification of interferon gamma (IFN-γ) TB biomarker detection. This nanostructured chitosan-capped copper indium tin sulfide (χt-c-CITS) nanomaterials served as an excellent sensing platform, improving aptamer loading by 84.6 % and signal response by 73.9 %. High sensitivity to changes in IFN-γ concentration was obtained with the χt-c-CITS-based aptasensor between 100 fM to 1 pM dynamic linear range, and a detection limit of 23.2 fM. Excellent electrochemical stability was achieved with 94 % and 95.6 % signal stability recorded after 20 repeated chronocoulometry measurements and a 32-day storage period, respectively. The aptasensor likewise showed excellent specificity and selectivity to IFN-γ in the presence of interfering agents, with potential application in real biological samples.