Use of personal glucose meter for detecting procalcitonin through a network of glucose encapsulated within liposomes

Sepsis is a life-threatening condition triggered by the host response to an infection. A worldwide healthcare problem, sepsis is one of the major causes of death in intensive care units, with a risk of mortality that increases by approximately 10% for every hour of delay in getting an appropriate treatment. However, sepsis can be difficult to distinguish from other non-infectious conditions in critically ill patients with systemic inflammatory response syndrome (SIRS) for example, which requires a different treatment. Procalcitonin (PCT), the pro-hormone of the hormone calcitonin, is considered an effective biomarker for sepsis, as it is released into the bloodstream in response to bacterial infections. The major advantage of PCT, compared with other biomarkers, is that its levels rapidly increase in the early stages of a sepsis infections. Nowadays, the quantification of PCT is a time-consuming test that requires laboratory-based instrumentation. This is particularly a problem when the patient needs serial PCT measurements during the diagnoses process, with multiple transfers of samples from the patient to a clinical laboratory. The inspiration of this thesis is to develop a new portable, fast, and sensitive immunosensor that can improve the safety of the patient by detecting PCT at early stages of sepsis. The developed immunoassay relies on repurposing a personal glucose meter (PGM) to indirectly detect and quantify PCT, using glucose encapsulated within liposomes that can release the sugar in presence of PCT, thus generating a reading on the PGM. Signal amplification can be achieved by liposome-liposome crosslinking with the introduction of a streptavidin-biotin link between liposomes. This generates a network of liposomes that is rich in glucose and then greatly amplify the signal of PGM. At the first step liposome with encapsulated glucose were prepared. At the second step, the as-synthesized liposomes with encapsulated glucose were added to the sandwich immunoassay to provide the tags, by conjugating the sandwich with the liposomes occurred through biotin - streptavidin link, and addition of a surfactant to release the glucose and generate a signal directly proportional to the concentration of the PCT in the sample. In this chapter, the performance of the assay was investigated for detecting PCT in blood sample. The last step includes the signal amplification of the signal through the liposome network.