T4 bacteriophage conjugated magnetic particles for E. coli capturing: Influence of bacteriophage loading, temperature and tryptone

Abstract

This work demonstrates the use of bacteriophage conjugated magnetic particles (FeO) for the rapid capturing and isolation of Escherichia coli. The investigation of T4 bacteriophage adsorption to silane functionalised FeO with amine (NH), carboxylic (COOH) and methyl (CH) surface functional groups reveals the domination of net electrostatic and hydrophobic interactions in governing bacteriophage adsorption. The bare FeO and FeO-NH with high T4 loading captured 3-fold more E. coli (∼70% capturing efficiency) compared to the low loading T4 on FeO-COOH, suggesting the significance of T4 loading in E. coli capturing efficiency. Importantly, it is further revealed that E. coli capture is highly dependent on the incubation temperature and the presence of tryptone in the media. Effective E. coli capturing only occurs at 37°C in tryptone-containing media with the absence of either conditions resulted in poor bacteria capture. The incubation temperature dictates the capturing ability of FeO/T4, whereby T4 and E. coli need to establish an irreversible binding that occurred at 37°C. The presence of tryptophan-rich tryptone in the suspending media was also critical, as shown by a 3-fold increase in E. coli capture efficiency of FeO/T4 in tryptone-containing media compared to that in tryptone-free media. This highlights for the first time that successful bacteria capturing requires not only an optimum tailoring of the particle's surface physicochemical properties for favourable bacteriophage loading, but also an in-depth understanding of how factors, such as temperature and solution chemistry influence the subsequent bacteriophage-bacteria interactions.

Preparation of functionalized magnetic nanoparticles conjugated with feroxamine and their evaluation for pathogen detection

“…Carboxylic acid groups were also introduced onto the same conjugate by using succinic anhydride to give the corresponding MNP@SiO 2 @-NHCOOH and MNP@SiO 2 @NHCOOH@Fa (6) similar to those reported by Gunawan and coworkers. 34 When testing the bacteria capture with these new conjugates, the colony counting did not show any signicant changes for the adsorption of Y. enterocolitica WC-A (wild type strain) indicating that the molecular recognition of the siderophore again was not observed ( Fig. 9A and B).…”

“…Therefore, our results are in good agreement with previous works reporting bacteria adsorption through free amine groups of functionalized MNP. 30,34,35 The bacteria adsorption achieved with MNP@SiO 2 particles can be attributed to mutually hydrophobic interaction. 36 In order to reduce the non-specic binding behavior due to the electrostatic interactions between the free amine functionalized nanoparticles and bacteria, we made attempts to block the surface of the particles with two different groups, one of them of neutral nature (Boc) and a second group with polar character (COOH).…”

Recent Progress in the Detection of Bacteria Using Bacteriophages: A Review

“…Yan et al [27] used such an approach that allowed for LOD of around 9 × 10 3 CFU/mL in the detection of S. aureus in apple juice within 90 min without any pre-enrichment. Liana and coworkers [69] used bacteriophage conjugated Fe 3 O 4 particles for the rapid capturing and isolation of E. coli. The authors focused on the optimal parameters of the operation of such a probe.…”

Determination of Air Filter Anti-Viral Efficiency against an Airborne Infectious Virus

“…These viruses were selected because they are relatively safe to handle in a biosafety level (BSL) I laboratory. These bacteriophages have been used in previous research works as surrogates for human and animal respiratory viruses (33)(34)(35) and in stringent test cases to evaluate the efficacy of antimicrobial agents (36,37). Each virus solution was prepared using 0.1 mL of virus stock defrosted at room temperature and poured into 50 mL of deionized (DI) water.…”