Study of electrical properties of nerve cells by conductive atomic force microscopy

Abstract

The prevalence of neurodegenerative diseases such as Alzheimer's disease (AD) and epilepsy, characterised by deterioration of the nervous system, continues to exhibit an exponential upward trend. Despite decades of research, the understanding of the underlying pathology and mechanisms of these neurodegenerative remains insufficient. Although scientists have proposed various ideas, the development of methods or drugs that can completely cure these diseases still has not yet been achieved. Previous research has focused on using biological methods to study the complex relationship between cells and related diseases. However, the study of the cellular physical properties in diseased states remains limited, especially when patients suffered from neurodegenerative diseases, the changes in the physical properties of nerve cells. In this work, we employed atomic force microscopy (AFM) and conductive atomic force microscopy (CAFM) to study the physical properties of SH-SY5Y cells, analysing their mechanical and electrical properties. Furthermore, we extend our work to study the pathogenesis and drug screening of related neurodegenerative diseases. The effect of AFM measurement parameters on the detection of cellular mechanical properties was studied to improve the accuracy of the obtained mechanical data. The effects of indentation force, indentation speed, lifting height and cantilever shape on the detection of cellular mechanical properties were studied, and the force curves obtained by detecting A549 cells using different measurement parameters were compared, which helps to choose and determine the most suitable detection parameters for the subsequent experiments. The neurotoxic effect of amyloid-beta (Aβ) on the physical properties of SH-SY5Y cells was studied in this work. Results showed the Aβ25-35, can significantly reducing the cell viability and altering the physical properties of SH-SY5Y cells, including cell morphology, membrane roughness, Young's modulus (YM), and membrane potential. This validated the neurotoxicity of Aβ25-35 from a physical perspective and provides data support for subsequent research. The neuroprotective effect of edaravone (EDA) was analysed from a perspective of cellular physical properties. The SH-SY5Y cells were treated with 20 μmol/L concentration of Aβ25-35 to simulate the AD environment for cells, and the cells of experimental groups were added with different concentrations of EDA simultaneously for 24 h. The results indicated that EDA can effectively protect cell viability of SH-SY5Y cells from being reduced by Aβ25-35, and also can protect multiple physical properties of SH-SY5Y cells affected by Aβ25-35. These results demonstrate the neuroprotective effect of EDA, and providing a new insight for the multi-targeted therapy of AD. Nimodipine (NM) was used to treat on SH-SY5Y cells, as the calcium imbalance was a deep trigger of oxidative stress and can also lead to AD. The effect of Aβ25-35 on the cell membrane was mainly studied, as Aβ25-35 could directly act on the cell membrane and its neurotoxicity could make the cell membrane rough and damage its integrity. The results indicated that NM could protect the viability of SH-SY5Y cells reduced by Aβ25-35 and alleviate related physical properties changes. It also could attenuate the damage of Aβ25-35 to the cell membrane, thereby reducing the impact on the cell membrane potential.