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Hemozoin Detection using Nitrogen-Vacancy centers in Diamond

Periodic Reporting for period 1 - HEMOTECT (Hemozoin Detection using Nitrogen-Vacancy centers in Diamond)

Reporting period: 2016-04-01 to 2018-03-31

"The HEMOTECT project aims at the development and implementation of a sensitive sensor for the detection of paramagnetic systems and, in particular, of hemozoin crystals.

Hemozoin crystals (HzC) are the byproduct of malaria infection. The Plasmodium parasite, the agent of malaria, during its intraerythrocytic cycle digests hemoglobin and releases heme which is highly toxic for itself. Detoxification is achieved by the transformation of heme into an iron-containing porphyrin crystal, namely the HzC.The HzC has magnetic and optical properties distinct from any other component of blood.

Malaria transmission has declined by ~40% in the period of 2010-2015 and the possibility of elimination (reduction of transmission to zero in a dened geographical area) in the current decade has been, for the 1rst time in years, considered. Approximately 3.4 billion people are at risk of malaria worldwide, with 627,000 deaths just in 2012, while by the year 2016 there were an estimated 216 million cases of malaria in 91 countries (an increase of 5 million cases over 2015).
Malaria is an entirely preventable and treatable disease, provided the recommended interventions are properly implemented, such as early diagnosis and timely treatment with appropriate anti-malaria medication. Currently, the most reliable and sensitive malaria diagnostic tools are (a) the observation of blood smears using microscopy, and (b) rapid-diagnostic tests (RDTs), which are antigen-based detectors.

These tools are the diagnostic ""gold standards standards"", but they come at a cost. Microscopy is labor intensive and requires trained staff, well equipped laboratories, and cannot be used for high-throughput screening in areas of low-parasitemia levels. RDTs are expected to become more sensitive and cheaper (current cost 75 cents), but they still produce false positives, are susceptible to high-temperature environments, and require 15 minutes to produce a result. It is therefore apparent that at present, there
is a large need for a new diagnostic method that will allow the rapid and denitive diagnosis of infected, asymptomatic, cases that remain undetectable by the currently used field methods.

A new physical tool has recently emerged as a unique magnetic-field sensor for physics and biology and it is based on the exploitation of the spin properties of one particular color center in diamond, known as the Nitrogen-Vacancy (NV) center. The NV center is formed by a substitutional nitrogen atom and a vacancy on adjacent lattice sites of the diamond crystal lattice, and possesses remarkable magneto-optic properties which allow for the highly sensitive detection of magnetic fields (as well as electric fields, pressure, and temperature) at the nanometer scale.

The main goal of the HEMOTECT project is to develop a novel technology that would allow for the label-free detection of HzC with sensitivity limits better than the currently used malaria diagnostic ""gold standards"". The implementation of an sensor using NV centers in diamonds allows for the detection of HzC with higher sensitivities and acquisition times faster than the current diagnostic ""gold standards"", and paves the way towards a novel malaria diagnostic technique. Our scientific breakthrough is the demonstration of the principles towards a versatile and easy-to-use and cost-effective instrumentation that could be used for the early diagnosis of malaria, and therefore, contribute to the eradication of one of the deadliest diseases in the world.

"The HEMOTECT project principle objectives were a) the design and development of highly sensitive magnetometric sensors, in particular magnetometers using NV-centers in diamonds, and b) the implementation of the developed diamond-based sensors for the detection of paramagnetic substances, in particular of hemozoin crystals, with higher sensitivities and faster acquisition times than the current malaria-diagnostic ""gold standard” techniques. In particular:
1. During the course of the project we worked on the development of several highly sensitive magnetometric devices and protocols employing NV-centers in diamond.
2. Our objective was the implementation of a diamond-based magnetometer for performing electron paramagnetic resonance (EPR) on paramagnetic spins in liquid and solids.
3. Highly sensitive detection of hemozoin crystals - During the HEMOTECT project we employed the developed sensors for the detection of hemozoin crystals to achieve higher sensitivities and faster acquisition times than the current malaria-diagnostic ""gold standard” techniques, and in particular blood smear microscopy. We also developed a novel alternative approach of sensing hemozoin crystals using direct magnetic imaging, which enables single-crystal resolution, is a background-free methodology and is sensitive only to structures with magnetic properties, thus, circumventing all problems related with blood smear microscopy.
4. Design and develop a highly sensitive non-destructive sensor of magnetic nanoparticles in flowing complex fluids: An additional outcome of the project was the development of an alternative magnetometric sensor and detection scheme for the detection of magnetic substances within flowing media. In particular, using high-performance atomic magnetometers we achieved the detection of magnetic nanoparticles with sizes of ~30nm at sub-picomolar sensitivities within flowing complex fluids, and managed to observe in real-time and in a non-destructive manner the separation of these nanoparticles from whole blood. Our developed sensor and technique is ideal within the context of novel therapeutic approaches that aim at removal of disease causing factors directly from a patient’s blood in an extracorporeal circuit using nanoparticles. These studies were realised during the final year of the project and resulted in novel results and methodologies that are expected to have significant scientific impact, not only within the field of malaria research, but in other biomedical and even in industrial fields.
Details of our work and results can be found in the publications of the project, and in publications that will be presented in scientific conferences, peer-reviewed journals, and open access publications, in the future.
During the course of the HEMOTECT project we developed novel sensing methodologies for the detection of magnetic systems using diamond-based and atomic-based magnetometers. Our primary motivation has been the detection of hemozoin crystals using the developed sensors and implement our technology as a new malaria diagnostic tool. An additional outcome of our project was the demonstration of a highly sensitive non-destructive sensor of magnetic nanoparticle in flowing complex fluids. Our developed technologies and detection approaches have broad applications in different research and industrial fields. Prominent examples are the application of our instruments for the diagnosis of malaria, as well as, other diseases that result in the generation of magnetic bio-products, the non-destructive measurement of magnetic nanoparticles in biomedical applications, but also in industrial applications.
Hemozoin crystals are a byproduct of malaria infection, and can be used for early malaria diagnosis.