Nonporous Silica Particles Research Articles

Application of mesoporous silica particles as an additive for controlling rheological, thermal, and filtration properties of water-based fluids

Mesoporous silica particles (MSP) have received increasing interest for various applications because of their unique features such as controlled pore size, low density, high chemical and thermal stability, and high surface area. In this study, MSP was applied as an additive in water-based drilling fluids (WBMs). The effect of MSP on the rheological, thermal, filtration, and structural properties of WBMs was investigated. The results were compared with those of analogous fluids containing conventional nonporous silica particles (SSP). Rheological assays showed shear-thinning and viscoelastic behavior, which were more noticeable for fluids including MSP. It was observed that low concentrations of MSP (0.25 %wt) can achieve the same rheological properties as the fluids with higher SSP content (up to 0.5 %wt). The rheological properties of SSP-containing fluids were not significantly affected by the presence of NaCl or aging tests. The theoretical Herschel–Bulkley model represents the rheological behavior of WBMs. The MSP-based WBMs exhibited better filtration properties before aging. The microstructures of the WBMs were analyzed using Scanning Electron Microscopy (SEM). A homogeneous distribution of SSP in the WBMs was observed, while particle agglomeration was observed in WBMs containing MSP. In addition, surface interactions were studied to elucidate the interactions between particles and fluid constituents. The surface interaction, assessed through ζ-potential and FTIR analysis, revealed that the binding affinities of BT, PAC, and XGD with MSP were augmented compared to their individual values. Based on the experimental results, MSP constitutes a promising alternative as an additive for the design of WBMs.

Comparison of superhydrophobic biodegradable PLA films with fluorine-free hexamethyldisilazane grafted silica and mesoporous silica particles

This study reports the surface coating of fluorine-free hexamethyldisilazane (HMDS) on non-porous silica particles (SPs) and mesoporous silica particles (MSPs), with nanopores arranged in the straight channels, and compares the degree of superhydrophobicity by coating them on biodegradable PLA film by gravure process. The particle sizes of SPs and MSPs are 50 nm and 800 nm, and the amount of HMDS grafted onto SPs and MSPs is 0.5% and 9.5%, respectively. The superhydrophobicity of these particles is confirmed by the measurement of water contact angle (WCA) as a function of HMDS concentration for SPs and MSPs from 0 to 1.6 M, respectively. The WCA of HMDS@SPs and HMDS@MSPs grafted with 1.6 M of HMDS is 152° and 151° (WCA of unmodified SPs and MSPs is 13.85° and 27.65°). To apply superhydrophobic PLA film coating, 5 wt% of HMDS@SPs and HMDS@MSPs were mixed with gravure solution and then coated on biodegradable polylactic acid (PLA) film. The results showed that the WCA of PLA film with HMDS@SPs and HMDS@MSPs were 98.40° and 152.31°, respectively. This remarkable difference in WCA is due to the dissociation of HMDS molecules grafted on the surface of SPs and MSPs, which are easily separated by the gravure solvent. For MSPs materials composed of many nanopores, the dissociated HMDS molecules are initially released into the solution but are retained within the nanopores. Therefore, the residual amount of HMDS molecules dissociated by the gravure solution is much higher in HMDS@MSPs than in HMDS@SPs.

Use graphene coated silica core shell particles to provide rapid, precise, and equivalent chemical composition distribution analysis for polyolefin materials by high temperature thermal gradient interaction chromatography

High temperature thermal gradient interaction chromatography (HT-TGIC) has been widely used to measure chemical composition distribution due to its applicability to separate crystalline and non-crystalline amorphous polyolefin materials. The compatibility of HT-TGIC with various detectors (infrared (IR), light scattering (LS), and viscometer) has also allowed a comprehensive analysis of molecular architecture of polyolefin and recycled plastics. The introduction of an easy-to-fabricate graphene coated onto non-porous silica particles as HT-TGIC column in 2020 showed a superior chromatographic performance over the traditional graphite column. A reduction in peak broadness (∼47 %) under identical experimental conditions was demonstrated in that research. This paper similarly uses a graphene column but with the focus on optimization of experimental parameters (concentration, and thermal cooling and heating rates etc.). Equivalent chemical composition distribution (CCD) data to that obtained by the incumbent graphite column over a wide range of polyolefins products was achieved, in addition to a shortened analysis time from 120 min down to 88 min per sample. The materials studied included semicrystalline linear low-density polyethylene (LLDPE), elastomers, terpolymers, model blends to mimic recycled plastics. The results also suggest that the elimination of substrate pores enable a better HT-TGIC separation. Coupling the ease and reproducibility of the graphene column fabrication process enables long term chromatographic robustness. This not only results in equivalent CCD data compared to the traditional graphite column but also a 27 % reduction in analysis time. These results demonstrate a substantial advancement of technology in the high throughput industrial laboratory setting where fast testing turnaround time is critical. In addition, simple fabrication with commercially available silica particles and graphene nanopowder provides a cost-effective approach to make HT-TGIC columns reproducibly.

