Gadolinium Nanoparticles Research Articles

High-sensitivity and spatial resolution benchtop cone beam XFCT imaging system with pixelated photon counting detectors using enhanced multipixel events correction method.

High atomic number element nanoparticles have shown potential in tumor diagnosis and therapy. X-ray fluorescence computed tomography (XFCT) technology enables quantitative imaging of high atomic number elements by specifically detecting characteristic X-ray signals. The potential for further biomedical applications of XFCT depends on balancing sensitivity, spatial resolution, and imaging speed in existing XFCT imaging systems. In this study, we utilized a high-energy resolution pixelated photon-counting detector for XFCT imaging. We tackled degradation caused by multi-pixel events in the photon-counting detector through energy and interaction position corrections. Sensitivity and spatial resolution imaging experiments were conducted using PMMA phantoms to validate the effectiveness of the multi-pixel events correction algorithm. After correction, the system's sensitivity and spatial resolution have both improved. Furthermore, XFCT/CBCT dual-modality imaging of gadolinium nanoparticles within mice subcutaneous tumor was successfully achieved. These results demonstrate the preclinical research application potential of the XFCT/CBCT dual-modality imaging system in high atomic number nanoparticle-based tumor diagnosis and therapy.

The effect of gadolinium and lanthanum orthovanadate nanoparticles on the content of vitamins (B2, A, E) and trace elements (Cu, Zn, Se) in the blood serum and liver of broiler chickens

As a result of scientific progress, substances in the nanoscale state are increasingly being introduced into various areas of human activity, including animal husbandry (poultry farming). In particular, nanotechnology is used successfully to enrich food products with minerals, vitamins, antioxidants, that is, they can increase the bioavailability of nutrients by oral administration. In this study, the content of vitamins (A, E, and B2 ) and trace elements (Zn, Cu, and Se) in the blood serum and liver of broiler chickens under the influence of gadolinium orthovanadate, lanthanum orthovanadate, and a mixture of all these was investigated. It was established that their administration to broiler chickens for 10 days at a dose of 0.2 mg/l of drinking water (an average of 0.09 mg/kg body weight) increases the bioavailability of vitamins B2 , A, and E and the trace elements selenium, copper and zinc, which was manifested by an increase in their concentrations in the blood serum compared to the control group (from 8.6% to 3.0 times for vitamins, and from 17.8% to 2.5 times for trace elements, P<0.05) and liver deposition (from 9.4% to 4.6 times for vitamins and from 6.3 to 56.3% for trace elements, P<0.05), with a prolonged effect after administration was stopped. The introduction of nanoparticles (both in mono-solutions and in a mixture), along with a vitamin preparation, indicates the possibility of increasing the content of vitamins and trace elements without their additional introduction, using the dietary resource more fully.

Protease-Mediated T1 Contrast Enhancement of Multilayered Magneto-Gadolinium Nanostructures for Imaging and Magnetic Hyperthermia.

In this work, we constructed a multifunctional composite nanostructure for combined magnetic hyperthermia therapy and magnetic resonance imaging based on T1 and T2 signals. First, iron oxide nanocubes with a benchmark heating efficiency for magnetic hyperthermia were assembled within an amphiphilic polymer to form magnetic nanobeads. Next, poly(acrylic acid)-coated inorganic sodium gadolinium fluoride nanoparticles were electrostatically loaded onto the magnetic nanobead surface via a layer-by-layer approach by employing a positively charged enzymatic-cleavable biopolymer. The positive-negative multilayering process was validated through the changes occurring in surface ζ-potential values and structural characterization by transmission electron microscopy (TEM) imaging. These nanostructures exhibit an efficient heating profile, in terms of the specific absorption rates under clinically accepted magnetic field conditions. The addition of protease enzyme mediates the degradation of the surface layers of the nanostructures with the detachment of gadolinium nanoparticles from the magnetic beads and exposure to the aqueous environment. Such a process is associated with changes in the T1 relaxation time and contrast and a parallel decrease in the T2 signal. These structures are also nontoxic when tested on glioblastoma tumor cells up to a maximum gadolinium dose of 125 μg mL-1, which also corresponds to a iron dose of 52 μg mL-1. Nontoxic nanostructures with such enzyme-triggered release mechanisms and T1 signal enhancement are desirable for tracking tumor microenvironment release with remote T1-guidance and magnetic hyperthermia therapy actuation to be done at the diseased site upon verification of magnetic resonance imaging (MRI)-guided release.

