AFM methods for studying the morphology and micromechanical properties of the membrane of human buccal epithelium cell

Abstract

AbstractUsing AFM methods in air under normal conditions in a wide range of local force effects ($${F}_{const}$$ F const < 40 μN) the relief, functional micromechanical properties (elasticity coefficient $$K$$ K , Young’s modulus $$E$$ E , elastic $${\Delta h}_{dfrm}$$ Δ h dfrm and plastic $${\Delta h}_{stiff}$$ Δ h stiff deformations) and adhesive properties (work $$A$$ A of adhesive forces $${F}_{adh}={F}_{adh}(x;y)$$ F adh = F adh ( x ; y ) ) of the membranes of living adult cells of human buccal epithelium were studied in the presence of a protective layer < 100 nm of buffer solution that prevented the cells from drying. Almost all geometric and functional characteristics of the membrane in the local approximation at the micro- and nanolevels are affected by size effects and obey the laws of fractal geometry. The Brownian multifractal relief of the membrane is characterized by dimension $${D}_{f}$$ D f < 2.56 and irregularities < 500 nm vertically and < 2 μm horizontally. Its response to elastic (≤ 6 nN), active (6–21 nN), or passive (> 21 nN) stimulation ($${F}_{const}$$ F const ) is a non-trivial selective process and exhibits a correspondingly elastic ($$K=$$ K = 67.4 N/m), active ($$K=$$ K = 80.2 N/m) and passive ($$K=$$ K = 84.5 N/m) responses. $$K=K({F}_{const})$$ K = K ( F const ) and $$E=E({F}_{const})$$ E = E ( F const ) depend on $${F}_{const}$$ F const . Having undergone slight plastic deformations $${\Delta h}_{stiff}$$ Δ h stiff < 300 nm, the membrane is capable of restoring its shape. We mapped ($$E=E(x;y)$$ E = E ( x ; y ) , $${D}_{f}$$ D f = 2.56; $${\Delta h}_{dfrm}={\Delta h}_{dfrm}(x;y)$$ Δ h dfrm = Δ h dfrm ( x ; y ) , $${D}_{f}$$ D f = 2.68; $${\Delta h}_{stiff}={\Delta h}_{stiff}(x;y)$$ Δ h stiff = Δ h stiff ( x ; y ) , $${D}_{f }$$ D f = 2.42, $$A=A\left(x;y\right)$$ A = A x ; y and $${F}_{adh}={F}_{adh}(x;y)$$ F adh = F adh ( x ; y ) ) indicating its complex cavernous structure.