Gd2O3 Nanoparticles Research Articles

Warm white broadband emission and tunable long lifetimes in Yb3+ doped Gd2O3 nanoparticles

Upconversion luminescence materials have stimulated growing attention in photovoltaic cell owning to the ability of converting a few low-energy photons into a single high-energy photon. However, there still remains a daunting challenge to achieve upconversion emission covering the entire visible spectrum in a single material. Here, an incandescent broadband white upconversion emission covering the entire visible region is realized in a single Gd2O3:Yb3+ nanoparticles by utilization of adverse multiphonon relaxation. Importantly, tunable long fluorescence lifetime can be synchronously implemented in the single material, where the lifetime range spans one order of magnitude. Furthermore, benefiting from the broadband emission, the luminescence intensity achieves 482-fold improvement as the power increase from 0.53 W to 1.51 W. These broadband emissions are enabled by engineering the pathways of nonradiative de-excitation via multiphonon relaxation. Based on the kinetic analysis and mechanism research, the photon avalanche is demonstrated to play an important role for broadband emission. The warm white emission together with its tunable long lifetime provides a new avenue for developing single emitter-based white-light-emission materials for next-generation display and lighting technologies.

Negative effects of rare earth oxide nanoparticles of La2O3, Nd2O3, and Gd2O3 on the ammonia-oxidizing microorganisms

Nanoparticles released into soil environment potentially impact microorganisms, which furtherly disturb terrestrial biogeochemical cycles. However, how rare earth oxide nanoparticles affect the functional microorganisms inhabited in natural soil is still unknown. This study was aimed to investigate the effect of different types of rare earth oxide nanoparticles on the ammonia-oxidizing microorganisms. Soil respectively added with 0, 10, 50, and 100 mg kg−1 of La2O3, Nd2O3, or Gd2O3 nanoparticle were incubated at 25 °C in the dark for 60 days. The potential ammonia oxidation (PAO), abundance and communities of ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB) were measured at the 1st, 7th, and 60th day. Our results showed that the PAO in soils with nanoparticles significantly decreased due to nanoparticle toxicity at the 1st day, but it gradually increased to the control level owing to the adaptation of AOA and AOB in soils with nano-Nd2O3 and nano-Gd2O3. Interestingly, the abundance of AOB as reflected by the qPCR analysis was upregulated for the hormesis effect of AOB responding to nano-Nd2O3 or nano-Gd2O3 with 50 mg kg−1 level. Moreover, terminal restriction fragment length polymorphism (T-RFLP) results suggested that the communities for AOA and AOB shifted with nanoparticles type and incubation time. Rare earth oxide nanoparticles could inhibit activities of ammonia-oxidizing microorganisms, and thus they might be used as potential nitrification inhibitors to improve nitrogen use efficiency in the agricultural ecosystems.

Nanocargo-Delivery Platform for Targeted Drug Delivery in Biomedical Applications: Magnetic Gd2O3 Nanoparticles in Porous SiO2

Nanocargo-Delivery Platform for Targeted Drug Delivery in Biomedical Applications: Magnetic Gd₂O₃ Nanoparticles in Porous SiO₂

PREPARATION of Gd2O3 NANOMATERIALS via SOLUTION COMBUSTION SYNTHESIS FOR OXIDATIVE COUPLING OF METHANE

In this study, in the production of Gd2O3 material which has many usage areas, solution combustion synthesis was used and the changes in the physical and structural properties of the material were investigated by changing the oxidant/fuel ratio. The resulting metal oxide powders were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, Thermogravimetric-Differential thermal analysis (TG-DTA) and scanning electron microscopy (SEM) analysis and tested in oxidative coupling of methane. Cubic and monoclinic phases were observed in Gd2O3 crystal structure at fuel-rich and stoichiometric conditions, and only cubic phase was determined at fuel-lean conditions. It was determined that the obtained powders were mesoporous and the highest BET surface area was obtained at stoichiometric oxidant/fuel ratio (18.6 m2/g). It was determined that the powders were formed from rather small particles (<30 nm) and with layered or stacked structure. The catalytic performance of Gd2O3 nanoparticles was found to be dependent on the BET surface area and crystal structure. The highest C2 yield was obtained at 720°C with Gd2O3-0.5 (8.5%).

