Surface Of Monolith Research Articles

Mercapto-Functionalized Porous Organosilica Monoliths Loaded with Gold Nanoparticles for Catalytic Application.

Porous organosilica monoliths have attracted much attention from both the academic and industrial fields due to their porous structure; excellent mechanical property and easily functionalized surface. A new mercapto-functionalized silicone monolith from a precursor mixture containing methyltrimethoxysilane; 3-mercaptopropyltrimethoxysilane; and 3-mercaptopropyl(dimethoxy)methylsilane prepared via a two-step acid/base hydrolysis–polycondensation process was reported. Silane precursor ratios and surfactant type were varied to control the networks of porous monolithic gels. Gold nanoparticles were loaded onto the surface of the porous organosilica monolith (POM). Versatile characterization techniques were utilized to investigate the properties of the synthesized materials with and without gold nanoparticles. Scanning electron microscopy was used to investigate the morphology of the as-synthesized porous monolith materials. Fourier transform infrared spectroscopy was applied to confirm the surface chemistry. 29Si nuclear magnetic resonance was used to investigate the hydrolysis and polycondensation of organosilane precursors. Transmission electron microscopy was carried out to prove the existence of well-dispersed gold nanoparticles on the porous materials. Ultraviolet–visible spectroscopy was utilized to evaluate the high catalytic performance of the as-synthesized Au/POM particles

Fast fabrication and modification of polyoctahedral silsesquioxane-containing monolithic columns via two-step photo-initiated reactions and their application in proteome analysis of tryptic digests

A fast and robust approach was developed to fabricate and modify hybrid monolithic columns via two-step photo-initiated reactions. At first, acrylopropyl polyoctahedral silsesquioxane (acryl-POSS) and 3-(triallyl silyl) propyl acrylate (TAPA) were chosen as precursors to synthesize poly (POSS-co-TAPA) monolithic column (monolith I) via photo-initiated free-radical polymerization within 10 min, which left lots of allyl groups on the surface of monolith. Secondly, two thiol-containing compounds, penicillamine and 1-octadecanethiol (ODT), were introduced to modify the prepared poly (POSS-co-TAPA) column via photo-initiated thiol-ene click reaction within 20 min. Finally, three resulting monolithic columns were applied to separate phenolic, anilines and antibiotics mixtures. These mixtures were baseline-separated on the monolith modified with penicillamine (monolith II), exhibiting better selectivity than both pristine monolith I and that modified with ODT (monolith III). Additionally, these columns were further used for separation of tryptic digest of HeLa cells by cLC-MS/MS. The 5071 unique peptides mapped to 2442 proteins were identified from HeLa cells digest on monolith II, which were superior over those on monolith III, but slightly lower than those on monolith I. These results demonstrated that these POSS-containing columns exhibited great separation ability for complex samples.

Green Silver Nanoparticles Confined in Monolithic Silica Disk-packed Spin Column for Human Serum Albumin Preconcentration

Background: In recent times many new uses have been found for nanomaterials that have undergone homogenous immobilization within porous supports. For this paper, immobilization of SNPs on a thiol-functionalized silica monolith using a fast, easy, environmentally friendly and costeffective process was performed. This was achieved by modifying the surface of a silica-based monolith using thiol groups, and then we fabricated green SNPs in situ, reducing an inorganic precursor silver nitrate solution (AgNO3) by employing tangerine peel extract as a reducing reagent, with Ag-thiol bonds forming along the monument. Doing this allows monoliths to be prepared in such a way that, as TEM analysis demonstrated, SNPs are evenly distributed along the rod's length. Once the materials had been fabricated, they were employed as a sorbent by being placed in a centrifuge. The SNP-thiol functionalized silica monolith was then tested using a standard protein (HSA). Methods: The process involves creating monolithic materials by employing a two-part sol-gel technique before modifying the surface of the silica-based monolith using thiol groups for hosting purposes. Homogenous surface coverage was achieved through the use of a non-toxic "green" reducing reagent (tangerine peel extract) to reduce a silver nitrate solution in place to create SNPs joined to the pore surface of a thiol-functionalized silica monolith, employing bonds of Ag-thiol. Once these materials were synthesized, they were classified by utilizing a number of methods based on SEM coupled with EDAX, TEM, AFM and BET analysis. The silica-based monolith, embedded with constructed SNPs, was employed as a sorbent in the preconcentration of human serum albumin (HSA). Results: The performance of the fabricated materials was measured against a silica-based monolith with no SNPs. Also, a silica monolith with constructed SNPs embedded was employed to capture HSA within a sample of human urine mixed with a double detergent concentrate (SDS). Such a monolith containing functionalized SNPs can be a highly effective sorbent for preconcentration of proteins in complex samples. Conclusion: It was shown to have superior performance compared to a bare silica-based monolith. Additionally, it was shown that a monolithic column modified by SNPs could preconcentrate spiked HSA in urine samples.

