A colorimetric sensing probe for chromium (III) ion based on domino like reaction

In this work, a gold nanobipyramid@Ag nanorod (AuNBP@Ag NR)-based sensor platform was developed for the quantitative, visual, and sensitive detection of Cr³⁺ ions in aqueous solutions. This assay provides quantitative detection of Cr³⁺, which relies on the absorbance change of AuNBP@Ag NRs due to morphological change of the AuNBP@Ag NRs induced by Cr³⁺. When AuNBP@Ag NRs and Cr³⁺ mix, the coordination reaction of the carboxyl groups of citrate and Cr³⁺ occurs, which leads to the collapse of Ag shell nanorods, similar to the domino effect, and obvious color changes from yellow to pink can be observed by the naked eye. When combined with UV-vis spectrophotometer-based colorimetric detection, a detection limit of 8.7 nM for Cr³⁺ in ultrapure water was achieved. With the advantages of high sensitivity, selectivity, and performance, we anticipate that the sensor will be helpful for the on-site, quantitative detection of Cr³⁺ ions in water samples.

Rare earth smart nanomaterials for bone tissue engineering and implantology: Advances, challenges, and prospects

Bone grafts or prosthetic implant designing for clinical application is challenging due to the complexity of integrated physiological processes. The revolutionary advances of nanotechnology in the biomaterial field expedite and endorse the current unresolved complexity in functional bone graft and implant design. Rare earth (RE) materials are emerging biomaterials in tissue engineering due to their unique biocompatibility, fluorescence upconversion, antimicrobial, antioxidants, and anti-inflammatory properties. Researchers have developed various RE smart nano-biomaterials for bone tissue engineering and implantology applications in the past two decades. Furthermore, researchers have explored the molecular mechanisms of RE material-mediated tissue regeneration. Recent advances in biomedical applications of micro or nano-scale RE materials have provided a foundation for developing novel, cost-effective bone tissue engineering strategies. This review attempted to provide an overview of RE nanomaterials' technological innovations in bone tissue engineering and implantology and summarized the osteogenic, angiogenic, immunomodulatory, antioxidant, in vivo bone tissue imaging, and antimicrobial properties of various RE nanomaterials, as well as the molecular mechanisms involved in these biological events. Further, we extend to discuss the challenges and prospects of RE smart nano-biomaterials in the field of bone tissue engineering and implantology.

Hydrothermal synthesis of Eu3+-doped BaMoO4 fluorescent probe for the selective detection of Fe3+ ions

BaMoO4:Eu3+ fluorescent probe materials have high selectivity and sensitivity for Fe3+-ion detection and can be applied to the detection of Fe3+ in actual wastewater.

Synthesis and surface modification of magnetic Fe3O4@SiO2 core-shell nanoparticles and its application in uptake of scandium (III) ions from aqueous media

The main objective of this work is to produce an eco-friendly and economically nano-adsorbent which can separate scandium metal ions Sc from a model aqueous phase prior to applying these adsorbents in industrial filed. The magnetic core-shell structure Fe3O4@SiO2 nanoparticles were synthesized by modified Stöber method and functionalized with (3-aminopropyl) triethoxysilane APTES as a coupling agent and ethylenediaminetetraacetic acid (EDTA) as a ligand. Magnetic nano support adsorbents exhibit many attractive opportunities due to their easy removal and possibility of reusing. The ligand grafting was chemically robust and does not appreciably influence the morphology or the structure of the substrate. To evaluate the potential, the prepared hybrid nanoparticles were used as nano-adsorbent for Sc ions from model aqueous solutions due to the fact that rare earth elements (REEs) have a strong affinity for oxygen and nitrogen donors. The iron oxide nanoparticles were prepared by co-precipitation method at pH 10 and pH 11 to get the best morphology and nanoscale dimensions of iron oxide magnetic nanoparticles. The particle size, morphology, specific surface area, and surface modification were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), and X-ray powder diffraction (XRD). The results showed that the Fe3O4 nanoparticles with average particle size of 15 ± 3 nm were successfully synthesized at pH 11, and 25 °C. Moreover, the prepared Fe3O4 nanoparticles were coated with amorphous SiO2 and functionalized with amino and carboxyl groups. The adsorption study conditions of Sc are as follows: the initial concentrations of the Sc model solution varied 10-50 mg/L, 20 mL volume, 20-80 mg of the Fe3O4@SiO2-COO adsorbent, pH range of 1-5, and 5 h contact time at 25 °C temperature. The adsorption equilibrium was represented with Langmuir, Freundlich, and Temkin isotherm models. Langmuir model was found to have the correlation coefficient value in good agreement with experimental results. However, the adsorption process followed pseudo-second-order kinetics.

