Aggregation Of Silica Nanoparticles Research Articles

Crack propagation behaviors in a nanoparticle‐filled rubber studied by in situ tensile electron microscopy

AbstractAlthough fracture resistance is critical for rubber materials, the fracture mechanisms are poorly understood from a microscopic perspective. In this study, a crack propagation process in rubber with silica nanoparticles, which is commonly used to enhance the mechanical properties of rubber materials, was successfully observed in situ with nanoscale resolution using transmission electron microscopy (TEM). The consecutive time‐sliced TEM images clarified that the crack tip propagated along the interfaces between the rubber matrix and aggregates of silica nanoparticles (rubber‐aggregate interfaces). Moreover, the path and propagation rate of the crack were significantly affected by the heterogeneous distribution of the silica aggregates, which resulted in a “stick–slip” propagation behavior of the crack tip. Detailed spatial strain analysis revealed that the local maximum principal strain () around the crack tip was nonuniform. The crack tip propagated through regions with large , delaminating the rubber‐aggregate interfaces. This study successfully demonstrated that the heterogeneous distribution of nanoparticles significantly affects the fracture behavior of nanoparticle‐filled rubbers.

Fiber template approach toward preparing one-dimensional silica nanostructure with rough surface

Silica nanofibers were grown on the surface of chitosan nanofibers used as templates by coating the surface with silica derived from the hydrolysis and condensation of tetraethoxysilane using ammonium hydroxide as a catalyst. This was followed by the decomposition of the chitosan template. The relationship between different processing factors (type of templates as well as amounts of catalyst and template) and the formation of silica nanofibers was examined. Varying the processing factors was found to be effective in controlling the morphology of the silica nanofibers. The use of chitosan nanofibers effectively led to the formation of one-dimensional silica nanofibers as the positively charged chitosan nanofibers promoted the deposition of the negatively charged silica nanoparticles through electrostatic attractive forces. Therefore, the chitosan nanofibers acted as good deposition sites for interacting with silica nanoparticles. Although a large amount of catalyst promoted the sol-gel reaction, the silica nanoparticles grew excessively in the solvent. Therefore, the surface structure of the prepared silica nanofibers could be controlled by varying the amount of chitosan template as this also varied the formation mechanism of the silica nanofibers. The resultant samples had a rough silica wall composed of densely assembled silica nanoparticles, with a high specific surface area (338 m2/g).

Understanding the temperature induced aggregation of silica nanoparticles decorated with temperature-responsive polymers: Can a small step in the chemical structure make a giant leap for a phase transition?

Temperature-responsive nanomaterials have gained increasing interest over the past decade due their ability to undergo conformational changes in situ, in response to a change in temperature. One class of temperature-responsive polymers are those with lower critical solution temperature, which phase separate in aqueous solution above a critical temperature. When these temperature-responsive polymers are grafted to a solid nanoparticle, a change in their surface properties occurs above this critical temperature, from hydrophilic to more hydrophobic, giving them a propensity to aggregate. This study explores the temperature induced aggregation of silica nanoparticles functionalised with two isomeric temperature-responsive polymers with lower critical solution temperature (LCST) behavior, namely poly(N-isopropyl acrylamide) (PNIPAM), and poly(2-n-propyl-2-oxazoline) (PNPOZ) with similar molecular weights (5000 Da) and grafting density. These nanoparticles exhibited striking differences in the temperature of aggregation, which is consistent with LCST of each polymer. Using a combination of small-angle neutron scattering (SANS) and dynamic light scattering (DLS), we probed subtle differences in the aggregation mechanism for PNIPAM- and PNPOZ-decorated silica nanoparticles. The nanoparticles decorated with PNIPAM and PNPOZ show similar aggregation mechanism that was independent of polymer structure, whereby aggregation starts by the formation of small aggregates. A further increase in temperature leads to interaction between these aggregates and results in full-scale aggregation and subsequent phase separation.

Hydrogel-Tissue Adhesion Using Blood Coagulation Induced by Silica Nanoparticle Coatings.