Porous polymeric monoliths: design and preparation towards environmental applications

Polymeric monoliths are porous substrates comprised of suitable monomer(s) beside a crosslinking agent and a radical initiator. The polymerization reaction may be thermally or radiation initiated in a mold. They take the shape of continuous rods or columns upon preparation. These materials are porous substrates used to overcome some deficiencies that arose from using the corresponding traditional monoliths such as ceramic and metallic ones. Increasing the efficiency of the monolith can be achieved via grafting the surface. Functional groups on the monolithic surface can be introduced to boost the performance of the monolith. Immobilizing nanoparticles; mainly the metallic ones onto the surface of the polymeric monolith enhances the efficiency of these columns and expands their application fields. Depositing the metal nanoparticles takes place via in-situ reduction of metal nanoparticles from their precursor salts or via ex-situ loading of previously prepared nanoparticles. There are various applications for polymeric monoliths; separation of proteins, small and large molecules can be mentioned. Monoliths are used in chromatographic separation applications beside catalytic implications. These monoliths represent the stationary phase. For expanding the separation application, polymeric monoliths can be applied in electrochromatographic separations. Besides, catalytic reactions can take place inside these monolithic rods.

Fabrication of interconnected macroporosity in geopolymers via inverse suspension polymerization

AbstractA new approach to fabricate geopolymer monoliths with interconnected macroporosity and a permeable structure is presented. This was achieved using an unconventional route of inverse suspension polymerization in which the aqueous geopolymer slurry consisting of potassium hydroxide, fumed silica, and natural metakaolin was dispersed in a continuous phase of soybean oil. The geopolymer monolith was synthesized by taking advantage of the so‐called “sticky period” that occurs during inverse suspension polymerization. During this period, individual droplets can coalesce but cannot re‐divide because of the partially polymerized matrix. We deliberately brought the partially polymerized geopolymer particles in proximity during the sticky period to fuse the particles. Hence this method, termed as “sticky period particle fusion,” helped to form a monolithic structure with inter‐particle spacing as macropores which resulted in high permeability. The sticky period was observed to depend on synthesis conditions such as stirring speed, temperature, and viscosity of continuous phase which in turn helped to tune the surface and pore properties of geopolymer monoliths. The BET surface area up to 67 m2/g and total pore volumes of 0.4 cm3/g from pycnometry were obtained.

Tailoring the surface chemistry of SiO2-based monoliths to enhance the selectivity of SALDI-MS analysis of small molecules

