Photoluminescent Porous Alginate Hybrid Materials Containing Lanthanide Ions

Luminescent macroporous aerogels of two-dimensional nanocrystals of metal halide perovskites with adjustable semiconducting bandgaps

In semiconducting aerogels, exciton-photon interactions occur in porous frameworks with solid-gas interfaces. Herein, by freezing and vacuum freeze-drying of cyclohexane dispersions of platelet-shaped nanocrystals of organic-inorganic metal halide perovskites, aerogels with macro-/meso-porosity, tunable luminescence in the visible light range, and photocurrent responses were fabricated.

Features of Luminescent Properties of Alginate Aerogels with Rare Earth Elements as Photoactive Cross-Linking Agents

Luminescent aerogels based on sodium alginate cross-linked with ions of rare earth elements (Eu3+, Tb3+, Sm3+) and containing phenanthroline, thenoyltrifluoroacetone, dibenzoylmethane, and acetylacetone as ligands introduced into the matrix during the impregnation of alginate aerogels (AEG), were obtained for the first time in a supercritical carbon dioxide medium. The impregnation method used made it possible to introduce organically soluble sensitizing ligands into polysaccharide matrices over the entire thickness of the sample while maintaining the porous structure of the aerogel. It is shown that the pore size and their specific area are 150 nm and 270 m2/g, respectively. Moreover, metal ions with content of about 23 wt.%, acting as cross-linking agents, are uniformly distributed over the thickness of the sample. In addition, the effect of sensitizing ligands on the luminescence intensity of cross-linked aerogel matrices is considered. The interaction in the resulting metal/ligand systems is unique for each pair, which is confirmed by the detection of broad bands with individual positions in the luminescence excitation spectra of photoactive aerogels.

A double responsive fluorescent platform for sensing heavy metal ions based on a dual-emitting fluorescent covalent organic framework hydrogel film

A new luminescent hybrid material with dual-emission centers (Eu@Dye@TpDq hydrogel) based on covalent organic framework (COF) has been successfully prepared. First, we designed a dye (coumarin) modified COF (TpDq) hybrid...

Covalent Grafting Terbium Complex to Alginate Hydrogels and Their Application in Fe3+ and pH Sensing

Biocompatible luminescent hydrogels containing covalently linked terbium complexes with a macrocyclic ligand are prepared by a facile method. The environmentally friendly preparation procedure is carried out at room temperature using water as a solvent. These new hybrid materials can act as luminescent sensors to detect Fe3+ with relative selectivity and high sensitivity. The hydrogels also show pH sensing with a wide range.

Diagnosis of penicillin allergy: a MOFs-based composite hydrogel for detecting β-lactamase in serum

A MOFs-based composite hydrogel 1@SA is presented for the diagnosis of penicillin anaphylaxis. This composite hydrogel reflects the enzymatic hydrolysis profiles of penicillin via β-lactamase. The determination of β-lactamase by this hydrogel was achieved through an “ON–OFF–OFF–ON” fluorescence trigger pattern. The potency of 1@SA was further demonstrated for its selectivity, sensitivity and convenient visual detection.

Hybrid luminescent alginate hydrogels containing lanthanide with potential for acetone sensing

Alginate hydrogels containing YVO₄–Eu³⁺ have been prepared by using a facile method. These luminescent hydrogels can be used as sensors to detect acetone with quick response and good reversibility.

A La3+-selective metallohydrogel with a facile gelator of a phenylalanine derivative containing an imidazole group

The first La3+-selective metallohydrogel was constructed by using a facile gelator of a phenylalanine derivative containing an imidazole group, N-(1H-imidazol-4-yl)methylidene-l-phenylalanine, namely La-ImF, which exhibits multi-stimuli responsive properties, including to heat, shearing, pH, etc. Various measurements were also carried out to obtain insights into the mechanism of gelation. Moreover, the La-ImF hydrogel can adsorb toxic dyes, making it a potential candidate for sewage treatment.

Characterization and study of luminescence enhancement behaviour of alginate-based hydrogels

Luminescence enhanced composites were fabricated via introducing 5-sulfosalicylic acid molecules into a Tb(iii)-based system to avoid being quenched by water.

