Table of contents

In this paper we first summarize our recent research on fabrication and structure characterization of conjugates of Fe₃O₄ nanoparticles (MNPs) encapsulated by several organic materials such as oleic acid (OL), starch (ST), dextran (D), chitosan (CS), O-carboxymethyl chitosan (OCMCS) and the copolymer of poly(styrene-co-acrylic acid (St-co-AA)). The ferrofluids stability and toxicity were also considered. The magnetic inductive heating (MIH) curves were measured using a set up with an alternating (ac) magnetic field of strength of 40–100 Oe and frequency of 180–240 kHz. We then present new results dealing with attempting to apply the MNP/copolymer ferrofluid for treatment of Sarcoma 180 tumor. In vitro as well as ex vivo MIH experiments were carried out as preparation steps in order to estimate the proper conditions for the in vivo MIH experiment. As for the latter, we have successfully carried out the treatment of solid tumor of size around 6 × 6 mm inoculated on Swiss mice with use of a dose of 0.3–0.4 mg ml⁻¹ ferrofluid injected subcutaneously into the tumor and field-irradiated for 30 min. Two groups of treated mice recovered in three weeks from MIH treatment three times during the first week. We finally show that curcumin loaded MNP-based conjugates showed themselves to be a potential agent for application as a bimodal contrast enhancer of magnetic resonance imaging (MRI) and fluorescence imaging. Additionally, in vitro and ex vivo studies by these two techniques evidenced that macrophage is capable of uptake and tends to carry the MNPs into a tumor.

Nanotechnology has great potential, as it can enhance the quality of life through its applications in various fields like agriculture and the food system. Around the world it has become the future of any nation. But we must be very careful with any new technology to be introduced regarding its possible unforeseen related risks that may come through its positive potential. However, it is also critical for the future of a nation to produce a trained future workforce in nanotechnology. In this process, to inform the public at large about its advantages is the first step; it will result in a tremendous increase in interest and new applications in all the domains will be discovered. With this idea, the present review has been written. There is great potential in nanoscience and technology in the provision of state-of-the-art solutions for various challenges faced by agriculture and society today and in the future. Climate change, urbanization, sustainable use of natural resources and environmental issues like runoff and accumulation of pesticides and fertilizers are the hot issues for today's agriculture. This paper reviews some of the potential applications of nanotechnology in the field of agriculture and recommends many strategies for the advancement of scientific and technological knowledge currently being examined.

We show the possibility of directional guided superradiance from a linear array of distant atoms separated by one or several wavelengths in a line parallel to the axis of a nanofiber. We find that the rate and efficiency of channeling of emission from the atoms into the fiber are cooperatively enhanced by the guided modes.

Curcumin (Cur) is a yellow compound isolated from rhizome of the herb curcuma longa. Curcumin possesses antioxidant, anti-inflammatory, anti-carcinogenic and antimicrobial properties, and suppresses proliferation of many tumor cells. However, the clinical application of curcumin in cancer treatment is considerably limited due to its serious poor delivery characteristics. In order to increase the hydrophilicity and drug delivery capability, we encapsulated curcumin into copolymer PLA-TPGS, 1,3-beta-glucan (Glu), O-carboxymethyl chitosan (OCMCs) and folate-conjugated OCMCs (OCMCs-Fol). These polymer-encapsulated curcumin nanoparticles (Cur-PLA-TPGS, Cur-Glu, Cur-OCMCs and Cur-OCMCs-Fol) were characterized by infrared (IR), fluorescence (FL), photoluminescence (PL) spectra, field emission scanning electron microscopy (FE-SEM), and found to be spherical particles with an average size of 50–100 nm, being suitable for drug delivery applications. They were much more soluble in water than not only free curcumin but also other biodegradable polymer-encapsulated curcumin nanoparticles. The anti-tumor promoting assay was carried out, showing the positive effects of Cur-Glu and Cur-PLA-TPGS on tumor promotion of Hep-G2 cell line in vitro. Confocal microscopy revealed that the nano-sized curcumin encapsulated by polymers OCMCs and OCMCs-Fol significantly enhanced the cellular uptake (cancer cell HT29 and HeLa).

We report for the first time the preparation of luminescent lanthanide nanomaterial (LLN) linked bioconjugates and their application as a label tool for recognizing virus in the processing line of vaccine industrial fabrication. Several LLNs with the nanostructure forms of particles or rods/wires with europium (III) and terbium (III) ions in lattices of vanadate, phosphate and metal organic complex were prepared to develop novel fluorescent conjugates able to be applied as labels in fluorescence immunoassay analysis of virus/vaccine.