A red luminescent Eu3+ doped conjugated microporous polymer for highly sensitive and selective detection of aluminum ions

A Eu³⁺ doped-CMP composite can be used as a chemosensor for highly sensitive and selective detection of Al³⁺.

Conjugated Microporous Polymers Doped with Rare Earth Ions: Synthesis, Characterization and Energy Transfer

In order to study the energy transfer between the conjugated polymer and rare-earth ions, a series of conjugated microporous polymers (CMPs) CMP-COOH@M (M=Eu³⁺ , Tb³⁺ , La³⁺ , and Sm³⁺ ) with different kinds of rare-earth ions was synthesized, in which the conjugated networks can effectively improve the luminescence of rare-earth ions due to the effective energy transfer from the CMP network to the rare-earth ions centers. The absolute quantum yield of CMP-COOH (Φ_FL ) is 29.1 %, while the Φ_FL value of CMP-COOH@Eu, CMP-COOH@Tb, CMP-COOH@La, and CMP-COOH@Sm is 9.4, 8.6, 14.3, and 9.1 %, respectively. This result indicates that the quantum efficiency of CMPs network is 1/2-1/3 of the original one due to the coordination of rare earth ions, that is, rare-earth ions can be recognized as fine modulators to adjust the emission color of CMPs in a controlled manner through controlling the species of rare-earth ions.

Near-IR emissive rare-earth nanoparticles for guided surgery

Intraoperative image-guided surgery (IGS) has attracted extensive research interests in determination of tumor margins from surrounding normal tissues. Introduction of near infrared (NIR) fluorophores into IGS could significantly improve the in vivo imaging quality thus benefit IGS. Among the reported NIR fluorophores, rare-earth nanoparticles exhibit unparalleled advantages in disease theranostics by taking advantages such as large Stokes shift, sharp emission spectra, and high chemical/photochemical stability. The recent advances in elements doping and morphologies controlling endow the rare-earth nanoparticles with intriguing optical properties, including emission span to NIR-II region and long life-time photoluminescence. Particularly, NIR emissive rare earth nanoparticles hold advantages in reduction of light scattering, photon absorption and autofluorescence, largely improve the performance of nanoparticles in biological and pre-clinical applications. In this review, we systematically compared the benefits of RE nanoparticles with other NIR probes, and summarized the recent advances of NIR emissive RE nanoparticles in bioimaging, photodynamic therapy, drug delivery and NIR fluorescent IGS. The future challenges and promises of NIR emissive RE nanoparticles for IGS were also discussed.

Influence of counter ions on structure, morphology, thermal stability of lanthanide complexes containing dipicolinic acid ligand

Two kinds of lanthanide coordination polymers formed by dipicolinic acid with lanthanide ions were synthesized by varying the counter ions. And their crystal structures, morphology and thermal stabilities were measured and compared. X-ray single-crystal diffraction analysis reveals that Na₃[Ln(DPA)₃] (Ln = Tb or Eu) stretches to a rigid network by means of bridging Na⁺ ion. Moreover, Na₃[Ln(DPA)]₃ exhibits good thermal stability and luminescent properties, and its optical properties can be remained even after heating at 200 °C more than 3 days. However, when Na⁺ in Na₃[Ln(DPA)₃] was replaced with NH₄⁺, i.e., (NH₄)₃[Ln(DPA)₃] with a supramolecular structure based on π-π stacking and other weak interactions, shows relatively poor thermal stability which leads to deterioration of their luminescence properties after heating treatment. This result confirms that the rigid frame structure of Na₃[Ln(DPA)]₃ plays a crucial role in improving its thermal stability and keeping its highly luminescent quantum efficiency.

