Development of 225Ac/213Bi generator based on α-ZrP-PAN composite for targeted alpha therapy

BACKGROUND

Radioligand therapy using alpha emitters has gained more and more prominence in the last decade. Despite continued efforts to identify new appropriate radionuclides, the combination of 225Ac/213Bi remains among the most promising. Bismuth-213 has been employed in clinical trials in combination with appropriate vectors to treat patients with various forms of cancer, such as leukaemia, bladder cancer, neuroendocrine tumours, melanomas, gliomas, or lymphomas. However, the half-life of 213Bi (T½ = 46 min) implies that its availability for clinical use is limited to hospitals possessing a 225Ac/213Bi radionuclide generator, which is still predominantly scarce. We investigated a new Ac/Bi generator system based on using the composite sorbent α-ZrP-PAN (zirconium(IV) phosphate as active component and polyacrylonitrile as matrix). The developed 225Ac/213Bi generator was subjected to long-term testing after its development. The elution profile was determined and the elution yield, the contamination of the eluate with the parent 225Ac and the contamination of the eluate with the column material were monitored over time.

RESULTS

The high activity (75 MBq of parent 225Ac) generator with a length of 75 mm and a diameter of 4 mm containing the composite sorbent α-ZrP-PAN with a particle size of 0.8 to 1.0 mm as the stationary phase, eluted with a mixture of 10 mM DTPA in 5 mM nitric acid, provided 213Bi with yields ranging from 77 % to 96 % in 2.8 mL of eluate, with parent 225Ac contamination in the order of 10-3 %, up to twenty days of use.

CONCLUSION

All the results of the monitored parameters indicate that the composite sorbent α-ZrP-PAN based separation system for the elution of 213Bi is a very promising and functional solution.

Amphoteric composite of ZrP and N-doped porous carbon: Synthesis, characterization, and potential use for cycloaddition of CO2

Composites of amorphous ZrP and N-doped carbon were prepared in a one-step pyrolysis process instead of general post-loading technique. Owing to their mesoporous structure (6-10 nm) and Zr content (up to 41 wt%), the amphoteric materials have potential use in the cycloaddition of CO2 to epoxides, which is an acid‒base tandem process including the ring opening of epoxides and the addition of CO2. Substantial work has been done on how starting materials impact the structure and performance of composite materials. The coordination between metal and melamine has been confirmed, and it can be implanted in the melamine-polymer initiation of formation of porous metal-carbon materials. The composite catalysts exhibit amphoteric properties, present broad-spectrum adsorption, and finally produce carbonates via cycloaddition of CO2 to epoxides. It is remarkable that the multiple characteristics of porous solids are stabilized, and no significant loss of catalytic performance is observed after four cycles.

Removal of ciprofloxacin antibiotic pollutants from wastewater using nano-composite adsorptive membranes

The emergence of antibiotics in water has been globally recognized as a critical pollution issue. Antibiotics (such as Ciprofloxacin (CPFX) pose a serious threat to humans and to the ecosystem due to its accumulation in water sources which can lead to chronic health problems and endanger aquatic life. It is therefore crucial to properly remove them from water. In this work, a nano-composite adsorptive membrane based on Zirconium Phosphate (ZrP) adsorbent supported on Polyethersulfone (PES) was synthesized and evaluated for the removal of CPFX from synthetic aqueous solutions. The membranes described here showed a very high antibiotic removal rate. The effect of various parameters such as the initial concentration of the antibiotic, the adsorbent dosage, contact time, pH, and temperature was studied. The equilibrium data were found to reasonably best fit with the Temkin isotherm model. The membranes showed a high ciprofloxacin removal (99.7%) as opposed to (68%) when PES membrane alone was used. Moreover, a significant improvement in the membrane's water flux (100.84 L/m².h) and permeability (97.62 L/m².hr.bar) were noticed as opposed to pure PES membrane's flux and permeability. The adsorptive membranes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET). The results confirmed the successful formation of ZrP nanoparticles adsorbent within the membrane matrix, and with enhanced hydrophilic properties. The membrane was successfully regenerated and reused up to 5 times. The results of this work showed the potential of such membranes for the removal of ciprofloxacin and at a high efficiency.