H-ferritin-nanocaged gadolinium nanoparticles for ultra-sensitive MR molecular imaging.

Rationale: Magnetic resonance imaging (MRI) is a powerful diagnostic technology by providing high-resolution imaging. Although MRI is sufficiently valued in its resolving morphology, it has poor sensitivity for tracking biomarkers. Therefore, contrast agents are often used to improve MRI diagnostic sensitivity. However, the clinically used Gd chelates are limited in improving MRI sensitivity owing to their low relaxivity. The objective of this study is to develop a novel contrast agent to achieve a highly sensitive tracking of biomarkers in vivo. Methods: A Gd-based nanoprobe composed of a gadolinium nanoparticle encapsulated within a human H-ferritin nanocage (Gd-HFn) has been developed. The specificity and sensitivity of Gd-HFn were evaluated in vivo in tumor-bearing mice and apolipoprotein E-deficient mice (Apoe-/-) by MRI. Results: The Gd-HFn probe shows extremely high relaxivity values (r1 = 549 s-1mM-1, r2 = 1555 s-1mM-1 under a 1.5-T magnetic field; and r1 = 428 s-1mM-1 and r2 = 1286 s-1mM-1 under a 3.0-T magnetic field), which is 175-fold higher than that of the clinically standard Dotarem (Gd-DOTA, r1 =3.13 s-1mM-1) under a 1.5-T magnetic field, and 150-fold higher under a 3.0-T magnetic field. Owing to the substantially enhanced relaxivity values, Gd-HFn achieved a highly sensitive tracking for the tumor targeting receptor of TfR1 and enabled the in vivo MRI visualization of tumors approaching the angiogenic switch. Conclusions: The developed Gd-HFn contrast agent makes MRI a more powerful tool by simultaneously providing functional and morphological imaging information, which paves the way for a new perspective in molecular imaging.

Caspase-3-Triggered Intracellular Gadolinium Nanoparticle Formation for T1-Weighted Magnetic Resonance Imaging of Apoptosis In Vivo.

Apoptosis, with a hallmark of upregulated protease Caspase-3, has been frequently imaged with various probes to reveal the therapeutic efficiencies of different drugs. However, activatable molecular probes with programmable self-assembling behaviors that enable enhanced T1-weighted magnetic resonance imaging (MRI) of apoptosis remain scarce. Herein, taking advantage of a CBT-Cys click reaction, we rationally designed a Caspase-3-activatable self-assembling probe Ac-Asp-Glu-Val-Asp-Cys(StBu)-Lys(DOTA(Gd))-CBT (DEVDCS-Gd-CBT) for apoptosis imaging in vivo. After Caspase-3 cleavage in apoptotic cells, DEVDCS-Gd-CBT underwent CBT-Cys click reaction to form a cyclic dimer, which self-assembled into Gd nanoparticles. With this probe, enhanced T1-weighted MR images of apoptosis were achieved at low magnetic fields in vitro, in cis-dichlorodiamineplatinum-induced apoptotic cells and in tail-amputation-simulated apoptotic zebrafish. We anticipate that the smart probe DEVDCS-Gd-CBT could be applied for T1-weighted MRI of apoptosis-related diseases in the clinic in the future.

