Xuan Phuc Nguyen

Chitosan and O-carboxymethyl chitosan modified Fe3O4 for hyperthermic treatment

In this study magnetic fluids were manufactured by the adsorption of chitosan (CS) and O-carboxymethyl chitosan (OCMCS) on Fe3O4 nanoparticles to be used as hyperthermic thermoseeds. Fe3O4 particles were characterized by physico-chemical methods such as: thermogravimetry analysis (TGA), x-ray diffraction (XRD), Raman spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). The SEM images and XRD patterns showed that the synthesized Fe3O4 nanoparticles were of single phase and spherical shape with 10–15 nm in diameter. The VSM measurements showed that Fe3O4 particles were superparamagnetic with saturation magnetization of 70 emu g−1. The adsorbed layers of CS and OCMCS on the magnetite surface (Fe3O4/CS) and (Fe3O4/OCMCS) were confirmed by FTIR, Raman spectra and SEM. In the ac magnetic field of 80 Oe and 236 kHz, the saturation heating temperatures of the sample Fe3O4/CS and Fe3O4/OCMCS were 100 and 98 °C, respectively. At the same concentration of Fe3O4 nanoparticles in suspension, the two magnetic fluids exhibited quite high heating capacity, with different behaviors of concentration dependence. The Fe3O4/CS and Fe3O4/OCMCS nanoparticles would serve as good thermoseeds for localized hyperthermia treatment of cancers.

Preparation and anti-cancer activity of polymer-encapsulated curcumin nanoparticles

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 50‐100nm, 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).

Graphene patterned polyaniline-based biosensor for glucose detection

This paper describes a glucose electrochemical biosensor, layer-by-layer fabricated from graphene and polyaniline films. Graphene sheets (0.5?0.5?cm2) with the thickness of 5?nm (15 layers) were synthesized by thermal chemical vapor deposition (CVD) under ambient pressure on copper tapes. Then they were transferred into integrated Fe3O4-doped polyaniline (PANi) based microelectrodes. The properties of the nanocomposite films were thoroughly characterized by scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM) and electrochemical methods, such as square wave voltametry (SWV) and chronoamperometry. The above graphene patterned sensor (denoted as Graphene/Fe3O4/PANi/GOx) shows much improved glucose sensitivity (as high as 47??A?mM?1?cm?2) compared to a non-graphene one (10?30??A?mM?1?cm?2, as previously reported in the literature). It can be expected that this proof-of-concept biosensor could be extended for other highly sensitive biodetection.

A novel nanofiber Cur-loaded polylactic acid constructed by electrospinning

Curcumin (Cur), extracted from the Curcuma longa L. plant, is well known for its anti-tumor, anti-oxidant, anti-inflammatory and anti-bacterial properties. Nanofiber mats of polylactic acid (PLA) loading Cur (5?wt%) were fabricated by electrospinning (e-spinning). Morphology and structure of the fibers were characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. The diameters of the obtained fibers varied from 200 to 300?nm. The release capacity of curcumin from curcumin-loaded PLA fibers was investigated in phosphate buffer saline (PBS) containing ethanol. After 24?h, 50% of the curcumin was released from curcumin-loaded PLA fibers. These results of electrospun (e-spun) fibers exhibit the potential for biomedical application.

Facile and solvent-free routes for the synthesis of size-controllable Fe 3 O 4 nanoparticles

Magnetite nanoparticles are one of the most important materials that are widely used in both medically diagnostic and therapeutic research. In this paper, we present some facile and non-toxic synthetic approaches for size-controllable preparations of magnetite nanoparticles, which are appropriate for biomedical applications, namely (i) co-precipitation; (ii) reduction‐precipitation and (iii) oxidation‐precipitation. Magnetic characterizations of the obtained nanoparticles have been studied and discussed. The oxidation precipitation route was chosen for investigation of the dependence of kinetic driven activation energy and that of coercive force on particle size (and temperature) during the course of the reaction. The structural‐magnetic behavior was also correlated. Being solvent and surfactant-free, these methods are advantageous for synthesis and further functionalization towards biomedical applications.

Some biomedical applications of chitosan-based hybrid nanomaterials

Being naturally abundant resources and having many interesting physicochemical and biological properties, chitin/chitosan have been found to be useful in many fields, especially biomedical ones. This paper describes the strategy to design multifunctional, hybrid chitosan-based nanomaterials and test them in some typical biomedical applications.

