Functional Magnetic Nanoparticles for Biodefense and Biological Threat Monitoring and Surveillance

Abstract

A new methodology toward biodefense and threat surveillance by water-dispersible, bactericidal, paramagnetic nanoparticles is presented. The nanoparticles consist of magnetite clusters (approximately 70 nm) modified by polyethyleneimine (PEI) and poly(hexamethylene biguanide) (PHMBG) and are prepared by a two-step procedure at an acceptable cost. The cationic nanoparticles are colloidally stable in water at pH < or = 10, where they sequester DNA or whole microbes. The nanoparticles and bound DNA are captured by high-gradient magnetic separation. Methods of efficient extraction and quantification of the DNA by real-time PCR are developed. Broad bactericidal activity of the nanoparticles is demonstrated at concentrations far below cytotoxicity levels for mammalian cells. The levels of the DNA detection sensitivity obtained in our experiments allow us to project the applicability of the developed method for the detection of DNA molecules of various germs.

Nanofluid optical property characterization: towards efficient direct absorption solar collectors

“…Unfortunately, surfactant-stabilized nanofluids are known to break down at elevated temperature [39]. For longer-term stability in a solar application, one can re-sonicate continuously or attempt more exotic preparation methods, such as those given in [34,40]. …”

Removal of reactive red-120 and 4-(2-pyridylazo) resorcinol from aqueous samples by Fe3O4 magnetic nanoparticles using ionic liquid as modifier

“…Surface modification of magnetic nanoparticles can be accomplished by physical/chemical adsorption of organic compounds by four major techniques: organic vapor condensation, polymer coating, surfactant adsorption and direct silanation [19,20]. This paper focuses on the preparation of magnetic nanoparticles of Fe 3 O 4 modified by ionic liquids (IL-Fe 3 O 4 ) and characterization by electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA).…”

Recent advances in surface engineering of superparamagnetic iron oxide nanoparticles for biomedical applications

“…The wide applications of superparamagnetic iron oxide nanoparticles (SPIONs) in magnetic fluids [1][2][3][4][5], data storage [6], catalysis [7][8][9][10], bioengineering and biosensors [11][12][13][14][15][16], environmental remediation [17][18][19][20][21], and magnetic inks for jet printing [22,23] have attarcted significatont attention worldwide. Recently, the potential usage of SPIONs have significantly increased due to their new applications in biotechnology and medicine [24].…”