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Nanoparticles (NPs) are promising candidates for different biomedical applications due to their excellent antimicrobial applications. However, the applications become limited due to the higher cost of NP synthesis. In his research work, Hydroxyapatite Nanoparticles (HANPs) have been synthesized in a cost-effective method to apply in biomedical applications. The synthesized HANPs have been characterized by different morphological and antimicrobial characterization methods. Ultraviolet–Visible (UV) spectroscopy was performed and a peak was obtained at 271nm which confirmed the formation of NPs and opened a new door for further analysis. Fourier Transformed Infrared Spectroscopy (FTIR) has been performed and the presence of functional groups such as hydroxides carbonates and phosphates have been identified. Transmission Electron Microscopy (TEM) analysis reveals the circular and smaller shape of the synthesized HANPs. The chemical elements of HA have been identified by EDS analysis. Sharp peaks identified by the X-Ray Diffraction (XRD) analysis confirm the formation of crystals in the synthesized HANPs. An excellent antimicrobial performance which is 99.99% has been obtained from the gram-positive and gram-negative bacterial strains. The obtained results suggest the potentiality of the synthesized HANPs in biomedical applications.

One-dimensional nanochains consisting of Cu nanoparticles and PVA nanofiber were prepared in the presence of a deoxidant NaHSO₃ by electrospinning. Their morphologies and stability were characterized by TEM and UV-vis spectra. The results show that three kinds of nanochains were formed according to the ratio of diameters of the nanoparticles to the nanofiber, i.e., Cu/PVA is equal to, larger, and smaller than 1. The nanochains are stable in air.

Nanosize SiO₂ particles with narrow size distribution were produced by modified Stober–Fink–Bohn method. Average particle size was determined as 170 nm by SEM image. Organosilica mesoporous molecular sieve (MCM-48) was synthesized. The calcined MCM-48 has pore diameter of 26.8 Å and a surface area of 1024 m²g^-1 by BET (Brunauer–Emmet–Teller) measurement.

The synthesis of the GaAs nanoparticles, having sizes 7 nm to 15 nm, by a low cost electrochemical technique has been reported. The absence of any foreign impurity has been confirmed by the Proton-Induced X-rays Emission analysis. Rutherford Backscattering measurement has been performed in order to estimate the thickness of the nanoparticle-generated thin film as a function of the electrolysis current density. The X-ray Photoelectron Spectroscopic study confirms the formation of GaAs and exhibits the binding energy shift of the core shell electrons as an implication of the nanostructure effect. Very weak infrared luminescence due to the radiative recombination of the impurity bound exciton has been detected from yttrium-doped GaAs nanocrystals, even at room temperature.

Nitrilotriacetate precursors have been used for synthesis of oxide materials. High permeability Mn–Zn ferrite with general formula Mn_xZn_1-xFe₂O₄ where x=0.3/0.35/0.4/0.45/0.5/0.55/0.6/0.65/0.7 were prepared using this novel method. Formation of cubic spinel structure was confirmed by XRD, which also provided information on formation of fine particle material. The magnetic properties of these materials were investigated after sintering the same at 950°C, 1150°C, 1250°C and 1350°C in nitrogen atmosphere and at 1050°C in air and were found to be interesting.

Mono- and bimetallic nanowires and particles were selectively synthesized in mesoporous silica templates, in which siliceous FSM-16 and organic–inorganic hybrid HMM-1 were used as templates. The metal nanowires and particles were characterized by several physicochemical methods. The mechanism for formation of Pt wires was studied, and migration of precursor Pt ions in the mesoporous channels is the key to the formation of the wires. The Pt wires can be isolated by dissolving silicate matrix in a good yield, and STM and HRTEM demonstrate that the wires extracted from HMM-1 has a nanonecklace structure, but the wire from FSM-16 shows a nanorod structure. The extracted Pt wires are stabilized by PPh₃. The nanowire composites show unique properties in magnetism and high catalytic performances in CO oxidation reaction.

A variety of DNA, protein or cell microarray devices and systems have been developed and commercialized. In addition to the biomolecule related analysis, they are also being used for pharmacogenomic research, infectious and genetic disease and cancer diagnostics, and proteomic and cellular analysis.¹ Currently, microarray is fabricated on a planar surface; this limits the amount of biomolecules that can be bounded on the surface. In this work, a planar protein microarray chip with nonplanar spot surface was fabricated to enhance the chip performance. A nonplanar spot surface was created by first coating the silica nanoparticles with albumin and depositing them into the patterned microwells. The curve surfaces of the nanoparticles increase the surface area for immobilization of proteins, which helps to enhance the detection sensitivity of the chip. Using this technique, proteins are immobilized onto the nanoparticles before they are deposited onto the chip, and therefore the method of protein immobilization can be customized at each spot. Furthermore, a nonplanar surface promotes the retention of native protein structure better than planar surface.² The technique developed can be used to produce different types of microarrays, such as DNA, protein and antibody microarrays.

