Hybrid Organic–Inorganic Silica Gel Carriers with Controlled Drug‐Delivery Properties

Pure and modified silica materials were synthesised by a sol–gel process and used as carrier for the controlled release of ibuprofen, selected as model drug. A one‐step synthesis was optimised for the preparation of various silica–drug composites by using tetraethoxysilane and 3‐aminopropyltriethoxysilane as precursors at different molar ratios. The presence of aminopropyl groups on the silica surface influences the drug‐delivery rate leading to a high degree the desorption process controlled.     

Calcium Phosphate‐Reinforced Photosensitizer‐Loaded Polymer Nanoparticles for Photodynamic Therapy

Calcium phosphate‐reinforced photosensitizer‐loaded polymer nanoparticles have been developed for photodynamic therapy. Chlorin e6 (Ce6)‐loaded core–shell–corona polymer micelles of poly(ethylene glycol)‐b‐poly(L ‐aspartic acid)‐b‐poly(L ‐phenylalanine) ( PEG-PAsp-PPhe ) were employed as template nanoparticles for mineralization with calcium phosphate (CaP). CaP deposition was performed by the electrostatic localization of calcium ions at the anionic PAsp middle shells and the subsequent addition of phosphate anions. CaP‐reinforced nanoparticles exhibited enhanced stability. The CaP mineral layer effectively inhibited Ce6 release from the Ce6‐loaded mineralized nanoparticles (Ce6‐NP‐CaP) at physiological pH value. At an acidic endosomal pH value of 5.0, Ce6 release was enhanced, owing to rapid dissolution of the CaP minerals. Upon irradiation of Ce6‐NP‐CaP‐treated MCF‐7 breast‐tumor cells, the cell viability dramatically decreased with increasing irradiation time. The phototoxicity of Ce6‐NP‐CaP was much higher than that of free Ce6. Non‐invasive optical‐imaging results indicated that Ce6‐NP‐CaP exhibited enhanced tumor specificity compared with free Ce6 and Ce6‐loaded non‐mineralized polymer nanoparticles (Ce6‐NP).     

Organic–Inorganic Hybrid Supermicroporous Iron(III) Phosphonate Nanoparticles as an Efficient Catalyst for the Synthesis of Biofuels

Here we report a novel family of crystalline, supermicroporous iron(III) phosphonate nanomaterials (HFeP‐1‐3, HFeP‐1‐2, and HFeP‐1‐4) with different Fe^III‐to‐organophosphonate ligand mole ratios. The materials were synthesized by using a hydrothermal reaction between benzene‐1,3,5‐triphosphonic acid and iron(III) chloride under acidic conditions (pH≈4.0). Powder X‐ray diffraction, N₂ sorption, transmission and scanning electron microscopy (TEM and SEM) image analysis, thermogravimetric and differential thermal analysis (TGA‐DTA), and FTIR spectroscopic tools were used to characterize the materials. The triclinic crystal phase [P$\bar 1$ (2) space group] of the hybrid iron phosphonate was established by a Rietveld refinement of the PXRD analysis of HFeP‐1‐3 by using the MAUD program. The unit cell parameters are a=8.749(1), b=8.578(1), c=17.725(3) Å; α=104.47(3), β=97.64(1), γ=113.56(3)°; and V=1013.41 ų. With these crystal parameters, we proposed an 24‐membered‐ring open framework structure for HFeP‐1. Compound HFeP‐1‐3, with an starting Fe/ligand molar ratio of 3.0, shows the highest Brunauer–Emmett–Telller (BET) surface area of 556 m²g^?1 and uniform supermicropores of approximately 1.1 nm. The acidic surface of the porous iron(III) phosphonate nanoparticles was used in a highly efficient and recyclable catalytic transesterification reaction for the synthesis of biofuels under mild reaction conditions.     

