ABSTRACT
A combined capture and detection method comprising of nano-immunomagnetic separation (NIMS) and surface enhanced Raman spectroscopy (SERS) was developed to detect Escherichia coli O157 from liquid media including apple juice. The capture antibodies (cAbs) were immobilized on magnetite-gold (Fe3O4/Au) magnetic nanoparticles (MNPs) which were used for separation and concentration of the E. coli O157 cells from model liquid food matrix. The capture efficiency (CE) for E. coli O157 using MNP was found to be approximately 84-94%. No cross reactivity was observed with background non-target organisms. There was a significant difference in the mean CE of bacteria captured by MNP and commercially sourced immunomagnetic microbeads (p<0.05). For the detection of target pathogen, SERS labels were prepared by conjugating gold nanoparticles with Raman reporter molecules and the detector antibody (dAb). Au-Raman label-dAb was interacted with gold coated MNP-cAb-E. coli O157 complex. The ability of this immunoassay to detect E. coli O157 in apple juice was investigated. We have successfully applied the synthesized Fe3O4/Au nanoclusters to E. coli O157 detection in apple juice using the SERS method. The lowest detectable bacterial cell concentration in apple juice was 10(2)CFU/mL with a total analysis time of less than an hour. This method presents a convenient way of preconcentration, separation, and detection of low levels of target pathogen from liquid food matrix.
Subject(s)
Beverages/microbiology , Escherichia coli O157/isolation & purification , Immunoassay/methods , Immunomagnetic Separation/methods , Malus/microbiology , Antibodies, Immobilized/biosynthesis , Antibodies, Immobilized/chemistry , Antibodies, Immobilized/isolation & purification , Ferrosoferric Oxide/chemistry , Gold/chemistry , Limit of Detection , Magnetite Nanoparticles/chemistry , Spectrum Analysis, RamanABSTRACT
The parallel synthesis of gamma-turn-inspired peptidomimetic libraries has been demonstrated through two approaches toward the preparation of 1,4-diazepin-5-ones. In the first approach, 1,4-diazepin-5-ones scaffolds were prepared on gram scale and subsequently diversified to produce libraries. In a second approach, libraries of 1,4-diazepin-5-ones were produced directly through a three-component strategy that maximizes the diversity obtained in a single step.
Subject(s)
Azepines/chemical synthesis , Molecular Mimicry , Peptides/chemistry , Acylation , Alkylation , Azepines/chemistryABSTRACT
A new small molecule inhibitor of bacterial cell division has been discovered using a high-throughput screen in Escherichia coli. Although the lead screening hit (534F6) exhibited modest inhibition of the GTPase activity of FtsZ (20+/-5% at 100microM of compound), a primary target for bacterial cell division inhibitors, several analogs caused potent bacterial growth inhibition with negligible antagonism of FtsZ GTPase activity. A library of analogs has been prepared and several alkyne-tagged photoaffinity probes have been synthesized for use in experiments to elucidate the primary target of this compound.
Subject(s)
Anti-Bacterial Agents/chemical synthesis , Cell Division/drug effects , Escherichia coli/drug effects , Growth Inhibitors/chemical synthesis , Pyrrolidines/chemical synthesis , Sulfonamides/chemical synthesis , Anti-Bacterial Agents/pharmacology , Cell Division/physiology , Escherichia coli/cytology , Escherichia coli/physiology , Escherichia coli Proteins/antagonists & inhibitors , Escherichia coli Proteins/physiology , Growth Inhibitors/pharmacology , Microbial Sensitivity Tests , Pyrrolidines/pharmacology , Sulfonamides/pharmacologyABSTRACT
The use of ring-opening metathesis (ROM) oligomers as soluble supports for a multistep reaction sequence is described. A Mitsunobu reaction followed by an in situ ROMP-mediated phase-trafficking purification is utilized to generate soluble ROM oligomers that are isolated via precipitation with methanol. Once formed, the ROM oligomers serve as soluble supports for further solution-phase reactions, including a ring-closing metathesis. After each step, the support-bound products are isolated by precipitation with a suitable solvent. [reaction--see text]