Due to their 3D geometry, surface chemistry, high porosity and large surface area, SiO2-based monoliths were explored as novel surface-assisted laser desorption/ionization-mass spectrometry (SALDI-MS) substrates for the sensitive and selective detection of small molecules of varying polarities. For this purpose, the surface of a hydrophilic SiO2 monolith was functionalized with moderately hydrophobic C-8 and more hydrophobic C-18 groups to form C8-SiO2 and C18-SiO2 monoliths, respectively. These monoliths were characterized using N2 adsorption-desorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). All of the monoliths displayed V isotherms and H1-type hysteresis loops, and they had surface areas of no less than 400 m2 g−1. The presence of bands at 2853 and 2927 cm−1 in the FTIR spectra of the respective C8-SiO2 and C18-SiO2 monoliths demonstrated that they contained alkyl chains on their surfaces. A proof-of-concept study was conducted to assess the ability of the SiO2-based monoliths to serve as substrates for SALDI-MS analysis of small molecules, including hydrophilic vitamin C, moderately hydrophobic caffeine and hydrophobic carbazole. When the hydrophilic SiO2 monolith was used as the SALDI substrate, the spectrum of vitamin C showed a large molecular ion signal, while that of carbazole exhibited only an insignificant ion signal. By contrast, the use of the hydrophobic monolith C18-SiO2 led to a high intensity molecular ion signal in the SALDI spectrum of nonpolar carbazole, while the spectrum of vitamin C showed a minimal ion signal. The observed selectivities appear to be a consequence of strong interactions occurring between the substrates and analytes of matching polarities that prevent early laser irradiation-induced analyte desorption. Furthermore, the studies showed that the more hydrophobic monolith C18-SiO2 displayed higher selectivity toward enhancing the SALDI signal of the longer chain fatty acid arachidic acid (C20), while the hydrophilic SiO2 monolith was highly selective in promoting shorter chain myristic acid (C14). In addition, the feasibility of using the C18-SiO2 monolith for SALDI detection of the hydrophobic antidepressant drugs desipramine and trimipramine in carbonated malt beverages was also evaluated. The results showed that this monolith enabled the detection of the protonated forms of these drugs, with respective limits of detection (LODs) of 10 µg mL−1 and 1 ng mL−1. This proof-of-principle study demonstrates that SiO2-based monoliths are potentially important SALDI substrates for the selective enhancement of SALDI signals of a vast range of small molecule analytes.

Pembuatan Kolom Monolit Mixed-Mode untuk Pemisahan Fenol dalam Kromatografi Cair Sistem Kapiler

A Mixed-Mode monolithic column prepared from Pentaeritrytol Tetraacrylate (PETRA) and Ethylene dimathacrylate (EDMA) was investigated and used in capillary liquid chromatography. The polymer composition was optimized by varying percentage ratio of monomer and porogens. Column A with rasio 35/65 (monomer/porogen) showed the optimum ratio. The polymerization of acrylic groups were conducted by in-situ preparation in capillary fused silica. Three phenol compounds were separated using this monolithic column using acetonitrile 100% as eluent. Monolith PETRA-EDMA also could work to separate polar and non-polar compound simultaneously by HILIC mode using acetonitrile 90% as eluent. The morphology surface of monolith was observed by scanning electron microscope (SEM) and mechanical stability in term of pressure drop was observed as well.

Differentiating π Interactions by Constructing Concave/Convex Surfaces Using a Bucky Bowl Molecule, Corannulene in Liquid Chromatography.

Convex-concave π conjugated surfaces in hemispherical bucky bowl such as corannulene (Crn) have shown increasing utility in constructing self-assembled new functional materials owing to its unique π electrons and strong dipole. Here, we investigate these specific molecular recognitions on Crn by developing new silica-monolithic capillary columns modified with Crn and evaluating their performance in the separation of different aromatic compounds by liquid chromatography (LC). We synthesized two Crn derivatives and conjugated them onto the surface of a silica monolith. The first Crn derivative was edge functionalized, which can undergo free inversion of a convex-concave surface. The second Crn derivative was synthesized by modifying the spoke of Crn, which suppresses the convex-concave inversion. Results of LC suggest that each surface showed different shape recognition based on π interaction. Furthermore, the concave surface of Crn showed strong CH-π interaction with a planar molecule, coronene, demonstrated by the shifts of the 1H NMR signals of both Crn and coronene resulting from the multiple interactions between Crn and π electrons in coronene. These results clearly demonstrated the presence of CH-π interactions at multiple points, and the role of shape recognition.