The fixation of hydrogels to biological tissues is a major challenge conditioning the development of implants and surgical techniques. Here, coatings of procoagulant nanoparticles are devised which use the presence of blood to create adhesion between hydrogels and soft internal organs. Those nanostructured coatings are simply adsorbed at the hydrogel surfaces and can rapidly activate the formation of an interfacial blood clot acting as an adhesive joint. This concept is demonstrated on pig liver capsules with model poly(ethylene-glycol) membranes that are intrinsically poorly adhesive. In the absence of blood, ex vivo peeling tests show that coatings with aggregates of bare silica nanoparticles induce a 2- to 4-fold increase in adhesion energy as compared to the uncoated membrane (3 ± 2 J m-2). This effect is found to scale with the specific surface area of the coating. The highest adhesion energies produced by these nanoparticle-coated membranes (10 ± 5 J m-2) approach the value obtained with cyanoacrylate glue (33 ± 11 J m-2) for which tearing of the tissue is observed. Ex vivo pull-off tests show an adhesion strength of coated membranes around 5 ± 1 kPa, which is significantly reduced when operating in vivo (1.0 ± 0.5 kPa). Nevertheless, when blood is introduced at the interface, the in vivo adhesion strength can be improved remarkably with silica coatings, reaching 4 ± 2 kPa after 40 min contact. In addition, these silica-coated membranes can seal and stop the bleeding produced by liver biopsies very rapidly (<30 s). Such a combination of coagulation and particle bridging opens promising routes for better biointegrated hydrogel implants and improved surgical adhesives, hemostats, and sealants.

A Study of the Optical Properties and Fabrication of Coatings Made of Three-Dimensional Photonic Glass

Photonic crystals employ optical properties based on optical, physical, chemical, and material science. Nanosilica particles have a high specific surface area and are widely used in nanotechnology research and biomedical applications. In this study, nanosilica particles were fabricated by sol–gel methods, and the particle sizes of the silica nanoparticles were 280, 232, and 187 nm, based on dynamic light scattering. The silica nanoparticle suspension solution was heated to boiling for fast evaporation processing for self-assembly to fabricate three-dimensional photonic glass for structural color coatings. The sample had an adjustable structural color (red: 640 nm, green: 532 nm, and blue: 432 nm). The microstructures of various structure-colored samples were arranged, but there was a disordered solid arrangement of silica nanoparticles. These were not perfect opal-based photonic crystals. Compared to opal-based photonic crystals, the arrangement of silica nanoparticles was a glassy structure with a short-range order. Due to the accumulation of silica nanoparticle aggregates, samples displayed a stable colloidal film, independent of the viewing angle. In our study, the fast solvent evaporation in the self-assembly process led to the formation of a colloidal amorphous array, and it fitted the requirement for non-iridescence. Non-iridescent photonic glass with various colors was obtained. This type of color coating has wide potential applications, including reflective displays, colorimetric sensors, textiles, and buildings.

Assembly of silica nanoparticles based on stimuli-responsive covalent bonding between glycopolymers and poly(phenylboronic acid)s

Covalent bonding between boronic acid and cis-diols is widely used to prepare stimuli-responsive nano materials. Herein, we report a kind of extremely rapid formation of boronate esters between glycopolymers and poly(phenylboronic acid)s for the assembly of silica nanoparticles. High-density poly(glycidyl methacrylate) brushes are first immobilized onto the surface of silica nanoparticles by surface initiated Cu(0) mediated reversible deactivation radical polymerization (SI-Cu(0)-RDRP). Subsequent post-polymerization modifications via click chemistry facilely fabricate the polymer scaffolds with pendent saccharides or phenylboronic acid (PBA) units. The rapid formation of boronate esters between glycopolymer and poly(PBA) induces further self-assembly and fast aggregation of nanoparticles. The sugar-containing boronate esters could survive under high temperature, excess monosaccharides and extreme pH. Hyper-cross-linked glycopolymer networks with tuned porous properties are prepared after etching of silica templates by hydrofluoric acid.

Multiscale Colloidal Assembly of Silica Nanoparticles into Microspheres with Tunable Mesopores

AbstractColloidal assembly of silica (nano)particles is a powerful method to design functional materials across multiple length scales. Although this method has enabled the fabrication of a wide range of silica‐based materials, attempts to design and synthesize porous materials with a high level of tuneability and control over pore dimensions have remained relatively unsuccessful. Here, the colloidal assembly of silica nanoparticles into mesoporous silica microspheres (MSMs) is reported using a discrete set of silica sols within the confinement of a water‐in‐oil emulsion system. By studying the independent manipulation of different assembly parameters during the sol–gel process, a design strategy is outlined to synthesize MSMs with excellent reproducibility and independent control over pore size and overall porosity, which does not require additional ageing or post‐treatment steps to reach pore sizes as large as 50 nm. The strategy presented here can provide the necessary tools for the microstructural design of the next generation of tailor‐made silica microspheres for use in separation applications and beyond.