Gd2O3, SiO2-Gd2O3 and SiO2-MnO2 nanoparticles as potential MRI contrast agents

Gd2O3, SiO2-Gd2O3 and SiO2-MnO2 nanoparticles were produced by the method of pulsed electron evaporation of oxide targets with condensation of the vapors in a vacuum. These materials are considered as probable contrast agents for magnetic resonance imaging (MRI). The Gd2O3 nanoparticles exhibit a rather high r1 and r2 relaxivities. These results point to the potential of using nanocrystals for MRI diagnosis. The mesoporous nanostructures SiO2-Gd2O3 and SiO2-MnO2 could be considered as multimodal theranostic agents.

Enhanced luminescence and paramagnetic properties of Gd2O3:Tb3+ multifunctional nanoparticles by K+/Co2+ doping

Multifunctional Gd2O3:Tb3+ nanoparticles doped with different concentrations of K+/Co2+ were synthesized by polyol method. The samples were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscope (SEM), X-ray energy spectrometer (EDS), Malvern laser particle size analyzer, transmission electron microscope (TEM), photoluminescence spectrometer (PL), vibrating sample magnetometer (VSM) and magnetic resonance imager (MRI). The results showed that the synthesized spherical particles were cubic crystals with a diameter of 12–15 nm. Significant increase in fluorescence intensity was observed for Gd2O3:Tb3+ doped with K+/Co2+ ions. The optimal doped ion concentrations were found to be 3 mol% K+ ions and 4 mol% Co2+ ions, and the corresponding absolute quantum yields (QYs) were 7.21% and 5.90%. The maximum magnetization was obtained for the sample doped with 3 mol% K+/Co2+ ions. The ion-doped samples showed enhanced r1 relaxivity of water protons. Therefore, the multifunctional nanoparticles Gd2O3:Tb3+ doped with K+/Co2+ ions can potentially be used in displays, luminescence and MR bimodal imaging, sensors, magnetic separat, and other applications.

Conduction and relaxation mechanisms in gadolinium oxide nanoparticle doped polyvinyl alcohol films

Concentration dependent dielectric and electrical properties of PVA-Gd2O3 nanocomposite films over a wide range of frequencies (100Hz-1 MHz) and temperatures (303 K–423 K) is reported here. TEM of the Gd2O3 nanoparticles showed that they could be indexed to the cubic phase. The frequency variation of the dielectric permittivity and dielectric loss could be explained by the Maxwell Wagner Sillar’s model. The dielectric permittivity decreased in the composite films contrary to observations in other similar systems. The complex impedance showed Arrhenius behavior and the activation energies decreased monotonically with increasing concentration. However the resistivity of the nanocomposite films shows an increase with concentration, the 4 wt% film showing the highest resistivity which indicates other contributions to conductivity. The Nyquist plot could be fitted to a simple parallel RC circuit showing the presence of long range conduction in these samples. The relaxation times varied from 10−4 to 10−6s and indicated a non-Debye type of relaxation. The master curve showed good overlap indicating that the same relaxation processes were active at all temperatures. The ac conductivity obeys Jonscher’s law and the exponent shows a monotonic decrease with temperature. This indicates that Correlated Barrier Hopping is the probable mechanism for conduction in these samples.

Evaluation of in vivo immunotoxicity for Ho3+-doped Gd2O3 nanoparticles as dual-modality nanoprobes

Rare-earth-doped gadolinium-oxide (Gd2O3) nanoparticles (NPs) are increasingly used for magnetic resonance imaging (MRI) and optical imaging (OI). However, to date, the poor data of in vivo hazard assessment has been one obstacle to its clinical deployment, especially the relative immunotoxicity in vivo. In this paper, we synthesized Ho3+-doped Gd2O3 NPs (HoNPs) for MRI and OI by laser ablation in liquid. To the best of our knowledge, we present here the most extensive biocompatibility in vitro (cell viability and apoptosis) and in vivo relative immunotoxicity (the level of cluster-of-differentiation (CD) markers in peripheral blood and relative gene expression of toxicity in the liver) in Balb/c mice. Our results indicate that HoNPs with satisfactory biocompatibility can be used as MRI (r1 relaxivity of 5.01 mM-1 s-1) and OI (strong blue fluorescence) dual-modal contrast agents in vitro. Importantly, there were significant differences in the expression levels of CD25, CD69, CD71, protein 38 (P38), extracellular regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), and protein 53 (P53) between the negative control and the HoNPs at 7 d after injection (p < 0.05). In conclusion, this work suggests that the nano-structure of HoNPs may reduce in vivo relative immunotoxicity. Therefore, it will be crucial to evaluate the above- mentioned indexes on in vivo relative immunotoxicity at 7 d after injection of these rare-earth-based biomaterials before molecular imaging in vivo.