Influence of nanoporosity on the nature of hydroxyapatite formed on bioactive calcium silicate model glass.

For hard tissue regeneration, the bioactivity of a material is measured by its ability to induce the formation of hydroxyapatite (HA) under physiological conditions. It depends on the dissolution behavior of the glass, which itself is determined by the composition and structure of glass. The enhanced HA growth on nanoporous than on nonporous glass has been attributed by some to greater specific surface area (SSA), but to nanopore size distribution by others. To decouple the influence of nanopore size and SSA on HA formation, we have successfully fabricated homogeneous 30CaO-70SiO2 (30C70S) model bioactive glass monoliths with different nanopore sizes, yet similar SSA via a combination of sol-gel, solvent exchange, and sintering processes. After incubation in PBS, HA, and Type-B carbonated HA (HA/B-CHA) form on nanoporous monoliths. The XPS, FTIR, and SEM analyses provide the first unambiguous demonstration of the influence of nanopore size alone on the formation pathway, growth rate, and microstructure of HA/CHA. Due to pore-size limited diffusion of PO43- , two HA/CHA formation pathways are observed: HA/CHA surface deposition and/or HA/CHA incorporation into nanopores. HA/CHA growth rate on the surface of a nanoporous glass monolith is dominated by the pore-size limited transport of Ca2+ ions dissolved from nanoporous glass substrates. Furthermore, with increasing nanopore size, HA/CHA microstructures evolve from needle-like, plate-like, to flower-like appearance. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 886-899, 2019.

Zwitterionic codeine-derived methacrylate monoliths for enantioselective capillary electrochromatography of chiral acids and chiral bases.

Thiol-ene click reaction of N-acetyl-L-cysteine methyl ester to codeine, followed by reaction with allyl isocyanate and hydrolysis to the corresponding zwitterionic chiral selector and its subsequent bonding to the surface of a methacrylate monolith provided a new chiral capillary column for enantiomer separation of chiral acids and chiral bases. First, the epoxy groups of a poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith were converted into amine residues, followed by reaction with allylglycidyl ether. In this way, a spacer arm was bonded to the surface before coating and cross-linking poly(3-mercaptopropyl methylsiloxane) (PMPMS) via radical addition (thiol-ene click reaction) to the surface. In order to improve the performance of the monolithic chiral stationary phase, thio ether and residual thiol groups were oxidized to sulfonyl and sulphonate groups, respectively. This novel chiral stationary phase (CSP) was evaluated by capillary electrochromatography (CEC) using two chiral model compounds, namely N-3,5-dinitrobenzoyl-R,S-leucine (retained by anion-exchange mechanism) and mefloquine (by cation-exchange process). The ion-exchange retention mechanism on the CSP was characterized for these two counterionic model solutes by varying the mobile phase composition, including the nature of solvents, the concentration of counter-ions and co-ions, and the acid-to-base ratio. A series of chiral β-blockers and amino acid derivatives was used to further check the performance of the modified monolith under the optimal conditions. Several enantiomers were baseline resolved with reasonable peak efficiencies (up to 60,000 theoretical plates per meter for the second eluted enantiomer).

Covalent immobilization of TiO2 within macroporous polymer monolith as a facilely recyclable photocatalyst for water decontamination

