Phage-functionalized magnetic separation for rapid and selective detection of Escherichia coli

Eigenfeld, Marco (author), Schneider, Benjamin (author), Kolb, Dagmar (author), Lisac, Ana (author), Podgornik, Aleš (author), Schwaminger, Sebastian P. (author)

Selective bacterial preconcentration remains a key challenge for improving downstream molecular detection. Here, we report carboxymethyl-dextran (CMD) coated magnetic nanoparticle clusters functionalized with lytic T4 bacteriophages (phage@CMD) for selective capture of Escherichia coli. Iron-oxide particles were synthesized by coprecipitation and characterized by dynamic light scattering (DLS), Fourier transform infrared (FT-IR) spectroscopy, and electron microscopy, revealing CMD-stabilized nanoparticle clusters with a hydrodynamic diameter of approximately 181 nm with moderate dispersity (PDI = 0.267). T4 phages were immobilized via EDC/Sulfo-NHS chemistry, yielding a functional loading of ∼5.54 × 10$^{12}$ PFU-equivalent g$^{–1}$ (∼0.053 phage per particle). An empirical Langmuir-type analysis was used solely to estimate surface loading capacity. Phage-functionalized particles enabled magnetic capture of E. coli, resulting in experimentally determined separation efficiencies of ∼20–40%, verified by CFU depletion and PCR analysis of particle-associated fractions. Magnetic preconcentration improved the practical PCR input threshold compared to direct amplification of untreated suspensions. While the study represents a proof-of-concept in laboratory media, limitations including random phage orientation, partial loss of activity after immobilization, and lack of complex-matrix validation are discussed. These findings support the use of phage@CMD as a modular magnetic preconcentration platform for bacteria prior to nucleic-acid–based analysis.

• Language: English
• Keywords: bacteria, genetics, infectious diseases, nanoparticles, viruses
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: Str. 37605-37618
• Numbering: Vol. 11, iss. 25
• PID: 20.500.12556/RUL-188123
• UDC: 602.3:578.347:620.3
• ISSN on article: 2470-1343
• DOI: 10.1021/acsomega.6c02406
• COBISS.SI-ID: 286107395
• Publication date in RUL: 18.09.2026

Record is a part of a journal

• Title: ACS omega
• Shortened title: ACS omega
• Publisher: American Chemical Society
• ISSN: 2470-1343
• COBISS.SI-ID: 525873945

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: bakterije, genetika, nalezljive bolezni, nanodelci, virusi

Projects

• Funder: DFG - German Research Foundation
• Funding programme: Deutsche Forschungsgemeinschaft
• Project number: 548540458