Magnetic Resonance Biosensor Research Articles

NMR Immunosensor Based on a Targeted Gadolinium Nanoprobe for Detecting Salmonella in Milk.

Detecting harmful pathogens in food is not only a crucial aspect of food quality management but also an effective way to ensure public health. In this paper, a complete nuclear magnetic resonance biosensor based on a novel gadolinium (Gd)-targeting molecular probe was developed for the detection of Salmonella in milk. First, streptavidin was conjugated to the activated macromolecular polyaspartic acid (PASP) via an amide reaction to generate SA-PASP. Subsequently, the strong chelating and adsorption properties of PASP toward the lanthanide metal gadolinium ions were exploited to generate the magnetic complex (SA-PASP-Gd). Finally, the magnetic complex was linked to biotinylated antibodies to obtain the bioprobe and achieve the capture of Salmonella. Under optimal experimental conditions, the sensor we have constructed can achieve a rapid detection of Salmonella within 1.5 h, with a detection limit of 7.1 × 103 cfu mL-1.

Rapid detection of Salmonella in milk by a nuclear magnetic resonance biosensor based on the streptavidin-biotin system and O-carboxymethyl chitosan target gadolinium probe

Rapid and sensitive detection of foodborne pathogens is of great importance for food safety. Here, a set of nuclear magnetic resonance (NMR) biosensors based on a O-carboxymethyl chitosan target gadolinium (Gd) probe was developed to quickly detect Salmonella in milk by combining NMR technology and bioimmunotechnology with membrane filtration technology. First, O-carboxymethyl chitosan (O-CMC) was biotinylated to prepare biotinylated O-carboxymethyl chitosan (biotin-O-CMC) through amide reaction, and biotinylated magnetic complexes (biotin-O-CMC-Gd) were obtained by using O-CMC, which has strong chelating adsorption on Gd. The target probe was obtained by combining biotin-O-CMC-Gd with the biotinylated antibody (biotin-antibody) via streptavidin (SA) by introducing the SA-biotin system. Then, Salmonella was captured by the target probe through antigen-antibody interaction. Finally, NMR was used to measure the longitudinal relaxation time (T1) of the filtrate collected by membrane filtration. This NMR biosensor with good specificity and high efficiency can detect Salmonella with the sensitivity of 1.8 × 103 cfu/mL within 2 h; in addition, it can realize the detection of complex samples because of its strong anti-interference capability and may open up a new method for rapid detection of Salmonella, which has a great application potential.

Rapid detection of Salmonella in milk with a nuclear magnetic resonance biosensor based on a streptavidin–biotin system and a polyamidoamine-dendrimer-targeted gadolinium probe

Rapid and sensitive detection technology is the key to preventing food-borne disease outbreaks. In this study, a low-field nuclear magnetic resonance (NMR) biosensor based on polyamidoamine dendrimers was prepared for the rapid detection of Salmonella in milk. The polyamidoamine dendrimer was biotinylated by amide reaction and chelated to diethylene triamine pentacetate acid and gadolinium to form magnetic complexes. The antibody and magnetic complexes were combined through a streptavidin-biotin system using streptavidin as an intermediate bridge to obtain the immunoprobe. Salmonella was captured by the immunoprobe via antigen-antibody interaction and then separated from the mixture by membrane filtration. Finally, the longitudinal relaxation signal of the filtrate was obtained by NMR. The biosensor had excellent anti-interference capability and could detect Salmonella within 1.5 h at a sensitivity of 103 cfu mL-1. This method based on NMR can realize detection in complex samples and has the potential to be a quick and nondestructive method for detecting target bacteria.