Silica particles convert thiol-containing molecules to disulfides

Synthetic amorphous silica is a common food additive and a popular cosmetic ingredient. Mesoporous silica particles are also widely studied for their potential use in drug delivery and imaging applications because of their unique properties, such as tunable pore sizes, large surfaces areas, and assumed biocompatibility. Such a nanomaterial, when consisting of pure silicon dioxide, is generally considered to be chemically inert, but in this study, we showed that oxidation yields for different compounds were facilitated by simply incubating aqueous solutions with pure silica particles. Three thiol-containing molecules, L-cysteine, glutathione, and D-penicillamine, were studied separately, and it was found that more than 95% of oxidation happened after incubating any of these compounds with mesoporous silica particles in the dark for a day at room temperature. Oxidation increased over incubation time, and more oxidation was found for particles having larger surface areas. For nonporous silica particles at submicron ranges, yields of oxidation were different based on the structures of molecules, correlating with steric hindrance while accessing surfaces. We propose that the silyloxy radical (SiO•) on silica surfaces is what facilitates oxidation. Density functional theory calculations were conducted for total energy changes for reactions between different aqueous species and silicon dioxide surfaces. These calculations identified two most plausible pathways of the lowest energy to generate SiO• radicals from water radical cations H2O•+ and hydroxyl radicals •OH, previously known to exist at water interfaces.

Effect of monodisperse mesoporous bioactive glass spheres (MBGs) on the mechanical properties and bioactivity of dental composites

Secondary caries is one of the main reasons for the failure of dental resin composites, and adding bioactive fillers such as bioactive glass and amorphous calcium phosphate to the resin composites has been proved to be an effective solution for this problem. In the present study, we investigated the effect of monodisperse mesoporous bioactive glass spheres (MBGs) we prepared on the mechanical properties and bioactivity of dental resins. The results revealed that compared with traditional bioactive glass (BG), MBGs fillers significantly enhanced the mechanical properties of the dental resin composites, whether they were added alone or as functional fillers together with nonporous silica particles. The dental resins filled with bimodal fillers (mass ratio of MBGs: nonporous silica = 10:50, total filler loading 60 wt%) exhibited the best mechanical performance. Their flexural strength was 37.66% higher than the samples with BG at the same filling proportion. Furthermore, the prepared MBGs possessed excellent monodispersity and sufficient apatite formation performance, and the biocompatibility of the composites were also improved by MBGs fillers. These suggest the potential use of the prepared MBGs as multifunctional fillers for the improvement of the performance of dental resins.

Cobalt oxide decorated porous silica particles: Structure and activity relationship in the catalytic oxidation of carbon monoxide

Porous (0.6–30 nm) and non-porous spherical silica nanoparticles are synthesized. These silicas with different morphologies are decorated with cobalt (2.9 wt%) using Co(NO3)2·6H2O as precursor. Co-SiO2 particles are studied by N2 sorption, TEM, XRD, XPS, FTIR and TPR-H2 methods. Specific surface area (SSA) of the prepared materials is 10–1200 m2/g. The main crystalline phase is identified as Co3O4. The activity of Co-SiO2 composites in the CO oxidation and preferential oxidation of CO (PROX) in a H2-rich gas mixture improves with increasing atomic ratios of Co/Si and Co3+/Co2+ on the silica surface. Catalysts with the large mesopores containing mainly Co2+ are the least active. Co-SiO2 composites based on synthetic opal grown by sedimentation of non-porous silica particles with the lowest SSA demonstrate the highest catalytic activity. The CO conversion reaches 100% at 150 °C in the absence of hydrogen, while in PROX the 90% conversion of CO is achieved at 170 °C. The large Co3O4 aggregates between non-porous spherical silica particles of opal are the most active and stable during CO-PROX reaction. The lower interaction of Co3O4 nanoparticles with this support promotes the stabilization of the oxidized state Co3+ and provides a higher yield of CO2 in CO-PROX reaction.