With regard to the LLNs, we have successfully synthesized nanoparticles around 10 nm of YVO₄:Eu(III), with high emission in the red spectral region, nanorod and nanowire of TbPO₄·H₂O and Eu_1-xTb_xPO₄·H₂O, width 5–7 nm and length 300 nm, showing very bright luminescence in green, and core/shell nanosized Eu(III) and Tb(III)/Eu(III) complexes with naphthoyl trifluoroacetone and tri-n-octylphosphineoxide (Eu.NTA.TOPO@PVP, Eu_XTb_1-X.NTA.TOPO). The appropriated core/shell structures can play a double role, one for enhancing luminescence efficiency and another for providing nanophosphors with better stability in water media for facilitating the penetration of nanophosphor core into a biomedical environment.

The organic functionalizations of the obtained LLNs were done through their surface encapsulation with a functional polysiloxane including active groups such as amine (NH₂), thiocyanate (SCN) or mecarpto (SH). The properties of functional sol-gel matrix have great influence on the luminescence properties, especially luminescence intensity of YVO₄:Eu(III), Eu.NTA.TOPO@PVP, TbPO₄·H₂O and Eu_xTb_1-xPO₄·H₂O. Bioconjugation processes of the functionalized LLNs have been studied with some bioactive molecules such as biotin, protein immunoglobulin G (IgG) or bovine serum albumin (BSA).

The results of LLN-bioconjugate linking with IgG for recognizing virus (vaccine) will be presented in brief. It is consistent to state that the LLN bioconjugates prepared from YVO₄:Eu(III)–nanoparticles, TbPO₄·H₂O nanorod or wire and EuNTA.TOPO@PVP nanosized core/shell complex could be used as labels for recognizing virus in diagnosis or in vaccine production by use of the fluorescence immunoassay (FIA) method. The fluorescence images of the incubated specimens consisting of LLN bioconjugate and vaccine fabricate could be obtained well in terms of sharpness, reproductivity and stability.

However, much work still needs to be done to develop an ordinary LLN-conjugate using the FIA method for analysis of virus and, moreover, to extend the study of biomedical cell processes at nano/microscale in practical application.

In this study, silver nanoparticles were synthesized from silver nitrate via a polyol method in ambient atmosphere. In our synthesis route, polyvinylpyrrolidone (PVP) is used as both size controller and capping agent, ethylene glycol acts both as solvent and reducing agent. The obtained silver nanoparticles were characterized by ultraviolet-visible spectrophotometry which indicated the formation of nanoparticles. Investigation of Fourier transform infrared spectroscopy clearly demonstrated the coordination between silver nanoparticles and PVP. Transmission electron microscopy (TEM) contributed to the particle size analysis. The surface plasmon resonance peak in absorption spectra of silver colloidal solution showed absorption from 406 to 409 nm. The average size of the resulting silver nanoparticles was below 10 nm with a dependency on the PVP concentration.

In this work ZnO and Mn-doped ZnO nanocrystals were synthesized by one-step aqueous solution method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray (EDX) analysis and photoluminescence (PL) spectroscopy have been used to characterize the samples in detail. The XRD studies revealed that the ZnO and Mn-doped ZnO had wurtzite structure (hexagonal). The composition analysis by EDX indicated the presence of small amounts of Mn. A strong and wide ultraviolet emission has been observed for the ZnO and Mn-doped ZnO nanocrystals as evidenced by the photoluminescence spectra at a wavelength of 384 and 389 nm respectively. As-synthesized ZnO and Mn-doped ZnO nanocrystals have a good crystal quality. ZnO and Mn-doped ZnO nanocrystals show diamagnetism at room temperature.

In this study the effect of different water conditions on the aggregation kinetics of nanosilver (nAg) is evaluated. The obtained results show that the aggregation rate of nAg increases with increasing electrolyte concentration. Divalent cation (Ca²⁺) can more effectively induce aggregation than monovalent cation (Na⁺). Critical coagulation concentration of nAg in NaCl solution is about 40 times higher than that in CaCl₂ solution. This study also indicates that aggregation rate of nAg in water condition containing high Ca²⁺ concentration in presence of humic acid is higher than that without humic acid due to the bridging effect of humic acid–Ca²⁺ complex. Finally, aggregation rate of nAg in seawater is higher than that in lake water.

