ResearchSpace :: Browsing by Author "Ombinda-Lemboumba, Saturnin"

Browsing by Author "Ombinda-Lemboumba, Saturnin"

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A comparison of two biosensing recognition elements using SPR for the detection of drug- resistant genes
(2025-07) Chauke, Sipho H; Tjale, Mabotse A; Maphanga, Charles P; Felix Dube, F; Ombinda-Lemboumba, Saturnin; Mthunzi-Kufa, P
The burden of tuberculosis (TB) infections is disproportionately high in low-income and resource-limited settings. This disparity exacerbates 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, particularly for the detection of drug-resistant forms. Therefore, optical-based diagnostic devices could solve this problem. Surface plasmon resonance (SPR) biosensors offer various advantages, including rapid analysis, high specificity, and sensitivity, as well as requiring small amounts of samples for analysis. For this study, two multidrug-resistant genes, namely, catalase-peroxidase (KatG) and enoyl reductase (InhA), were detected using a custom-built surface plasmon resonance (SPR) setup. Biotinylated and thiolated deoxyribonucleic acid (DNA) probes, specific to the two genes (KatG and InhA), were used as biorecognition elements to capture KatG and InhA target DNA. The SPR setup was used for the analysis of the binding interactions occurring on the gold-coated slides. The SPR biosensor setup indicated binding interactions through the changes in reflected intensities. The reflected intensities indicated the differences in the resonance angle between each experimental test. This is the initial step to identifying the best characterization of DNA as biorecognition elements for detecting drug-resistant mutations using an SPR-based setup.
Biocongugation of gold nanoparticles for surface plasmon resonance sensor
(SPIE, 2019-03) Manoto, Sello L; Malabi, Rudzani; Ombinda-Lemboumba, Saturnin; Mthunzi-Kufa, Patience
Over the past few years gold nanoparticle (AuNPs) have become extremely interesting because they possess enhanced optical, electrical and chemical properties. AuNPs have the ability to form robust conjugates with biomolecules such as antibodies and can enhance optical signals making them suitable for a variety of diagnostic applications including the surface plasmon resonance (SPR) technique. SPR is a highly sensitive and label free optical technique which is widely used for detecting biological analytes and analysing the interaction between different types of biomolecules. In this study, bioconjugation was achieved by covalently attaching antibodies to AuNPs and gold coated slides were used as SPR sensor chips in Kretschmann configuration. Several UV/VIS excitation spectra were collected before and after AuNPs were conjugated to antibodies. The results showed that the sensitivity of the SPR system significantly increased because of the bioconjugation of antibodies to AuNPs and this is a promising approach for biosensing applications.
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.
Characterisation of a Bessel beam optical cell sorting system using microspheres
(SPIE, 2020-02) Lugongolo, Masixole Y; Ombinda-Lemboumba, Saturnin; Manoto, Sello L; Mthunzi-Kufa, Patience
Accurate sorting of specific particles in a mixed population is a desirable capability in the field of biomedical sciences. This enables researchers to purify samples by selecting only the particles of interest. Optical sorting is achieved by using a Bessel beam, which is a non-diffracting, propagation invariant light pattern consisting of concentric rings around a bright central core. This type of beam profile has the ability to employ optical forces in manipulating matter in a sterile environment without physical interaction. The concentric rings enable the simultaneous manipulation of particles of various characteristics in multiple planes due to the different power intensity distributions. Sorting with Bessel beam is an attractive approach using small sample volumes (microliter ranges), which becomes beneficial when working with rare particles of interest and in small samples. In this study a home built Bessel beam optical sorting setup was used to sort polystyrene and silica microspheres of different sizes and refractive indices. Our preliminary results showed that the polystyrene microspheres travelled quicker than the silica type of spheres with the same size due to the high refractive indices. These findings indicate the potential application of sorting different cells with varying refractive indices such as differentiating HIV infected cells from uninfected cells.
Chemical sensor nanotechnology in pharmaceutical drug research
(2022-08) Thobakgale, Setumo L; Ombinda-Lemboumba, Saturnin; Mthunzi-Kufa, Patience
The 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.
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, Patience
Human 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.
