Praseodymium ion, Pr3+ doped Gd2
O2
S nanophosphors were successfully synthesized via gamma irradiation route
along with the heat treatment. The effect of the gamma irradiation (0-150 kGy) on the structural, morphology and
photoluminescence properties of Gd2
O2
S:Pr3+ were characterized via X-ray diffraction (XRD), field emission scanning
electron microscope (FESEM) and photoluminescence spectroscopy (PL). The thermal properties of precursor sample
were tested by the thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The chemical bonding of
the precursor samples were analyzed by Fourier transform infrared spectroscopy (FT-IR). The XRD result confirmed the
formation of hexagonal phase of Gd2
O2
S:Pr3+ without the presence of any impurities. The FESEM inspection showed the
non-symmetrical shape of particles transformed into grain-like shape. The optimum photoluminescence (PL) emission
intensities of Gd2-xO2
S:xPr3+ occur at 50 kGy dose of gamma irradiation and 2 mol% concentration dopant of Pr3+ ions.
The spectra under 325 nm UV excitation shows a strong green emission at 515 nm, which match the 3
P0 → 3
H4
transition
of Pr3+ ions. The Gd2
O2
S:Pr3+ nanophosphors possessed many useful approaches in various applications mainly as
radiation detection and biomedical diagnostic.
Unilamellar liposomes composed of dipalmitoylphosphatidylcholine (DPPC) were prepared by the reverse-phase
evaporation method and extrusion through a polycarbonate membrane filter. Liposomes at 0.7 mg/mL lipid concentration
in deionized water were exposed to gamma irradiation at a dose in the range 0.5 to 25 kGy. Gamma irradiation of
liposomes resulted in the degradation of DPPC lipids into free fatty acids, lysophosphatidylcholine and 1,2-palmitoylphosphatidic
acid (DPPA). The effect of gamma irradiation towards the physical stability of liposomes was investigated
by means of dynamic light scattering (DLS), transmission electron microscopy (TEM) and zeta potential analysis. From
the DLS analysis, no significant changes were observed in the hydrodynamic size of liposomes. TEM images indicate that
the liposomes surface became smoother and rounder as higher irradiation doses were applied. Zeta potential analysis
showed that gamma irradiation of DPPC liposomes at radiation doses as low as 0.5 kGy resulted in a drastic rise in the
magnitude of the zeta potential. The results also demonstrate that gamma irradiation of liposomes suspension enhanced
the overall stability of liposomes. Hence, it can be concluded that gamma irradiation on DPPC liposomes may potentially
produce liposomes with higher stability.