Dye-sensitized lanthanide containing nanoparticles for luminescence based applications

Due to their exceptional luminescent properties, lanthanide (Ln) complexes represent a unique palette of probes in the spectroscopic toolkit. Their extremely weak brightness due to forbidden Ln electronic transitions can be overcome by indirect dye-sensitization from the antenna effect brought by organic ligands. Despite the improvement brought by the antenna effect, (bio)analytical applications with discrete Ln complexes as luminescent markers still suffers from low sensitivity as they are limited by the complex brightness. Thus, there is a need to develop nano-objects that cumulate the spectroscopic properties of multiple Ln ions. This review firstly gives a brief introduction of the spectral properties of lanthanides both in complexes and in nanoparticles (NPs). Then, the research progress of the design of Ln-doped inorganic NPs with capping antennas, Ln-complex encapsulated NPs and Ln-complex surface functionalized NPs is presented along with a summary of the various photosensitizing ligands and of the spectroscopic properties (excited-state lifetime, brightness, quantum yield). The review also emphasizes the problems and limitations encountered over the years and the solutions provided to address them. Finally, a comparison of the advantages and drawbacks of the three types of NP is provided as well as a conclusion about the remaining challenges both in the design of brighter NPs and in the luminescence based applications.

Ligand-Sensitised LaF3 :Eu3+ and SrF2 :Eu3+ Nanoparticles and in Vitro Haemocompatiblity Studies

Luminescent Ln³⁺ -doped nanoparticles (NPs) functionalised with the desired organic ligand molecules for haemocompatibility studies were obtained in a one-pot synthesis. Chelated aromatic organic ligands such as isophthalic acid, terephthalic acid, ibuprofen, aspirin, 1,2,4,5-benzenetetracarboxylic acid, 2,6-pyridine dicarboxylic acid and adenosine were applied for surface functionalisation. The modification of the nanoparticles is based on the donor-acceptor character of the ligand-nanoparticle system, which is an alternative to covalent functionalisation by peptide bonding as presented in our recent report. The aromatic groups of selected ligands absorb UV light and transfer their excited-state energy to the dopant Eu³⁺ ions in LaF₃ and SrF₂ NPs. Herein, we discuss the structural and spectroscopic characterisation of the NPs and the results of haemocompatibility studies. Flow cytometry analysis of the nanoparticles' membrane-binding is also presented.

HSA functionalized Gd2O3:Eu3+ nanoparticles as an MRI contrast agent and a potential luminescent probe for Fe3+, Cr3+, and Cu2+ detection in water

PVP capped Gd₂O₃:Eu³⁺ (PVP@Gd₂O₃:Eu³⁺) and HSA functionalised PVP@Gd₂O₃:Eu³⁺ (HSA@PVP@Gd₂O₃:Eu³⁺) NPs as fluorescent detection probe for metal ion detection and MRI contrast agent.

Trivalent rare-earth activated hexagonal lanthanum fluoride (LaF3 :RE3+ , where RE = Tb, Sm, Dy and Tm) nanocrystals: Synthesis and optical properties

The LaF₃ nanocrystals through a facile hydrothermal route with hexagonal structures have been synthesized via doping of trivalent rare earth (RE³⁺ ) ions - RE = Tb, Sm, Dy and Tm - with rod-like and perforated morphologies using NH₄ F as fluorine precursor. Hexagonal phase formation was confirmed by powder X-ray diffraction. The crystalline sizes were calculated by the Scherrer equation where found to have an average crystalline size of 12 to 35 nm. The morphological studies of the nanocrystals were carried out by means of transmission electron microscopy (TEM). The LaF₃ :Tm³⁺ ,Sm³⁺ ions show the characteristic emission of Tb³⁺ and Tm³⁺ respectively. In Sm³⁺ -doped LaF₃ , three prominent emission peaks at 561, 597 and 641 nm were found, which belong to ⁴ G_5/2  → ⁶ H_5/2 , ⁴ G_5/2  → ⁶ H_7/2 (magnetic dipole) and ⁴ G_5/2  → ⁶ H_9/2 (electric dipole) transitions, respectively. The Dy³⁺ activated LaF₃ shows blue and yellow emission and the corresponding CIE color coordinate show white light emission (CCT value 10650 K).

Singular wavelength dependence on the sensitization of lanthanides by graphene quantum dots

Graphene quantum dots can photosensitize the emission of terbium cations with a photoluminescence efficiency that increases at shorter wavelengths.

Highly sensitive and selective detection of picric acid using a one pot biomolecule inspired polyindole/CdS nanocomposite

Picric acid has become a serious pollution source of groundwater, soil and other security applications due to its explosivity and high toxicity.

Application of photo degradation for remediation of cyclic nitramine and nitroaromatic explosives

Photo degradation is a rapid and safe remediation process and advances in continuous-flow photochemistry can scale-up yields of photo degradation.

One-pot synthesis of 2-thenoyltrifluoroacetone surface functionalised SrF2:Eu3+ nanoparticles: trace level detection of water

Trace level detection of water by 2-thenoyltrifluoroacetone Surface functionalised fluorescent lanthanide (Eu³⁺) doped SrF₂ nanoparticles.