Comparing the plasmonic properties of laser and chemically synthesized SeNPs for localized surface plasmon resonance detection
(2025-09) Mcotshana, Zenande KS; Thwala, Nomcebo L; Ombinda-Lemboumba, Saturnin; Ramokolo, Lesiba R; Sekhwama, Masindi; Thobakgale, Setumo L; Lugongolo, Masixole Y; Hlekelele, Lerato; Mpofu, Kelvin T; Van Steen, E; Mthunzi-Kufa, P
Localized surface plasmon resonance (LSPR) sensing offers a rapid, label-free, and highly sensitive approach for detecting biomolecular interactions. This study investigates the LSPR characteristics of selenium (Se) nanoparticles (NPs) synthesized via two distinct approaches: pulsed laser ablation in liquid and chemical reduction, for the development of an optical sensor to detect Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The laser ablation method produced ligand-free Se NPs with high purity and narrow size distribution, while the chemical reduction route yielded NPs with tunable morphology and surface functionalization capability. The selenium NPs (SeNPs) were characterized by ultraviolet–visible spectroscopy, dynamic light scattering, and high-resolution transmission electron microscopy. Raman spectroscopy was used to determine the functional groups on the surfaces of SeNPs. Thereafter, an optical biosensing substrate pre-coated with 3-aminopropyltriethoxysilane was functionalized with the SeNPs and conjugated with SARS-CoV-2 monoclonal antibodies to offer specificity for SARS-CoV-2. After characterization, the biosensing substrate was used for detecting SARS-CoV-2 pseudovirus (analyte) using LSPR. In the presence of SARS-CoV-2, the local refractive index around the SeNPs functionalized with the antibody increased, leading to a red shift in the LSPR peak when compared to the control sample. Furthermore, when the antibody captured the SARS-CoV-2 antigen, the SeNPs synthesized by the chemical reduction approach (C-SeNPs) exhibited a higher redshift compared to laser-synthesized SeNPs, indicating that C-SeNPs are good candidates for biosensing applications in optical techniques. The difference in LSPR shifts between the two types of NPs reflects their unique sensitivity to biomolecular interactions. These findings demonstrate that synthesis method selection influences LSPR sensor performance, and highlight the potential of Se NPs, particularly those prepared by the chemical reduction method, as promising plasmonic transducers for fast and cost-effective COVID-19 diagnostics.
Controlling the quantum world with light
(2012-10) Uys, H; Akhalwaya, I; Botha, N; Burd, S; Hendriks, A; Madigoe, R; Ombinda-Lemboumba, Saturnin; Smit, A; Kloppers, H; Steyn, J; Botha, L
In this presentation the authors discuss the technological relevance of quantum mechanics, and describe how researchers use light to control the atomic and molecular world at its most fundamental level.
Could low level laser therapy and highly active antiretroviral therapy lead to complete eradication of HIV-1 in vitro?
(SPIE, 2017-01) Lugongolo, Masixole Y; Manoto, Sello L; Ombinda-Lemboumba, Saturnin; Maaza, M; Mthunzi-Kufa, Patience
Human immunodeficiency virus (HIV-1) infection remains a major health problem despite the use of highly active antiretroviral therapy (HAART), which has greatly reduced mortality rates. Due to the unavailability of an effective vaccine or a treatment that would completely eradicate the virus, the quest for new and combination therapies continues. In this study we explored the influence of Low Level Laser Therapy (LLLT) in HIV-1 infected and uninfected cells. Literature reports LLLT as widely used to treat different medical conditions such as diabetic wounds, sports injuries and others. The technique involves exposure of cells or tissue to low levels of red and near infrared laser light. Both HIV infected and uninfected cells were laser irradiated at a wavelength of 640 nm with fluencies ranging from 2 to 10 J/cm2 and cellular responses were assessed 24 hours post laser treatment. In our studies, laser therapy had no inhibitory effects in HIV-1 uninfected cells as was indicated by the cell morphology and proliferation results. However, laser irradiation enhanced cell apoptosis in HIV-1 infected cells as the laser fluencies increased. This led to further studies in which laser irradiation would be conducted in the presence of HAART to determine whether HAART would minimise the detrimental effects of laser irradiation in infected cells.