Highly efficient removal of strontium from contaminated wastewater by a porous zirconium phosphate material

Effective and efficient disposal of radioactive pollution has been crucial for responding to unexpected nuclear accidents and guaranteeing the sustainable development of nuclear energy. In this study, a kind of porous zirconium phosphate was synthesized with a sol-gel process followed by a post-synthesis modification to remove the radioactive Sr²⁺ from wastewater. The prepared materials were characterized by different technologies including FT-IR, SEM-EDS, XRD and XPS, and then the adsorption performance was evaluated in batch and column modes. Experimental results suggested that the porous zirconium phosphate adsorbent was successfully prepared with Na⁺ dispersed in the channels for exchange. It inherited the excellent properties of zirconium dioxide aerogel and exhibited mesoporous structure and large specific surface area. Compared with traditional zirconium phosphate, the adsorption kinetics and the adsorption capacity were improved simultaneously. Especially, it showed excellent selectivity towards Sr²⁺ among different cations, and even could remove the low-level Sr²⁺ from natural seawater efficiently, which powerfully demonstrated that the prepared material could be applied in the treatment of practical wastewater. Spectra studies uncovered that the adsorption activities were dominated by the ion exchange mechanism between external Sr²⁺ and interlaminar Na⁺ or H⁺. In conclusion, this paper not only reports a novel synthesis strategy for the acquisition of porous zirconium phosphate, but also presents a promising adsorbent for the Sr²⁺ removal.

Metastable nano-zirconium phosphate inside gel-type ion exchanger for enhanced removal of heavy metals

Nanotechnology has provided a new opportunity for water decontamination from trace heavy metals, yet the relatively poor acidic stability remains a major obstacle for the nano-adsorbents, given that acidic treatment is frequently used to regenerate the heavy metal-saturated adsorbents. Zirconium phosphate (ZrP) is very promising for water treatment due to its absolute insoluble nature, though it interacts with heavy metals mainly through the non-specific electrostatic attraction. Herein, we prepared the ultrafine ZrP (~3.9 nm) inside the commercially available gel-type cation exchanger (N001), i.e., the sulfonated poly(styrene-co-divinylbenzene) bead. The resultant nanocomposite ZrP@N001 contained the amorphous nanoparticles (NPs) with metastable γ-ZrP structure as the main phase, unlike the layered α-ZrP formed inside the macroporous cation exchanger D001 (referred to as ZrP@D001). As a result, ZrP@N001 could selectively adsorb heavy metals through inner-sphere coordination, possessing a much stronger adsorption affinity than ZrP@D001, as confirmed by XPS analysis. In both batch and column assays on the Pb(II)-polluted water, ZrP@N001 exhibited superior adsorption performance over ZrP@D001. After adsorption, the exhausted ZrP@N001 was fully refreshed by acidic treatment for a 5-cyclic adsorption-regeneration run with constant removal efficiencies. This study may open a door for the rational design of highly efficient water purifiers for heavy metal control.

Nanoarmored Multi-Enzyme Cascade Catalysis

This chapter reports a single-step preparation of nanoarmored bi-enzyme systems assembled on 1-D and 2-D nanomaterials, with glucose oxidase and peroxidase enzymes as model systems for cascade bio-catalysis. This is a simple and facile method to both exfoliate the bulk 1D (carbon nanotubes, CNT) and 2D nanomaterials (α-Zirconium phosphate, α-ZrP) and bind the enzymes in a single step. Exfoliation of the bulk material enhances the accessible surface area of the materials for the enzyme binding, and it also boosts the diffusion of reagents from the bulk phase to the active sites of the bio-catalysts. For example, a mixture of horseradish peroxidase, glucose oxidase, and bovine serum albumin (BSA) were adsorbed on the surfaces of the α-ZrP nanoplates or carbon nanotubes (CNT) as the bulk materials are exfoliated simultaneously, in a one-step process. The resulting bio-catalysts were thoroughly characterized by powder X-ray diffraction, electron microscopy, biochemical and biophysical methods, while enzyme activity studies proved successful binding of enzymes with retention of activities or even enhancements in their specific activities. For example, GOx/HRP/BSA/CNT displayed 6 times the activity of a mixture of GOx/HRP/BSA, under otherwise identical conditions. Similarly, GOx/HRP/BSA/ZrP had 3.5 times the activity of the corresponding mixture of GOx/HRP/BSA, in the absence of the nanoplates. These robust nano-dispersions worked extraordinarily well as active bio-catalysts. These two kinds of fabricated biocatalyst dispersions are also highly stable.

