This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A novel nanovesicle-based platform developed at Institute of Science Tokyo can measure hydrostatic pressure by converting pressure-induced molecular changes into fluorescence signals. The researchers developed pyrene-modified polyionic complex vesicles and demonstrated that variations in the vesicles' membrane stiffness regulate their pressure sensitivity.
Softer vesicles showed strong sensitivity in the 0.1–50 MPa range, while stiffer vesicles showed pressure-dependent changes in fluorescence lifetime. These findings enable the investigation of hydrostatic pressure–dependent phenomena in diverse inaccessible environments. The study is published in ACS Applied Nano Materials.
Hydrostatic pressure is the compressive pressure exerted on an object from all directions by a surrounding fluid at rest. It can influence many physical, chemical and biological processes, making its measurement important in diverse environments, ranging from the deep ocean to living tissues. Despite its importance, measuring this parameter at microscopic scales remains challenging, particularly in aqueous and biological environments.
Existing molecular sensors face limitations such as poor water solubility, insufficient sensitivity in the megapascal range or operational difficulties in biological settings. Against this backdrop, a research team led by assistant professor Hayato L. Mizuno and associate professor Yasutaka Anraku from Institute of Science Tokyo, Japan, along with professor Gaku Fukuhara from Kyushu University, Japan, developed a nanovesicle platform for hydrostatic pressure sensing.
Their study introduces pyrene-modified polyionic complex vesicles, or Pyr-PICsomes, whose membrane stiffness directly regulates their fluorescence response to pressure. "An important aspect of our platform is that it does not rely on a single sensing mechanism," says Mizuno. "By changing the membrane stiffness, we can access different fluorescence readouts, providing flexibility in how the pressure is measured." PICsomes are polymer-based vesicles that self-assemble in water from oppositely charged polymers.
The researchers chemically crosslinked PICsome membranes using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). The EDC concentration was used to adjust the membrane stiffness while maintaining the vesicle size at approximately 100 nm in diameter. They then incorporated pyrene molecules, which act as pressure-sensitive fluorescent probes, into the membrane.
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