Fluorescent detection and imaging of Hg 2+ using a novel phenanthroline derivative based single- and two-photon excitation

Electron injection effect in In2O3 and SnO2 nanocrystals modified by ruthenium heteroleptic complexes

In this work, the optical characteristics and conductivity under photoactivation with visible light of hybrids based on nanocrystalline SnO2 or In2O3 semiconductor matrixes and heteroleptic Ru(ii) complexes were studied. The heteroleptic Ru(ii) complexes were prepared based on 1H-imidazo[4,5-f][1,10]phenanthroline and 2,2'-bipyridine ligands. Nanocrystalline semiconductor oxides were obtained by chemical precipitation with subsequent thermal annealing and characterized by XRD, SEM and single-point BET methods. The heteroleptic Ru(ii) complexes as well as hybrid materials were characterized by time-resolved luminescence and X-ray photoelectron spectroscopy. The results showed that the surface modification of SnO2 nanoparticles with heteroleptic ruthenium complexes led to an increase in conductivity upon irradiation with light appropriate for absorption by organometallic complexes. In the case of In2O3, the deposition of Ru(ii) complexes resulted in a decrease in conductivity, apparently due to the special structure of the surface layer of the semiconductor.

Phenanthroline-Based Polyarylate Porous Membranes with Rapid Water Transport for Metal Cation Separation

The selective separation of ions in terms of extremely similar size and properties remains an important challenge in water purification. We innovated a kind of porous nanofilm via interfacial polymerization using rigid heterocyclic ligands to achieve high valent cation selectivity and rapid water/ion transport. The interconnected microporosity and uniformly distributed cation-affinitive sites of the ultrathin membranes enabled water permeation (7.5 L m^-2 h^-1 bar^-1), ion permeance of Na⁺ (1.5 mol m^-2 h^-1 bar^-1), and Mg²⁺/Na⁺ permselectivity (2.1) during nanofiltration. The forward osmosis exhibited a prominent water flux of 95 LMH at 1 M NaCl draw solution, which expanded various applications. The polyarylate membranes comprising 4,7-diphenyl-1,10-phenanthroline showed a higher water permeation and ion selectivity than the planar monomers, e.g., resorcinol. A distinct fluorescence responsiveness existed between membranes and cations for the interaction characterization. Host-guest nuclear magnetic resonance (NMR) spectroscopy and solid-state nuclear magnetic resonance spectroscopy characterized the preferential affinitive of divalent/high-valent cations in the interconnected microporous powders; an ultraviolet spectrophotometer characterized the light responsiveness of the porous nanofilms. Such an active membrane has potential applications in selective separation and adsorption of cations, photocatalytic materials, photosensors, and other fields.

Enhanced Two-Photon Fluorescence and Fluorescence Imaging of Novel Probe for Calcium Ion by Self-Assembly with Conjugated Polymer

The calcium ion (Ca2+) isa highly versatile intracellular signal messenger regulating many different cellular functions. It is important to design probes with good fluorescence and two-photon (TP) active cross-sections (Φδ) to explore the concentration distribution of Ca2+. In this manuscript, a novel TP fluorescence calcium probe (BAPTAVP) with positive charges, based on the classical Ca2+ indicator of BAPTA (1,2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetra acetic acid), and a conjugated polymer (PCBMB) with negative charges were designed and synthesized. The results from transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS), and the zeta potential (ZP) showed that nanoparticles were obtained by the self-assembly of PCBMB and BAPTAVP. Moreover, the fluorescence properties of BAPTAVP were effectively improved by fluorescence resonance energy transfer (FRET) with PCBMB and attenuating the intramolecular charge transfer (ICT) after the addition of Ca2+. The quantum yield and Φδ of PCBMB-BAPTAVP increased by about four and six times in comparison to those of BAPTAVP, respectively. The TP fluorescence imaging experiments indicated that the PCBMB-BAPTAVP system could effectively detect Ca2+ in living cells with high sensitivity.

Highly Sensitive Detection of Melamine Based on the Fluorescence Resonance Energy Transfer between Conjugated Polymer Nanoparticles and Gold Nanoparticles

Adding melamine as additives in food products will lead to many diseases and even death. However, the present techniques of melamine detection require time-consuming steps, complicated procedures and expensive analytical apparatus. The fluorescent assay method was facile and highly sensitive. In this work, a fluorescence resonance energy transfer (FRET) system for melamine detection was constructed based on conjugated polymer nanoparticles (CPNs) and gold nanoparticles (AuNPs). The energy transfer efficiency is up to 82.1%, and the system is highly selective and sensitive to melamine detection with a lower detection limit of 1.7 nmol/L. Moreover, the interaction mechanism was explored. The results showed that the fluorescence of CPNs were firstly quenched by AuNPs, and then restored after adding melamine because of reducing FRET between CPNs and AuNPs. Lastly, the proposed method was carried out for melamine detection in powdered infant formula with satisfactory results.