Monodisperse core–shell silica particles as a high-performance liquid chromatography packing material: Facile in situ silica sol-gel synthesis

In recent years, core–shell silica particles (CSSPs) have been increasingly used for highly efficient separation at fast flow rates and relatively low back pressures in high-performance liquid chromatography (HPLC). However, material synthesis techniques for producing CSSPs economically in batch processes remain elusive. In this report, a practical and straightforward method for the preparation of CSSPs is presented. By refluxing freshly prepared nonporous silica particles in ammonia–water solution in the presence of poly(diallyldimethylammonium chloride) at 70–100 °C, CSSPs with shell thicknesses of up to 300 nm and pore sizes from 8 to 25 nm were easily prepared. The effects of the synthetic conditions on the shell thickness, surface area, and pore size were investigated in detail, and the method reproducibility was evaluated in scale-up experiments. A mechanism of CSSP formation is also proposed. The CSSPs were characterized via scanning electron microscopy, transmission electron microscopy, laser particle size (dynamic light scattering) analysis, and nitrogen adsorption and desorption experiments. The synthesized 3.4-μm CSSPs were functionalized with dimethyloctadecylchlorosilane and used as an HPLC packing material, exhibiting excellent separation performance for both small molecules and large biomolecules. In summary, we report the simplest method developed thus far for the preparation of monodisperse core–shell silica particles suitable for HPLC column packing.

Effects of different silica intermediate layers for hydrogen diffusion enhancement of palladium membranes applied to porous stainless steel support

Porous stainless steel (SUS) supports were modified with double intermediate layers, silicalite-1 and γ-alumina, to enhance the hydrogen diffusion of a thin palladium membrane. One of layers, silicalite-1, was prepared using the hydrothermal synthetic method on porous SUS supports. The differences in expansion/contraction behaviors caused by different thermal coefficients of expansion between silicalite-1 and the SUS resulted in a lowering of the durability of the membrane. Intermediates layers of mesoporous MCM-48 powders or commercial spherical non-porous silica particles were then applied to porous SUS supports via aspiration, γ-alumina was introduced by dip-coating, and the Pd membrane was subjected to electro-less plating. H2 permeance of the Pd membrane (membrane thickness: 11 μm) containing spherical silica particles was around 10 × 10−6 mol·m−2·s−1·Pa−1 at 600 °C, which was higher than that of the Pd membrane (membrane thickness: 7 μm) containing MCM-48. The durability of the Pd membrane containing spherical silica particles was higher than that of the version containing MCM-48 powders. These results suggest that commercial spherical non-porous silica particles will uniformly occupy the pores of the SUS tubes and enhance the H2 permeance and durability of the Pd membrane.

The elution behavior of cyclosporine congeners in a developed HPLC system reflects the lipophilicity

Recently, the development of cyclic peptide drugs has accelerated. To develop an analytical method to determine the physicochemical properties of these lipophilic drug candidates, we investigated the separation mechanism of cyclosporine congeners A, B, C, and D using HPLC with a column packed with 2-μm nonporous octadecylsilyl silica particles at high temperature. The four congeners were eluted with good repeatability in terms of retention time, peak area, and theoretical plate number. A difference of one amino acid in the eleven amino-acid sequence of the cyclosporine congeners was able to be recognized by our system within 4 min by isocratic elution, and the resolution was greater than 1.68. The calculated logP values of these congeners were well correlated with the retention factors with a correlation coefficient of 0.991. We could elucidate the separation mechanism of cyclosporine congeners on the high-temperature HPLC system. These results show that this method using HPLC on a column packed with 2-μm nonporous octadecylsilyl silica particles can be used for studying the lipophilicity of cyclosporine congeners.