Titanium dioxide (TiO₂) nanoparticles in the anatase phase were coated on fly ash by using a sol–gel method. The TiO₂ nanoparticles coated on fly ash were produced from titanium tetraisopropoxide (Ti(OPrⁱ)₄ 3.3 M) in absolute ethanol, and the fly ash was added into this alcoholic solution. The ratio of TiO₂ nanoparticles to fly ash in the coating process was 1:10 by weight. The ethanolic solution was loaded into a pouch type cellophane membrane and placed for 1 h in a clear solution which containing 1:1 (v/v) ratio of absolute ethanol and distilled water with 0.5–1% concentrated (25%) ammonia solution. After the dialysis process was completed, the mixture was then allowed to dry in an oven at 100–110°C and was calcined in a furnace over the temperatures range of 400–800°C. TiO₂ nanoparticles were then analyzed and characterized by using the techniques of XRD, SEM, EDS, TEM, and BET. The crystalline sizes of anatase form were found to be in the range of 15–20 nm. The characteristics of TiO₂ nanoparticles coated on fly ash were further investigated by utilizing SEM and EDS methodologies. The correlations among crystalline phase, particle size, morphology, and specific surface area were investigated.

The number, size and distribution of nanoparticles in urines of healthy people and stone patients were investigated by transmission electron microscopy (TEM). The results showed that the number of nanoparticles in healthy urines are more than that in lithogenic urines. The size of most nanoparticles in healthy urines ranges from 100 to 350 nm. However, the size of nanoparticles in patient urines changes from 100 nm to 1000 nm and more. A dynamic model about the formation of urinary stones was established. From this model, the nanoparticles in normal urines are stable, yet those in patient urines would easily aggregate to larger-size crystals and finally urinary stones formed. The results in this paper provide a new thought for preventing formation and recurrence of urinary stones.

The electromagnetic response of a nanoparticle of an ion-doped polymeric elastic insulator, commonly called an electret, is considered in the continuum model of a uniformly charged elastic sphere. The spectral formulae for the frequency of optically induced spheroidal and torsional shear oscillations driven by bulk force of elastic and dielectric stresses are obtained in analytic form. Particular attention is given to the relaxation dielectric mode of the electrostriction response and its stability in the lowest quadrupole mode. The practical usefulness of ultrafine particles of electrets as biolabels capable of accumulating like-charged inclusions uniformly dispersed over the spherical volume of an elastic matrix is briefly discussed.

Hydrogen storage in a metallic nanoparticle was simulated by classical molecular dynamics. Distribution of hydrogen atoms inside nanoparticle was investigated by changing length and energy parameters of metal–H bonds. Hydrogen atoms diffused into the particle and distributed homogeneously in case of weak metal–H bonds. In case of strong metal–H bonds, a hydrogen-rich surface layer was observed which suppresses the inward diffusion of hydrogen atoms. Structural modification of nanoparticle accompanied by grain boundary formation due to hydrogen loading was also observed. These variations in dynamical and structural features are considered to affect the hydrogen storage properties in nanoparticles.

Nanocrystalline Pd electrocatalyst promoted with transition metal oxide (Co₃O₄, NiO, and CoNiO_x) is successfully synthesized on high surface carbon support by using intermittent microwave heating (IMH) method. The physical properties of the catalysts are characterized by XRD, TEM, and EDX. The results show that there is no significant microstructure change between Pd and Pd-oxide electrocatalysts and the particle sizes are in the range 5.8–3.9 nm. The linear sweep voltammogram and chronoamperometry results for the electro-oxidation of ethanol show that Pd-oxide/C electrocatalysts exhibit much better electrochemical activity and stability as compared with pure Pd/C electrocatalyst. The results show that Pd–CoNiO_x/C exhibits the best stability and highest electro-oxidation activity, indicating the promising potential as an alternative electrocatalysts for the direct ethanol fuel cells.

Hybrid light emitting nanoparticles with diameter range from 2 to 4 nm were prepared via grafting organic-conjugated chains directly onto an inorganic rigid cage polyhedral oligomeric silsesquioxanes (POSS). The unique properties of these particles show evidence of quantum confinement effect on the conjugated short chains by two barriers of POSS cage and alkyl chains. The confinement effects are revealed in five aspects. First, the UV and PL spectra redshift as increasing the length of conjugated chains. This phenomenon can be considered as size effect. Second, PL spectra of these nanoparticles in solid film blueshift from that in most of organic solvents, which can be considered as limited intra- or inter-molecular interactions existed within the nanoparticles. Third, the Raman bands of the conjugated chains in these nanoparticles are redshifted and broadening with respect to their bulk counterparts. The systematic peak shifting and broadening of the Raman bands provided additional confirmation that the conjugated chains in hybrid nanoparticles at bulk state are isolated without any π–π stacking. Fourth, TEM and SEM images showed the particle size in a range of 2–4 nm and the nanoparticles in bulk state are noncrystalline materials. Lastly, the PL spectrum of the nanoparticle at low temperature was studied and found no change in PL position and intensity as temperature increasing from 4 K to 150 K.