This study focused on the covalent immobilization of TiO2 on the surface of a porous polymer monolith by a two-step method. Firstly, porous polymeric monolith with trimethoxysilane anchor groups was fabricated by w/o emulsion templated copolymerization of vinyl acetate (VAc) and methacryloxypropyl-trimethoxysilane (MPS). Then, anatase TiO2 were covalently immobilized within the voids of poly(VAc-MPS) monolith via an acid-catalyzed co-condensation of the trimethoxysilane group with a TiO2 sol precursor at low temperate. Scanning electron microscopy images demonstrated that both poly(VAc-MPS) and Ti-P(VAc-MPS) possess dense honeycomb-like macroporous structures. The chemical structure analysis by Fourier transform infrared spectroscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy revealed that (i) acid-catalyzed sol-gel method in this case could fully convert the amorphous TiO2 sol to anatase TiO2 even at low temperature (70°); (ii) TiO2 particles were covalently immobilized within the voids of the polymer monolith via Si–O–Ti linkage; (iii) acid-catalyzed hydrolysis of the trimethoxysilane groups and VAc led to significant increase in the hydrophilicity of the obtained hybrid porous monolith, Ti-P(VAc-MPS), with a water contact angle of 19.6°. Exemplified by the photo-degradation of methyl orange (MO) in aqueous solution, Ti-P(VAc-MPs) exhibited good photocatalytic activity and excellent recyclability for water decontamination. The as-prepared Ti-P(VAc-MPS) monolith could be efficiently regenerated for cyclic runs without further energy-consuming separation process such as centrifugation and filtration. The present approach opens a green way for obtaining other porous inorganic-organic photocatalyst for water contaminant removal.

Facile method for surface etching of silica aerogel monoliths

In this work we demonstrate the use of a commercial CO2 laser cutting system to etch the surface of silica aerogel monoliths without causing overall structural damage to the monoliths. Text, photographs and other images can be readily reproduced on an aerogel surface. The visual appearance of the etched aerogel sample depends on the orientation of the sample and the viewer relative to the light source, which renders this approach visually attractive for applications in fine art, fenestration and architecture.

One-step preparation of emulsion-templated amino-functionalized porous organosilica monoliths for highly efficient Cr(VI) removal

In this study, we reported that the amino-functionalized organosilica monoliths (amino-OSMs) without need post-synthesis functionalization were prepared in one-step emulsion-templated method. Herein, formation of organosilica skeleton and amino-functionalization of skeleton surface can be simultaneously realized by addition of ammonia. The SEM images showed that the amino-OSMs had a rich pore structures with high adjustability via the simple change in formulation of the emulsions. The successful graft of amino groups on the surface of the organosilica monolith was confirmed by EDS and XPS measurements. The amino-OSMs prepared in this work show the excellent Cr(VI)-removal capacity from the aqueous solution. It is demonstrated that Cr(VI) adsorption on amino-OSM-3 was best described by Langmuir models and pseudo-second-order kinetic. The adsorption efficiency of amino-OSM-3 for Cr(VI) was measured to be 92.8% at room temperature, still remained as high as 85.1% after five recycles as indicative of the good durability. Furthermore, the treated capacity of amino-OSM-3 is 4.25 kg·g−1 with initial concentration of 200 μg·L−1 through the column with a height of 0.5 cm. Correspondingly, Cr(VI) aqueous solution after treatment meet the requirement of the World Health Organization water discharge standard with Cr(VI) concentration as low as 50 μg·L−1. This work paves the way for the scale-up production of amino-OSMs using emulsion-templated technique for potential application in heavy metal removal.

Preparation and Characterization of Hierarchically Porous SiO<sub>2</sub>@C@MnO<sub>2 </sub>Monoliths

Hierarchical porous SiO2@C@MnO2monoliths have been fabricated by two step approaches: Elemental carbon was covered the internal surface of porous silica monoliths with impregnation and carbonized in inert atmosphere, and MnO2was directly grown on the skeleton of SiO2@C accompanied by redox reaction between C and KMnO4. The effects of glucose and KMnO4concentrations, and hydrothermal reaction on the morphology of MnO2particles on the surface of SiO2monoliths were investigated in detail. The results showed that the optimal factors of reaction condition involved 0.08 mol·L-1glucose solution, 0.03 mol·L-1KMnO4solution and the reaction time of 5 h. SEM images and BET results indicated that the macroporous structure of the as-prepared material was preserved after modification, while the specific surface area and pore volume decreased with increasing amount of MnO2to some degree. The XPS spectra of SiO2@C@MnO2is in good agreement with reported data in MnO2. The crystal phase of MnO2was α-MnO2after thermal treatment at the temperature of 600 °C from the XRD patterns. Three-dimensional porous well-defined morphological SiO2@C@MnO2be promising materials for the catalytic elimination of air pollutants since large quantities can be obtained from porous structure combined with α-MnO2equipped with high active performance.

