Age determination of blood spots in forensic medicine by force spectroscopy

• Published in: Forensic science international Vol. 170; no. 1; pp. 8 - 14
• Main Authors: Strasser, Stefan, Zink, Albert, Kada, Gerald, Hinterdorfer, Peter, Peschel, Oliver, Heckl, Wolfgang M, Nerlich, Andreas G, Thalhammer, Stefan
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ireland Ltd 20.07.2007; Elsevier; Elsevier Limited
• Subjects: AFM; Age determination; Biological and medical sciences; Blood clots; Blood Coagulation - physiology; Blood spots; Blood Stains; Chromatography; Criminal investigations; Elasticity; Erythrocyte Membrane - physiology; Experiments; Force spectroscopy; Forensic medicine; Forensic Pathology; Forensic sciences; General aspects; Humans; Influence; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Medicine; Methods; Microscopy, Atomic Force; Models, Biological; Pathology; Public health. Hygiene; Public health. Hygiene-occupational medicine; Spectrum analysis; Studies; Time Factors; AFM; Blood spots; Forensic medicine; Force spectroscopy; Age determination; Atomic force microscopy; Forensic science; Force; Legal medicine; Exploration; Forensic aspect; Determination; Spectrometry; Blood trace; Age
• ISSN: 0379-0738; 1872-6283
• DOI: 10.1016/j.forsciint.2006.08.023

Abstract We present a new tool for the estimation of the age of bloodstains, which could probably be used during forensic casework. For this, we used atomic force microscopy (AFM) for high-resolution imaging of erythrocytes in a blood sample and the detection of elasticity changes on a nanometer scale. For the analytic procedure we applied a fresh blood spot on a glass slide and started the AFM detection after drying of the blood drop. In a first step, an overview image was generated showing the presence of several red blood cells, which could easily be detected due to their typical “doughnut-like” appearance. The consecutively morphological investigations in a timeframe of 4 weeks could not show any alterations. Secondly, AFM was used to test the elasticity by recording force–distance curves. The measurements were performed immediately after drying, 1.5 h, 30 h and 31 days. The conditions were kept constant at room temperature (20 °C) and a humidity of 30%. The obtained elasticity parameters were plotted against a timeline and repeated several times. The elasticity pattern showed a decrease over time, which are most probably influenced by the alteration of the blood spot during the drying and coagulation process. The preliminary data demonstrates the capacity of this method to use it for development of calibration curves, which can be used for estimation of bloodstain ages during forensic investigations.