Sustainable and reagent-free mercury trace determination in natural waters using nanogold dipsticks

Determination of mercury traces in the hydrosphere is an important and still challenging analytical task. Here we report on a novel solid phase extraction (SPE) method for total dissolved mercury (Hg) determination in natural waters using newly developed nanogold-coated dipsticks. Straightforward preparation of the dipsticks comprises golf film deposition onto glass substrates modified with APTMS-coated non-porous silica particles (ø = 300 nm). Subsequent annealing process leads to an immobilized gold nanoparticle (AuNP) layer on the surface of the flat sampling sticks, which was characterized in detail by electron microscopy. For selective Hg accumulation into this active AuNP layer, the dipstick is immersed in the water sample for a few seconds up to 10 min depending on the concentration range of the sample and desired sensitivity. After thermal desorption of Hg from the sticks subsequent quantification by atomic fluorescence spectroscopy (AFS) is performed. Several parameters for SPE like duration, temperature, turbulent and stagnant conditions, as well as heating duration for Hg release were investigated and optimized. The limit of detection was found to be as low as 0.18 ng Hg L−1 for 10 min extraction duration and calculated to be 10 ng L−1 for a dipping time of only 10 s. High reproducibility with relative standard deviations ≤4.9% (n = 3) is given. In addition, high repeatability and low batch-to-batch variation for individually prepared dipsticks confirm feasibility of the approach. The validity of the optimized approach was confirmed by successful recovery experiments in real seawater (R = 105%), river water (R = 98%) and the certified reference material ERM-CA400 (seawater; R = 94%).

Phase evolution during one-pot synthesis of amine modified mesoporous silica materials: Preparation, properties, carbon dioxide adsorption

Amino-functionalized mesoporous MCM-41 materials were synthesised by co-condensation of amino-organosiloxane precursors, namely 3-aminopropyltrimethoxysiloxane (APS), 3-(methylamino)propyltrimethoxysiloxane (MAPS) and 3-(phenylamino)propyltrimethoxysiloxane (PAPS) with tetraethyl orthosilicate (TEOS) in water solution containing ammonia and in the presence of surfactant as templating agent. The ratio of amino-organosiloxanes to TEOS in the synthesis mixture was 3, 5, 10, 20 and 30 wt%. The prepared samples were characterized by Small Angle X-ray Scattering (SAXS), High-Resolution Transmission Electron Microscopy (HRTEM), Thermogravimetric Analysis (TGA) and N2 adsorption/desorption. It followed from the measurements that the ordered porous materials of hexagonal symmetry were obtained at small ratios of APS and MAPS to TEOS (3, 5, 10 wt%). At larger ratios (20 and 30 wt%), disordered or non-porous amorphous amino-functionalized silica particles were obtained. For the PAPS precursor, hexagonally-packed structures were observed up to a PAPS to TEOS ratio of 30 wt%, when a transition to a lamellar phase occurs. The reasons of the structural changes are discussed in terms of modifications in the effective shapes of the cylindrical micelle aggregates, caused by different hydrophilicity/hydrophobicity of the used amine precursors and their interactions with surfactant micelles. To better understand the origin of this behavior, lattice Monte Carlo simulations of simple coarse-grained surfactant solutions were performed. All prepared samples were used to study CO2 adsorption. It was found that CO2 adsorption capacity in the samples increased with the increasing concentration of amino-organosiloxane precursor, independently of the surface area. These results imply that CO2 adsorption primarily takes place on amine active centers and physical adsorption, which is dependent on the high surface area, plays a less important role in CO2 adsorption on these materials.

Pore Diameter of Mesoporous Silica Modulates Oxidation of H2O2-Sensing Chromophore in a Porous Matrix.

Hydrogen peroxide (H2O2) is an attractive chemical because of its bleaching properties in paper and pulp industry and as a disinfectant in the food, water, and medical industries. However, it is important to monitor the residual H2O2 level after its usage and prevent any unintended health problems or chemical reactions. Most H2O2 sensors often utilize fluorophores or electrical circuitry that requires an additional irradiation or a digital display. To this end, this study presents a 3,3',5,5'-tetramethylbenzidine (TMB)/horseradish peroxidase (HRP)-loaded patch that alerts the presence of high H2O2 levels by generating a visible blue color. We hypothesized that water-insoluble TMB immobilized within mesoporous silica particles of proper pore diameter and structure would act as a colorimetric indicator through the H2O2-mediated oxidation within a cross-linked patch. We examined this hypothesis by immobilizing TMB molecules in mesoporous silica particles with 2 and 7 nm diameter cylindrical pores as well as on nonporous silica particles. Then, we loaded these TMB-silica particles and HRP in a porous alginate patch via sequential in situ cross-linking reaction and lyophilization. In the presence of 25-5000 μM H2O2, which simulate H2O2 concentrations found in residual disinfecting fluids, the patch loaded with TMB-mesoporous silica particles with 7 nm diameter pores generated a distinct blue color with varying intensities depending on the H2O2 concentration. The design principles demonstrated in this study should be applicable to a broad array of sensors to be integrated into a moldable, three-dimensional matrix.