Enzyme immobilization using two processing methods onto silica core-shell particles

Two methods of enzyme immobilization onto silica core-shell particles were developed. The first method involved the immobilization of Candida rugosa lipase inside a previously synthesized mesoporous silica layer (deposited at 80°C) surrounding a dense silica core. To prevent lipase leakage from the support, an outer mesoporous silica layer was deposited at 40°C around the first silica layer containing the immobilized lipase. The deposition of the second layer was performed at a relatively lower temperature, to prevent thermal inactivation of the immobilized enzyme. The internal silica layer was obtained by assembling primary silica nanoparticles generated from highly basic sodium silicate solution at 80°C on the surface of poly (diallyldimethylammonium chloride) (PDDA) functionalized silica core particles. The average shell thickness and pore size of the internal silica layer was ∼60nm and 24nm, respectively. The effect of process parameters on generation and aggregation of silica nanoparticles prepared from highly basic sodium silicate solution was also investigated. The aggregation of silica particles generated at 40°C and 80°C took place after 840s and 570 of reactions, respectively. The immobilization efficiency of lipase on the mesoporous silica monolayer was 80%. A decline of immobilized lipase activity was approximately 6 times after 10 reaction cycles due to lipase leakage from the monolayered shell. An outer mesoporous silica layer was deposited at 40°C onto the surface of previously PDDA-functionalized monolayered silica core-shell particles containing the immobilized lipase. The average thickness and pore size of outer mesoporous silica layer was ∼60nm and 17nm, respectively. The activity of lipase immobilized inside the bilayered shell was further reduced due to diffusion resistance within the outer silica layer and PDDA layer however, it was retained for the next reaction cycles.The pore size of mesoporous silica layer obtained at 80°C was insufficient to allow invertase immobilization. Thus, the second method for the immobilization of invertase was developed. It involved the preparation of the mesoporous silica layer simultaneously with invertase immobilization at 40°C. The immobilized invertase showed decreased activity, but it was not hampered by substrate inhibition, as in the case of the free enzyme, due to the location of the enzyme inside the mesoporous silica layer, where the mass transfer resistance for the substrate to the enzyme active site was present.

Aggregation of Silica Nanoparticles in Sol-Gel Processes to Create Optical Coatings with Controllable Ultralow Refractive Indices.

Optical coatings with controllable ultralow refractive indices are of profound significance in optical areas. However, it remains a challenge to fabricate such coatings using a simple method. Here we develop an effective and simple approach to create ultra-low-index coatings. This approach was based on a modified sol-gel process, with a key process that involved the aggregation of silica nanoparticles via the addition of a polymer surfactant (e.g., polyvinylpyrrolydone) in sols before coating. The approach involves three steps: the synthesis of silica sols under ammonia catalysis in ethanol (Stöber method), the addition of polyvinylpyrrolydone in the silica sols to induce the aggregation of the silica nanoparticles, and the formation of ultra-low-index coatings by depositing the aggregated silica sols on substrates. Through varying the aggregation extent, this approach produced coatings with controllable refractive indices ranging from 1.17 to 1.07. To the best of our knowledge, the minimum index value of 1.07 from our coating is among the lowest refractive indices ever reported. The ultra-low-index coatings demonstrated excellent optical properties, with which perfect quarter-wavelength antireflection coatings (maximum transmittance ∼100%) and broadband antireflection coatings (transmittance >98% from 400 to 1100 nm) can be prepared. One advantage of the antireflection coatings is that their transmission is less dependent on the refractive index and the thickness of the stacking layer, which make it promising in large-scale production. Moreover, the coatings can be made hydrophobic (water contact angle 136°) by exposing the coatings to a hexamethyldisilazane atmosphere, exhibiting high environmental stability in a humid environment. The aggregation of silica nanoparticles in sol-gel processes provides a scalable alternative to the current approaches for creating ultra-low-index coatings.