Hierarchical porous cellulose/activated carbon composite monolith for efficient adsorption of dyes

Cheap and efficient adsorbents to remove contaminants of toxic dye molecules from wastewater are strongly in demand for environmental reasons. This study provides a novel design of a monolithic adsorbent from abundant materials via a facile synthetic procedure, which can greatly reduce the problems of the tedious separation of adsorbents from treated wastes. A hierarchically porous cellulose/activated carbon (cellulose/AC) composite monolith was prepared by thermally-induced phase separation of cellulose acetate in the presence of AC, using a mixture of DMF and 1-hexanol, followed by alkaline hydrolysis. The composite monolith had alarge specific surface area with mesopore distribution. It not only showed high uptake capacity towards methylene blue (MB) or rhodamine B (RhB) but could also simultaneously adsorb MB and RhB from their mixture, in which the adsorption of one dye was not influenced by the other one. Remarkable effects of solution pH, initial concentration of dye (C 0), contact time, adsorbent dosage and temperature on the adsorption of MB and RhB onto the composite monolith were demonstrated. The binding data for MB and RhB adsorption on the composite monolith fitted the Freundlich model well, suggesting a heterogeneous surface of the composite monolith. The monolith could retain around 90% of its adsorption capacity after 8 times reuse. These data demonstrate that the cellulose/AC composite monolith has a large potential as a promising adsorbent of low cost and convenient separation for dye in wastewater.

MOF immobilization on the surface of polymer-cordierite composite monoliths through in-situ crystal growth

Abstract Scalable fabrication methods to concentrate metal-organic frameworks (MOFs) on the surface of monoliths are highly desirable for their deployment at an industrial scale. In this study, we report the growth of a thick layer of MOF film on the surface of Torlon-monolith composite adsorbent. In our previous work, we demonstrated immobilization of MOFs on monolithic substrates by various techniques including layer-by-layer + secondary growth and in-situ dip coating. Although these earlier methods showed promising results, the MOFs weight loading did not exceed 55 wt%. Here we demonstrate the improvement in coating a thicker film of MOF on the monolith walls using a novel technique that involves pre-seeding of MOF powder onto the monolith using a Torlon polymer solution. This coating procedure is not only simpler and eliminates the complexity of previously reported procedures, but also results in higher MOF loadings. Whereas the earlier loading was 52 wt% for MOF-74 (Ni) and 55 wt% for UTSA-16 (Co), the new loading has been found to be ∼73 wt% for MOF-74 (Ni) and a maximum of ∼80% for UTSA-16 (Co). In addition, the substrates treated with this new method have shown improved CO2 adsorption capacities with similar kinetics to that of the earlier method. This simple method opens up fascinating possibilities for scalable fabrication of MOF-coated monoliths with tuned properties tailored to various gas separation applications.

Synthesis and growth behavior of CeO 2 /ZrO 2 /LaAlO 3 nanorods on hierarchical macroporous γ-alumina monoliths

Abstract Different kinds of metal oxide nanorods (CeO 2 , ZrO 2 and LaAlO 3 ) grown on hierarchical macroporous γ-alumina monolith with excellent thermostability and mechanical strength are successfully synthesized by combining sol-gel method with boiled water-bath crystallization. Different kinds of metal oxide nanorods have different growth behavior. Monolayer stripe CeO 2 nanorods with approximately equal length accumulated by nanoparticles covered mainly on the surface of the skeleton. Minor ZrO 2 nanoparticles not only accumulated on the surface but also grew on hollow and conjunct part of the skeleton as well as the internal surface of the pore channels in a stagger and grid way. While the LaAlO 3 crystal particles were grown mainly on the skeleton surface of alumina monolith but hardly any on the internal surface. In addition, the dipping time and temperature of metal ions have important effects on the nanoparticles morphology. The unique combination of excellent support and auxiliaries candidates can be used as promising functional materials in the field of heat/mass transfer, microchannel and separation especially in heterogeneous catalysis.