Design and FDTD simulation of photonic crystal based sensor for biosensing applications
(SPIE, 2019-03) Manoto, Sello L; Mabena, Chemist M; Malabi, Rudzani; Ombinda-Lemboumba, Saturnin; Mthunzi-Kufa, Patience
Photonic crystals (PhCs) is a unique and flexible class of optical devices that are able to manipulate the electromagnetic fields of light. PhCs is a subwavelength grating structure with a periodic arrangement of a high refractive index layer coated on a low refractive index material and can provide a strong light confinement depending on the size, periodicity and the refractive index. Finite difference time domain (FDTD) method can be used to simulate the electromagnetic properties of light through complex structures such as PhCs, because of the precision of the method in the description of geometry and properties of the material. In this study, FDTD software from Lumerical was used to design and simulate the electromagnetic properties of the PhCs based sensor for biosensing applications. The transmission, reflection and absorption characteristics through the proposed PhCs structure was analysed using a visible wavelength range of 400- 700 nm. The boundary conditions were correctly chosen and consisted of periodic boundary conditions and perfectly matched layers. The results revealed that the transmission and reflectance were dependent on the period of the PhCs and the enhanced electric field was confined in an area allowing for interaction with biological analytes.
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, Patience
Iodine 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.
Detection of biological analytes using surface plasmon resonance as a biosensing technique for possible development of a point of care diagnostic tool
(SPIE, 2019-02) Malabi, Rudzani; Manoto, Sello L; Ombinda-Lemboumba, Saturnin; Maaza, Malik; Mthunzi-Kufa, Patience
Surface Plasmon Resonance (SPR) is a very powerful optical sensing technique that detects bimolecular binding interactions and it has turned out to be a suitable platform for clinical analysis. In biological and chemical sensing applications, SPR is used to monitor molecular binding real-time and it also promotes epitope mapping for determining biomolecular structures such as the interactions of proteins, DNA and viruses. This sensing technique also provides sensitive, label free and real-time monitoring of reactions. In this study we have built, characterized and optimized the SPR system for biosensing applications. Spectroscopy and scanning electron microscopy were used to characterize the surface of the SPR biosensor chip functionalized with antibodies. The home-built SPR system was successful in detecting biological analytes thereby paving a way into designing a label-free point-of-care (POC) diagnostic tool.
Detection of mycobacterium tuberculosis using gold nanoparticles conjugated to TB antibodies
(2021-03) Maphanga, Charles P; Manoto, Sello L; Ombinda-Lemboumba, Saturnin; Mthunzi-Kufa, Patience
In 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.
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.
Development of collinear transmission plasmonic biosensor for detection of HIV-1
(SPIE, 2020-02) Ombinda-Lemboumba, Saturnin; Manoto, Sello L; Maphanga, Charles P; Malabi, Rudzani; Mthunzi-Kufa, Patience
Surface Plasmon Resonance (SPR) which is widely used to study interactions between different types of biomolecules, has emerged as a technique of choice for rapid and quantitative analyses. However, there are still some challenges on the use of the classical SPR optical configuration. The prism-based configuration setup requires precise alignment of light onto the sample surface and the oblique reflection angle plane yield optical aberration. In this work we have built, characterized and optimized a simple collinear transmission geometry plasmonic system for the detection of HIV-1. Here, a continuous wave laser at 785 nm with power output of 300 mW was used as light source and a 40X objective lens coupled to a CCD camera was used to collect and detect the transmitted intensity change. Furthermore, a white light source was used to study the wavelength dependency of the sample. We present our findings which may be useful to develop biomedical devices for point-of-care diagnostics and healthcare applications.
The effect of low-level laser therapy on severe acute respiratory syndrome coronavirus-2 infected cells
(2024-03) Mngwengwe, Luleka; Lugongolo, Masixole Y; Ombinda-Lemboumba, Saturnin; Ismail, Y; Mthunzi-Kufa, Patience
SARS-CoV-2 is a threat to public health due to its ability to undergo crucial mutations, increasing its infectivity and decreasing the vaccine's effectiveness. There is a need to find and introduce alternative and effective methods of controlling SARS-CoV-2. LLLT treats diseases by exposing cells or tissues to low levels of red and near-infrared light. The study aims to investigate for the first time the impact of LLLT on SARS-CoV-2 infected HEK293/ACE2 cells and compare them to uninfected ones. Cells were irradiated at 640 nm, at different fluences. Subsequently, the effects of laser irradiation on the virus and cells were assessed using biological assays. Irradiated uninfected cells showed no changes in cell viability and cytotoxicity, while there were changes in irradiated infected cells. Furthermore, uninfected irradiated cells showed no luciferase activity while laser irradiation reduced luciferase activity in infected cells. Under SEM, there was a clear difference between the infected and uninfected cells.