Synthesis, radiolabeling, and investigation of bombesin-modified gadolinium nanoparticles as a potential SPECT/MRI agent for prostate cancer

Synthesis, radiolabeling, and investigation of bombesin-modified gadolinium nanoparticles as a potential SPECT/MRI agent for prostate cancer

Consolidation of Gold and Gadolinium Nanoparticles: An Extra Step towards Improving Cancer Imaging and Therapy

The multifactorial nature of cancer still classifies the disease as one of the leading causes of death worldwide. Modern medical sciences are following an interdisciplinary approach that has been fueled by the nanoscale revolution of the past years. The exploitation of high-Z materials, in combination with ionizing or non-ionizing radiation, promises to overcome restrictions in medical imaging and to augment the efficacy of current therapeutic modalities. Gold nanoparticles (AuNPs) have proven their value among the scientific community in various therapeutic and diagnostic techniques. However, the high level of multiparametric demands of AuNP experiments in combination with their biocompatibility and cytotoxicity levels remain crucial issues. Gadolinium NPs (GdNPs), have presented high biocompatibility, low cytotoxicity, and excellent hemocompatibility, and have been utilized in MRI-guided radiotherapy, photodynamic and photothermal therapy, etc. Τhe utilization of gadolinium bound to AuNPs may be a promising alternative that would reduce phenomena, such as toxicity, aggregation, etc., and could create a multimodal in vivo contrast and therapeutic agent. This review highlights multi-functionalization strategies against cancer where gold and gadolinium NPs are implicated. Their experimental applications and limitations of the past 5 years will be analyzed in the hope of enlightening the benefits and drawbacks of their proper combination.

Intracellular Construction of Cathepsin B-Guided Gadolinium Nanoparticles for Enhanced T2 -Weighted MR Tumor Imaging.

Magnetic resonance imaging (MRI) is a superior and noninvasive imaging technique with unlimited tissue penetration depth and superb spatiotemporal resolution, however, using intracellular self-assembly of Gd-containing nanoparticles to enhance the T2 -weighted MR contrast of cancer cells in vivo for precise tumor MRI is rarely reported. The lysosomal cysteine protease cathepsin B (CTSB) is regarded as an attractive biomarker for the early diagnosis of cancers and metastasis. Herein, taking advantage of a biocompatible condensation reaction, a "smart" Gd-based CTSB-responsive small molecular contrast agent VC-Gd-CBT is developed, which can self-assemble into large intracellular Gd-containing nanoparticles by glutathione reduction and CTSB cleavage to enhance the T2 -weighted MR contrast of CTSB-overexpressing MDA-MB-231 cells at 9.4T. In vivo T2 -weighted MRI studies using MDA-MB-231 murine xenografts show that the T2 -weighted MR contrast change of tumors in VC-Gd-CBT-injected mice is distinctly larger than the mice injected with the commercial agent gadopentetate dimeglumine, or co-injected with CTSB inhibitor and VC-Gd-CBT, indicating that the accumulation of self-assembled Gd-containing nanoparticles at tumor sites effectively enhances the T2 -weighted MR tumor imaging. Hence, this CTSB-targeted small molecule VC-Gd-CBT has the potential to be employed as a T2 contrast agent for the clinical diagnosis of cancers at an early stage.

Recent Metal Nanotheranostics for Cancer Diagnosis and Therapy: A Review.

In recent years, there has been an increasing interest in using nanoparticles in the medical sciences. Today, metal nanoparticles have many applications in medicine for tumor visualization, drug delivery, and early diagnosis, with different modalities such as X-ray imaging, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), etc., and treatment with radiation. This paper reviews recent findings of recent metal nanotheranostics in medical imaging and therapy. The study offers some critical insights into using different types of metal nanoparticles in medicine for cancer detection and treatment purposes. The data of this review study were gathered from multiple scientific citation websites such as Google Scholar, PubMed, Scopus, and Web of Science up through the end of January 2023. In the literature, many metal nanoparticles are used for medical applications. However, due to their high abundance, low price, and high performance for visualization and treatment, nanoparticles such as gold, bismuth, tungsten, tantalum, ytterbium, gadolinium, silver, iron, platinum, and lead have been investigated in this review study. This paper has highlighted the importance of gold, gadolinium, and iron-based metal nanoparticles in different forms for tumor visualization and treatment in medical applications due to their ease of functionalization, low toxicity, and superior biocompatibility.

