Investigation of the effect of nitrogen, boron, sulphur, and phosphor as doping elements on carbon dots, where boron-carbon dots performed good potential for bioimaging application with best optical properties and specific targeting features.

In this research, mercapto-silica coated magnetite (Fe3O4-SiO2-SH) has been prepared in aqueous solution through a simple approach so called a one-pot process. The Fe3O4-SiO2-SH was prepared in nitrogen condition by mixing magnetite, 3-mercaptopropyltrimethoxysilane (MPTMS), and sodium silicate (Na2SiO3) solution extracted from rice hull ash, and adjusting the pH of 7.0 using hydrochloric acid. The residue was washed with deionized water, dried at 150°C and separated with an external magnetic field. In that work, the volume of MPTMS and Na2SiO3 was varied and the total amount of Si represented as silica was kept constant. Characters of the material including the functional group presence, the structure, the porosity, the morphology and stability toward various solvents were identified and evaluated. Results of characterization indicated that mercapto-silica has been coated magnetite particle with a simple one-pot process. Coating mercapto-silica on magnetite increases particle size, surface area, and chemical stability. Additionally, Fe3O4-SiO2-SH also shows high stability toward various organic solvents. The magnetic property of magnetite does not change after coating and the addition of nonmagnetic material still gives high value of maximum saturation magnetization. The presence of mercapto groups effective for interaction with heavy metal ions, the high chemical stability without removing the magnetic property promises the prospective application of Fe3O4-SiO2-SH in the future such as for separation and removal of heavy metal ions from aquatic environments.

In this research, the adsorption of Au(III) ion on ionic imprinted amino-silica hybrid (Im-ASH) in aqueous solution has been studied. Im-ASH was synthesized via sol-gel technique using a solution of sodium silicate (Na2SiO3) from rice hull ash (RHA) as the precursor and Au(III) ion as the template. Adsorption was carried out in a batch system with variation of pH, contact time, and Au(III) ion concentration. The selectivity of adsorbent toward Au(III) was examined in the presence of Cu(II) ion. The result of the kinetic study demonstrated that the adsorption of Au(III) ion followed pseudo-second order. The optimum adsorption of Au(III) on Im-ASH and non-Im-ASH was obtained at pH of 3.0. Im-ASH was twice as selective toward Au(III) ion than ASH was.

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Nanofiber has become one of tissue engineering examples and has extensive application on medical field, particularly as a wound healing and wound dressing. In this research, nanofiber composite based on polycaprolactone and collagen was successfully obtained via electrospinning process and further developed as host of naproxen as anti-inflammatory agents. Addition of copper ferrite (CuFe 2 O 4 ) nanoparticles on the nanocomposite becomes an advance part on this study to control of naproxen release. Several characterizations were furnished to prove the design composite nanofiber and its drug release analysis performed to find out the kinetic model and naproxen release mechanism from nanofibers. CuFe 2 O 4 nanoparticles have potential to be used to control naproxen release in nanofiber that lead to decrease level of drug released, where mostly follow the Korsmeyer-Peppas model. The release of naproxen was certainly influenced by pH value, in which the drug was easier to release on base, instead of acid or neutral condition. Varied naproxen and nanoparticle compositions were prepared to reach optimum formulation of the release. This study provides fundamental data for the effect of magnetic nanoparticle on drug release process.

Adsorption of Au(III) in multi-metal systems Au/Cu/Ni on mercapto modified silica coated on magnetite (Fe 3 O 4 /SiO 2 -SH) has been studied. Fe 3 O 4 /SiO 2 -SH was synthesized via sol-gel process by using magnetite obtained through co-precipitation of Fe 2+ /Fe 3+ salt mixture with NH 4 OH as the precipitating solution, sodium silicate solution extracted from rice hull ash and 3-mercaptopropyltrimethoxysilane (MPTMS) as the mercapto group source. Fe 3 O 4 /SiO 2 -SH was characterized with Fourier transform infrared (FTIR) spectrophotometer, X-ray diffraction (XRD) and ion chromatography for sulfur analysis. Optimization of Au(III) adsorption in a batch system was carried out as function of pH, contact time and ion concentration. Adsorption kinetics was evaluated with pseudo-first order and pseudo-second order models based on the data of contact time variation, while the adsorption isotherm was studied based on Langmuir and Freundlich models. The adsorbed metal ions Au(III), Cu(II) and Ni(II) quantitatively were calculated based on the difference of metal concentrations before and after adsorption analyzed with flame atomic absorbance spectrophotometer (FAAS). Results of characterization showed that Fe 3 O 4 /SiO 2 -SH has been successfully synthesized. Adsorption of Au(III) on Fe 3 O 4 /SiO 2 -SH slightly decreased with increasing the pH in a range of 2.0-6.0 and fits to pseudo-second order model with the rate constant of 1.37x10 -3 g mg -1 min -1 . Fe 3 O 4 /SiO 2 -SH shows a linear plot of Langmuir isotherm model with adsorption the capacity for Au(III) of 125 mg/g. Adsorption on multimetal systems shows that capacity of Au(III) on Fe 3 O 4 /SiO 2 -SH is higher than that of Cu(II) and Ni(II), and high selectivity for Au(III) toward Cu(II) and Ni(II) ions.

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