Gold nanomaterials are becoming increasingly important in a variety of applications. The size and shape control in the chemical synthesis of nanostructures is particularly important due to their potential in sensing or imaging applications. Snake-shaped gold nanostructures have been synthesized using environmentally benign conditions. Hydroxyethyl cellulose (HEC) was used as a reducing and stabilizing agent for the synthesis of gold nanostructures from hydrogen tetrachloroaurate(III) trihydrate (HAuCl₄) in water. The gold nanostructures showed snake-shaped particles with a head size from 30 to 50 nm and a tail length of 100 nm to 600 nm. The size of the nanostructure can be easily tailored by varying the concentrations of HAuCl₄ and HEC. The UV–Vis spectroscopy studies showed that the gold nanostructures have a strong visible absorption in the range of 525–535 nm. The particles were purple in color and stable for several months in solution without aggregation.

In the present study, results concerning the structural and photoluminescence properties of ZnO:Co nanocrystalline powders synthesized using an oxalate precursor decomposition method are reported. The XRD profiles reveal that all the samples are in hexagonal wurtzite structure. The values of the lattice parameters a and c are found to be decreasing linearly with Co content change. Surface morphological studies have also been carried out using SEM and TEM analyses. The origin of photoluminescence from ZnO and Co:ZnO has been reported.

The nanocrystalline La_0.8Te_0.2MnO₃ samples are prepared by sol-gel method and show rhombohedral crystal structure with R3c space group at room temperature. The calculated crystallite sizes are ~55 nm, 40 nm and 25 nm for calcined at 700°C, 800°C and 900°C temperatures. The SEM images show the grain size increases as the calcination temperature increases and the values are in good agreement with that obtained from X-ray diffraction analysis. The samples undergo paramagnetic to ferromagnetic transition and follow Curie–Weiss law in the paramagnetic region. The maximum entropy change are ~3.2 J kg^-1 K^-1, 3 J kg^-1 K^-1 and 2 J kg^-1 K^-1 for a field change of 20 kOe for 55 nm, 40 nm and 25 nm samples respectively. In the framework of Landau theory of phase transition, the experimentally observed magnetic entropy change and theoretical predicted model fits well for all the nanoparticles.

Nanosize barium sulfate (BaSO₄) particles prepared with dodecyl benzene sulfonic acid (DBSA) in ethanol–water reaction system are used to prepare BaSO₄/polypropylene (PP) nanocomposites by melt mixing method. It is then made into hybrid fibers by melt spinning and subsequent drawing with different ratios. The hybrid fibers are characterized by rheology, morphology, thermal stability and mechanical properties, respectively. The results indicate that the DBSA-modified BaSO₄ can improve the spinnability of BaSO₄/PP hybrid multifilament even at high BaSO₄ nanoparticles concentration. DBSA can be used as compatibilizer to enhance the interface interaction of BaSO₄/PP nanocomposites, because DBSA contains both hydrophobicity long alkyl chain and hydrophilic sulfonic group. Therefore, it can improve the performances of BaSO₄/PP hybrid multifilament.

Production of nanoparticles by precipitation is a relatively simple process but the control of product particle size distribution is difficult. In this paper, nanosize barium sulfate (BaSO₄) particles are prepared with dodecyl benzene sulfonic acid (DBSA) in ethanol–water reaction system at room temperature. The BaSO₄ nanoparticles are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), powder X-ray diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA), respectively. The results indicated that the average diameter of spherical BaSO₄ is about 46 nm modified with 5 wt.% DBSA, which have good dispersion in the presence of a certain concentration NH₃ ⋅ H₂O. It suggests that the high dispersion is attributed to presence of a thin layer of barium alkyl sulfate, which is formed and coated onto the surface of BaSO₄ particles during the reaction process. The thin films on the surface of the BaSO₄ effectively modified the surface and properties, which also control the particle size and morphology.

The local stress concentration on 2D nanosheets is investigated for saponite layered nanoparticles by means of X-ray diffraction (XRD) and positronium (Ps) annihilation spectroscopy. XRD experiments indicated that the layered structure for the mechanochemically milled sample is maintained in the presence of H₂O molecules. Ps annihilation studies of self-assembly revealed that the 2D nanosheets are well in-plane ordered after uniaxial pressure compaction without H₂O molecules due to the efficient propagation of stress concentration. The present results of both XRD and Ps lifetime spectroscopy clearly demonstrates that the stress concentration on the 2D nanosheets can be reduced in the presence of H₂O molecules.

Aquatic pteridophyte (Azolla sp.) was taken to assess its potential to synthesize the metal (Au) nanoparticles. The synthesized particles were characterized using X-ray, UV-visible, scanning and transmission electron microscopy analyses. Nanoparticles almost spherical in shape having the sizes of 5–17nm are found. UV-visible study revealed the surface plasmon resonance at 538nm. Responsible phytochemicals for the transformation were principally phenolics, tannins, anthraquinone glycosides and sugars present abundantly in the plant thereby bestowing it adaptive prodigality. Also, the use of Azolla sp. for the synthesis of gold nanoparticles offers the benefit of eco-friendliness.