The effects of low level laser therapy on both HIV-1 infected and uninfected TZM-bl cells
(Wiley, 2017-01) Lugongolo, Masixole Y; Manoto, Sello L; Ombinda-Lemboumba, Saturnin; Maaza, M; Mthunzi-Kufa, Patience
Human immunodeficiency virus (HIV-1) infection remains a major health problem despite the use of highly active antiretroviral therapy (HAART), which has greatly reduced mortality rates. Due to the unavailability of an effective vaccine and treatment that would completely eradicate the virus in infected individuals, the quest for new therapies continues. Low level laser therapy (LLLT) involves the exposure of cells to low levels of red or infrared light. LLLT has been widely used in different medical conditions, but not in HIV-1 infection. This study aimed to determine the effects of LLLT on HIV-1 infected and uninfected TZM-bl cells. Both infected and uninfected cells were irradiated at a wavelength of 660 nm with different fluences from 2 J/cm2 to 10 J/cm2 . Changes in cellular responses were assessed using cell morphology, viability, proliferation, cytotoxicity and luciferase activity assays. Upon data analysis, uninfected irradiated cells showed no changes in cell morphology, viability, proliferation and cytotoxicity, while the infected irradiated cells did. In addition, laser irradiation reduced luciferase activity in infected cells. Finally, laser irradiation had no inhibitory effect in uninfected cells, whereas it induced cell damage in a dose dependent manner in infected cells.
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.
Efficient femtosecond driven SOX 17 delivery into mouse embryonic stem cells: Differentiation study
(SPIE, 2017-01) Thobakgale, Setumo L; Manoto, Sello L; Ombinda-Lemboumba, Saturnin; Maaza, M; Mthunzi-Kufa, Patience
Embryonic stem cells have great promise in regenerative medicine because of their ability to self-renew and differentiate into various cell types. Delivery of therapeutic genes into cells has already been achieved using of chemical agents and viral vectors with high transfection efficiencies. However, these methods have also been documented as toxic and in the latter case they can cause latent cell infections. In this study we use femtosecond laser pulses to optically deliver genetic material in mouse embryonic stem cells. Femtosecond laser pulses in contrast to the conventional approach, minimises the risk of unwanted side effects because photons are used to create transient pores on the membrane which allow free entry of molecules with no need for delivery agents. Using an Olympus microscope, fluorescence imaging of the samples post irradiation was performed and decreased expression of stage specific embryonic antigen one (SSEA-1) consistent with on-going cellular differentiation was observed. Our results also show that femtosecond laser pulses were effective in delivering SOX 17 plasmid DNA (pSOX17) which resulted in the differentiation of mouse embryonic stem cells into endoderm cells. We thus concluded that laser transfection of stem cells for the purpose of differentiation, holds potential for applications in tissue engineering as a method of generating new cell lines.
Evaluation of a photonic crystal-based biosensing platform for HIV viral load quantification
(2025-08) Ombinda-Lemboumba, Saturnin; Manoto, SB; Maphanga, Charles P; Lugongolo, Masixolo Y; Tjale, Mabotse A; Mngwengwe, Luleka; Kasem, MA; Elfaham, MM; El-Hussein, A; Mthunzi-Kufa, Patience
Accurate quantification of HIV viral load (VL) is critical for monitoring antiretroviral therapy (ART) efficacy. Traditional VL testing methods are often expensive and require centralized laboratory infrastructure, limiting their accessibility in resource-constrained settings. In the current study, we present a photonic crystal (PhC)- based optical biosensor functionalized with anti-HIV-gp120 antibodies for the sensitive detection of HIV-1 pseudovirus. Characterization techniques, including dynamic light scattering, zeta potential analysis, UV–visible spectroscopy, and scanning electron microscopy, confirmed effective antibody-analyte interactions. Transmission spectroscopy revealed significant resonance wavelength shifts corresponding to varying viral titers. The proposed biosensor demonstrated reliable detection and quantification down to a concentration of 0.99 × 10 TCID 50 /ml (D3), with measurable resonance wavelength shifts clearly distinguishable from background signals. The detection limit was as low as 0.99 × 10 3 TCID 50 /ml. Validation with real-time quantitative PCR (rt- qPCR) demonstrated the biosensor’s sensitivity. These findings underscore the potential of the PhC-based biosensor as a rapid, accurate, and accessible platform for HIV VL monitoring, particularly in low-resource environments.

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