Preparation and application of silica nanoparticles-Ocimum basilicum seeds bio-hybrid for the efficient immobilization of invertase enzyme

For efficient utilization of immobilized invertase enzyme, a novel bio-hybrid support comprising silica nanoparticles and Ocimum basilicum seed was synthesized. Ocimum basilicum seeds provide a natural fibrouspellicular structure which acts as template for assembly of silica nanoparticles. Bio-hybrids of two different morphologies have been obtained by changing the physico-chemical conditions of the assembly process. Developed bio-hybrids were characterized through small angle X-ray scattering (SAXS), scanning electron microscopy (SEM), Synchrotron radiation based X-ray micro-computed tomography (SRμCT), Brunauer–Emmett–Teller (BET) and Fourier transform infrared spectroscopy (FTIR). Incorporation of the nanoparticles results to a fourfold increase in the available surface area of the seeds which is one of the important criteria for an immobilizing support. Synthesized bio-hybrids were used for the immobilization of commercially applicable invertase enzyme and efficient loading of enzyme was realized. Enzyme immobilized bio-hybrids could be easily separated out and reused up to eight times with 82 % retention of enzyme activity. Present work suggests that the unique features of the bio-hybrid make it suitable candidate for immobilization of enzymes in general.

Inorganic/organic nanocomposite ion gels with well dispersed secondary silica nanoparticles.

We have previously reported tough inorganic/organic nanocomposite (NC) ion gels composed of silica particles and poly(N,N-dimethylacrylamide) (PDMAAm) networks and a large amount of ionic liquid. In this study, the network structure and toughening mechanism of NC ion gels were investigated. The NC ion gels showed characteristic mechanical properties; i.e. the stress was significantly increased at a highly elongated state. In addition, the NC ion gels showed an almost elastic mechanical property, which was completely different from that of our other developed inorganic/organic tough ion gels named double-network (DN) ion gels. It was found from structural observation that secondary silica nanoparticles dispersed well in the NC ion gel. It was also found that some of the secondary silica nanoparticles had a ring-like structure which would incorporate PDMAAm chains. From the silica particle content dependency on stress–strain curves of inorganic/organic NC ion gels, it was inferred that the secondary silica particles could serve as a movable cross-linker of PDMAAm chains in the NC ion gel.

Application of a linear electrodynamic quadrupole trap for production of nanoparticle aggregates from drying microdroplets of colloidal suspension

We have made advancements in a linear electrodynamic quadrupole trap (LEQT) to produce various nanoparticle microaggregates and drop patterns by evaporation-driven aggregation in levitating droplets of colloidal suspensions and to analyse their properties. The LEQT is mounted in a small chamber with well controlled atmospheric parameters, such as temperature and relative humidity, to trap droplets ranging from ∼70 μm down to ∼1 μm in diameter and provide a controlled environment to study formation of nanoparticle aggregates. Transient and final dry microstructures formed during the droplet drying life-time have been deposited on a silicon substrate placed in the bottom part of the trap and studied off-line with scanning electron microscopy (SEM). The experimental results are supported/supplemented by the numerical model of evaporation-driven aggregation under various conditions. The application of the CUDA technology allowed us to simulate aggregation of a few hundred thousand nanoparticles of several types. Using the LEQT we investigated highly-ordered aggregates of silica nanoparticles, composites of silica and gold nanoparticles as well as sodium dodecyl sulfate (SDS) crystalline microstructures and aggregates of silica nanoparticles with SDS. We observed the formation of microstructures at the successive stages of aggregation and under various experimental conditions. The observed final microstructures demonstrate the technical capabilities and versatility of the LEQT for its adaptation for droplet drying scale-up applications such as spray drying.

Colloidal particle aggregation in three dimensions.

Colloidal systems are of importance not only for everyday products, but also for the development of new advanced materials. In many applications, it is crucial to understand and control colloidal interaction. In this paper, we study colloidal particle aggregation of silica nanoparticles, where the data are given in a three-dimensional micrograph obtained by high-angle annular dark field scanning transmission electron microscopy tomography. We investigate whether dynamic models for particle aggregation, namely the diffusion limited cluster aggregation and the reaction limited cluster aggregation models, can be used to construct structures present in the scanning transmission electron microscopy data. We compare the experimentally obtained silica aggregate to the simulated postaggregated structures obtained by the dynamic models. In addition, we fit static Gibbs point process models, which are commonly used models for point patterns with interactions, to the silica data. We were able to simulate structures similar to the silica structures by using Gibbs point process models. By fitting Gibbs models to the simulated cluster aggregation patterns, we saw that a smaller probability of aggregation would be needed to construct structures similar to the observed silica particlestructure.

