Malaria Diagnostics

The imminent scenario of malaria burden on endemic regions burdens healthcare and is a threat to non-endemic regions. Microscopy and rapid diagnostic tests (RDTs) remain the gold standard for malaria detection in resource-constrained regions. They still present low sensitivity at low parasite density, however, with microscopy also requiring trained personnel, expensive and time consuming. Affordable, rapid, specific, sensitive and simple malaria diagnostics remain elusive. Molecular-based diagnostics, polymerase chain reaction and loop-mediated isothermal amplification, although highly sensitive even at low parasitemia, still have challenges hindering their use in resource-constrained regions. This chapter discusses the conventional microscopy, spectroscopy, RDTs and molecular platforms in malaria detection. It also highlights current interventions on mitigations of their existing hurdles and adaptability to developing regions. Such inventions include the amalgamation of different techniques, nanotechnology and artificial intelligence

Application of Plasmonic Nanostructures in Molecular Diagnostics and Biosensor Technology: Challenges and Current Developments

The recent global pandemic caused by Covid-19 enforced the urgent need for accessible, reliable, and accurate point-of-care rapid diagnostics based on plasmonic nanostructures. This is because fast and reliable testing was the key driver in curbing the spread of Covid-19. The traditional methods of diagnostics and biosensors often require expensive infrastructure and highly qualified and trained personnel, which limits their accessibility. These limitations perpetuated the impact of Covid-19 in most countries because of the lack of easily accessible point-of-care rapid diagnostic kits. This review revealed that portable and reliable point-of-care diagnostic kits are very crucial in reaching large populations, especially in underdeveloped and developing countries. This gives perspective to novel point-of-care applications. Furthermore, water quality is a very crucial part of food safety, especially in developing countries faced with water contamination. In this chapter, we explored the various challenges and recent developments in the use of plasmonic nanostructures for application in molecular diagnostics and biosensing for the detection of infectious diseases and common environmental pathogens

More than magnetic isolation: Dynabeads as strong Raman reporters towards simultaneous capture and identification of targets

Dynabeads are superparamagnetic particles used for immunomagnetic purification of cells and biomolecules. Post-capture, however, target identification relies on tedious culturing, fluorescence staining and/or target amplification. Raman spectroscopy presents a rapid detection alternative, but current implementations target cells themselves with weak Raman signals. We present antibody-coated Dynabeads as strong Raman reporter labels whose effect can be considered a Raman parallel of immunofluorescent probes. Recent developments in techniques for separating target-bound Dynabeads from unbound Dynabeads makes such an implementation feasible. We deploy Dynabeads anti-Salmonella to bind and identify Salmonella enterica, a major foodborne pathogen. Dynabeads present signature peaks at 1000 and 1600 1/cm from aliphatic and aromatic C-C stretching of polystyrene, and 1350 1/cm and 1600 1/cm from amide, alpha-helix and beta-sheet of antibody coatings of the Fe2O3 core, confirmed with electron dispersive X-ray (EDX) imaging. Their Raman signature can be measured in dry and liquid samples even at single shot ~30 x 30-micrometer area imaging using 0.5 s, 7 mW laser acquisition with single and clustered beads providing a 44- and 68-fold larger Raman intensity compared to signature from cells. Higher polystyrene and antibody content in clusters yields to the larger signal intensity and conjugation to bacteria strengthens clustering as a bacterium can bind to more than one bead as observed via transmission electron microscopy (TEM). Our findings shed light on the intrinsic Raman reporter nature of Dynabeads, demonstrating their dual function for target isolation and detection without additional sample preparation, staining, or unique plasmonic substrate engineering, advancing their applications in heterogeneous samples like food, water, and blood.Comment: 35 pages, 19 figures, submitted to the Journal of Raman Spectroscop

The synthesis, characterisation and application of phosphorylated multiwalled carbon nanotubes for the treatment of radioactive waste

