Magnetic iron oxide nanoparticles (MIONPs) play a major role in the emerging fields of nanotechnology to facilitate rapid advancements in biomedical and industrial platforms. The superparamagnetic properties of MIONPs and their environment friendly synthetic methods with well-defined particle size have become indispensable to obtain their full potential in a variety of applications ranging from cellular to diverse areas of biomedical science. Thus, the broadened scope and need for MIONPs in their demanding fields of applications required to be highlighted for a comprehensive understanding of their state-of-the-art. Many synthetic methods, however, do not entirely abolish their undesired cytotoxic effects caused by free radical production and high iron dosage. In addition, the agglomeration of MIONPs has also been a major problem. To alleviate these issues, suitable surface modification strategies adaptive to MIONPs has been suggested not only for the effective cytotoxicity control but also to minimize their agglomeration. The surface modification using inorganic and organic polymeric materials would represent an efficient strategy to utilize the diagnostic and therapeutic potentials of MIONPs in various human diseases including cancer. This review article elaborates the structural and magnetic properties of MIONPs, specifically magnetite, maghemite and hematite, followed by the important synthetic methods that can be exploited for biomedical approaches. The in vivo cytotoxic effects and the possible surface modifications employed to eliminate the cytotoxicity thereby enhancing the nanoparticle efficacy are also critically discussed. The roles and applications of surface modified MIONPs in medical and industrial platforms have been described for the benefits of global well-being.

We hereby report a methodology that permits a quantitative investigation of the temporal self-organization of submicron sized superparamagnetic composite particles in the presence of an external magnetic field. The kinetics of field-induced self-organization into linear chains, time-dependent chain-size distribution, resolved growth steps ͑condensation, polarization, colinearity, and concatenation͒, the average chain growth rate, and interparticle interaction length were calculated in the presence of a 120 G external magnetic field using optical microscopy and "in-house" developed image analysis software. The measurements are in good agreement with theoretical assumptions.Superparamagnetic particles and field-induced selfassembly kinetics have attracted much attention. 1-4 Though theoretical modeling of self-organization has been reported, 5-9 experimental studies are important because such systems are not composed of monodisperse particles and contain a variety of interparticle interactions. A number of spatial and temporal experimental studies have been previously reported. 10-17 However, scattering techniques require additional assumptions upon data fitting and electron microscopes will not observe self-organization process resolved in time. These limitations can be overcome by introducing superparamagnetic nanoparticles in submicron sized emulsion droplets, silica or latex matrix and observing their temporal kinetics and mechanical properties with an optical microscope. 4,10-14,18-21 These studies provided the average cluster size and its power-law dependency at long aggregation times as predicted by Smoluchowski equation and dipolar interactions controlled aggregation mechanism. 4,21 However, putative different growth rates and direct measurements on effective interparticle interactions have not yet been visualized. We hereby report that the self-assembly is a four step process and the experimental effective interaction length of individual magnetic particles.Citrate stabilized magnetite nanoparticles ͑9-nm average diameter͒ were synthesized through co-precipitation technique at 60°C 22 and inserted into silica matrix using modified Stöber process. 23 The weight percentage of magnetite in the composite particles was 28.8%. Since the particles' surface ͑746 nm average size, polydispersity index 0.26, pH 8.9͒ was covered with silica ͑isoelectric point ϳ2͒, they easily re-dispersed in water. Two solenoid copper coils of 1000 turns each were placed at both slide edges. A sample of dispersed particles was placed in a 50 micron well and sealed with a cover slide to avoid evaporation and drifting. Bright field microscopy ͑Leica TCS SP5, 60x objective͒ images were collected each second in the absence of field ͑first 5 s͒, during the field ͑for 45 s͒ and after the field was turned off ͑for 10 s͒. Each frame was Fourier filtered with a high pass filter, discarding the first 3 points in the Fourier domain. Several parameters are computed for each object: centroid location, area, length, width, and orientation ͑angle͒ w...

