Spatiotemporal analysis of Escherichia coli membrane permeabilization and uptake kinetics induced by a single microbubble cavitation event

Drab, Mitja (author), Iglič, Aleš (author), Stopar, David (author), Pandur, Žiga (author)

A single cavitation microbubble can transiently disrupt the cellular membrane, providing a chemicalfree, targeted drug delivery mechanism. Here, we investigate the spatiotemporal dynamics of membrane permeabilization in an Escherichia coli (E. coli) monolayer exposed to a single cavitation event. Using high-resolution fluorescence microscopy and propidium iodide (PI) uptake as a marker of membrane disruption, we tracked the response of 5565 individual cells around the center of the cavitation event over timescales from microseconds to minutes and spatial scales from 1 to 165 µm. PI uptake rates exhibited a strong spatial dependence, with cells closer to the cavitation center showing rapid and extensive permeabilization. A modified Goldman equation describing PI concentrations inside and outside the cells was used and related to the spatiotemporal measurements of fluorescence intensity. The model accurately captured the first-order PI uptake kinetics, which resulted in saturated fluorescence intensity profiles. Additionally, the model predicted an exponential decay of permeability post-cavitation, implicitly suggesting that pore-resealing dynamics were taking place. Membrane permeability decreased with distance as 1/r, with a characteristic decay time of approximately 3.4 min. Our model thus predicts cell damage induced by a single cavitation event in both space and time. In the present case, where the cavitation bubble reached maximum radius of 29.7 µm, we found that at a distance of 11 µm from the cavitation center,~50% of cell membranes are damaged and permeable to PI, but a pore-resealing mechanism reduces this damage to~1% after 10 min. Our results are consistent with existing sonoporation studies and offer novel insights for optimizing cavitationassisted drug delivery and biofilm disruption strategies.

• Language: English
• Keywords: cavitation, bacterial cells, poration, propidium iodide uptake, Goldman equation
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FE - Faculty of Electrical Engineering; FS - Faculty of Mechanical Engineering; BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 12 str.
• Numbering: 15, art. 42593
• PID: 20.500.12556/RUL-176478
• UDC: 577
• ISSN on article: 2045-2322
• DOI: 10.1038/s41598-025-26554-4
• COBISS.SI-ID: 259523587
• Publication date in RUL: 02.12.2025

Record is a part of a journal

• Title: Scientific reports
• Shortened title: Sci. rep.
• Publisher: Springer Nature
• ISSN: 2045-2322
• COBISS.SI-ID: 18727432

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: kavitacija, bakterijske celice, poracija, privzem propidijevega jodida, Goldmanova enačba