The internal structure of gadolinium and perfluorocarbon-loaded polymer nanoparticles affects 19F MRI relaxation times.

19F magnetic resonance imaging (19F MRI) is an emerging technique for quantitative imaging in novel therapies, such as cellular therapies and theranostic nanocarriers. Nanocarriers loaded with liquid perfluorocarbon (PFC) typically have a (single) core-shell structure with PFC in the core due to the poor miscibility of PFC with organic and inorganic solvents. Paramagnetic relaxation enhancement acts only at a distance of a few angstroms. Thus, efficient modulation of the 19F signal is possible only with fluorophilic PFC-soluble chelates. However, these chelates cannot interact with the surrounding environment and they might result in image artifacts. Conversely, chelates bound to the nanoparticle shell typically have a minimal effect on the 19F signal and a strong impact on the aqueous environment. We show that the confinement of PFC in biodegradable polymeric nanoparticles (NPs) with a multicore structure enables the modulation of longitudinal (T1) and transverse (T2) 19F relaxation, as well as proton (1H) signals, using non-fluorophilic paramagnetic chelates. We compared multicore NPs versus a conventional single core structure, where the PFC is encapsulated in the core(s) and the chelate in the surrounding polymeric matrix. This modulated relaxation also makes multicore NPs sensitive to various acidic pH environments, while preserving their stability. This effect was not observed with single core nanocapsules (NCs). Importantly, paramagnetic chelates affected both T1 and T219F relaxation in multicore NPs, but not in single core NCs. Both relaxation times of the 19F nucleus were enhanced with an increasing concentration of the paramagnetic chelate. Moreover, as the polymeric matrix remained water permeable, proton enhancement additionally was observed in MRI.

Accelerated brachytherapy with the Xoft electronic source used in association with iodine, gold, bismuth, gadolinium, and hafnium nano-radioenhancers

PurposeThe current study was designed to calculate the dose enhancement factor (DEF) of iodine (I), gold (Au), bismuth (Bi), gadolinium (Gd), and hafnium (Hf) nanoparticles (NP)s by Monte Carlo (MC) modeling of an electronic brachytherapy source in resection cavities of breast tumors. Methods and materialsThe GEANT4 MC code was used for simulation of a phantom containing a water-filled balloon and a Xoft source (50 kVp) to irradiate the margins of a resected breast tumor. NPs with a diameter of 20 nm and concentrations from 1 to 5% w/w were simulated in a tumor margin with 5 mm thickness as well as a hypothetical breast model consisting of spherical island-like residual tumor-remnants. The DEFs for all NPs were calculated in both models. ResultsIn the margin-loaded model, for the concentration of 1% w/w heavy atom, DEFs of 2.5, 2.3, 2.1, 2, and 1.7 were calculated for Bi, Au, I, Hf, and Gd NPs (descending order), which increased, almost linearly with concentration for all NPs. Moreover, normal tissue dose behind the NP-loaded margin declined significantly depending on NP type and concentration. When modeling residual tumor islands, DEF values were very close to the margin-loaded values except for Bi and I, where DEFs of 2.55 and 1.7 were seen, respectively. ConclusionsConsiderable dose enhancements were obtained for the heavy atom NPs studied in the partial breast brachytherapy with a Xoft electronic source. In addition, normal tissue doses were lowered in the points beyond the NP-loaded margin. The findings revealed promising outcomes and the probability of improved tumor control for NP-aided brachytherapy with the Xoft electronic source.

