One-Step Carbon Coating and Polyacrylamide Functionalization of Fe3O4 Nanoparticles for Enhancing Magnetic Adsorptive-Remediation of Heavy Metals.

Magnetic nanoparticles are used in adsorptive removal of heavy metals from polluted wastewater. However, their poor stability in an acidic medium necessitates their protection with a coating layer. Coating magnetic nanoparticles with carbon showed proper protection but the heavy metal removal efficiency was slightly weak. However, to boost the removal efficiencies of surface functionalization, polyacrylamide was applied to carbon-coated Fe3O4 nanoparticles. In this paper, to facilitate the synthesis process, one-step carbon coating and polyacrylamide functionalization were conducted using the hydrothermal technique with the aim of enhancing the adsorptive removal capacity of Fe3O4 nanoparticles towards some heavy metals such as Cu(II), Ni(II), Co(II), and Cd(II). The results showed that the one-step process succeeded in developing a carbon coating layer and polyacrylamide functionality on Fe3O4 nanoparticles. The stability of the magnetic Fe3O4 nanoparticles as an adsorbent in an acidic medium was improved due to its resistance to the dissolution that was gained during carbon coating and surface functionalization with polyacrylamide. The adsorptive removal process was investigated in relation to various parameters such as pH, time of contact, metal ion concentrations, adsorbent dose, and temperature. The polyacrylamide functionalized Fe3O4 showed an improvement in the adsorption capacity as compared with the unfunctionalized one. The conditions for superior adsorption were obtained at pH 6; time of contact, 90 min; metal solution concentration, 200 mg/L; adsorbent dose, 0.3 g/L. The modeling of the adsorption data was found to be consistent with the pseudo-second-order kinetic model, which suggests a fast adsorption process. However, the equilibrium data modeling was consistent with both the Langmuir and Freundlich isotherms. Furthermore, the thermodynamic parameters of the adsorptive removal process, including ΔG°, ΔH°, and ΔS°, indicated a spontaneous and endothermic sorption process. The developed adsorbent can be utilized further for industrial-based applications.

Boron neutron capture therapy demonstrated in mice bearing EMT6 tumors following selective delivery of boron by rationally designed liposomes.

The application of boron neutron capture therapy (BNCT) following liposomal delivery of a (10)B-enriched polyhedral borane and a carborane against mouse mammary adenocarcinoma solid tumors was investigated. Unilamellar liposomes with a mean diameter of 134 nm or less, composed of an equimolar mixture of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine and incorporating Na3[1-(2'-B10H9)-2-NH3B10H8] in the aqueous interior and K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer, were injected into the tail veins of female BALB/c mice bearing right flank EMT6 tumors. Biodistribution studies indicated that two identical injections given 24 h apart resulted in tumor boron levels exceeding 67 µg/g tumor at 54 h--with tumor/blood boron ratios being greatest at 96 h (5.68:1; 43 µg boron/g tumor)--following the initial injection. For BNCT experiments, tumor-bearing mice were irradiated 54 h after the initial injection for 30 min with thermal neutrons, resulting in a total fluence of 1.6 × 10(12) neutrons per cm(2) (±7%). Significant suppression of tumor growth was observed in mice given BNCT vs. control mice (only 424% increase in tumor volume at 14 d post irradiation vs. 1551% in untreated controls). In a separate experiment in which mice were given a second injection/irradiation treatment 7 d after the first, the tumor growth was vastly diminished (186% tumor volume increase at 14 d). A similar response was obtained for mice irradiated for 60 min (169% increase at 14 d), suggesting that neutron fluence was the limiting factor controlling BNCT efficacy in this study.

Fabrication of mesoporous silica shells on solid silica spheres using anionic surfactants and their potential application in controlling drug release.

In this work, mesoporous shells were constructed on solid silica cores by employing anionic surfactante. A co-structure directing agent (CSDA) has assisted the electrostatic interaction between negatively charged silica particles and the negatively charged surfactant molecules. Synthetic parameters such as reaction time and temperature had a significant impact on the formation of mesoporous silica shelld and their textural properties such as surface area and pore volume. Core-mesoporous shell silica spheres were characterized by small angle X-ray scattering, transmission electron microscopy, and N(2) adsorption–desorption analysis. The synthesized particles have a uniformly mesoporous shell of 34–65 nm and possess a surface area of ca. 7–324 m2/g, and pore volume of ca. 0.008–0.261 cc/g. The core-mesoporous shell silica spheres were loaded with ketoprofen drug molecules. The in vitro drug release study suggested that core-mesoporous shell silica spheres are a suitable nanocarrier for drug molecules offering the possibility of having control over their release rate.

BNCT induced immunomodulatory effects contribute to mammary tumor inhibition.