Understanding the effects of different growth factors on cancer metastasis will enable researchers to develop effective post-surgery therapeutic strategies to stop the spread of cancer. Conventional Boyden chamber assays to evaluate cell motility in metastasis studies require high volumes of reagents and are impractical for high-throughput analysis. A microfluidic device was designed for arrayed assaying of prostate cancer cell migration towards different growth factors. The device was created with polydimethylsiloxane (PDMS) and featured two wells connected by 10 micro channels. One well was for cell seeding and the other well for specific growth factors. Each channel has a width of 20 μm, a length of 1 mm and a depth of 10 μm. The device was placed on a culture dish and primed with growth media. Lung-metastasized cells in suspension of RPMI 1640 media¹ supplemented with 2% of fetal bovine serum (FBS) were seeded in the cell wells. Cell culture media with epidermal growth factor (EGF) of 25, 50, 75, 100 and 125 ng ml⁻¹ concentrations were individually added in the respective growth factor wells. A 5-day time-lapsed study of cell migration towards the chemoattractant was performed. The average numbers of cells per device in the microchannels were obtained for each attractant condition. The results indicated migration of cells increased from 50 to 100 ng ml⁻¹ of EGF and significantly decreased at 125 ng ml⁻¹ of EGF, as compared to control.

This paper presents the results on the fabrication of highly sensitive fluorescence biosensors for pesticide detection. The biosensors are actually constructed from the complex of quantum dots (QDs), acetylcholinesterase (AChE) and acetylthiocholine (ATCh). The biosensor activity is based on the change of luminescence from CdSe and CdTe QDs with pH, while the pH is changed with the hydrolysis rate of ATCh catalyzed by the enzyme AChE, whose activity is specifically inhibited by pesticides. Two kinds of QDs were used to fabricate our biosensors: (i) CdSe QDs synthesized in high-boiling non-polar organic solvent and then functionalized by shelling with two monolayers (2-ML) of ZnSe and eight monolayers (8-ML) of ZnS and finally capped with 3-mercaptopropionic acid (MPA) to become water soluble; and (ii) CdTe QDs synthesized in aqueous phase then shelled with CdS. For normal checks the fabricated biosensors could detect parathion methyl (PM) pesticide at very low contents of ppm with the threshold as low as 0.05 ppm. The dynamic range from 0.05 ppm to 1 ppm for the pesticide detection could be expandable by increasing the AChE amount in the biosensor.

Newly emerging and being rapidly developed, plasmonics is a key prospective direction of research in nanoscience and nanotechnology. Numerous experimental works on a large variety of photonic processes in which the plasmons play substantial roles have been done, but there are only few theoretical works on these processes, and they are mainly phenomenological. In the present paper we propose an approach based on functional integral formalism, which would be able to be applied to the theoretical study of all physical processes with the participation of plasmons. After the presentation of the basics of functional integral technique, this technique is applied to the study of systems of interacting electrons in nanomaterials. The dynamical equation of plasmon is derived and quantum plasmonic field introduced. In the case of homogeneous and isotropic electron gas in three-dimensional space, this dynamical equation gives rise to the plasmon dispersion exactly coinciding with that derived from the conventional theories. However, the proposed calculation method, based on functional integral technique, can be effectively applied to the study of plasmons in nanostructures with complicated shapes, while the conventional theories are not able to be applied.

We irradiate sub- and super-critical benzene, in which metallocene such as ferrocene or cobaltocene is dissolved, with a UV laser of 266 nm wavelength, and show that benzene and metallocenes are dissociated and iron- and cobalt-containing carbon onions (Fe@C and Co@C) are created. The operational temperature of the present method is much lower than that of conventional ones for the growth of nanomaterials and therefore coagulation among metal-containing carbon onions is avoided. The average diameters of the core iron and cobalt nanoparticles are, respectively, 7.5 and 7.2 nm, whereas the thickness of the layers of carbon onions surrounding the core metal particles is 3.2 nm in both Fe@C and Co@C cases. The metal-containing carbon onions show superparamagnetic characteristics.

In this study we investigate the fabrication of a fluorescence resonance energy transfer (FRET)-based nanosensor for the detection of clenbuterol. The nanosensor consists of CdTe quantum dots coated by clenbuterol recognizable agent naphthol and diazotized clenbuterol. Changes in maximal photoluminescent intensities of the nanosensor were utilized to measure clenbuterol concentrations. The maximal photoluminescent intensities of the nanosensor were found to decrease with increasing clenbuterol concentrations, following a linear correlation. We have successfully fabricated a nanosensor for detection of clenbuterol with sensitivity up to 10 pg ml⁻¹.

