Abstract
Considering the increased incidence of bacterial infections and the emergence of multidrug resistant bacteria at the global level, we designed superparamagnetic iron oxide nanoparticles as nanosensors for the assessment of antimicrobial susceptibility through magnetic relaxation. In this report, we demonstrate that iron oxide nanosensors, either dextran-coated supplemented with Con A or silica-coated conjugated directly to Con A, can be used for the fast (1) quantification of polysaccharides, (2) assessment of metabolic activity and (3) determination of antimicrobial susceptibility in blood. The use of these polysaccharide nanosensors in the determination of antimicrobial susceptibility in the clinic or the field, and the utilization of these nanoprobes in pharmaceutical R&D are anticipated.
Highlights
In the last 20 years, there has been a dramatic increase in the emergence of antibiotic-resistant bacteria, leading to elevated bacterial pathogenesis at the global level [1,2]
Superparamagnetic nanoparticles have been used as magnetic relaxation sensors for the detection of various targets [10,15,16,17,18, 19,20,21,22], these nanoprobes have not been previously utilized for the detection of metabolic activity, which might lead to the potential development of nanosensors capable of determining antimicrobial susceptibility in complex media
In our first set of experiment, we investigated if our dextrancoated iron oxide nanoparticles (d =,150 nm, R2 = 300 mM21s21) were responsive to changes in starch concentration upon bacterial growth
Summary
In the last 20 years, there has been a dramatic increase in the emergence of antibiotic-resistant bacteria, leading to elevated bacterial pathogenesis at the global level [1,2]. Superparamagnetic nanoparticles have been used as magnetic relaxation sensors for the detection of various targets [10,15,16,17,18, 19,20,21,22], these nanoprobes have not been previously utilized for the detection of metabolic activity, which might lead to the potential development of nanosensors capable of determining antimicrobial susceptibility in complex media. The polysaccharide nanosensors’ clustering should result in a significant change in the spin-spin relaxation time (T2) of the solution’s water protons, facilitating the reliable identification of effective antimicrobial agents This can be achieved using dextran-coated iron oxide nanoparticles along with a protein with high affinity to carbohydrates, such as Concanavalin A (ConA) [23,24], in a competition assay. The higher the rate of bacterial metabolic activity, the fewer amount of the available polysaccharides (such as starch) would be, resulting in prominent changes in the sample’s DT2 when compared to those of the sterile medium (Figure 1)
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