DSB and SSB damages by 0.1–20 MeV protons enhanced by high-Z nanoparticles computed using Geant4-DNA

The interaction of protons in the energy range of 0.1 to 20 MeV with water sphere, as the target volume, containing DNA molecules has been simulated using Geant4-DNA toolkit. PDB format of DNA was used as DNA molecules were distributed randomly inside the target volume. The number of DNA damage is calculated in the absence of nanoparticles. Then the simulation has been repeated in the presence of 3 different nanoparticles (gold, gadolinium and iodine), in the identical physical and geometric conditions. The number of DNA damages without nanoparticles was in agreement with previous studies. Simulations results demonstrate that adding gold nanoparticles leads to increase damage yields in DNA. Increase of the yield between 10% to 50% were observed for SSB and DSB. Enhancement of the yield damage in the case of gadolinium and iodine nanoparticles was observed to be 4% and 9% less than that of gold nanoparticles.

Achieving Effective Multimodal Imaging with Rare-Earth Ion-Doped CaF2 Nanoparticles.

Nowadays, cancer poses a significant hazard to humans. Limitations in early diagnosis techniques not only result in a waste of healthcare resources but can even lead to delays in diagnosis and treatment, consequently reducing cure rates. Therefore, it is crucial to develop an imaging probe that can provide diagnostic information precisely and rapidly. Here, we used a simple hydrothermal method to design a multimodal imaging probe based on the excellent properties of rare-earth ions. Calcium fluoride co-doped with ytterbium, gadolinium, and neodymium (CaF2:Y,Gd,Nd) nanoparticles (NPs) is highly crystalline, homogeneous in morphology, and displays a high biosafety profile. In addition, in vitro and ex vivo experiments explored the multimodal imaging capability of CaF2:Y,Gd,Nd and demonstrated the efficient performance of CaF2:Y,Gd,Nd during NIR-II fluorescence/photoacoustic/magnetic resonance imaging. Collectively, our novel diagnosis nanoparticle will generate new ideas for the development of multifunctional nanoplatforms for disease diagnosis and treatment.

A Facile and Universal Method for Preparing Polyethylene Glycol-Metal Hybrid Nanoparticles and Their Application in Tumor Theranostics.

Metal ions are of widespread interest owing to their brilliant biomedical functions. However, a simple and universal nanoplatform designed for assembling a range of functional metal ions has not been explored. In this study, a concept of polyethylene glycol (PEG)-mediated transport of metal ions is proposed. 31 types of PEG-metal hybrid nanoparticles (P-MNPs) are successfully synthesized through anionic ring-opening polymerization (ROP), "thiol-ene" click reaction, and subsequent incorporation with multiple metal ions. Compared with other methods, the facile method proposed in this study can provide a feasible approach to design MNPs (mostly <200nm)containing different metal ions and thus to explore their potential for cancer theranostics. As a proof-of-concept demonstration, four types P-MNPs, i.e., PEG-metal hybrid copper nanoparticles (PEG-Cu NPs), ruthenium nanoparticles (PEG-Ru NPs), and manganese nanoparticles (PEG-Mn NPs) or gadolinium nanoparticles (PEG-Gd NPs), are proven to be tailored for chemodynamic therapy, photothermal therapy, and magnetic resonance imaging of tumors, respectively. Overall, this study provides several metal ions-based nanomaterials with versatile functions for broad applications in cancer theranostics. Furthermore, it offers a promising tool that can be utilized for processing other metal-based nanoparticles and exploring their potential in the biomedical field.

Detection of Kidney Dysfunction through In Vivo Magnetic Resonance Imaging with Renal-Clearable Gadolinium Nanoprobes.

Kidney dysfunction is a clinical syndrome that can subsequently result in lethal kidney failure. The exploration of emerging bioimaging contrast agents with translational potential is highly challenging for a feasible diagnosis of kidney dysfunction. Herein, a class of renal-clearable gadolinium nanoparticles (Gd@PEG NPs) with an ultrasmall size of ∼5 nm, good monodispersity, and T1 relaxivity are synthesized using mesoporous silica nanoparticles as the template. Assisted by such renal-clearable Gd@PEG NPs, the diagnosis of kidney dysfunction in a mice model with a damaged kidney has been achieved through in vivo noninvasive magnetic resonance imaging. As a result, this work paves the way to synthesize monodispersible ultrasmall Gd contrast agents, facilitating the exploration of translational strategies for an in vivo analysis of kidney dysfunction.

