PhD Discussions Sessions: Elena Lantero and Manuel López

Targeting Plasmodium falciparum with DNA aptamers

Malaria still remains as one of the main causes of mortality in many developing countries. Caused by parasitic infection of Plasmodium species, the World Health Organization has launched an ambitious plan to eradicate malaria, which will require population mass screening and treatment. In this context, the current diagnostic gold standard is light microscopy of peripheral blood smears, which is time and labor intensive, and needs prepared personnel and continuous training. Alternatively, antigen-based rapid tests have limited sensitivity and do not provide quantitative measure; and PCR-based molecular methods, although sensitive, demand for highly trained personnel and costly reactives. Besides, most current antimalarials have known resistances and new forms of treatment such as targeted delivery are interesting tools to prevent further spreading of such resistances.

Accordingly, malaria massive screening and treatment will require new rapid, sensitive, simple and economically affordable methods, able to detect even asymptomatic infected patients and low-density infections. Screening for new bioreceptors is required in order to increase the sensitivity of current antigen-based malaria rapid diagnosis or to develop new treatments. Antibody production often involves the use of laboratory animals and is time-consuming and costly, especially when the target is Plasmodium, whose variable antigen expression complicates the development of long-lived biomarkers. To circumvent these obstacles we have applied the Systematic Evolution of Ligands by EXponential enrichment (SELEX) method to the rapid identification of DNA aptamers against Plasmodium-infected red blood cells (pRBCs). This type of synthetic bioreceptor is expected to display higher dry-storage and lyophilisation stability than antibodies. Five 70 bp-long ssDNA sequences having a highly specific binding of pRBCs versus non-infected erythrocytes have been identified by using cell-SELEX with fixed pRBCs.

Photons to electrons:  Single molecule and time resolved Photosynthetic complex electron transfer study

We present our work on the electron transfer process of plant photosynthetic complex I (PSI). PSI is a membrane protein complex that captures sunlight energy and uses it to shuttle and energize electrons throughout thylakoid membrane, bringing them from a low energy state in one side of the membrane to a very energetic state in the other side.

We study the electron transfer process between photo-oxidized and photo-reduced peripherical cofactors of the protein and their respective protein redox partners performing electrochemical bulk and single molecule photocurrent measurements as protein sample is irradiated with LED and femtosecond pulsed lasers.

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