Electrospun Poly(acrylic acid)/Silica Hydrogel Nanofibers Scaffold for Highly Efficient Adsorption of Lanthanide Ions and Its Photoluminescence Performance

Combined with the features of electrospun nanofibers and the nature of hydrogel, a novel choreographed poly(acrylic acid)-silica hydrogel nanofibers (PAA-S HNFs) scaffold with excellent rare earth elements (REEs) recovery performance was fabricated by a facile route consisting of colloid-electrospinning of PAA/SiO2 precursor solution, moderate thermal cross-linking of PAA-S nanofiber matrix, and full swelling in water. The resultant PAA-S HNFs with a loose and spongy porous network structure exhibited a remarkable adsorption capacity of lanthanide ions (Ln(3+)) triggered by the penetration of Ln(3+) from the nanofiber surface to interior through the abundant water channels, which took full advantage of the internal adsorption sites of nanofibers. The effects of initial solution pH, concentration, and contact time on adsorption of Ln(3+) have been investigated comprehensively. The maximum equilibrium adsorption capacities for La(3+), Eu(3+), and Tb(3+) were 232.6, 268.8, and 250.0 mg/g, respectively, at pH 6, and the adsorption data were well-fitted to the Langmuir isotherm and pseudo-second-order models. The resultant PAA-S HNFs scaffolds could be regenerated successfully. Furthermore, the proposed adsorption mechanism of Ln(3+) on PAA-S HNFs scaffolds was the formation of bidentate carboxylates between carboxyl groups and Ln(3+) confirmed by FT-IR and XPS analysis. The well-designed PAA-S HNFs scaffold can be used as a promising alternative for effective REEs recovery. Moreover, benefiting from the unique features of Ln(3+), the Ln-PAA-S HNFs simultaneously exhibited versatile advantages including good photoluminescent performance, tunable emission color, and excellent flexibility and processability, which also hold great potential for applications in luminescent patterning, underwater fluorescent devices, sensors, and biomaterials, among others.

Ca(ii) and Ce(iii) homogeneous alginate hydrogels from the parent alginic acid precursor: a structural study

Alginate hydrogels are suitable for the encapsulation of biomolecules and microorganisms for the building of bioactive materials.

Alginate/porous silica matrices for the encapsulation of living organisms: tunable properties for biosensors, modular bioreactors, and bioremediation devices

The encapsulation of living cells within inorganic silica hydrogels is a promising strategy for the design of biosensors, modular bioreactors, and bioremediation devices, among other interesting applications, attracting scientific and technological interest. These hostguest multifunctional materials (HGFM) combine synergistically specific biologic functions of their guest with those of the host matrix enhancing their performance. Although inorganic immobilization hosts present several advantages over their (bio)polymer-based counterparts in terms of chemical and physical stability, the direct contact of cells with silica precursors during synthesis and the constraints imposed by the inorganic host during operating conditions have proved to influence their biological response. Recently, we proposed an alternative two-step procedure including a pre-encapsulation in biocompatible polymers such as alginates in order to confer protection to the biological guest during the inorganic and more cytotoxic synthesis. By means of this procedure, whole cultures of microorganisms remain confined in small liquid volumes generated inside the inorganic host, providing near conventional liquid culture conditions.Moreover, the fact of protecting the biological guest during the synthesis of the host, allows extending the synthesis parameters beyond biocompatible conditions, tuning the microstructure of the matrix. In turn, the microstructure (porosity at the nanoscale, radius of gyration of particles composing the structure, and fractal dimension of particle clusters) is determinant of macroscopic parameters, such as optical quality and transport properties that govern the encapsulation material’s performance. Here, we review the most interesting applications of the two-step procedure, making special emphasis on the optimization of optical, transport and mechanical properties of the host as well as in the interaction with the guest during operation conditions.

