Ultrasensitive detection of bacteria using core-shell nanoparticles and a NMR-filter system

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Original entry: Warren Lloyd Ung, APPHY 225, Fall 2009

"Ultrasensitive detection of bacteria using core-shell nanoparticles and a NMR-filter system"
Hakho Lee, Tae-Jong Yoon, and Ralph Weissleder.
Angewandte Chemie Internation Edition (2009).

Soft Matter Keywords

magnetic nanoparticles, biosensors, NMR, microfluidics

Figure 1: Magnetic nanoparticles for bacterial targetting, also called cannonballs (CBs). (a) Magnetic nanoparticles with a large iron core and a thin ferrite shell, (b) high resolution image of magnetic nanoparticles, (c) X-ray powder diffractogram reveals a spinel structure, which reveals the ferrite nature of the shell, and (d) CB had high saturation magnetization at approximately 139 emu/g, but were superparamagnetic at room temperature.
Figure 2: Microfluidic NMR device
Figure 3: Bacterial Separation and Concentration. (a) The bacteria are captured at the filter interface, while excess nanoparticles are washed away; (b) demonstration of device operation with optical micrographs; (c) optimization of the number of washing steps; and (d) image of bacterial capture in the membrane filter.

Summary

Lee et al have constructed a device, which can detect bacteria in biological samples, by targeting magnetic nanoparticles (MNP) to attach to the bacteria of interest and detecting the resultant change in nuclear magnetic resonance (NMR) signal in solution. The NMR signal is sensed by a miniature NMR coil built into a microfluidic device. In this particular study, they demonstrate the capacity for detecting small quantities of Mycobacterium tuberculosis in the context of a relevant biological context, sputum. Such a device could have an impact on the point of care diagnosis of infectious diseases, such as tuberculosis, which is still a major cause of death worldwide. In addition, the techniques introduced here are general enough that they could be applied to the detection of many different kinds of bacteria in a wide range of samples.

Applications

The detection of the bacterial pathogens, which cause various kinds of symptoms and diseases, is a powerful ability for physicians and other medical personnel for diagnosing patients. In many cases, an accurate and expedient diagnosis is the first step in allowing for effective treatments.


Soft Matter Discussion

The magnetic nanoparticles These nanoparticles increase the spin-spin relaxation time of protons in solution,

The presence of the nanoparticles is confirmed by

The device detailed here has two key elements. The magnetic nanoparticles developed here can be selectively to attached to any bacteria