Hierarchical nanoarchitecture of zirconium phosphate/graphene oxide: Robust electrochemical platform for detection of fenitrothion

We report the rational design of nanocomposite with zirconium phosphate encapsulated on graphene oxide (ZrP/GO) for the highly sensitive and selective analysis of fenitrothion (FT). The characteristics of ZrP/GO nanocomposite are systematically analyzed by various in-depth electron microscopic, spectroscopic and analytical techniques. The ZrP/GO nanocomposite modified electrodes show better electrochemical response towards FT than other electrodes. The improved electrochemical activity of nanocomposite is attributed to large surface area, high conductivity, numerous active surface sites, GO nanosheets served as the conductivity matrix while preventing ZrP from agglomeration and the synergistic effect of ZrP and GO. Benefitting from the unique features, our fabricated sensor exhibits the superior performance in terms of wide working range (0.008-26 μM), appropriate peak potential (-0.61 V), low limit of detection (0.001 µM), high sensitivity (6 µA µM^-1 cm^-2) with the regression coefficient of 0.999. Additionally, the electrochemical sensor also displays good selectivity, excellent stability (99.6%), reproducibility (4.9%) and reusability (6.1%). The practical applicability of ZrP/GO sensor is shown by performing the detection of FT in water samples. These results clearly suggest that the ZrP/GO nanocomposite is an efficient electrode material for the future real-time environmental monitoring of FT.

Decontamination of seawater from 137Cs and 90Sr radionuclides using inorganic sorbents

In this work, we have studied sorption of ¹³⁷Сs and ⁹⁰Sr radionuclides from seawater under batch conditions by ferrocyanide sorbents based on hydrated titanium and zirconium dioxides (Т-35, NPF-HTD), clinoptilolite and glauconite (NPF-GL, NPF-CL) natural aluminosilicates, zirconium phosphate (T-3A), modified hydrated titanium dioxide (T-3K) as well as by manganese dioxide based on hydrated titanium dioxide (MD-HTD). Isotherms of sorption and dependences of cesium distribution coefficients on salt content and calcium concentration were obtained. Distribution coefficients of cesium and strontium were calculated. Stability of spent sorbents against radionuclides leaching was studied in from the point of view of their further treatment. The NPF-GL and NPF-HTD sorbents are recommended for treatment of seawater-based liquid radioactive waste with various salinity; these sorbents possess high distribution coefficients of cesium 10⁴ and 10⁵ ml/g even at the salinity of waste as high as 100 g L^-1. Distribution coefficients of strontium from seawater were (1.0-1.9)·10² ml/g for all sorbents that is conditioned by the presence of colloidal species of strontium (34 ± 7%) in the simulated seawater. Capacities of the sorbents for strontium varied within 200-310 mg/g. The sorbents strongly retain adsorbed radionuclides: the total percentage of leaching for 28 days was 4.4%, 2.2% and 3.1% for ¹³⁷Cs leaching from the NPF-HTD, T-35 and T-3A sorbents respectively and 10.7% for ⁹⁰Sr leaching from the NPF-CL sorbent.

Synthesis of super hydrophilic cellulose-alpha zirconium phosphate ion exchange membrane via surface coating for the removal of heavy metals from wastewater

In this study, commercial cellulose membranes were surface coated with alpha‑zirconium phosphate nanoparticles (α-ZrP-n) to study their impact on the overall removal efficiency of heavy metals from synthetic metal mixture wastewater solution. A total of four homogeneous solutions (0.25, 0.50, 0.75, and 1.00 wt%) of α-ZrP-n were prepared by sonicating the nanoparticles in deionized water. These solutions were used to surface coat the commercial cellulose membranes. The Scanning Electron Microscopy (SEM) along with Energy Dispersive Spectroscopy (EDS) were used to confirm the attachment of α-ZrP-n on the cellulose membrane surface. Furthermore, the structural characteristics of the α-ZrP-n modified cellulose membranes were also studied. The water contact angle results showed that all coated membranes remained super-hydrophilic. The porosity of the membranes decreased to 48% with the addition of 1.00 wt% α-ZrP-n compared to 65% for the pristine membrane. The mechanical strength has improved from 3.4 MPa for the pristine membrane to about 4 MPa for the 1.00 wt% α-ZrP-n membrane. Similarly, the thermal stability was found to be slightly enhanced as evidenced by the increase in decomposition temperature to 280 and 285 °C in the 0.75 and 1.00 wt% α-ZrP-n membranes, respectively. Furthermore, a removal efficiency of 97.0 ± 0.6, 98.0 ± 0.5, 99.5 ± 0.2, and 91.5 ± 2.0% for Cu (II), Zn (II), Ni (II), and Pb (II), respectively, was observed with the 0.50 wt% α-ZrP-n membrane. This removal was achieved at a flux of 41.85 ± 0.87 × 10³ LMH. Increasing the α-ZrP-n concentration further did not show any improvement in the overall removal efficiency. However, it led to 46% flux reduction in the 1.00 wt% α-ZrP-n membrane. The mechanism of removal of the heavy metal ions was postulated to be a combination of ion exchange and electrostatic attraction of the strong negatively charged α-ZrP-n membranes and the free metal ions in the wastewater solution.