The synthesis of poly(lactide)-vitamin E TPGS (PLA-TPGS) copolymer and its utilization to formulate a curcumin nanocarrier

Curcumin is a natural substance that exhibits the ability to inhibit and/or treat carcinogenesis in a variety of cell lines, but because of its poor solubility in water the treatment efficacy is limited. In this paper we report on the fabrication of self-assembled micelle nanoparticles loaded with a curcumin drug by use of a biocompatible copolymer of PLA-TPGS (d-a-tocopheryl polyethylene glycol 1000 succinate—vitamin E TPGS) conjugate. The polylactide (PLA)-TPGS copolymer synthesized by ring-opening polymerization was characterized by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H NMR) techniques. The surface morphology of PLA-TPGS and curcumin loaded PLA-TPGS was determined by field emission scanning electron microscopy (FE-SEM). The absorption and fluorescence examinations indicated that due to micellar capsulation the intensity of both types of spectra increased by about 4 times in comparison with those of the free curcumin sample.

Biomedical and environmental applications of magnetic nanoparticles

This paper presents an overview of syntheses and applications of magnetic nanoparticles (MNPs) at the Institute of Materials Science, Vietnam Academy of Science and Technology. Three families of oxide MNPs, magnetite, manganite and spinel ferrite materials, were prepared in various ways: coprecipitation, sol?gel and high energy mechanical milling. Basic properties of MNPs were characterized by Vibrating Sample Magnetometer (VSM) and Physical Properties Measurement Systems (PPMS). As for biomedical application, the aim was to design a novel multifunctional, nanosized magnetofluorescent water-dispersible Fe3O4-curcumin conjugate, and its ability to label, target and treat tumor cells was described. The conjugate possesses a magnetic nano Fe3O4 core, chitosan (CS) or Oleic acid (OL) as an outer shell and entrapped curcumin (Cur), serving the dual function of naturally autofluorescent dye as well as antitumor model drug. Fe3O4-Cur conjugate exhibited a high loading cellular uptake with the help of a macrophage, which was clearly visualized dually by Fluorescence Microscope and Laser Scanning Confocal Microscope (LSCM), as well as by magnetization measurement (PPMS). A preliminary magnetic resonance imaging (MRI) study also showed a clear contrast enhancement by using the conjugate. As for the environmental aspect, the use of magnetite MNPs for the removal of heavy toxic metals, such as Arsenic (As) and Lead (Pb), from contaminated water was studied.

The effect of artificial boundary grain on the magneto- and electro-transport properties of (1 − x)La0.7Ca0.3MnO3+xA (A=Al2O3 and Ag) nanocomposite

The magneto- and electro-transport properties of two series of nanocrystalline (1−x)La0.7Ca0.3MnO3+xA (A: Al2O3 and Ag) composites have been systematically and thoroughly studied. The observed electronic transport behavior over the whole temperature range (5–300 K), especially the change in metal–insulator transition temperature with increasing Al2O3 and Ag content while the ferromagnetic–paramagnetic transition remained unaffected, was explained by applying a two-component phenomenological model. We have attributed the unusual low-temperature resistivity upturn of composites to a change in charging energy. Most interestingly, magneto-transport measurements showed that the low-field magnetoresistance (LFMR), as well as the high-field magnetoresistance (HFMR), displayed a Curie–Weiss-like law behavior. Basing on the spin-polarized transport of conduction electrons at the grain boundaries, we have analyzed our experimental data and found that the temperature dependence of low- and high-field magnetoresistance is controlled predominantly by the nature of the temperature response of surface magnetization of particles. The competition between grain-boundary pinning strength (k), magnetic field and thermal energy (kBT) created the temperature sensitive behavior of magnetoresistance as well as that of surface spin susceptibility (χ b).

Magnetic heating characteristics of La0.7SrxCa0.3-xMnO3 nanoparticles fabricated by a high energy mechanical milling method

Magnetic inductive heating (MIH) of nanoparticles (NPs) attracts considerable research attention, first because of its application to hyperthermia in biological tissues. Most reports so far have dealt with magnetite NPs with a Curie temperature, TC, of as high as above 500 °C. In this paper, we present results of a MIH study in an ac field of frequency 219 and 236 kHz and strength of 40–100 Oe for several samples of La0.7SrxCa0.3−x MnO3 NPs of TC in the region of hyperthermia, that is some tens of degrees above human body temperature. The particle materials were fabricated by a high energy mechanical milling method combined with calcining at various temperatures in the range of 600–900 °C. The heating temperatures of the samples were observed to saturate at a field irradiating time of less than 10 min and at temperatures ranging from 40 to 75 °C depending on the strontium content, the NP concentration, c, and the field parameters. A sudden change in heating rate was clearly revealed in several heating curves for the case of low applied field and low c, which was considered to be related to the onset of a strong decrease in zero-field cooling (ZFC) magnetization of NPs. The initial temperature increase slope, dT/dt, and the saturation temperature, Ts will be analyzed as dependent on the NP concentration. Field dependences of the specific loss power will be analyzed and discussed for various concentrations, c. Evidence of fluid viscosity influence will also be noted.