A novel method for post-mortem interval estimation based on tissue nano-mechanics
Forensic estimation of post-mortem interval relies on different methods, most of which, however, have practical limitations or provide insufficient results, still lacking a gold standard method. In order to better understand the phenomenon of rigor mortis and its applicability to the post-mortem interval estimation, we decided to use atomic force microscopy, a tool often employed to measure mechanical properties of adherent cells. Thus, we surgically removed skeletal muscle samples of three forensic cases from 0 to 120 h post-mortem and quantitatively evaluate two parameters: the Young’s modulus (E), which gives information about the sample stiffness, and the hysteresis (H), which estimates the contribution of viscous forces. Despite being a preliminary study, the obtained results show that the temporal behavior of E well correlates with the expected evolution of rigor mortis between 0 and 48 h post-mortem, and then monotonically decreases over time. Unfortunately, it is strongly affected by inter-individual variability. However, we found that H provides measurable data along a time-dependent curve back to the starting point, and these data measured on different subjects collapse onto a single master curve, getting rid of the inter-individual variability. Although a larger sampling should be performed to improve the result reliability, this finding is strongly suggestive that the evaluation of rigor mortis should involve the measure of the nanoscale dissipative behavior of muscular tissues.
KeywordsTime since death Rigor mortis Atomic force microscope Nano-mechanics
Atomic force microscope
- 4.Saukko P, Knight B (2015) Knight’s forensic pathology fourth edition. Edward Arnold, LondonGoogle Scholar
- 16.Papi M, Brunelli R, Familiari G, Frassanito MC, Lamberti L, Maulucci G, Monaci M, Pappalettere C, Parasassi T, Relucenti M, Sylla L, Ursini F, de Spirito M (2012) Whole-depth change in bovine zona pellucida biomechanics after fertilization: how relevant in hindering polyspermy? PLoS One 7:e45696CrossRefGoogle Scholar
- 18.Stylianou A, Lekka L, Stylianopoulos T (2018) AFM assessing of nanomechanical fingerprints for cancer early diagnosis and classification: from single cell to tissue level. Nanoscale 10.45:20930–20945Google Scholar