Towards the early malaria detection based on magneto-optical methods in specialty optical fiber

Abstract

Malaria is one of the most serious vector-borne diseases and a major public health concern worldwide. This potentially lethal disease is spread by mosquitos in tropical areas. During a mosquito bite, single-celled plasmodium parasites are carried by infected mosquitos and enter the human bloodstream. Plasmodium falciparum is the parasite that causes malaria's most severe form. Globally, 300 to 500 million people are infected with the disease every year and 1.5 to 2.7 million people die as a result. The majority of malaria detection techniques rely on expertise, sophisticated assays as well as time consuming processes. The general subject of this thesis pertains to optical fiber sensors based on photonic crystal fibers (PCF) and specialty fibers (SF). We want to know what are the benefits of using PCF and SF instead of conventional sensing techniques. In particular, we are interested in the detection of malaria pigment in the early stages of infection. Malaria pigment also known as hemozoin (Hz) is a byproduct of the disease formed during the growth cycle of the parasites. These pigments have triclinic crystal structure with various morphology depending on the parasite species. They usually have an elongated rod-like shape with a length ranging from 300 nm to 1 µm. Malaria pigments are inert, insoluble in aqueous solution with dark-brown color and a paramagnetic feature. In a healthy individual, Hz is not present. As a result, Hz serves as a diagnostic biomarker of malaria infection. The significance and oddities of this biocrystal have prompted scientists to investigate it as a potential target for diagnostics and therapies against the disease using innovative techniques. Basically, extracting natural Hz (nHz) is a time-consuming and costly process that needs special biomedical facilities as well as the expertise to infect living hosts (e.g. rats) with malaria and obtain the nHz. Therefore, there is a strong argument for promoting new research advances in this area to work with the synthetic form of Hz (SHz), aka β-hematin. This Hz imitation has a structure that is physically and chemically comparable to its natural counterpart. Several prior works have studied the synthesis of Hz while others investigated the physicochemical characteristics of SHz production. However, there are still gaps in the scientific literature on how to control the size of SHz compounds so as to obtain similar dimensions to the naturally occurring Hz. The main goal of this thesis is to detect SHz employing PCF based on the magnetic feature of Hz. In this regard, a systematic procedure to produce SHz with controllable size features that are compatible with nHz was demonstrated. In addition, a detailed physical characterization was performed on the resulting samples, using various techniques including vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and refractive index (RI) measurements. To the best of our knowledge, no study has produced SHz of comparable size to natural ones as well as considering structural, optical, chemical, and magnetic properties in one study. This thesis is structured in three different parts. In the first step, the ability of the proposed sensor to detect the presence of magnetic particles in aqueous solution was considered. In this step the air holes of PCF infiltrated with magnetic fluid (MF) and the transmitted power of the PCF was monitored in presence of magnetic field. In the next step, we focused on synthesizing the mimic of nHz through straightforward procedure followed by detailed characterization. Finally, we considered the sensor performance to detect SHz in aqueous solution with various concentrations.

Date	13 Apr 2023
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Bora Ung (Supervisor) & Ricardo Izquierdo (Co-supervisor)