Magnetic wire active microrheology of human respiratory mucus

Author(s)

Radiom, Milad ^{[1, 2]} ; Henault, Romain ^[1] ; Mani, Salma ^{[2, 3, 4]} ; Iankovski, Aline Grein ^[1] ; Norel, Xavier ^{[3, 4]} ; Berret, Jean-Francois ^[1]

Affiliation

^[1] Univ Paris, CNRS, Mat & Syst Complexes, F-75013 Paris - France

^[2] Swiss Fed Inst Technol, D HEST, Inst Food Nutr & Hlth, Zurich - Switzerland

^[3] Univ Paris, INSERM, UMR S 1148, CHU X Bichat, F-75018 Paris - France

^[4] Paris 13 Univ, F-93430 Villetaneuse - France

• Document type: Journal article
• Source: SOFT MATTER; v. 17, n. 32 JUL 2021.
• Web of Science Citations: 0

Abstract

Mucus is a viscoelastic gel secreted by the pulmonary epithelium in the tracheobronchial region of the lungs. The coordinated beating of cilia moves mucus upwards towards the pharynx, removing inhaled pathogens and particles from the airways. The efficacy of this clearance mechanism depends primarily on the rheological properties of mucus. Here we use magnetic wire based microrheology to study the viscoelastic properties of human mucus collected from human bronchus tubes. The response of wires between 5 and 80 mu m in length to a rotating magnetic field is monitored by optical time-lapse microscopy and analyzed using constitutive equations of rheology, including those of Maxwell and Kelvin-Voigt. The static shear viscosity and elastic modulus can be inferred from low frequency (3 x 10(-3)-30 rad s(-1)) measurements, leading to the evaluation of the mucin network relaxation time. This relaxation time is found to be widely distributed, from one to several hundred seconds. Mucus is identified as a viscoelastic liquid with an elastic modulus of 2.5 +/- 0.5 Pa and a static viscosity of 100 +/- 40 Pa s. Our work shows that beyond the established spatial variations in rheological properties due to microcavities, mucus exhibits secondary inhomogeneities associated with the relaxation time of the mucin network that may be important for its flow properties. (AU)

• FAPESP's process: 18/16330-3 - Self-assembly of thermo- and magneto-responsive building blocks for the fabrication of novel biomarkers
• Grantee: Aline Grein Iankovski
• Support type: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 17/04571-3 - Magnetic Janus nanoparticles
• Grantee: Aline Grein Iankovski
• Support type: Scholarships in Brazil - Post-Doctorate