Alzheimer's disease (AD) is the most common form of dementia, and its early detection using reliable molecular biomarkers is believed to be best approach to controlling and even curing it. Herein, we develop an ultrasensitive electrochemical nanobiosensor to quantify serum miR-137 as a validated biomarker of AD. Electrochemically-reduced graphene oxide (ERGO) and gold nanowires (AuNWs) are used to modify the surface of a screen-printed carbon electrode (SPCE) with the application of an intercalated label, doxorubicin (Dox). The fabrication steps are analysed via field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS), as well as two reliable electrochemical methods, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that the linear range of the nanobiosensor is from 5.0 to 750.0 fM and its limit of detection is 1.7 fM. In addition, the nanobiosensor shows a great performance in specificity experiments and is able to discriminate between target oligos versus non-specific oligos (one-base mismatch target; three-base mismatch target, non-specific miR-21 and miR-155) very well. The evaluation of the sensing mechanism of the developed nanobiosensor in actual human serum reveals its potential clinical applications for the early detection of AD in the future.

The simulated liposome models provide events in molecular biological science and cellular biology. These models may help to understand the cell membrane mechanisms, biological cell interactions, and drug delivery systems. In addition, the liposomes model may resolve specific issues such as membrane transports, ion channels, drug penetration in the membrane, vesicle formation, membrane fusion, and membrane protein function mechanism. One of the approaches to investigate the lipid membranes and the mechanism of their formation is by molecular dynamics (MD) simulations. In this study, we used the coarse-grained MD simulation approach and designed a liposome model system. To simulate the liposome model, we used phospholipids that are present in the structure of natural cell membranes (1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE)). Simulation conditions such as temperature, ions, water, lipid concentration were performed based on experimental conditions. Our results showed a liposome model (ellipse vesicle structure) during the 2100 ns was formed. Moreover, the analysis confirmed that the stretched and ellipse structure is the best structure that could be formed. The eukaryotic and even the bacterial cells have elliptical and flexible structures. Usually, an elliptical structure is more stable than other assembled structures. The results indicated the assembly of the lipids is directed through short-range interactions (electrostatic interactions and, van der Waals interactions). Total energy (Van der Waals and electrostatic interaction energy) confirmed the designed elliptical liposome structure has suitable stability at the end of the simulation process. Our findings confirmed that phospholipids DOPC and DOPE have a good tendency to form bilayer membranes (liposomal structure) based on their geometric shapes and chemical-physical properties. Finally, we expected the simulated liposomal structure as a simple model to be useful in understanding the function and structure of biological cell membranes. Furthermore, it is useful to design optimal, suitable, and biocompatible liposomes as potential drug carriers.