Recently YVO₄:Eu³⁺ nanophosphors have attracted more and more attention because of the scientific interest in them and their potential applications in optoelectronics, laser physics, and especially in agrobiology and medicine. In this work we investigated the effect of soft-template agent on size and properties of YVO₄:Eu³⁺ nanoparticles. By using hexadecyltrimethyllammonium bromide (HTAB), sodium dodecyl sulfate (SDS) or dioctyl sodium sulfosuccinate (AOT), the sizes of YVO₄:Eu³⁺ nanoparticles could be controlled in the range from 12 to 16 nm. The fluorescent intensity of YVO₄:Eu³⁺ nanoparticles synthesized in the presence of HTAB, SDS or AOT strongly increased. The structure and morphology of YVO₄:Eu³⁺ nanophosphors have been characterized by x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The novel fluorescent YVO₄:Eu³⁺ nanocrystals with reduced size to around 15 nm become more effective toward the development of an ultrahigh sensitive fluorescent label in immunoassay for bioactive molecules, cells and tissues.

Synthesis of silver nanoparticles (NPs) has become a fascinating and important field of applied chemical research. In this paper silver NPs were prepared using silver nitrate (AgNO₃), gelatin, and cetyl trimethyl ammonium bromide (CTAB). The prepared silver NPs were exposed under the laser ablation. In our photochemical procedure, gelatin acts as a biopolymer and CTAB acts as a reducing agent. The appearance of surface plasmon band around 410 nm indicates the formation of silver NPs. The nature of the prepared silver NPs in the face-centered cubic (fcc) structure are confirmed by the peaks in the x-ray diffraction (XRD) pattern corresponding to (111), (200), (220) and (311) planes. Monodispersed, stable, spherical silver NPs with diameter about 10 nm were obtained and confirmed by high-resolution transmission electron microscope (HRTEM).

This report highlights the fabrication of fluorescence biosensors based on CdTe quantum dots (QDs) for specific detection of H5N1 avian influenza virus. The core biosensor was composed of (i) the highly luminescent CdTe/CdS QDs, (ii) chromatophores extracted from bacteria Rhodospirillum rubrum, and (iii) the antibody of β-subunit. This core part was linked to the peripheral part of the biosensor via a biotin–streptavidin–biotin bridge and finally connected to the H5N1 antibody to make it ready for detecting H5N1 avian influenza virus. Detailed studies of each constituent were performed showing the image of QDs-labeled chromatophores under optical microscope, proper photoluminescence (PL) spectra of CdTe/CdS QDs, chromatophores and the H5N1 avian influenza viruses.

An in situ chemical polymerization method was applied in order to prepare polyaniline-multiwalled carbon nanotube (PANI-MWCNT) composites with different concentrations of MWCNT. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, optical absorption and photoluminescence analyses of the composites were performed to investigate the structural, morphological and optical properties of the composites. Electrical transport properties of different PANI-MWCNT composites were investigated in the temperature range 77 K ⩽ T ⩽  300 K in the presence and also in the absence of a magnetic field up to 1 T. The dc resistivity of the composites follows Mott's variable range hopping theory. Two different slopes have been observed in temperature variation of resistivity, which occurs due to the presence of MWCNT in the polymer matrix. The magnetoconductivity of the samples at different temperatures is negative, which can be explained by the wavefunction shrinkage effect.

This paper reports the theoretical and experimental study of one-dimensional (1D) multilayer nanoporous silicon (NPS) photonic band gap (PBG) microcavity (MC) structures for optical sensor device applications. A theoretical framework to model the reflectance spectra relying on the Bruggeman's effective medium approximation (BEMA) and the transfer matrix method (TMM) was established for the 1D nanoporous silicon microcavity (1D-NPSMC) optical sensor device structures. Based on the theoretical background, 1D-NPSMC sensor device structures were fabricated using electrochemical dissolution of silicon wafer in hydrofluoric (HF) acid. The refractive index of the 1D-NPSMC structures was tuned by changing current density and the thickness was tuned by changing the etching time. Wavelength shifts (Δλ) in the measured reflectance spectra were analyzed for the detection of the analyte in the porous structure. The sensing device performance was tested by different organic solvents, which showed good linear relation between the refractive index of analyte inside the pores and the wavelength shift. The application of proposed structures can be extended for the optical sensing of chemicals, gas, environmental pollutants, pathogens etc.