Potenziare il rilevamento della proteina α-Synuclein usando un sensore QCM a liposomi immobilizzati in una soluzione salina e acida

Population aging has increased the prevalence of age-related neurodegenerative diseases, with Parkinson's disease (PD) now the fastest-growing neurological condition worldwide, expected to double in prevalence by 2050. In this study, we investigated the detection and sensitivity of α-Synuclein (αSyn) protein, one of the causative agents of Parkinson's Disease, so we can be able to have an early diagnosis so that the patients can start the treatments and adapt at the early stage of the disease. In this study, a quartz crystal microbalance (QCM) sensor was used to detect and evaluate αSyn. The QCM is a mechanical mass sensor that can detect the mass of material attached to the sensor surface as a change in the resonance frequency of a vibrating quartz crystal. In this sensor, liposomes were immobilized via self-assembled monolayer on the surface of the gold electrode and then measurements were made. In this study, to improve the detection and sensitivity of αSyn, the recently reported effect of salt in solution and the latest effect of an acidic solution to promote aggregation of the proteins were investigated to increase sensitivity and speed of detection. To do so, we opted for a NaCl solution of 0.5M concentration, because at higher concentrations there may occur the effect called “salting out”, in which salt precipitates the protein, thus reducing the specificity of detection of the αSyn protein. While having a lower concentration doesn’t increase much the specificity of detection of the αSyn protein. Furthermore, to increase the speed of detection of the protein, we used two different buffer solutions to have the best choice of solution for each pH used. In this study, we are investigating the range of pH between 7 and 4, with pH 4 being the lowest limit before the proteins start to auto aggregate and pH 7 being the highest limit, because it’s the physiological pH in which all the biological reactions happen. The purpose of this research is to look for an accessible way to detect one of the main causes of the Parkinson's Disease, to set a valid biomarker for further diagnosis. Keywords: QCM, Parkinson's Disease, pH, salt, α-Synuclein