Upconversion luminescence of Er&lt;SUP align="right"&gt;3+&lt;/SUP&gt; doped Y&lt;SUB align="right"&gt;2O&lt;SUB align="right"&gt;3 and Gd&lt;SUB align="right"&gt;2O&lt;SUB align="right"&gt;3 nanophosphors

The luminescence process and mechanism of Er3+ doped Y2O3 and Gd2O3 nanophosphors are investigated with focus on their upconversion luminescence properties. Here the strong up-conversion (UC) emissions of both Y2O3:Er3+ nanoparticles prepared by combustion with EDTA and Gd2O3:Er3+ nanospheres synthesised by multistep chemical reaction using urea have been measured at room or low temperatures. The downward-conversion luminescence spectra in visible and near infrared region have been assigned from the transitions in the energy level system of Er3+ion. For Y2O3:Er3+nanoparticles, the upconversion luminescent intensity depends on excitation power at 980 nm have properly indicated the two photon process which are the calculated slope values of main transitions in Er3+ions: 2H11/2-4I15/2, 4S3/2-4I15/2and 4F9/2-4I15/2 are 2.07, 1.72, 1.87 (0.5% Er) and 2.32, 1.82 and 2.07 (Er 1.0%) respectively. The integral intensity of the red band is smaller than that of the green band in the upconversion emission of nanoparticles Y2O3 doped with Er3+ with 0.50, 1.00 and 1.50%. However it was the integral intensity of red emission bands that dominated in Gd2O3: 1% Er3+. The lifetimes of the band in green colour peaked at 562 nm upon excitation at 380 nm in Y2O3:Er3+ with 0.50, 1.00 and 1.50%, and have shown the two sequent time decay processes, the shorter and the longer, both in millisecond scale, 0.14 ms (0.5%); 0.28 ms (1.00%) and 0.13 ms (1.50%) and 4.49 ms (0.5%); 6.89 ms (1.00%) and 5.16 ms (1.50%), respectively. For the nanoparticles Gd2O3: 1% Er the intensity decrease of the upconversion emission peaked at 562 nm with only a single process with a decay time of 1.24 ms. Both nanophosphors Y2O3 and Gd2O3 doped with Er3+ are promising materials to develop multifunctional units for medical applications.

Assessment of Gd2O3 nanoparticles as exogenous imaging contrast agent for swept source optical coherence tomography

Optical coherence tomography (OCT) is a non-invasive and non-contact imaging technique that uses the reflection of light waves for tissue imaging. Compared to all other OCT variants, the swept-source OCT (SS-OCT) configuration offers higher imaging speed, better signal-to-noise ratio, and more resolution. Despite its numerous advantages, SS-OCT greatly suffers from limited contrast and reduced penetration ability. Over the years, several nanoparticles (NPs) like AgNP, TiO2, ZnO, etc have been exploited extensively as exogenous contrast agents to enhance the image contrast. Subsequently, herein, we have presented gadolinium oxide (Gd2O3) as a potential exogenous contrast agent for 3D non-invasive depth-resolved imaging of animal (chicken breast) tissue using an in-house developed SS-OCT system with centre wavelength of 1060 nm. In this work, OCT imaging of agar filled capillary tubes (phantoms) and chicken breast tissue (in vitro) was performed both with and without the application of Gd2O3 NPs. Scattering coefficient and contrast-to-noise ratio (CNR) calculations were done to study the effect of Gd2O3 NPs on the tissue sample at different time exposures. Post analysing the OCT images, a significant increase, in contrast, observed with time, where both the scattering coefficient (0.4879 mm−1 to 1.3782 mm−1) and the CNR of OCT B-scans (12.42 dB to 42.21 dB) increased substantially.