Synthesis of Hollow Silica Nanoparticle Aggregates from Asymmetric Methyltrimethoxysilane Using a Modified SBA-15 Method

This work presents the synthesis and characterization of hollow silica particles that were fabricated with the asymmetric methyltrimethoxysilane (MTMS) as the only silica precursor, by using a modified SBA-15 synthesis method, for the first time. The MTMS concentration was varied in the range from 0.300 to 0.900 M. The hollow silica nanoparticulate material characteristics were compared to those of SBA-15 silica made by using tetraethyl orthosilicate. The hollow silica nanoparticle aggregates (named as MS-Asym) showed varied nanoparticle shapes from irregular to close to spherical, with multiple hollow pores as characterized by SEM and TEM. This result is very different from SBA-15, which has a ropelike shape. X-ray diffraction data showed that the MS-Asym silica samples were disordered compared to the ordered SBA-15. Nitrogen sorption measurements suggested that the SBA-15 is mainly mesoporous, whereas MS-Asym has a combined microporous and mesoporous structure. Furthermore, attenuated total reflectance-Fourier transform infrared spectroscopy spectra infer a different polymerization mechanism occurs for MS-Asym compared to that of SBA-15 silica.

Control of Silver Coating on Raman Label Incorporated Gold Nanoparticles Assembled Silica Nanoparticles.

Signal reproducibility in surface-enhanced Raman scattering (SERS) remains a challenge, limiting the scope of the quantitative applications of SERS. This drawback in quantitative SERS sensing can be overcome by incorporating internal standard chemicals between the core and shell structures of metal nanoparticles (NPs). Herein, we prepared a SERS-active core Raman labeling compound (RLC) shell material, based on Au–Ag NPs and assembled silica NPs (SiO2@Au@RLC@Ag NPs). Three types of RLCs were used as candidates for internal standards, including 4-mercaptobenzoic acid (4-MBA), 4-aminothiophenol (4-ATP) and 4-methylbenzenethiol (4-MBT), and their effects on the deposition of a silver shell were investigated. The formation of the Ag shell was strongly dependent on the concentration of the silver ion. The negative charge of SiO2@Au@RLCs facilitated the formation of an Ag shell. In various pH solutions, the size of the Ag NPs was larger at a low pH and smaller at a higher pH, due to a decrease in the reduction rate. The results provide a deeper understanding of features in silver deposition, to guide further research and development of a strong and reliable SERS probe based on SiO2@Au@RLC@Ag NPs.

Oxyanion-Binding in a Bioinspired Nanoparticle-Assembled Hybrid Microsphere Structure: Effective Removal of Arsenate/Chromate From Water

We demonstrate a bioinspired assembly wherein the specific interaction of polyamines with multivalent anions allows the assembly of silica nanoparticles to generate hybrid microsphere structures while this very phenomenon further provides ways for the microspheres to adsorb oxyanions like arsenate and chromate. In a typical method based on the biomineralization of diatomaceous biosilica structure, thus produced nanoparticle-assembled microspheres with a porous structure and hybrid functionalities exhibit efficient adsorption and separation of these toxic anions from water. The adsorption follows Freundlich isotherm with an inference for stronger interaction between adsorbate and adsorbent with nonuniform distribution of adsorption affinities. The opportunities to tune the composition with respect to the multivalent anion and their interaction with the polyamine, charge ratio, and so forth, illustrate the design of bioinspired robust structures with efficient oxyanion-binding property and recyclability. Th...

Dynamic moduli and creep damping analysis of short carbon fiber reinforced polymer hybrid nanocomposite containing silica nanoparticle-on the nanoparticle size and volume fraction dependent aggregation

A hierarchical micromechanical procedure in conjunction with the elastic-viscoelastic correspondence principle is presented to estimate the dynamic moduli and creep damping capacity of short carbon fiber (CF) reinforced polymer hybrid nanocomposite (HNC) containing silica nanoparticle (SNP). At First, an analytical expression is derived to extract the damping properties in the frequency domain associated with a power law creep-time model. Then, a third phase known as interphase whose properties vary gradually, is taken into account to model the SNP/polymer interactions. The polymer matrix and the interphase obey a viscoelastic constitutive law. The CF random orientation is involved in the analysis as well. The effects of various parameters, including the SNP content, aggregation state and size; the CF content; the interphase properties; and the loading frequency (LF) on the HNC elastic modulus, creep compliance, storage modulus, loss modulus, and hysteresis loop are examined. As a novel idea, the SNP aggregation state is considered to be dependent on the SNP volume fraction (SNPVF). The SNP size effect is speculated by a newly presented intuition-based idea validated by the molecular dynamics simulation. Acceptable agreements in comparison with experiments prove the accuracy of the proposed model in the case that the intensity of the SNP aggregation is dependent on the SNPVF. It is found that a threshold for the SNPVF value can be reported to improve the HNC effective properties that beyond it, they tend to degenerate. It is also revealed that the SNP aggregation effect on the loss modulus diminishes as the LF increases in the manner that no change occurs in the LFs beyond 1e7 Hz. Additionally, the HNC overall properties are greatly affected by the NP diameters less than 20 nm.