Rapid Analysis of Cyclic Peptide Cyclosporine A by HPLC Using a Column Packed with Nonporous Particles.

We developed a rapid and efficient analytical technique for cyclosporine A using HPLC on a column packed with 2-µm nonporous octadecylsilyl silica particles. Under optimized conditions, cyclosporine A was separated with high resolution from other cyclic peptides within 3 min, because the mass transfer resistance in the stationary phase was reduced by the use of the small, nonporous particles. Although the plate number increased greatly with the increase in the column temperature, the retention times were not affected. This behavior is different from other cyclic peptides or linear peptides. Based on its physicochemical characteristics, cyclosporine A is a poor hydrogen bond donor, and has a small topological polar surface area, low rotatable bond count, and high log P value. These results show that cyclosporine A is structurally rigid and undergoes poor water solvation even at high temperature. In the context of the rapid development of cyclic peptides with similar physicochemical characteristics to cyclosporine A, our developed method is useful for the development of cyclic peptide therapeutics.

Preparation of Ultraviolet Curing Type Silicone Rubbers Containing Mesoporous Silica Fillers.

Here we have been focusing on mesoporous silica (MPS) as inorganic filler material to improve the mechanical strength of silicone rubbers. The MPS particles are more effective in reducing the coefficient of thermal expansion (CTE) and hardening silicone rubber composites when compared to commercially available nonporous silica particles. In this study, we utilize ultraviolet curing type silicone rubbers and prepare MPS composites according to a simple single-step method. From an industrial viewpoint, simplifying the fabrication processes is critical. The thermal stability and mechanical strength are examined in detail in order to showcase the effectiveness of MPS particles as filler materials.

Rationally Turning the Interface Activity of Mesoporous Silicas for Preparing Pickering Foam and "Dry Water".

We develop a novel protocol to prepare smart, gas/water interface-active, mesoporous silica particles. This protocol involves modification of highly mesoporous silicas with a mixture of hydrophobic octyl organosilane and hydrophilic triamine organosilane. Their structure and compositions are characterized by transmission electron microscopy (TEM), N2 sorption, solid state NMR, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FT-IR), thermogravimetric analysis (TGA), and elemental analysis. It is demonstrated that our protocol enables the interface activity of mesoporous silica particles to be facilely tuned, so that the stable gas-water interfaces ranging from air bubbles dispersed in water (Pickering foam) and water droplets dispersed in air ("dry water") can be achieved, depending on the molar ratio of these two organosilanes. The "dry water" is not otherwise attainable for the analogous nonporous silica particles, indicting the uniqueness of the chosen mesoporous structures. Moreover, these particle-stabilized Pickering foams and "dry waters" can be disassembled in response to pH. Interestingly, it was found that aqueous potassium carbonate droplets stabilized by these interface-active mesoporous silica particles ("dry K2CO3-containing water") could automatically capture CO2 from a simulated flue gas with enhanced adsorption rate and adsorption capacity when compared to the aqueous potassium carbonate bulk solution. This study not only supplies a novel type of efficient, smart, gas/water interface-active mesoporous silica particles but also demonstrates an innovative application of mesoporous materials in gas adsorption.

Enhanced Acrylate Production from 2-Acetoxypropanoic Acid Esters

Reaction conditions and reactor geometry for producing acrylates in high yield from lactic acid-derived 2-acetoxypropanoic acid (APA) esters are presented. An acrylate ester yield of 75% is achieved from methyl and benzyl APA esters at 550 °C in a fixed bed reactor filled with nonporous silica particles, carbon dioxide as a diluent gas, and acetic acid as a co-feed with the APA ester. The yield from methyl and benzyl APA esters is remarkably higher than from ethyl or butyl esters of APA, which have hydrogen atoms on the β-carbon of the ester functional group and thus can undergo alkene elimination, leading to reduced acrylate yield. Under optimum conditions, APA conversion to acrylates is stable over 30 h of continuous operation with little carbon deposition on the contact material.