Tris‐Functionalized Hybrid Anderson Polyoxometalates: Synthesis,Characterization, Hydrolytic Stability and Inversion of Protein Surface Charge

Single‐ and double‐sided functionalized hybrid organic–inorganic Anderson polyoxomolybdates with Ga^III and Fe^III positioned as central heteroatoms have been synthesized in a mild, two‐step synthesis in an aqueous medium. Compounds 1 – 4 were isolated as hydrated salts, [TBA]₃[GaMo₆O₁₈(OH)₃{(OCH₂)₃CCH₂OH}]×12 H₂O ( 1 ) (TBA=tetrabutylammonium), Na₃[FeMo₆O₁₈{(OCH₂)₃CCH₂OH}₂]×11 H₂O ( 2 ), [TMA]₂[GaMo₆O₁₈(OH)₃{(OCH₂)₃CNH₃}]×7 H₂O ( 3 ) (TMA=tetramethylammonium), and Na[TMA]₂[FeMo₆O₁₈(OH)₃{(OCH₂)₃CNH₃}](OH)×6 H₂O ( 4 ). All the compounds were characterized based on single‐crystal X‐ray diffraction (SXRD), FTIR, UV/Vis, thermogravimetric, ESI‐MS, NMR, and elemental analyses. Compound 1 was also crystallized with two smaller organic cations, giving [TMA]₃[GaMo₆O₁₈(OH)₃{(OCH₂)₃CCH₂OH}]×n H₂O ( 5 ) and [GDM]₃[GaMo₆O₁₈(OH)₃{(OCH₂)₃CCH₂OH}]×n H₂O ( 6 ) (GDM=guanidinium) and were characterized based on UV/Vis, NMR, FTIR, and elemental analyses. The use of these compounds as additives in macromolecular crystallography was investigated by examining their hydrolytic stability by using ESI‐MS in a pH range of 4 to 9. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) analysis showed that BSA remains intact in a solution containing up to 100 equivalents of 1 or 4 over more than four days at 20 °C. Zeta potential measurements demonstrate that 1 – 4 induce charge inversions on the positively charged surface of BSA (1 mg mL^?1) with concentrations starting as low as 1.29 mM for compounds 1 and 2 , which have the highest negative surface charge.     

Assembly of Multiple Components in a Hybrid Microcapsule: Designing a Magnetically Separable Pd Catalyst for Selective Hydrogenation

In analogy to the role of long‐chain polyamines in biosilicification, poly‐L ‐lysine facilitates the assembly of nanocomponents to design multifunctional microcapsule structures. The method is demonstrated by the fabrication of a magnetically separable catalyst that accommodates Pd nanoparticles (NPs) as active catalyst, Fe₃O₄ NPs as magnetic component for easy recovery of the catalyst, and silica NPs to impart stability and selectivity to the catalyst. In addition, polyamines embedded inside the microcapsule prevent the agglomeration of Pd NPs and thus result in efficient catalytic activity in hydrogenation reactions, and the hydrophilic silica surface results in selectivity in reactions depending on the polarity of substrates.     

Organic–Inorganic Hybrid Saponites Obtained by Intercalation of Titano‐Silsesquioxane

The synthesis and characterization of two bifunctional composite materials based on synthetic saponite clays is here presented. These materials were prepared by intercalation of a Ti‐containing aminopropylisobutyl polyhedral oligomeric silsesquioxane (Ti‐NH₂POSS) in synthetic saponite samples containing interlayer sodium (Na‐SAP) or protons (H‐SAP). Hybrid organic–inorganic materials, Ti‐NHM‐1 and Ti‐NHM‐2, were obtained upon ion exchange. Structural, spectroscopic, and thermal properties of both hybrid materials were investigated in detail along with their catalytic activity in cyclohexene oxidation.     