Colloidal silica bearing thin polyacrylate coat: A facile inorganic modifier of acrylic emulsions for fabricating hybrid films with least aggregation of silica nanoparticles

Novel nano-composite emulsions consisting of colloidal silica particles covered with thin polyacrylate coat (PreEm) were successfully prepared with the aid of a nonionic surfactant having a low cloud point (Tcp = 40 °C). This nonionic surfactant first deposited on the surface of colloidal silica particles above its Tcp to provide the sites for adsorption and the following polymerization of acrylic monomer. Scanning transmission electron microscopy of the colloidal particles obtained after the polymerization indicated the presence of very thin coat layer of polyacrylate (c.a., 1–3 nm nm in thickness) around silica nanoparticles. These PreEm particles were readily incorporated into the ordinary acrylic emulsions (AcEm) to obtain silica/ polyacrylate mixed emulsions (PreEm/ AcEm). It was revealed that the mixed emulsions can give transparent coating films at a silica/polyacrylate ratio below 150/100 in which the colloidal particles were distributed in the polymer matrix without aggregation. This morphology was in sharp contrast with the particle aggregation morphologies shown by the films obtained from the naked colloidal silica-AcEm mixed emulsion and the conventional nanocomposite emulsion consisting of silica particles covered with thick polyacrylate coat. The PreEm/ AcEm films exhibited increased hardness with increasing the silica contents to 150%. These data supported the effectiveness of PreEm in controlling the properties of silica-polyacrylate hybrid films.

Synthesis of hierarchical sieve-like mesoporous silica nanoparticle aggregates via centrifugal method for drug delivery system

A facile approach towards the synthesis of a novel hierarchical sieve-like structure of mesoporous silica nanoparticle aggregates (hsMSNA) is reported using a centrifugal method at room temperature, based on the Kelvin-Helmholtz instability and soft-template method. The developed approach is simple and can potentially be applied for scaled-up preparation. Importantly, scanning electron microscopy, transmission electron microscopy, small-angle X-ray diffraction, and nitrogen adsorption-desorption experiments characterize the mesoporous silica as hsMSNA consisting of 40–100nm mesoporous silica nanoparticles piled at 1–2 μm cylindrical pores in sieve-like tissues. Further, various pore sizes and sieve-, mesh-, and vesicular-like structures can be obtained by adjusting the reaction conditions. The Brunauer-Emmett-Teller specific surface area is as large as 500 m2/g with a 47cm3/g pore volume, facilitating easy drug loading and delivery. Cytotoxicity assays show that the samples are not cytotoxic under a high concentration of 200 μg/mL. Finally, the high drug encapsulation efficiency and sustained release behaviors indicats the considerable potential of the hsMSNA as a drug delivery system in the field of nanomedicine.

Designing Microreactors Resembling Cellular Microenvironment via Polyamine-Mediated Nanoparticle-Assembly for Tuning Glucose Oxidase Kinetics.

Spatial confinement of glucose oxidase (GOx) in the hollow interior of a bioinspired matrix via polyamine mediated silica nanoparticle assembly under environmentally benign conditions is demonstrated herein. In a similarity to the biosilicification processes in diatoms, we use poly(allylamine hydrochloride) (PAH) to direct the assembly of silica nanoparticles on CaCO3 spheres as the removable core. When this assembly process is performed on the CaCO3 spheres, which are preloaded with GOx in a postsynthesis method, microspheres encapsulating GOx are formed. Interestingly, the encapsulated GOx in these microreactors exhibits activity with a Michaelis-Menten constant ( KM) that is 2- to 3-fold less compared with the free enzyme in the solution. While the microenvironment of the organic (PAH)-inorganic (silica) hybrid system can be advantageous for the substrate to interact with enzyme, the effective pH in the vicinity of the entrapped enzyme may also be accountable for the improved activity, resulting in the lower apparent KM and enhanced specificity constant ( kcat/ KM). A 2-fold higher thermal stability of the encapsulated GOx compared with free GOx in solution further demonstrates the efficacy of the integrated architecture. Additionally, the PAH by virtue of its buffering capability allows the microspheres in imparting pH stability to the encapsulated GOx. Therefore, the method is not only a greener process for performing enzyme immobilization but also anticipated to aid in designing microreactors for enhanced enzyme activity.