Membrane interactions of mesoporous silica nanoparticles as carriers of antimicrobial peptides

Membrane interactions are critical for the successful use of mesoporous silica nanoparticles as delivery systems for antimicrobial peptides (AMPs). In order to elucidate these, we here investigate effects of nanoparticle charge and porosity on AMP loading and release, as well as consequences of this for membrane interactions and antimicrobial effects. Anionic mesoporous silica particles were found to incorporate considerable amounts of the cationic AMP LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES (LL-37), whereas loading is much lower for non-porous or positively charged silica nanoparticles. Due to preferential pore localization, anionic mesoporous particles, but not the other particles, protect LL-37 from degradation by infection-related proteases. For anionic mesoporous nanoparticles, membrane disruption is mediated almost exclusively by peptide release. In contrast, non-porous silica particles build up a resilient LL-37 surface coating due to their higher negative surface charge, and display largely particle-mediated membrane interactions and antimicrobial effects. For positively charged mesoporous silica nanoparticles, LL-37 incorporation promotes the membrane binding and disruption displayed by the particles in the absence of peptide, but also causes toxicity against human erythrocytes. Thus, the use of mesoporous silica nanoparticles as AMP delivery systems requires consideration of membrane interactions and selectivity of both free peptide and the peptide-loaded nanoparticles, the latter critically dependent on nanoparticle properties.

One-pot synthesis of micron partly hollow anisotropic dumbbell shaped silica core-shell particles.

A facile method is described to prepare micron partly hollow dumbbell silica particles in a single step. The obtained particles consist of a large dense part and a small hollow lobe. The spherical dense core as well as the hollow lobe are covered by mesoporous channels. In the case of the smaller lobe these channels are responsible for the permeability of the shell which was demonstrated by confocal imaging and spectroscopy.

Teicoplanin bonded sub-2 μm superficially porous particles for enantioseparation of native amino acids

Superficially porous particles (SPPs) demonstrate superior efficiency than totally porous particles in chiral separations. In order to obtain high efficiency and fast separation, sub-2μm SPPs with high surface area are synthesized, and with teicoplanin bonded, such materials are successfully applied into the rapid enantioseparation of native amino acids. In brief, 1.27±0.06μm nonporous silica particles are prepared by a modified seeded growth method, followed by mesoporous shell fabrication via one-pot templated dissolution and redeposition strategy, and pore size expansion via acid-refluxing. The diameter of the formed SPPs is 1.49±0.04μm, with the shell thickness as 206nm. Nitrogen physisorption experiments show that the Brunauer–Emmett–Teller (BET) specific surface area is 213.6m2/g and pore size is 9nm. After teicoplanin derivatization with bonding capacity as 83.3μmol/g, the prepared chiral stationary phase is packed into a stainless steel tube with the geometry of 50mm×2.1mm i.d.. In less than 6.4min, six native amino acids (norleucine, alanine, valine, methionine, leucine, norvaline) are enantioseparated with resolution factors ranging from 1.9 to 5.0. Besides, the resolution for chiral separation is improved with ethanol-water instead of methanol-water as the mobile phase. Moreover, the low temperature gives higher resolution, but longer retention time and higher backpressure. Finally, the effect of flow rate on enantiomeric separation is studied and fast chiral separation within 1min is obtained with flow rate of 0.4mL/min. All these results show that the synthesized teicoplanin bonded sub-2μm SPPs have great potential to achieve the enantioseparation of native amino acids with high resolution and rapid speed.

Flavonoid adsorption and stability on titania-functionalized silica nanoparticles

The interaction of flavonoids with silica surfaces is of interest for separation and recovery of these natural products with potential anti-oxidant and anti-inflammatory properties. The benefit of tailored silica materials for natural product separation is based on the ability to readily tune their surface functionality and pore structure. In this work, the adsorption of quercetin, a model plant-derived flavonoid, was measured on silica particles (450 nm diameter) that were non-functionalized, hydrophobically functionalized (16.2 mg decyl groups/g) or titania modified (0.33–9.83 mg TiO2/g). Quercetin interactions with these functionalized silica particles were interpreted from adsorption measurements on non-porous silica particles, which eliminate the potential diffusional and steric constraints of pores. Titania functionalized particles are found to exhibit significantly increased adsorption capacities compared to non-functionalized and decyl functionalized materials, presumably due to binding of quercetin to the metal oxide, and this capacity increased linearly with surface coverage of titania. The ability to recover the activity of bound quercetin is demonstrated using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. This investigation provides guidelines for the surface modification of both porous and nonporous silica for the recovery of natural product flavonoids, taking advantage of the binding properties of the functionalized silica surface.