Bimetal oxide decorated graphene oxide (Gd2O3/Bi2O3@GO) nanocomposite as an excellent adsorbent in the removal of methyl orange dye

Methyl orange (MO) dye, with frequent usage in several industries, is a threat to the environment owing to its toxic nature. Wastewater from several industries must be treated before release to the environment. Here, we have synthesized Gd2O3/Bi2O3@GO nanocomposite through the one-pot hydrothermal method as an adsorbent for removal of methyl orange dye and then the result was compared with Bi2O3@GO and Gd2O3@GO nanocomposites. From X-Ray diffraction (XRD) study hexagonal Bi2O3 nanoparticle and cubic Gd2O3 nanoparticles were found on the GO sheets and the functional groups in the nanocomposite were also confirmed from the Fourier transform infrared (FT-IR) spectroscopy technique. Morphologically, flakes type Bi2O3 nanoparticle and granular Gd2O3 nanoparticle were observed on GO sheets, which were further analyzed through transmission electron microscopy (TEM) technique. At an optimized contact time (45 min), amount (5.0 mg), pH (6) and temperature (35 °C), the adsorption study was performed. The adsorption capacity of the Bi2O3@GO, Gd2O3@GO and Gd2O3/Bi2O3@GO nanocomposite were measured to be 308 mg g−1 and 392 mg g−1 and 544 mg g−1, respectively. The removal efficiency of Bi2O3@GO, Gd2O3@GO and Gd2O3/Bi2O3@GO nanocomposite were recorded to be 72%, 82.3%, and 95%, respectively. The adsorption experiment with Gd2O3/Bi2O3@GO nanocomposite follows the Langmuir adsorption isotherms and pseudo-second-order kinetic model.

Biogenic synthesis of nanostructured Gd2O3: Structural, optical and bioactive properties

Nanostructured Gd2O3 has been synthesized using the leaf broth of Annona reticulate. The formation of nanoparticles is confirmed by XRD and TEM analysis. UV–visible and PL studies are employed to characterize the optical nature of the samples and the thermal analysis of the as prepared material has been performed to ascertain the proper annealing temperature. XRD pattern shows cubic structure with average particle size of about 25 nm. FTIR spectra reveal the possible biomolecules responsible for the formation of nanoparticles and their stabilization. Raman spectrum with characteristic band located at 360 cm−1 for the Fg mode supports the cubic phase of the nanostructured Gd2O3. Biocompatibility of synthesized nanoparticles is evaluated by carrying out the cytotoxic test against normal fibroblast cell lines and surviving fraction of normal cell lines are found to be above 75% up to a concentration of 50μg/mL. The antimicrobial activity of developed nanoparticles are screened against K. Pneumonae and S.aureus bacterial cell lines and substantial inhibition zones are observed in the dose dependent study. Moreover, this study also investigates the antioxidant efficacy of Gd2O3 nanoparticles using DPPH and superoxide free radical scavenging assays. With a concentration of 20μg/mL of the synthesized nanoparticles 70% scavenging is observed. The method of synthesis is simple, cost-effective and unexplored as it follows an ecofriendly protocol for the production of biologically active nanostructured Gd2O3.

Synthesis, characterization, and X-ray attenuation properties of polyacrylic acid-coated ultrasmall heavy metal oxide (Bi2O3, Yb2O3, NaTaO3, Dy2O3, and Gd2O3) nanoparticles as potential CT contrast agents

Ultrasmall heavy metal oxide nanoparticles are potential candidate materials for X-ray computed tomography (CT) contrast agents because they possess high X-ray attenuation powers owing to high X-ray attenuation coefficients of heavy metal atoms and high density of heavy metal atoms per nanoparticle. In this study, five kinds of polyacrylic acid (PAA)-coated ultrasmall heavy metal oxide (Bi2O3, Yb2O3, NaTaO3, Dy2O3, and Gd2O3) nanoparticles were synthesized and their X-ray attenuation properties were investigated. The estimated average particle diameters were 2.3 ± 0.1, 1.7 ± 0.1, 1.5 ± 0.1, 1.8 ± 0.1, and 1.9 ± 0.1 nm for PAA-coated ultrasmall Bi2O3, Yb2O3, NaTaO3, Dy2O3, and Gd2O3 nanoparticles, respectively. All of the nanoparticle suspension samples exhibited a high colloidal stability, a high biocompatibility, and X-ray attenuation powers which were stronger than that of a commercial iodine contrast agent Ultravist® at the same atomic concentration and much stronger, at the same number density. The effectiveness of the nanoparticle suspension samples as CT contrast agents was demonstrated by acquiring in vivo CT images by using one of the samples (i.e., PAA-coated ultrasmall Bi2O3 nanoparticles). After intravenous injection into the mouse tail vein, positive contrast enhancements in various organs were observed.

