Biomolecular absorption of ultrasound

Abstract

Understanding of the mechanisms of the interaction of ultrasound and biomolecules is essential to a thorough understanding of the present biophysical and medical applications of ultrasound and to the systematic and efficient accomplishment of future advances. Experimental evidence indicates that the biomolecules present in tissues play an important role in the ultrasonic propagaTion properties of tissues. Classical absorption mechanisms apparently play no significant role at the biomolecular level. Chemical and structural relaxation mechanisms have been proposed to explain the acoustic behavior observed, although generalized dispersion relationships have been reported to apply as well. Specific mechanisms of absorption for biomolecules in suspension at neutral pH have not been determined. Molecular size plays a role (in a “threshold” sense) in absorption but not in propagation speed. Molecular conformation appears to be important in some cases but not in others. Biomolecular‐solvent equilibria and biomolecule‐biomolecule interactions apparently are involved in the absorption processes.