Hydrophobic Forces Are Relevant to Bacteria-Nanoparticle Interactions: Pseudomonas putida Capture Efficiency by Using Arginine, Cysteine or Oxalate Wrapped Magnetic Nanoparticles

Abstract

Size, shape and surface characteristics strongly affect interfacial interactions, as the presented among iron oxide nanoparticles (NPs) aqueous colloids and bacteria. In other to find the forces among this interaction, we compare three types of surface modified NPs (exposing oxalate, arginine or cysteine residues), based on a simple synthesis and derivation procedure, that allows us to obtain very similar NPs (size and shape of the magnetic core). In this way, we assure that the main difference in the synthesized NPs are the oxalate or amino acid residue exposed, an ideal situation to compare their bacterial capture performance, and so too the interactions among them. Field emission scanning electron microscopy showed homogeneous distribution of particle sizes for all systems synthesized, close to 10 nm. Magnetization, zeta potential, Fourier transformed infrared spectrometry and other studies allow us further characterization. Capture experiments of Pseudomonas putida bacterial strain showed a high level of efficiency, independently of the amino acid used to wrap the NP, when compared with oxalate. We show that bacterial capture efficiency cannot be related mostly to the bacterial and NP superficial charge relationship (as determined by z potential), but instead capture can be correlated with hydrophobic and hydrophilic forces among them.

Design of new hydrolyzed collagen‐modified magnetic nanoparticles to capture pathogens

“…This behavior can be observed in Figure 4B, where many bacteria was observed at the surface of the MNPs, thus demonstrating the potential of this system for bacterial enrichment from samples. The capture efficacies here reported are higher than the values previously described 27,49–51 …”

“…Arg@MNPs showed an efficacy superior to 90% in capturing E. coli ATCC®15597 and Bacillus subtilis from water samples 21 . Another study with the same coated MNPs showed a capture efficacy of 95% for Pseudomonas putida 27 . The use of H‐Coll@MNPs has potential to target microorganisms expressing adhesins; however, its use for bacterial capture was never described.…”

“…In fact, solutions with high concentrations of MNPs are unstable and should be avoided. Moreover, Figueredo et al, 27 Angermann and Töpfer 47 . and Xu et al 48 reported that Fe 3 O 4 NPs tend to agglomerate and clump in high concentrated solutions, thus decreasing the surface area available for bacterial capture.…”

“…Fe 3 O 4 nanoparticles (Fe@MNPs) were prepared by co‐precipitation of iron salts (Fe 2+ : Fe 3+ ) at a 1:2 molar ratio, as previously reported by Figueredo et al, 27 with some adjustments. Briefly, 2.25 g of FeCl 2 .4H 2 O and 6.22 g of FeCl 3 .6H 2 O were added to 200 ml of deionized water and mechanically stirred at 50 °C for 30 min, under a nitrogen gas flow.…”

Reusable cysteine-ferrite-based magnetic nanopowders for removal of lead ions from water

“…Another interesting binding behavior of cysteine on the nanoparticle surface deduced from the spectra is the formation of cystine, as already observed in similar nanomaterials 52,53 and indicated by the XRD results. Indeed, the bands at 2581 (D), 847 (E), 676 (F) and 540 cm −1 (H) are characteristic of symmetric NH 3 + stretching, NH 3 + rocking, C-S and S-S stretching of cystine, respectively [54][55][56] . The formation of cystine is further demonstrated by SER measurements (Figure 4), where the strong characteristic S-S vibration at 500 cm −1 is observed 57,58 .…”