Nuclear magnetic resonance biosensor based on streptavidin–biotin system and poly-l-lysine macromolecular targeted gadolinium probe for rapid detection of Salmonella in milk

An accurate biosensor for rapid detection of Salmonella via low-field nuclear magnetic resonance (NMR) technology was developed. First, poly-l-lysine (PLL) containing several amino groups was modified with diethylene triamine pentacetate acid (DTPA) and gadolinium (Gd). The antibody was bound to Gd–DTPA–PLL through streptavidin and biotin interaction to obtain the probes. After the capture of Salmonella using the probes, the mixture was filtered to separate the excess probes. Finally, the filtrate was collected and measured by NMR. This method was successfully used in the simultaneous detection of Salmonella in pure culture and milk. The detection sensitivity was 2.4 × 104 cfu mL−1, and the overall detection process could be finished in 2 h. Because of the remarkable specificity of the probe and strong anti-interference, it was suitable for the direct detection of the complex matrix. The NMR biosensor has great potential to become a very promising biological molecular detection method.

Portable nuclear magnetic resonance biosensor and assay for a highly sensitive and rapid detection of foodborne bacteria in complex matrices

BackgroundNuclear magnetic resonance (NMR) technique is a powerful analytical tool in determining the presence of bacterial contaminants in complex biological samples. In this paper, a portable NMR-based (pNMR) biosensor and assay to detect the foodborne bacteria Escherichia coli O157:H7 is reported. It uses antibody-functionalized polymer-coated magnetic nanoparticles as proximity biomarker of the bacteria which accelerates NMR resonance signal decay.ResultsThe pNMR biosensor operates at 0.47 Tesla of magnetic strength and consists of a high-power pulsed RF transmitter and an ultra-low noise sensing circuitry capable of detecting weak NMR signal at 0.1 μV. The pNMR biosensor assay and sensing mechanism is used in detecting E. coli O157:H7 bacteria in drinking water and milk samples. Experimental results demonstrate that by adding a filtration step in the assay, the pNMR biosensor is able to detect E. coli O157:H7 as low as 76 CFU/mL in water samples and as low as 92 CFU/mL in milk samples in about one min.ConclusionThe pNMR biosensor assay and sensing system is innovative for foodborne bacterial detection in food matrices. The lowest detection level for E. coli O157:H7 in water and milk samples is essentially 101 CFU/mL. Although the linear range of detection is only from 101 to 104 CFU/mL, the wider detection range spans from 101 CFU/mL to 107 CFU/mL. Existing pNMR biosensors have detection limits at 103-104 CFU/mL only. The detection technique can be extended to other microbial or viral organisms by merely changing the specificity of the antibodies. Besides food safety, the pNMR biosensor described in this paper has potential to be applied as a rapid detection device in biodefense and healthcare diagnostic applications.

Highly sensitive detection of protein biomarkers via nuclear magnetic resonance biosensor with magnetically engineered nanoferrite particles.

Magnetic-based biosensors are attractive for on-site detection of biomarkers due to the low magnetic susceptibility of biological samples. Here, we report a highly sensitive magnetic-based biosensing system that is composed of a miniaturized nuclear magnetic resonance (NMR) device and magnetically engineered nanoferrite particles (NFPs). The sensing performance, also identified as the transverse relaxation (R2) rate, of the NMR device is directly related to the magnetic properties of the NFPs. Therefore, we developed magnetically engineered NFPs (MnMg-NFP) and used them as NMR agents to exhibit a significantly improved R2 rate. The magnetization of the MnMg-NFPs was increased by controlling the Mn and Mg cation concentration and distribution during the synthesis process. This modification of the Mn and Mg cation directly contributed to improving the R2 rate. The miniaturized NMR system, combined with the magnetically engineered MnMg-NFPs, successfully detected a small amount of infectious influenza A H1N1 nucleoprotein with high sensitivity and stability.

Novel Molecular and Nanosensors for In Vivo Sensing

In vivo sensors are an emerging field with the potential to revolutionize our understanding of basic biology and our treatment of disease. In this review, we highlight recent advances in the fields of in vivo electrochemical, optical, and magnetic resonance biosensors with a focus on recent developments that have been validated in rodent models or human subjects. In addition, we discuss major challenges in the development and translation of in vivo biosensors and present potential solutions to these problems. The field of nanotechnology, in particular, has recently been instrumental in driving the field of in vivo sensors forward. We conclude with a discussion of emerging paradigms and techniques for the development of future biosensors.