Effect of geometrical configuration of reactor on a ZrP nano-dispersion process using ultrasonic irradiation

This study investigated the position of ultrasonic irradiation source and reactor geometry on fragmentation rate of a layered compound, α-zirconium phosphate (α-ZrP). By numerically solving the acoustic pressure distribution using COMSOL Multiphysics®, it is clarified the mechanism whereby the operating factors influenced the α-ZrP dispersion to make a suggestion of guideline of the process design method. Two vessels made of glass with a flat-bottom and a spherical-bottom, respectively, were used. Although the flat-bottom vessel at lower horn position showed the best performance of fragmentation, the region of high acoustic pressure field in the flat bottom vessel sharply narrowed and the transmittance became prominently low. On the other hand, no significant difference of the transmittance value in the spherical bottom vessel between the cases of low and high horn positions could be observed and the spherical bottom vessel was robust for the horn position. These results suggest that not only the magnitude of acoustic pressure but also the size of high acoustic pressure region is also an important factor and a spherical bottom vessel is one of suitable shape which gives large size of high acoustic pressure region regardless of the horn position.

Composite Membranes Containing Nanoparticles of Inorganic Ion Exchangers for Electrodialytic Desalination of Glycerol

Composite membranes were obtained by modification of heterogeneous polymer cation and anion-exchange membranes with nanoparticles of zirconium hydrophosphate and hydrated zirconium dioxide, respectively. The ion-exchange materials were investigated with the methods of electron microscopy, potentiometry, voltammetry, and impedance spectroscopy. Single nanoparticles, which were precipitated in aqueous media, form aggregates, when the composites are in a contact with polar organic solvent. Both single nanoparticles (up to 10 nm) and their aggregates (up to 200 nm) were precipitated in ion-exchange polymers in glycerol media. Non-aggregated nanoparticles improve electrical conductivity of the ion-exchange materials, the aggregates are barriers against fouling. The membranes were applied to NaCl removal from highly concentrated glycerine-water mixture containing organic additives (byproduct of biodiesel production). As opposite to pristine materials, the composites demonstrate stability against fouling.

Tuning Tribological Performance of Layered Zirconium Phosphate Nanoplatelets in Oil by Surface and Interlayer Modifications

Two-dimensional (2D) inorganic layered nanoplatelets exhibit superior lubricating properties in both solid states and oil dispersions. In this paper, we have systematically investigated the effects of surface and interlayer modifications on the tribological performance of layered α-zirconium phosphate (ZrP) nanoplatelets in mineral oil. The pristine layered ZrP nanoplatelets were first reacted with silanes of different alkyl chains to achieve outer surface modifications, followed by intercalation with different alkyl amines to alter the interlayer spacing. Friction and anti-wear studies on ZrP nanoplatelets with various modifications in mineral oils suggest that a longer alkyl chain on the outer surfaces along with a small increase in interlayer spacing would lead to a better tribological behavior especially under a relatively heavy load condition. Our results illustrate the ability of tuning the tribological properties of 2D layered nanoplatelets in oils by varying their surface and interlayer functionalities and would be helpful for understanding the underlying tribological mechanisms of nanolubricating oils containing 2D layered nanoplatelets. Graphical abstract ᅟ.

Treatment of lead contaminated water by a PVDF membrane that is modified by zirconium, phosphate and PVA