In the United States, breast cancer is one of the most common and the second leading cause of cancer-related death in women. Treatment modalities for mammary tumor are surgical removal of the tumor tissue followed by either chemotherapy or radiotherapy or both. Radiation therapy is a whole body irradiation regimen that suppresses the immune system leaving hosts susceptible to infection or secondary tumors. Boron neutron capture therapy (BNCT) in that regard is more selective, the cells that are mostly affected are those that are loaded with 109 or more 10B atoms. Previously, we have described that liposomal encapsulation of boron-rich compounds such as TAC and MAC deliver a high payload to the tumor tissue when injected intravenously. Here we report that liposome-mediated boron delivery to the tumor is inversely proportional to the size of the murine mammary (EMT-6) tumors. The plausible reason for the inverse ratio of boron and EMT-6 tumor size is the necrosis in these tumors, which is more prominent in the large tumors. The large tumors also have receding blood vessels contributing further to poor boron delivery to these tumors. We next report that the presence of boron in blood is essential for the effects of BNCT on EMT-6 tumor inhibition as direct injection of boron-rich liposomes did not provide any added advantage in inhibition of EMT-6 tumor in BALB/c mice following irradiation despite having a significantly higher amount of boron in the tumor tissue. BNCT reaction in PBMCs resulted in the modification of these cells to anti-tumor phenotype. In this study, we report the immunomodulatory effects of BNCT when boron-rich compounds are delivered systemically.

Toxicity response of highly colloidal, bioactive, monodisperse SiO2@ Pr(OH)3 hollow microspheres.

In a facile synthesis, highly colloidal, bioactive Pr(OH)3-encapsulated silica microspheres (PSMSs) with an average diameter of 500-700 nm were successfully prepared via a sol-gel process followed by heat treatment. The phase formation, morphology, surface and optical properties of the as-synthesized PSMSs were characterized by various techniques including X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM), N2-adsorption-desorption, energy dispersive X-ray (EDX) analysis, Fourier transform infrared (FTIR) and UV/vis spectroscopy. The PSMSs were semi-amorphous or ultra-small in size, highly dispersible in water, mesoporous, irregular in size and spherical in shape. The SEM images show a well-ordered broad nanoporous structure which is preserved after coating with Pr(OH)3 molecules, demonstrating interaction between the optically active Pr3+ ion and silanol (Si-OH) groups via hydrogen bonding. Optical spectra show well-resolved weak intensity 4f-4f absorption transitions in the visible region of the Pr3+ ion, indicating successful grafting of the Pr(OH)3 layer. Toxicity was measured by MTT and NRU assays to determine potential toxicity. Cell viability was suppressed with increasing dosage of PSMSs, but showed greater than 55% cell viability at a concentration of 200 µg/mL, resulting in low toxicity. Due to its high aqueous dispersibility, optical activity, excellent biocompatibility and low toxic nature, it could be a favorable material for biomedical and drug delivery applications.

Mesoporous multi-silica layer-coated Y2O3:Eu core-shell nanoparticles: Synthesis, luminescent properties and cytotoxicity evaluation.

Mesoporous multi-layered silica-coated luminescent Y2O3:Eu nanoparticles (NPs) were prepared by a urea-based decomposition process, and their surfaces were gradually modified with nanoporous and mesoporous silica layers using modified sol-gel methods. The synthesized luminescent core-shell NPs were characterized thoroughly to investigate their structural, morphological, thermal, optical, photo luminescent properties and their surface chemistry. The morphology of the core NPs were nearly spherical in shape and were nano-sized grains. The observed luminescent efficiency of the mesoporous multi-layered silica-coated luminescent core NPs was gradually reduced because of bond formation between the Y2O3:Eu core and the amorphous silica shell via YOSiOH bridges on the surface of the NPs; the bonds suppressed the non-radiative transition pathways. Biocompatibility tests on Human breast cancer cells using the 3­(4,5­Dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide and lactate dehydrogenase assays indicated that the core-shell NPs were non-toxic even at high concentrations. The mesoporous SiO2 layer played a key role in perfecting the solubility, biocompatibility, and non-toxicity of the NPs. The zeta potential, surface chemistry (Fourier transform infrared spectroscopy), and optical absorption spectral analyses revealed the high hydrophilicity of the as-prepared core-shell NPs because of the active surface-functionalized silanol (SiOH) groups, which could potentially offer many exciting opportunities in photonic-based biomedical applications.

Preparation and characterization of N-isopropylacrylamide/acrylic acid copolymer core-shell microgel particles.

A new method has been developed to prepare smart copolymer microgels that consist of well defined temperature sensitive cores and pH sensitive shells. The microgels were obtained from N-isopropylacrylamide (NIPAAm) and acrylic acid (AAc), containing different mole ratios of AAc. Transmission electron micrographs of the microgels show that the colloidal copolymers are nearly monodisperse spheres (core-shell structures). The lower critical solution temperatures (LCSTs) (or phase separation temperatures) of the aqueous microgel solutions were measured by cloud-point method. At slight acidic conditions, the LCST decreased with increase in AAc content, which suggests that the hydrophobic group of NIPAAm has a greater influence on the LCST than the polar COOH group at those conditions. An increase of pH value leads to a significant increase in LCST due to the formation of a more hydrophilic copolymer. The LCST were studied as a function of copolymer composition over the pH range from 4.0 to 6.5. Because the pK(a) of the polymers can be tuned to fall close to neutral pH, these polymer compositions can be dispersed to have phase transitions triggered near physiological pH or at slight acidic pH values that fall within acidic gradients found in biology. Because of their stimuli-responsive behavior, these nanoscale materials are excellent candidates for biotechnology and biomedical applications where small changes in pH or temperature are of great consequence.