Metal@COFs: Covalent Organic Frameworks as Templates for Pd Nanoparticles and Hydrogen Storage Properties of Pd@COF‐102 Hybrid Material

Three‐dimensional covalent organic frameworks (COFs) have been demonstrated as a new class of templates for nanoparticles. Photodecomposition of the [Pd(η³‐C₃H₅)(η⁵‐C₅H₅)]@COF‐102 inclusion compound (synthesized by a gas‐phase infiltration method) led to the formation of the Pd@COF‐102 hybrid material. Advanced electron microscopy techniques (including high‐angle annular dark‐field scanning transmission electron microscopy and electron tomography) along with other conventional characterization techniques unambiguously showed that highly monodisperse Pd nanoparticles ((2.4±0.5) nm) were evenly distributed inside the COF‐102 framework. The Pd@COF‐102 hybrid material is a rare example of a metal‐nanoparticle‐loaded porous crystalline material with a very narrow size distribution without any larger agglomerates even at high loadings (30 wt %). Two samples with moderate Pd content (3.5 and 9.5 wt %) were used to study the hydrogen storage properties of the metal‐decorated COF surface. The uptakes at room temperature from these samples were higher than those of similar systems such as Pd@metal–organic frameworks (MOFs). The studies show that the H₂ capacities were enhanced by a factor of 2–3 through Pd impregnation on COF‐102 at room temperature and 20 bar. This remarkable enhancement is not just due to Pd hydride formation and can be mainly ascribed to hydrogenation of residual organic compounds, such as bicyclopentadiene. The significantly higher reversible hydrogen storage capacity that comes from decomposed products of the employed organometallic Pd precursor suggests that this discovery may be relevant to the discussion of the spillover phenomenon in metal/MOFs and related systems.     

Development of Multinuclear Polymeric Nanoparticles as Robust Protein Nanocarriers

One limitation of current biodegradable polymeric nanoparticles is their inability to effectively encapsulate and sustainably release proteins while maintaining protein bioactivity. Here we report the engineering of PLGA–polycation nanoparticles with a core–shell structure that act as a robust vector for the encapsulation and delivery of proteins and peptides. The optimized nanoparticles can load high amounts of proteins (>20 % of nanoparticles by weight) in aqueous solution without organic solvents through electrostatic interactions by simple mixing, thereby forming nanospheres in seconds with diameters <200 nm. The relationship between nanosphere size, surface charge, PLGA–polycation composition, and protein loading is also investigated. The stable nanosphere complexes contain multiple PLGA–polycation nanoparticles, surrounded by large amounts of protein. This study highlights a novel strategy for the delivery of proteins and other relevant molecules.     

Redox Active Mesoporous Hybrid Materials by In situ Syntheses with Urea‐linked Triethoxysilylated Phenothiazines

Triethoxysilyl functionalized phenothiazinyl ureas were synthesized and immobilized by in situ synthesis into mesoporous hybrid materials. The designed precursor molecules influence the structure of the final materials and the intermolecular distance of the phenothiazines. XRD and N₂ adsorption measurements indicate the presence of highly ordered two‐dimensional hexagonally structured functional materials, while the incorporation of the organic compounds in the solid materials was proved by means of ¹³C and ²⁹Si solid state NMR spectroscopy as well as by FT‐IR spectroscopy. Upon oxidation with (NO)BF₄ or SbCl₅, stable phenothiazine radical cations were generated in the pores of the materials, which was detected by means of UV/Vis, emission, and EPR spectroscopies.     

Incorporation of Fe3O4 Nanoparticles into Organometallic Coordination Polymers by Nanoparticle Surface Modification

Surface‐modified Fe ₃ O ₄ nanoparticles (NPs) can be obtained by substituting [(η⁵‐semiquinone)Mn(CO)₃] for oleylamine surface protecting groups. The resulting NP can function as a nucleus or template to generate crystalline coordination polymers that contain superparamagnetic Fe₃O₄ NPs. Hybridized magnetic properties can be obtained by introducing paramagnetic metal nodes, such as Mn²⁺, into the polymers (see picture).

