Blood culture is traditionally a time-consuming method and has not changed significantly in several decades. Using nanotechnology, such as the use of magnetic nanoparticles (MNPs), the blood culture process may be streamlined. An important advantage of using MNPs to capture bacteria is the simple separation of bacteria from biological samples using magnets. Indeed, high bacteria capture efficiencies have been realized using MNPs. The binding events between MNPs and bacteria can be tightly controlled through carefully selected biorecognition events, using molecules such as vancomycin, daptomycin, antibodies, and others. These biomolecules can be readily conjugated onto MNPs followed by tethering to bacteria, thus enabling detection using the beacon produced by the bacteria conjugated MNPs. Methods to prepare bioconjugated MNPs and their performance with bacteria are reviewed. Finally, future directions on bacteria detection using giant magnetoresistance (GMR) biosensors are discussed.

We have designed and utilized a simple molecular recognition system to study the substituent effects in aromatic interactions. Recently, we showed that 3- and 3,5-disubstituted benzoyl leucine diethyl amides with aromatic rings of varying electronic character organized into homochiral dimers in the solid state through a parallel displaced π-π interaction and two hydrogen bonds, but no such homochiral dimerization was observed for the unsubstituted case. This phenomenon supports the hypothesis that substituents stabilize π-π interactions regardless of their electronic character. To further investigate the origin of substituent effects for π-π interactions, we synthesized and crystallized a series of 4-substituted benzoyl leucine diethyl amides. Surprisingly, only two of the 4-substituted compounds formed homochiral dimers. A comparison among the 4-substituted compounds that crystallized as homochiral dimers and their 3-substituted counterparts revealed that there are differences in regard to the geometry of the aromatic rings with respect to each other, which depend on the electronic nature and location of the substituent. The crystal structures of the homochiral dimers that showed evidence of direct, local interactions between the substituents on the aromatic rings also displayed nonequivalent dihedral angles in the individual monomers. The crystallographic data suggests that such "flexing" may be the result of the individual molecules orienting themselves to maximize the local dipole interactions on the respective aromatic rings. The results presented here can potentially have broad applicability towards the development of molecular recognition systems that involve aromatic interactions.

Described herein is a unique and inexpensive method that outperforms commercial methods that amplify the streptavidin-biotin recognition event. Amplification induced by streptavidin and biotinylated protein causes the formation of a large detectable polymer. This approach enjoys a 100-fold decrease in detection limit in comparison with the commercial methods.

Efforts to treat bloodstream infections, which have a relatively high mortality rate, are delayed by the lengthy multi-step process required to identify the causative bacteria. Due to this delay, broad spectrum antibiotics are prescribed on a presumptive basis, leading to the rise of antibiotic resistant microorganisms. Here, as proof of principle, we describe a colourimetric sensor that rapidly identifies opportunistic pathogenic bacteria in a single step in TSB media. The device is composed of a reaction chamber and an array of chemoresponsive dyes deposited on a substrate in a prearranged pattern. This single step, disposable, automated system can detect and identify of eight strains of bacteria, starting with clinically relevant concentrations bacteria in twenty four hours in TSB media. Thus, this technology may be used to streamline the current blood culture process by combining detection and identification in a single step.

A series of benzoyl leucine amides of varying electronic character were prepared. All of the 3‐ and 3,5‐disubstituted compounds assembled into homochiral dimers in the solid state. However, no homochiral dimerization was observed in the unsubstituted case and in several 4‐substituted cases (shown in yellow). The crystallographic data suggests that local interactions between the dipoles may stabilize the interaction in several of the dimers (shown in red) and provides a driving force for homochiral dimerization. For more details see the Full Paper by J. R. Carey et al. on