Acinetobacter baumannii (A. baumannii)
strains are common nosocomial pathogens that can cause infections
and can easily become resistant to antibiotics. Thus, analytical methods
that can be used to rapidly identify A. baumannii from complex samples should be developed. Tail fiber proteins derived
from the tail fibers of bacteriophages can recognize specific bacterial
surface polysaccharides. For example, recombinant tail proteins, such
as TF2 and TF6 derived from the tail fibers of bacteriophages ϕAB2
and ϕAB6, can recognize A. baumannii clinical
isolates M3237 and 54149, respectively. Thus, TF2 and TF6 can be used
as probes to target specific A. baumannii strains.
Generally, TF2 and TF6 are tagged with a hexahistidine (His6) for ease of purification. Given that His6 possesses
specific affinity toward alumina through His6–Al
chelation, TF2- and TF6-immobilized alumina-coated magnetic nanoparticles
(Fe3O4@Al2O3 MNPs) were
generated through chelation under microwave heating (power, 900 W)
for 60 s in this study. The as-prepared TF2-Fe3O4@Al2O3 and TF6-Fe3O4@Al2O3 MNPs were used as affinity probes to trap trace A. baumannii M3237 and 54149, respectively, from sample
solutions. Matrix-assisted laser desorption/ionization mass spectrometry
capable of identifying bacteria on the basis of the obtained fingerprint
mass spectra of intact bacteria was used as the detection tool. Results
demonstrated that the current approach can be used to distinguish A. baumannii M3237 from A. baumannii 54149
by using TF2-Fe3O4@Al2O3 and TF6-Fe3O4@Al2O3 MNPs
as affinity probes. Furthermore, the limits of detection of the current
method for A. baumannii M3237 and 54149 are ∼105 and ∼104 cells mL–1,
respectively. The feasibility of using the developed method to selectively
detect A. baumannii M3237 and 54149 from complex
serum samples was demonstrated.
Escherichia coli O157:H7 is a pathogen, which can generate Shiga-like toxins (SLTs) and cause hemolytic-uremic syndrome. Foodborne illness outbreaks caused by E. coli O157:H7 have become a global issue. Since SLTs are quite toxic, effective medicines that can reduce the damage caused by SLTs should be explored. SLTs consist of a single A and five B subunits, which can inhibit ribosome activity for protein synthesis and bind with the cell membrane of host cells, respectively. Pigeon ovalbumin (POA), i.e. a glycoprotein, is abundant in pigeon egg white (PEW) proteins. The structure of POA contains Gal-α(1→4)-Gal-β(1→4)-GlcNAc ligands, which have binding affinity toward the B subunit in SLT type-1 (SLT-1B). POA immobilized gold nanoparticles (POA-Au NPs) can be generated by reacting PEW proteins with aqueous tetrachloroauric acid in one-pot. The generated POA-Au NPs have been demonstrated to have selective trapping-capacity toward SLT-1B previously. Herein, we explore that POA-Au NPs can be used as protective agents to neutralize the toxicity of SLT-1 in SLT-1-infected model cells. The results show that the cells can be completely rescued when a sufficient amount of POA-Au NPs is used to treat the SLT-1-infected cells within 1 h.
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