Light assisted molecular immobilization has been used for the first time to engineer covalent bioconjugates of superparamagnetic nanoparticles and proteins. The technology involves disulfide bridge disruption upon UV excitation of nearby aromatic residues. The close spatial proximity of aromatic residues and disulfide bridges is a conserved structural feature in proteins. The created thiol groups bind thiol reactive surfaces leading to oriented covalent protein immobilization. We have immobilized a model carrier protein, bovine serum albumin, onto Fe(3)O(4)@Au core-shell nanoparticles as well as arrayed it onto optically flat thiol reactive surfaces. This new immobilization technology allows for ultra high dense packing of different bio-molecules on a surface, allowing the creation of multi-potent functionalized active new biosensor materials, biomarkers identification and the development of nanoparticles based novel drug delivery system.

The epidermal growth factor receptor (EGFR) is a member of the ErbB family of receptor tyrosine kinases. EGFR is activated upon binding to e.g. epidermal growth factor (EGF), leading to cell survival, proliferation and migration. EGFR overactivation is associated with tumor progression. We have previously shown that low dose UVB illumination of cancer cells overexpressing EGFR prior to adding EGF halted the EGFR signaling pathway. We here show that UVB illumination of the extracellular domain of EGFR (sEGFR) induces protein conformational changes, disulphide bridge breakage and formation of tryptophan and tyrosine photoproducts such as dityrosine, N-formylkynurenine and kynurenine. Fluorescence spectroscopy, circular dichroism and thermal studies confirm the occurrence of conformational changes. An immunoassay has confirmed that UVB light induces structural changes in the EGF binding site. A monoclonal antibody which competes with EGF for binding sEGFR was used. We report clear evidence that UVB light induces structural changes in EGFR that impairs the correct binding of an EGFR specific antibody that competes with EGF for binding EGFR, confirming that the 3D structure of the EGFR binding domain suffered conformational changes upon UV illumination. The irradiance used is in the same order of magnitude as the integrated intensity in the solar UVB range. The new photonic technology disables a key receptor and is most likely applicable to the treatment of various types of cancer, alone or in combination with other therapies.

Considering the huge demands for economical and reliable eco-remediation applications, the goal of the present work is to synthesize cost-effective and functionally efficient magnetic layered nanocomposite adsorbents for the effective adsorption of dyes followed by easy separation from wastewater. This would ensure good reusability of adsorbents without altering its adsorption capacity in a relatively short time manner. To achieve this, different molecular weights of polyethylene glycol (PEG)modified Fe 3 O 4 combined with Mg−Al-layered double hydroxides (MAN-LDH) were synthesized and characterized using powder Xray diffraction, Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, differential thermal analysis, energy-dispersive X-ray, and inductively coupled plasma optical emission spectroscopy. The efficacy of various adsorption parameters for the removal of methyl orange (MO) from water using Fe 3 O 4 -PEG-Mg-Al-LDH (FPL) adsorbents with different molecular weights of PEG (2FPL, 4FPL, and 6FPL) were investigated, and the results were compared. The maximum adsorption capacities of 2FPL, 4FPL, and 6FPL for MO were found to be 775.19, 826.44, and 833.33 mg/g, respectively. Detailed adsorption studies confirm that the higher adsorption capacity of 6FPL is due to the fast exchange of anions (NO 3 − ) by MO in the interlayers of MAN-LDH, larger surface area, hydrogen bonding, and electrostatic interaction between adsorbate and adsorbent. The thermodynamic data indicate that the adsorption behavior is spontaneous and endothermic in nature. The reusability of all FPL adsorbents is observed to be excellent. The MAN-LDH recoated after the 31st-cycle nanocomposites show a recovery of 100% adsorption efficiency, similar to the freshly prepared 6FPL. Such systematic studies greatly help in advancing the applications of newly functionalized nanomaterials toward ecoremediation approaches.