M.Sc.Radionuclides exist in the environment because of natural and human activities that are an essential part of our lives. Nuclear processing, medicinal applications (using isotopes) and electric power production by nuclear stations are few examples of human activities that result in production of radioactive waste (RAW). The nuclear power stations in our world have to store their waste in such a manner that the present and future generations are protected from harmful radiations and this is a challenge. Exposure to RAW can result in severe, diverse and irreversible consequences such as damage of the ecosystem, pollution, cancers, birth mutations, to mention just a few. Solvent extraction (SE) technique is currently used to purify large volumes of secondary liquid waste before they are released to the environment or stored. However, even after the SE purification, highly radioactive liquid waste is given off. This highly radioactive liquid waste is solidified in a glass matrix (vitrification). In an attempt to reduce the disposal of large volumes of secondary RAW generated during the purification technology, this study was initiated to investigate the possibility of using multiwalled carbon nanotubes (MWCNTs) as part of the SE technique. As the main nuclear liquid extraction processes involve tributyl phosphate (TBP), the MWCNTs were linked to TBP, polymerised to give a MWCNTs-TBP polymer that was tested in the nuclear environment. This polymer should possess good chelating properties due to the inclusion of the phosphate and should be a good absorbent as MWCNTs are promising absorbent carbon materials. To test the hypothesis of the study MWCNTs-TBP polymer was tested for uranium extraction. The MWCNTs-TBP polymer gave a zero Kd value which indicates that the adsorption capacity of the polymer to remove radionuclides from waste streams was not successful. The MWCNTs were then tested for iodine-131 extraction whereby they were compared with single walled carbon nanotubes (SWCNTs) and double walled carbon nanotubes (DWCNTs). In this test SWCNTs gave a Kd value of 81694 mL/g which proved that they can be used in nuclear waste applications

Application of Raman Spectroscopy in Biomedical Diagnostics

In vivo cellular imaging and in vitro assays or sensors are fundamentally used to study the spatiotemporal interaction of molecules at biological interfaces. The study of these interfaces informs various applications such as diagnostics/detection of foreign materials or processes in the biological system. Raman spectroscopy, an optical, non-destructive, label-free fingerprinting tool offers a wide array of applications in both in vitro and in vivo diagnostics owing to its relatively short acquisition time, non-invasiveness and ability to provide biochemical molecular information. It has been explored in tissue imaging, in vitro diagnosis, DNA/RNA analysis, metabolic accretions, single cell analysis photodynamic therapy, etc. The chapter details the application of the optical Raman platform in the detection and imaging of diseases/tissues. The challenges associated with SERS applications and the future outlook as a biomedical diagnostic tool are also discussed

Development of a Versatile Half-Strip Lateral Flow Assay toward the Detection of Rift Valley Fever Virus Antibodies

Rift Valley fever (RVF) is a mosquito-borne zoonotic disease that is caused by the Rift Valley fever virus (RVFV); Bunyaviridae: Phlebovirus. RVF disease can affect several different species, including ruminants, camels and humans and thus present a dual threat to public health and livestock food production in endemic regions. In livestock, the RVFV infection is characterised by an acute hepatitis, abortion and high mortality rates in new-born animals. The current RVF diagnostic techniques have shown good sensitivity. However, they require extensive sample processing and complex instrumentation. Owing to speed, low cost, ease of use, and most importantly, the ability to diagnose diseases at sites where they are managed, lateral flow immunoassays (LFIA) are the most widely used point-of-care (POC) tools for disease diagnosis. In this study, a lateral flow assay (LFA) device that is able to detect antibodies against RVFV, with a minimum detectable concentration of 0.125 mg/mL, was successfully developed. The LFA also successfully detected RVFV antibodies in reference RVFV sera. Protein A (ProA), which has the ability to bind immunoglobulins from different species, was used in the detection probe, giving the developed RVFV LFA potential for multi-species diagnosis

Polylactide-based Magnetic Spheres as Efficient Carriers for Anticancer Drug Delivery

To improve traditional cancer therapies, we synthesized polylactide (PLA) spheres coencapsulating magnetic nanoparticles (MNPs, Fe₃O₄) and an anticancer drug (doxorubicin, DOX). The synthesis process involves the preparation of Fe₃O₄ NPs by a coprecipitation method and then PLA/DOX/Fe₃O₄ spheres using the solvent evaporation (oil-in-water) technique. The Fe₃O₄ NPs were coated with oleic acid to improve their hydrophobicity and biocompatibility for medical applications. The structure, morphology and properties of the MNPs and PLA/DOX/Fe₃O₄ spheres were studied using various techniques, such as FTIR, SEM, TEM, TGA, VSM, UV–vis spectroscopy, and zeta potential measurements. The in vitro DOX release from the spheres was prolonged, sustained, and pH-dependent and fit a zero-order kinetics model and an anomalous mechanism. Interestingly, the spheres did not show a DOX burst effect, ensuring the minimal exposure of the healthy cells and an increased drug payload at the tumor site. The pronounced biocompatibility of the PLA/DOX/Fe₃O₄ spheres with HeLa cells was proven by a WST assay. In summary, the synthesized PLA/DOX/Fe₃O₄ spheres have the potential for magnetic targeting of tumor cells to transform conventional methods