Gadolinium and Polythiophene Functionalized Polyurea Polymer Dots as Fluoro-Magnetic Nanoprobes.

A rapid and one-pot synthesis of poly 3-thiopheneacetic acid (PTAA) functionalized polyurea polymer dots (Pdots) using polyethyleneimine and isophorone diisocyanate is reported. The one-pot mini-emulsion polymerization technique yielded Pdots with an average diameter of ~20 nm. The size, shape, and concentration of the surface functional groups could be controlled by altering the synthesis parameters such as ultrasonication time, concentration of the surfactant, and crosslinking agent, and the types of isocyanates utilized for the synthesis. Colloidal properties of Pdots were characterized using dynamic light scattering and zeta potential measurements. The spherical geometry of Pdots was confirmed by scanning electron microscopy. The Pdots were post-functionalized by 1,4,7,10 tetraazacyclododecane-1,4,7,10-tetraacetic acid for chelating gadolinium nanoparticles (Gd3+) that provide magnetic properties to the Pdots. Thus, the synthesized Pdots possess fluorescent and magnetic properties, imparted by PTAA and Gd3+, respectively. Fluorescence spectroscopy and microscopy revealed that the synthesized dual-functional Gd3+-Pdots exhibited detectable fluorescent signals even at lower concentrations. Magnetic levitation experiments indicated that the Gd3+-Pdots could be easily manipulated via an external magnetic field. These findings illustrate that the dua- functional Gd3+-Pdots could be potentially utilized as fluorescent reporters that can be magnetically manipulated for bioimaging applications.

Synthesis and characterization of gadolinium nanoparticles using polyol method as a candidate for MRI Contrast Agent

This research is related to the preparation and initial characterization of gadolinium nanoparticles as a Magnetic Resonance Imaging (MRI) contrast agent. Nanomaterial-based contrast agents aim to improve clearer imaging, longer examination retention times with lower toxicity than gadolinium ion-based contrast agents, and evaluate the potential use of MRI contrast agents for early detection of cancer. Gadolinium nanoparticles were synthesized using polyol method with stabilizer and chemical reaction process at high temperature. The stabilizers used are diethylene glycol (DEG) and triethylene glycol (TEG). The reaction process was carried out at 180°C for 4 hours to obtain gadolinium nanoparticles with uniform size and shape. The results of hydrodynamic and visual measurements using DLS and HRTEM instruments on the gadolinium nanoparticles produced were 50 nm and 18 nm, respectively. The results of the characterization of the crystal structure obtained the X-ray diffraction pattern in the crystal plane (222), which is a typical for the Gd2O3 crystal phase. Characterization of chemical bonds using FTIR showed absorption at 1438-1627 cm−1, 1000-1138 cm−1 and 450-795 cm−1 indicated the presence of Gd-O bond vibrations, while absorption at 1310-1466 cm−1 indicated the presence of Gd-O-Gd bonds. This is evidenced by the similarity with the absorption peak of commercial Gd2O3. The content of free Gd3+ ions found in the synthesized products detected was only about 0.99% of the Gd3+ precursors used.

Simultaneous enhancement of T1 and T2 magnetic resonance imaging of liver tumor at respective low and high magnetic fields.

