Thermodynamic models formulated based on the Landau free-energy expansion are popular and well suited to studies involving properties of the ferro/para-electric transition, or near it. Indeed, the general nature of thermodynamics, from which the strength of the model is derived, allows a valid model to be constructed based on simple functional forms with parameters fitted to experiments, by passing the mechanistic complexity. Despite inaccuracy due to the neglect of fluctuations, this approach has been proven effective and powerful for recent research development of ferroelectrics in nanoscale. Efforts in some important works have recently faced much challenge, when free-energy contributions have to be incorporated to account for the presence of depolarization fields, surfaces and other defects. To minimize the problems with mechanistic obscurity, it is of paramount importance that the electromagnetics, mechanics and thermodynamics involved are accounted for explicitly and with full self-consistency. It is important that the free-energy functional of nanoscale ferroelectric systems, such as ferroelectric thin films （FTF）, bilayers （FB）, superlattices （FS）, nanowires （FNW）, nanotubes （FNT） and tunneling junctions （FTJ） etc., must be derived thermodynamically from first principles.
In this paper,we introduce our finding of the effects of C_(60) nanoparticles (NP) infiltration on mechanical properties of cell and its membrane.Atomic force microscopy (AFM) is used to perform indentation on both normal and C_(60) infiltrated red blood cells (RBC) to gain data of mechanical characteristics of the membrane.Our results show that the mechanical properties of human RBC membrane seem to be altered due to the presence of C_(60) NPs.The resistance and ultimate strength of the C_(60) infiltrated RBC membrane significantly decrease.We also explain the mechanism of how C_(60) NPs infiltration changes the mechanical properties of the cell membrane by predicting the structural change of the lipid bilayer caused by the C_(60) infiltration at molecular level and analyze the interactions among molecules in the lipid bilayer.The potential hazards and application of the change in mechanical characteristics of the RBCs membrane are also discussed.Nanotoxicity of C_(60) NPs may be significant for some biological cells.