     

Multicomponent Organic Metal Halide Hybrid with White Emissions

Zero‐dimensional (0D) organic metal halide hybrids, in which organic and metal halide ions cocrystallize to form neutral species, are a promising platform for the development of multifunctional crystalline materials. Herein we report the design, synthesis, and characterization of a ternary 0D organic metal halide hybrid, (HMTA)₄PbMn_0.69Sn_0.31Br₈, in which the organic cation N‐benzylhexamethylenetetrammonium (HMTA⁺, C₁₃H₁₉N₄⁺) cocrystallizes with PbBr₄^2?, MnBr₄^2?, and SnBr₄^2?. The wide band gap of the organic cation and distinct optical characteristics of the three metal bromide anions enabled the single‐crystalline “host–guest” system to exhibit emissions from multiple “guest” metal halide species simultaneously. The combination of these emissions led to near‐perfect white emission with a photoluminescence quantum efficiency of around 73 %. Owing to distinct excitations of the three metal halide species, warm‐ to cool‐white emissions could be generated by controlling the excitation wavelength.     

Tryptophan photooxidation promoted by new hybrid materials prepared by condensation of naphthalene imides with silicate by the sol–gel process

Three novel hybrid organic/inorganic materials were synthesized from 4-substituted (NO₂, Br, H) 1,8-naphthalene imide-N-propyltriethoxysilane by the sol–gel process. These materials were obtained as a xerogel and partially characterized. The ability to photosensitize the oxidation and degradation of tryptophan indole ring by these materials was studied through photophysical and photochemical techniques. Although the derivatives containing Br and NO₂ as substituent do not cause efficient tryptophan photodamage, the hybrid material obtained from 1,8-naphthalic anhydride is very efficient to promote tryptophan photooxidation. By using laser flash photolysis it was possible to verify the presence of naphthalene imide transient radical species. The presence of oxygen causes an increase of the yield of radical formation. These results suggest that the mechanism of photodegradation of tryptophan occurs by type I, i.e. the transient radical (TrpH⁺) formed by the direct reaction of the triplet state of the naphthalene imide moiety with tryptophan. Thus a inorganic–organic hybrid material that can be used to promote the oxidation of biomolecules was obtained.     

Tunable Thermoelastic Anisotropy in Hybrid Bragg Stacks with Extreme Polymer Confinement

Controlling thermomechanical anisotropy is important for emerging heat management applications such as thermal interface and electronic packaging materials. Whereas many studies report on thermal transport in anisotropic nanocomposite materials, a fundamental understanding of the interplay between mechanical and thermal properties is missing, due to the lack of measurements of direction‐dependent mechanical properties. In this work, exceptionally coherent and transparent hybrid Bragg stacks made of strictly alternating mica‐type nanosheets (synthetic hectorite) and polymer layers (polyvinylpyrrolidone) were fabricated at large scale. Distinct from ordinary nanocomposites, these stacks display long‐range periodicity, which is tunable down to angstrom precision. A large thermal transport anisotropy (up to 38) is consequently observed, with the high in‐plane thermal conductivity (up to 5.7 W m^?1 K^?1) exhibiting an effective medium behavior. The unique hybrid material combined with advanced characterization techniques allows correlating the full elastic tensors to the direction‐dependent thermal conductivities. We, therefore, provide a first analysis on how the direction‐dependent Young's and shear moduli influence the flow of heat.     

Stabilizer‐Guided Inhibition of Protein–Protein Interactions

The discovery of novel protein–protein interaction (PPI) modulators represents one of the great molecular challenges of the modern era. PPIs can be modulated by either inhibitor or stabilizer compounds, which target different though proximal regions of the protein interface. In principle, protein–stabilizer complexes can guide the design of PPI inhibitors (and vice versa). In the present work, we combine X‐ray crystallographic data from both stabilizer and inhibitor co‐crystal complexes of the adapter protein 14‐3‐3 to characterize, down to the atomic scale, inhibitors of the 14‐3‐3/Tau PPI, a potential drug target to treat Alzheimer’s disease. The most potent compound notably inhibited the binding of phosphorylated full‐length Tau to 14‐3‐3 according to NMR spectroscopy studies. Our work sets a precedent for the rational design of PPI inhibitors guided by PPI stabilizer–protein complexes while potentially enabling access to new synthetically tractable stabilizers of 14‐3‐3 and other PPIs.