Enhanced Photocatalytic Activity of Directly Assembled Fe₂O₃/Gd₂O₃@TiO₂-Based Nanosheets.

TiO₂-based nanosheets (TNSs) modified with surface-enriched Fe₂O₃ and Gd₂O₃ nanoparticles (NPs) have been synthesized via a direct interfacial assembly strategy. The TNSs with a unique two-dimensional structure are favorable for supporting Fe₂O₃ and Gd₂O₃ NPs for photocatalytic applications. The prepared samples were characterized using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), BET, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectra (DRS), photoluminescence (PL) spectroscopy and the surface photocurrent (SPC) technique. The photocatalysts exhibited large specific surface area (160-260 m²/g). The co-modification with Fe₂O₃ and Gd₂O₃ NPs influenced the crystallinity and surface area of the TNSs, and improved visible-light absorption. Surface photocurrent and PL studies revealed that the photogenerated charge carrier separation efficiency could be improved by an appropriate amount of NPs. The optimized nanostructure exhibited photocatalytic efficiency for rhodamine B (RhB) degradation and H₂ production is 5.66-fold and 2.99-fold respectively than those of TNSs under visible-light irradiation. The enhancement is attributed to the combined effect of Gd₂O₃ and Fe₂O₃ NPs in the Fe₂O₃/Gd₂O₃@TNSs composites. The simultaneous use of two different types of NPs led to a fast separation and slow recombination of photoinduced electron-hole pairs. A mechanism is proposed to explain the enhanced visible-light photocatalytic activity.

Ultrafast degradation of common organic dyes in presence of gadolinium oxide/graphene oxide in water

Gadolinium oxide/graphene oxide (Gd2O3/GO) nanocomposite has been prepared by a simple method in N,N-dimethylformamide (DMF) and employed as an excellent catalyst for common organic dyes degradation under ultrasound. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) data revealed that the Gd2O3 nanoparticles were successfully attached on the surface of GO sheets. The High efficiencies of common dyes (methylene blue, methyl orange, methyl violet rhodamine B, fuchsin base, thymolphthalein, crystal violet and eosin) degradation within 15 min illustrated that the as-synthesized nanocomposite was an ultrafast, stable, recyclable, and economical material for environment related applications.

Temperature dependent upconversion properties of Yb3+:Ho3+ co-doped Gd2O3 nanoparticles prepared by pulsed laser ablation in water

Yb 3+ :Ho 3+ co-doped Gd 2 O 3 nanoparticles were successfully synthesized by pulsed laser ablation in water under different laser energy. The phase structure, morphology, crystallization and upconversion photoluminescence properties of obtained samples were investigated using X-Ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and photoluminescence spectra. The mechanism of the upconversion process was discussed based on the energy level diagram and power dependent upconversion emission. Upconversion mechanisms and thermal effects caused by absorption of excitation laser were discussed. Temperature dependent green and red emissions of Yb 3+ :Ho 3+ co-doped Gd 2 O 3 nanoparticles under the excitation of 980 nm were investigated in the low temperature range of 130 K–280 K. Non-radiative decay rate theory was used to explain the difference of quenching rates of green and red emissions. A further study on temperature sensing properties based on fluorescence intensity ratio ( FIR ) of green and red emissions was carried out. The FIR as a function of temperature can be well fitted by the model based on the thermal quenching theory. The relative sensitivity reaches its maximum value of 0.804% K −1 at 216 K.

Preparation and investigation of suitability of gadolinium oxide nanoparticle doped polyvinyl alcohol films for optoelectronic applications

Gd2O3 nanoparticles synthesized by solution combustion method were used to prepare PVA-Gd2O3 nanocomposite films of varying concentrations (2 wt%–6 wt% of filler) by solution casting method. Being a rare earth oxide, gadolinium oxide was expected to exhibit good photoluminescence and the nanocomposite was expected to be flexible as well. The Gd2O3 nanoparticles prepared were found to be in cubic phase with an average size of 19 nm. Raman spectra showed the incorporation of Gd2O3 into the polymer matrix. Scanning electron microscope images revealed that the particles were porous in nature, agglomerated and distributed evenly on the surface of the film in the form of clusters. The UV–Visible absorption spectra gave direct optical energy band gap value in the range 5.78–4.86 eV. Both band gap as well as the Urbach energy are seen to decrease with increasing concentration of the dopant. Four prominent photoluminescence peaks were observed in all the three composite films in the UV region (318 nm), deep blue region (396 nm), blue region (477 nm) and green region (553 nm). The color purity of the films using CIE coordinates was found to be the highest, 82.81%, in the 2 wt% film making this film a promising material for blue OLED’s and blue flexible screens.

