Visco-Hyperelastic Characterization of the Equine Immature Zona Pellucida.

Mohammad Minooei,Elisa Ficarella,Bartolomeo Trentadue,Marco De Spirito,Massimiliano Papi,Luciano Lamberti,Elisabetta Toma,Lorenzo Santoro,Catalin I Pruncu

doi:10.3390/ma14051223

Abstract

This article presents a very detailed study on the mechanical characterization of a highly nonlinear material, the immature equine zona pellucida (ZP) membrane. The ZP is modeled as a visco-hyperelastic soft matter. The Arruda–Boyce constitutive equation and the two-term Prony series are identified as the most suitable models for describing the hyperelastic and viscous components, respectively, of the ZP’s mechanical response. Material properties are identified via inverse analysis based on nonlinear optimization which fits nanoindentation curves recorded at different rates. The suitability of the proposed approach is fully demonstrated by the very good agreement between AFM data and numerically reconstructed force–indentation curves. A critical comparison of mechanical behavior of two immature ZP membranes (i.e., equine and porcine ZPs) is also carried out considering the information on the structure of these materials available from electron microscopy investigations documented in the literature.

Highlights

Atomic force microscopy (AFM) is a well-established approach to the mechanical characterization of cells and biopolymer networks [1,2,3,4,5,6,7,8,9,10]
The typical assumption made in AFM investigations on biological materials is to have elastic behavior, which may range from linear elasticity to hyperelasticity
Lamberti et al [13,29,30,31] carried out several studies on the mechanical response of zona pellucida (ZP) membranes of bovine, porcine and equine species

Summary

Introduction

Atomic force microscopy (AFM) is a well-established approach to the mechanical characterization of cells and biopolymer networks [1,2,3,4,5,6,7,8,9,10]. Viscous forces may drive the nanoindentation response of biopolymer networks even at low indentation rates [19]. Cellular membranes comprising polymeric networks are typical examples of viscoelastic materials. In this regard, Lamberti et al [13,29,30,31] carried out several studies on the mechanical response of zona pellucida (ZP) membranes of bovine, porcine and equine species. Knowing the mechanical response of the ZP allows us to identify key

Objectives

Methods

Results

Conclusion