Lead contamination is one of the most serious problems in drinking water facing humans. In this study, a novel zirconium phosphate modified polyvinyl alcohol (PVA)-PVDF membrane was developed for lead removal. The zirconium ions and PVA were firstly coated onto a PVDF membrane through crosslinking reactions with glutaraldehyde, which was then modified by phosphate. The adsorption kinetics study showed that most of ultimate uptake occurred in 5 h. The adsorption increased with an increase in pH; the optimal adsorption was achieved at pH 5.5. The experimental data were better described by Langmuir equation than Freundlich equation; the maximum adsorption capacity was 121.2 mg-Pb/g at pH 5.5, much higher than other reported adsorptive membranes. The membrane exhibited a higher selectivity for lead over zinc with a relative selectivity coefficient (Pb(2+)/Zn(2+)) of 9.92. The filtration study showed that the membrane with an area of 12.56 cm(2) could treat 13.9 L (equivalent to 73,000 bed volumes) of lead containing wastewater with an influent concentration of 224.5 μ g/L to meet the maximum contaminant level of 15 μ g/L. It was demonstrated that the membrane did well in the removal of lead in both simulated wastewater and lead-spiked reservoir water and had a good reusability in its applications. The XPS studies revealed that the lead uptake was mainly due to cation exchange between hydrogen ions and lead ions.

Synthesis and characterization of insulin/zirconium phosphate@TiO2 hybrid composites for enhanced oral insulin delivery applications

In this work, a series of composites of insulin (Ins)/zirconium phosphate (ZrP) were synthesized by intercalation method, then, these composites were coated with TiO₂ by sol-gel method to prepare Ins/ZrP@TiO₂ hybrid composites and the drug release of the composites was investigated by using UV-Vis spectroscopy. Ins/ZrP (10, 30, 60 wt%) composites were prepared by intercalation of insulin into the ZrP layers in water. Then Ins/ZrP composites were coated with different amounts of TiO₂ (30, 50, 100 wt %) by using titanium tetra n-butoxide, as precursor. Formation of intercalated Ins/ZrP and Ins/ZrP@TiO₂ hybrid composites was characterized by FT-IR, FE-SEM, BET and XRD analysis. Zeta potential of the optimized Ins/ZrP@TiO₂ hybrid composite was determined -27.2 mV. Cytotoxic effects of the optimized Ins/ZrP@TiO₂ hybrid composite against HeLa and Hek293T cell lines were evaluated using MTT assay and the results showed that designed drug delivery system was not toxic in biological environment. Compared to the Ins/ZrP composites, incorporation of TiO₂ coating enhanced the drug entrapment considerably, and reduced the drug release. The Ins/ZrP composites without TiO₂ coating released the whole drug after 30 min in pH 7.4 (phosphate buffer solution) while the TiO₂-coated composites released the entrapped drug after 20 h. In addition to increasing the shelf life of hormone, this nanoencapsulation and nanocoating method can convert the insulin utilization from injection to oral and present a painless and more comfortable treatment for diabetics.

Sonochemically synthesized biocompatible zirconium phosphate nanoparticles for pH sensitive drug delivery application

The present work reports the synthesis of biocompatible zirconium phosphate (ZP) nanoparticles as nanocarrier for drug delivery application. The ZP nanoparticles were synthesized via a simple sonochemical method in the presence of cetyltrimethylammonium bromide and their efficacy for the delivery of drugs has been tested through various in-vitro experiments. The particle size and BET surface area of the nanoparticles were found to be ~48 nm and 206.51 m(2)/g respectively. The conventional MTT assay and cellular localization studies of the particles, performed on MDA-MB-231 cell lines, demonstrate their excellent biocompatibility and cellular internalization behavior. The loading of curcumin, an antitumor drug, onto the ZP nanoparticles shows the rapid drug uptake ability of the particles, while the drug release study, performed at two different pH values (at 7.4 and 5) depicts pH sensitive release-profile. The MTT assay and cellular localization studies revealed higher cellular inhibition and better bioavailability of the nanoformulated curcumin compared to free curcumin.

Heterogeneous catalyst-assisted thermochemical conversion of food waste biomass into 5-hydroxymethylfurfural

A novel thermochemical conversion route has been developed that yields 5-hydroxymethylfurfural (HMF) from food waste biomass (FWB) in the presence of a heterogeneous catalysts (zirconium phosphate (ZrP)). The ZrP catalyst was prepared by precipitation followed by calcination at 400 (ZrP-400) and 600 °C (ZrP-600) and was characterized by SEM, XRD, XPS, N2 sorption and NH3-TPD. The optimized reaction conditions were identified to maximize HMF yield by varying the type of catalyst, the catalyst loading and the reaction time. The highest HMF yield achieved was 4.3%. On average 33% higher yield for ZrP-600 was obtained compared to that for ZrP-400, which might be due to higher number of acid sites on ZrP-600. The ZrP catalyst was easily regenerated by thermal treatment and showed stable activity upon its reuse. Preliminary calculations of the "minimum selling price" of HMF suggest that it is economically attractive to make this industrially-relevant chemical from FWB.