Development of nano-immunosensor with magnetic separation and electrical detection of Escherichia coli using antibody conjugated Fe3O4@Ppy.

Detection of bacterial pathogens is the need of the hour due to the increase in antibiotic resistance and the infusion of multi-drug-resistant parasites. The conventional strategies such as ELISA, PCR, and MNP based tests for the detection are efficient but they are cost, time, lab, and manpower intensive. Thus, warranting a simple and effective technique for rapid detection of bacterial pathogens. Magnetic nanoparticles (NPs) have proved to be better alternatives for separation of bacterial pathogens from a variety of sample sources. However, the use of magnetic NPs has not been successful in the detection of these parasites. The current work involves the coating of magnetic NPs (Fe3O4) with a conducting polymer (polypyrrole; Ppy) to facilitate simultaneous separation and detection. Electrical (conductivity) measurement was the mode of choice due to the sensitivity, accuracy, and ease it offers. To enhance the conductivity, carboxylic groups were expressed on the Fe3O4@Ppy complex and to ensure specificity, E. coli specific antibodies were conjugated. The resulting complex at various process parameters was characterized using FTIR, VSM, and SEM. SEM images were recorded to ensure bacterial separation at optimal process parameters. The impedance analysis and conductivity measurements were carried out for the sample volume of 15 µl. The bacterial suspension from 101-106 CFU ml-1 was successfully detected with a limit of detection of 10 CFU ml-1 within 10 min using a simplistic detection method.

Applications of cobalt ferrite nanoparticles in biomedical nanotechnology.

Magnetic nanoparticles (MNPs) are very attractive especially for biomedical applications, among which, iron oxide nanoparticles have received substantial attention in the past decade due to the elemental composition that makes them biocompatible and degradable. However recently, other magnetic nanomaterials such as spinel ferrites that can provide improved magnetic properties such as coercivity and anisotropy without compromising on inherent advantages of iron oxide nanoparticles are being researched for better applicability of MNPs. Among various spinel ferrites, cobalt ferrite (CoFe2O4) nanoparticles (NPs) are one of the most explored MNPs. Therefore, the intention of this article is to provide a comprehensive review of CoFe2O4 NPs and their inherent properties that make them exceptional candidates, different synthesis methods that influence their properties, and applications of CoFe2O4 NPs and their relevant applications that have been considered in biotechnology and bioengineering.