An experimental study about the application of Gadolinium oxide nanoparticles in magnetic theranostics

In this paper, based on comparing magnetisms, relaxation time, magnetic resonance images (MRI) and the magnetic hyperthermia, the ability of Gadolinium oxide (Gd2O3) nanoparticles for theranostics purposes was investigated. For this, Gd2O3 nanoparticles in 10 and 5 nm sizes were synthesized using DEG and PVP stabilizers, respectively. According to VSM results, these nanoparticles are superparamagnetic and had one hundred times smaller relaxation time in comparison with commercial Gadolinium chelates. In RPMI 1640, compared to Dotarem and Gadovist as two clinical Gadolinium chalets, T1-weighted images proved the superiority of Gd2O3 nanoparticles in contrast production at concentrations ranging from 0.025 to 0.1 mM. In addition, induction of a 200 kHz alternating magnetic field for 240 s was led to a temperature growth ∼12 °C and 14 °C for 10 and 5 nm nanoparticles, respectively. These outstanding magnetic properties of Gd2O3 nanoparticles are likely attributed to their size and these nanoparticles therefore are proposed as novel theranostices agents for more researches about magnetic theranostics.

1H NMR Relaxometric Analysis of Paramagnetic Gd2O3:Yb Nanoparticles Functionalized with Citrate Groups

Gd2O3 nanoparticles doped with different amount of Yb3+ ions and coated with citrate molecules were prepared by a cheap and fast co-precipitation procedure and proposed as potential “positive” contrast agents in magnetic resonance imaging. The citrate was used to improve the aqueous suspension, limiting particles precipitation. The relaxometric properties of the samples were studied in aqueous solution as a function of the magnetic field strength in order to evaluate the interaction of the paramagnetic ions exposed on the surface with the water molecules in proximity. The nanoparticles showed high relaxivity values at a high magnetic field with respect to the clinically used Gd3+-chelates and comparable to those of similar nanosytems. Special attention was also addressed to the investigation of the chemical stability of the nanoparticles in biological fluid (reconstructed human serum) and in the presence of a chelating agent.

Microwave-assisted combustion synthesis of silica-coated Eu:Gd2O3 nanoparticles for MRI and optical imaging of cancer cells

Development of contrast agent for imaging modalities is very much essential to identify the cancer cells at an early stage. Due to the advances in the field of nanotechnology, nanoparticle-based contrast agents are being developed with better imaging capabilities at minimum concentrations. When the paramagnetic gadolinium oxide (Gd2O3) nanoparticles are doped with the luminescent europium (Eu3+) ions, it results in superior magneto-optical properties. This property makes the nanoparticles suitable for MRI and optical dual modal cancer imaging. In this article, europium doped Gd2O3 (Eu:Gd2O3) nanoparticles were synthesized by microwave-assisted combustion method. Citric acid (C6H8O7) which is a biocompatible and less reactive fuel was used to prepare the Eu:Gd2O3 nanoparticles for the first time. Silica was coated over the Eu:Gd2O3 nanoparticles for improving the biocompatibility. X-ray diffraction studies reveal that after coating, the crystallinity was found to decrease. The synthesized nanoparticles have spherical morphology with the average diameter of 10 nm. The presence of silica was observed in the Fourier transform infrared (FTIR) spectrum and transmission electron microscopy images. In the photoluminescence studies, the emission peak at 612 nm confirms the presence of Eu3+ ions. Decay times of the uncoated and silica-coated samples were calculated to be 1.1 and 0.9 ms respectively. The in vitro cytotoxicity analysis suggests that the silica-coated nanoparticles are slightly toxic up to the concentration of 200 µg/mL. The magnetic measurement confirms the paramagnetic behaviour of the synthesized nanoparticles. The nanoparticles shows bright contrast images with the relaxivity value of 5.01/(mM)/s, suggest that the silica-coated nanoparticles have potential applications in MRI.