Lanthanide induced formation of novel luminescent alginate hydrogels and detection features

Responsive photo-luminescent soft matters have led to the design of optical sensors and switches. In this research, two new organic-inorganic type hybrid hydrogels have been fabricated by the self-assembly of sodium alginate and lanthanide elements. The incorporation of europium ions (Eu(3+)) (or terbium ions (Tb(3+))) was required for the gelation of the dissolved alginate and thermally stable gels were formed. It has been found that red/green emissions derived from lanthanide ions were clearly identified in pure aqueous media through the metal coordination interactions with assembled alginate. These supramolecular structures could partially prevent the Eu(3+) (or Tb(3+)) from being attacked by high frequency vibrations. More importantly, the lanthanide luminescence could be switched "off-on" in the presence of the anthrax biomarker sodium dipicolinate (NaDPA). The detection limits (for NaDPA) were determined to be 8.3×10(-8)M and 9.0×10(-8)M based on Eu(III) and Tb(III) gel, respectively.

Nasal delivery of analgesic ketorolac tromethamine thermo- and ion-sensitive in situ hydrogels

Ketorolac tromethamine (KT) was potent to treat moderate to moderately severe pains. However, KT solutions for nasal delivery lost quickly from the nasal route. Thermo- and ion-sensitive in-situ hydrogels (ISGs) are appropriate for nasal drug delivery because the intranasal temperature maintains ∼37 °C and nasal fluids consist of plentiful cations. In this study, a novel nasal thermo- and ion-sensitive ISG of KT was prepared with thermo-sensitive poloxamer 407 (P407) and ion-sensitive deacetylated gellan gum (DGG). The optimal formulation of the KT ISG consisted of 3% (w/v) DGG and 18% (w/v) P407 and its viscosity was up to 7.63 Pas at 37 °C. Furthermore, penetration enhancers and bacterial inhibitors were added and their fractions in the ISG were optimized based on transmucosal efficiencies and toxicity on toad pili. Sulfobutyl ether-β-cyclodextrin of 2.5% (w/v) and chlorobutanol of 0.5% (w/v) were chosen as the penetration enhancer and the bacterial inhibitor, respectively. The Fick's diffusion and dissolution of KT could drive it continuous release from the dually sensitive ISG according to the in vitro investigation. Two methods, writhing frequencies induced by acetic acid and latency time of tails retracting from hot water, were used to evaluate the pharmacodynamics of the KT ISG on the mouse models. The writhing frequencies significantly decreased and the latency time of tail retracting was obviously prolonged (p<0.05) for the KT ISG compared to the control. The thermo- and ion-sensitive KT ISG had appropriate gelation temperature, sustained drug release, improved intranasal absorption, obvious pharmacodynamic effect, and negligible nasal ciliotoxicity. It is a promising intranasal analgesic formulation.

Silica@proton-alginate microreactors: a versatile platform for cell encapsulation

Acid gelation of alginate allows the inclusion of living cultures within sol–gel silica hydrogels. The formed beads spontaneously revert into a liquid viable culture.

Lanthanide-containing photoluminescent materials: from hybrid hydrogel to inorganic nanotubes

Functional photoluminescent materials are emerging as a fascinating subject with versatile applicability. In this work, luminescent organic-inorganic hybrid hydrogels are facilely designed through supramolecular self-assembly of sodium cholate, and lanthanide ions such as Eu(3+), Tb(3+), and Eu(3+)/Tb(3+). Fluorescence microscopy and TEM visualization demonstrates the existence of spontaneously self-assembled nanofibers and 3D networks in hybrid hydrogel. Photoluminescence enhancement of lanthanide ions is realized through coordination with cholate and co-assembly into 1D nanofibers, which can successfully shield the Eu(3+) from being quenched by water. The photoluminescence emission intensity of a hybrid hydrogel exhibits strong dependence on europium/cholate molar ratio, with maximum emission appearing at a stoichiometry of 1:3. Furthermore, the emission color of a lanthanide-cholate hydrogel can be tuned by utilizing different lanthanide ions or co-doping ions. Moreover, photoluminescent lanthanide oxysulfide inorganic nanotubes are synthesized by means of a self-templating approach based on lanthanide-cholate supramolecular hydrogels. To the best of our knowledge, this is the first time that the lanthanide oxysulfide inorganic nanotubes are prepared in solution under mild conditions.