Stable and magnetically reusable nanoporous magnetite micro/nanospheres for rapid extraction of carcinogenic contaminants from water

Schematic shows the overall experimental details of hydrothermal process and formation of porous structures with magnetic separability test.

Europium(III) complex-functionalized magnetic nanoparticle as a chemosensor for ultrasensitive detection and removal of copper(II) from aqueous solution

Ultrasensitive, accurate detection and separation of heavy metal ions is very important in environmental monitoring and biological detection. In this paper, a highly sensitive and specific detection method for Cu(2+) based on the fluorescence quenching of a europium(III) hybrid magnetic nanoprobe is presented. This nanoprobe can detect Cu(2+) over a wide pH range (5.0-10.0) with a detection limit as low as 0.1 nM and it can be used for detecting Cu(2+) in living cells. After the magnetic separation, the Cu(2+) concentration decreased to 1.18 ppm, which is less than the US EPA drinking water standard (1.3 ppm), and more than 70% Cu(2+) could be removed when the amount of nanocomposite 1 reached 1 mg.

Selective uptake of rare earths from aqueous solutions by EDTA-functionalized magnetic and nonmagnetic nanoparticles

Magnetic (Fe3O4) and nonmagnetic (SiO2 and TiO2) nanoparticles were decorated on their surface with N-[(3-trimethoxysilyl)propyl]ethylenediamine triacetic acid (TMS-EDTA). The aim was to investigate the influence of the substrate on the behavior of these immobilized metal coordinating groups. The nanoparticles functionalized with TMS-EDTA were used for the adsorption and separation of trivalent rare-earth ions from aqueous solutions. The general adsorption capacity of the nanoparticles was very high (100 to 400 mg/g) due to their large surface area. The heavy rare-earth ions are known to have a higher affinity for the coordinating groups than the light rare-earth ions but an additional difference in selectivity was observed between the different nanoparticles. The separation of pairs of rare-earth ions was found to be dependent on the substrate, namely the density of EDTA groups on the surface. The observation that sterical hindrance (or crowding) of immobilized ligands influences the selectivity could provide a new tool for the fine-tuning of the coordination ability of traditional chelating ligands.

Superparamagnetic iron oxide nanoparticles stabilized by a poly(amidoamine)-rhenium complex as potential theranostic probe

Three-component nanocomposites, constituted by a superparamagnetic iron oxide core coated with a polymeric surfactant bearing tightly bound Re(CO)3 moieties, were prepared and fully characterized. The water soluble and biocompatible surfactant was a linear poly(amidoamine) copolymer (PAA), containing cysteamine pendants in the minority part (ISA23SH), able to coordinate Re(CO)3 fragments. For the synthesis of the nanocomposites two methods were compared, involving either (i) peptization of bare magnetite nanoparticles by interaction with the preformed ISA23SH-Re(CO)3 complex, or (ii) "one-pot" synthesis of iron oxide nanoparticles in the presence of the ISA23SH copolymer, followed by complexation of Re to the SPIO@ISA23SH nanocomposite. Full characterization by TEM, DLS, TGA, SQUID, and relaxometry showed that the second method gave better results. The magnetic cores had a roundish shape, with low dispersion (mean diameter ca. 6 nm) and a tendency to form larger aggregates (detected both by TEM and DLS), arising from multiple interactions of the polymeric coils. Aggregation did not affect the stability of the nano-suspension, found to be stable for many months without precipitate formation. The SPIO@PAA-Re nanoparticles (NPs) showed superparamagnetic behaviour and nuclear relaxivities similar or superior to commercial MRI contrast agents (CAs), which make them promising as MRI "negative" CAs. The possibility to encapsulate (186/188)Re isotopes (γ and β emitters) gives these novel NPs the potential to behave as bimodal nanostructures devoted to theranostic applications.