Fast analysis of glycosides based on HKUST-1-coated monolith solid-phase microextraction and direct analysis in real-time mass spectrometry.

Glycosides are a kind of highly important natural aromatic precursors in tobacco leaves. In this study, a novel HKUST-1-coated monolith dip-it sampler was designed for the fast and sensitive analysis of trace glycosides using direct analysis in real-time mass spectrometry. This device was prepared in two steps: in situ polymerization of monolith in a glass capillary of dip-it and layer-by-layer growth of HKUST-1 on the surface of monolith. Sufficient extraction was realized by immersing the tip to solution and in situ desorption was carried out by plasma direct analysis in real time. Compared with traditional solid-phase microextraction protocols, sample desorption was not needed anymore, and only extraction conditions were needed to be optimized in this method, including the gas temperature of direct analysis in real time, extraction time, and CH3 COONH4 additive concentration. This method enabled the simultaneous detection of six kinds of glycosides with the limits of detection of 0.02-0.05μg/mL and the linear ranges covering two orders of magnitude with the limits of quantitation of 0.05-0.1μg/mL. Moreover, the developed method was applied for the glycosides analysis of three tobacco samples, which only took about 2s for every sample.

High performance liquid chromatography analysis of 100-nm liposomal nanoparticles using polymer-coated, silica monolithic columns with aqueous mobile phase

Recently, nanoparticles have garnered considerable attention, and the demand for a rapid and simple method for their analysis has increased accordingly. The bimodal pores (few μm- and few tens nm-sized pores) of monolithic columns were thought to be suitable for the separation of nanoparticles and small molecules; however, the residual silanol groups on the column surface resulted in the strong adsorption of liposomes and hindered their analysis. To overcome this problem, we modified the surface of the silica monolith via a two-step process and developed three silica monolithic columns coated with three different polymers: glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (HEMA), and N-vinylpyrrolidone (VP). These were used for the analysis of 100-nm liposomal nanoparticles. Since 15% polymer coating prevented the nanoparticle adsorption, liposomes (AmBisome®) and pegylated liposomes (DOXIL®) were eluted rapidly (within 1min) using these columns, without using organic solvents in the mobile phase. Molecular leaching from the liposomes, as well as protein adsorption to the liposomes (corona formation) could be evaluated using the polymer-coated columns, thus illustrating their utility in the rapid and simple analysis of 100-nm liposomal nanoparticles.

Grafted Polymethylhydrosiloxane on Hierarchically Porous Silica Monoliths: A New Path to Monolith-Supported Palladium Nanoparticles for Continuous Flow Catalysis Applications.

Polymethylhydrosiloxane has been grafted on the surface of a hierarchically porous silica monolith using a facile catalytic reaction between Si-H and silanol to anchor the polymer. This easy methodology leads to the functionalization of the surface of a silica monolith, where a large amount of free Si-H bonds remain available for reducing metal ions in solution. Palladium nanoparticles of 15 nm have been synthesized homogeneously inside the mesopores of the monolith without any stabilizers, using a flow of a solution containing Pd2+. This monolith was used as column-type fixed bed catalyst for continuous flow hydrogenation of styrene and selective hydrogenation of 3-hexyn-1-ol, in each case without a significant decrease of the catalytic activity after several hours or days. Conversion, selectivity, and stereoselectivity of the alkyne hydrogenation can be tuned by flow rates of hydrogen and the substrate solution, leading to high productivity (1.57 mol g(Pd)-1 h-1) of the corresponding cis-alkene.