Background: Nowadays, magnetic resonance imaging (MRI) is routinely applied in clinical diagnosis. However, using one contrast agent (CA) to simultaneously enhance the T1 and T2 MR contrast at low and high magnetic fields respectively has not been reported.Methods: Herein, we investigated the MR property of a γ-glutamyl transpeptidase (GGT)-instructed, intracellular formed gadolinium nanoparticle (DOTA-Gd-CBT-NP) at low and high magnetic fields.Results: Experimental results showed that DOTA-Gd-CBT-NP possesses a low r2/r1 ratio 0.91 which enables it to enhance T1 MR imaging of liver tumor at 1.0 T, and a high r2/r1 ratio 11.8 which renders the nanoparticle to largely enhance T2 MR imaging of liver tumor at 9.4 T.Conclusion: We expect that our GGT-responsive Gd-nanoparticle could be applied for simultaneous T1 and T2 MRI diagnosis of early liver cancer in clinic at respective low and high magnetic fields when the 9.4 T MR machine is clinically available in the future.

Synthesis of Gadolinium Complexes Using Medicinal Plant Extracts

Background: Gadolinium compounds are used as contrast enhancers in MRI imaging. Generally, free metal ions are not used in MRI imaging due to their toxicity. To reduce the toxicity of the free form of the metal, complexing agents are employed for making nanoparticles. Due to their low toxicity and natural abundance, plant extracts having potential to function as chelating agents are good alternatives for the formation of gadolinium nanoparticles. Methods: Aqueous extracts of five plant species, including Thymus daenensis Celak, Nepeta sessilifolia Bung, Crocus sativus L., Salvia hydrangea DC. ex Benth, and Hymenocrater incanus Bunge were prepared. Five complexes were produced as the result of each extract’s reaction with gadolinium nitrate solution in the presence of 1 mM solution of NaOH. The obtained complexes were analyzed adopting the Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy dispersive x-ray analysis (EDAX) techniques. Results: EDAX analysis of the obtained complexes confirmed the presence of gadolinium in all complexes. Among the five complexes, the highest percentage of gadolinium (21.07) was recorded for the complex derived from the extract of H. incanus Bunge, while the lowest one (9.33) was detected for the complex derived from the T. daenensis Celak. Despite adopting various methods to disperse the complex particles in deionized water in order for determining the particle size, the high adhesion of the particles prevented the determination of the desired particle size in nanoscale. Conclusion: Although synthesizing the complexes was successful and EDAX confirmed the presence of gadolinium metal in them, SEM analysis failed to prove their nanoparticle structure. The high tendency of solid particles to adhere was found to prevent the formation of independent nanoparticles in solution.

Effect of Bismuth, Gadolinium, and Cadmium Nanoparticles on Biomass, Carotenoid, and Lipid Content of Dunaliella salina (Dunal) Teodoresco.

Dunaliella salina is an extremophytic microalga and known as an excellent source of β-carotene and eicosapentanoeic acid. Moreover, D. salina has also been used in aquaculture feeds to increase the growth rate of fish and shrimp. Hence, many studies have been involved in searching for new approaches to increase the biomass of D. salina in the aquatic farming industry. This is the first report investigating the effect of bismuth oxide (Bi2O3), gadolinium oxide (Gd2O3), and cadmium telluride (CdTe) nanoparticles (NPs) on the growth of D. salina in controlled laboratory conditions. Extensive growth curve analysis was performed along with biochemical assays to determine chlorophyll-a, carotenoid, and total lipid content of D. salina under the influence of NPs. It is revealed that the lower concentration (100µg/ml) of Bi2O3 is favorable for D. salina growth, while higher concentrations (200 and 300µg/ml) inhibited the cell proliferation significantly. Similarly, Bi2O3 treatment led to the increase in chlorophyll-a, carotenoid, and lipid content of microalga compared to untreated culture. Gd2O3 exerted a growth inhibitory effect on microalga for initial 15days which is later overcome by microalga showing a drastic increase in biomass after 60days of cultivation. However, CdTe NPs displayed minor elevation in growth rate. Interestingly, the presence of Gd2O3 NPs in culture media demonstrated the highest carotenoid and total lipid content of algal cells among all three-tested NPs. Hence, Gd2O3 NPs can be considered as a vital additive during the industrial culturing of D. salina.