Amine-modified Silica Nanoparticles Research Articles

Fabrication and characterization of novel PES-based nanocomposite hollow fiber membranes for the hemodialysis process

In the hemodialysis process, membrane filtration is used to clean blood. Urea and creatinine are two significant substances that should be removed from the blood during hemodialysis, which takes a great deal of time. To decrease the hemodialysis process time, in this study, we fabricated novel polyethersulfone nanocomposite hollow fiber membranes with silica and amine-modified silica nanoparticles via the non-solvent induced phase separation (NIPS) method. Membranes have been evaluated in a membrane contactor system by two modes of contact with fresh sweeper fluid (retentate process) and recycled sweeper fluid (circulated process) to remove urea and creatinine from a synthetic blood-like solution. Fourier transform infrared (FTIR) was carried out along with pure water flux, contact angle, mechanical strength, field emission electron microscope test (FESEM), and X-ray diffraction (EDX) to characterize the synthesized nanoparticles and fabricated membranes. The results revealed that modification of membranes by silica and amine-modified silica nanoparticles increased the urea and creatinine removal rate from the feed as the modified membranes’ separation mechanisms were adsorption and diffusion. Furthermore, removal of urea and creatinine were higher in the retentate process than the circulated process. The membrane samples containing 1.5% amine-modified silica nanoparticles had the highest urea and creatinine removal rate compared to the other modified membranes containing fewer or higher amine-modified silica and/or silica nanoparticles in the both retentate and circulated processes. The adsorption kinetics showed that the adsorption of urea and creatinine on the surface of the silica and amine-modified silica nanoparticles were consistent with the pseudo-second kinetic model, meaning rapid and possibly irreversible adsorption.

Spontaneous Imbibition Oil Recovery by Natural Surfactant/Nanofluid: An Experimental and Theoretical Study.

Organic surfactants have been utilized with different nanoparticles in enhanced oil recovery (EOR) operations due to the synergic mechanisms of nanofluid stabilization, wettability alteration, and oil-water interfacial tension reduction. However, investment and environmental issues are the main concerns to make the operation more practical. The present study introduces a natural and cost-effective surfactant named Azarboo for modifying the surface traits of silica nanoparticles for more efficient EOR. Surface-modified nanoparticles were synthesized by conjugating negatively charged Azarboo surfactant on positively charged amino-treated silica nanoparticles. The effect of the hybrid application of the natural surfactant and amine-modified silica nanoparticles was investigated by analysis of wettability alteration. Amine-surfactant-functionalized silica nanoparticles were found to be more effective than typical nanoparticles. Amott cell experiments showed maximum imbibition oil recovery after nine days of treatment with amine-surfactant-modified nanoparticles and fifteen days of treatment with amine-modified nanoparticles. This finding confirmed the superior potential of amine-surfactant-modified silica nanoparticles compared to amine-modified silica nanoparticles. Modeling showed that amine surfactant-treated SiO2 could change wettability from strongly oil-wet to almost strongly water-wet. In the case of amine-treated silica nanoparticles, a strongly water-wet condition was not achieved. Oil displacement experiments confirmed the better performance of amine-surfactant-treated SiO2 nanoparticles compared to amine-treated SiO2 by improving oil recovery by 15%. Overall, a synergistic effect between Azarboo surfactant and amine-modified silica nanoparticles led to wettability alteration and higher oil recovery.

Polyvinyl alcohol membrane incorporated with amine-modified silica nanoparticles and ionic liquid for facilitated transport of CO2

The application of polymeric membranes in post-combustion carbon capture is limited by solution-diffusion. In this work, polyvinyl alcohol (PVA) membranes with facilitated transport of carbon dioxide (CO2) were improved by incorporating the fixed carrier, amine-modified silica nanoparticles (SiO2) and the mobile carrier [bmim][Tf2N] ionic liquid. The BET surface area of diethanolamine (DEA)-modified SiO2 nanoparticles decreased from 150.14 m2/g to 22.68 m2/g, but they improved the surface hydrophilicity of PVA membranes more significantly than the unmodified SiO2 nanoparticles due to the existence of secondary amine groups. Fourier transform infrared spectra confirmed the incorporation of secondary amine and anion of IL that can facilitate CO2 permeation. The thermogravimetric analysis also revealed that the thermal stability of PVA membranes was improved by incorporating inorganic nanoparticles and ionic liquid. The thickness of the dense PVA layer coated on polyethersulfone support increased by incorporating SiO2 and DEA-modified SiO2 nanoparticles, as shown by scanning electron microscope images. The positive effects of SiO2 nanoparticles on the CO2 separation performance of PVA membranes were enhanced by reducing the particle size and increasing particle loading. DEA elevated the enhancement through the Zwitterion mechanism. [bmim][Tf2N] IL also improved the CO2 separation performance of PVA membranes. Hence, the PVA membrane containing 2 wt% of DEA-modified SiO2 nanoparticles (15-20 nm) and 0.4 M of [bmim][Tf2N] IL in ethanol attained a CO2 permeance of 3016 GPU and CO2/N2 selectivity of 62.08.

Bio-based polybenzoxazine superhydrophobic coating with active corrosion resistance for carbon steel protection

A bio-based benzoxazine, synthesized from cardanol, stearylamine and paraformaldehyde, was utilized to develop a superhydrophobic polybenzoxazine double-layer coating with active protection for carbon steel. This double-layered coating consists of an active anti-corrosive primer and a superhydrophobic topcoat. Halloysite nanocontainers with 2-mercaptobenzimidazole were embedded in the primer to achieve active corrosion resistance. The superhydrophobic topcoat constructed of low-surface-energy polybenzoxazine and amine-modified silica nanoparticles can acquire reinforced passive anticorrosive barrier. The durable double-layer coating could still maintain its superhydrophobicity, even after 60 days of treatment at −20 °C or 100 °C, or 100 cycles of sandpaper abrasion. More importantly, the electrochemical measurement results indicated that the polybenzoxazine superhydrophobic coating maintained outstanding anti-corrosion performance during 90 days immersion in NaCl solution.

Injectable and Self-Healing Nanocomposite Hydrogels with Ultrasensitive pH-Responsiveness and Tunable Mechanical Properties: Implications for Controlled Drug Delivery.

Injectable, self-healing, and pH-responsive hydrogels are great intelligent drug delivery systems for controlled and localized therapeutic release. Hydrogels that show pH-sensitive behaviors in the mildly acidic range are ideal to be used for the treatment of regions showing local acidosis like tumors, wounds and infections. In this work, we present a facile preparation of an injectable, self-healing, and supersensitive pH-responsive nanocomposite hydrogel based on Schiff base reactions between aldehyde-functionalized polymers and amine-modified silica nanoparticles. The hydrogel shows fast gelation within 10 s, injectability, and rapid self-healing capability. Moreover, the hydrogel demonstrates excellent stability under neutral physiological conditions, while a sharp gel-sol transition is observed, induced by a faintly acidic environment, which is desirable for controlled drug delivery. The pH-responsiveness of the hydrogel is ultrasensitive, where the mechanical properties, hydrolytic degradation, and drug release behaviors can alter significantly when subjected to a slight pH change of 0.2. Additionally, the hydrogel's mechanical and pH-responsive properties can be readily tuned by its composition. Its excellent biocompatibility is confirmed by cytotoxicity tests toward human dermal fibroblast cells (HDFa). The novel injectable, self-healing, and sensitive pH-responsive hydrogel serves as a promising candidate as a localized drug carrier with controlled delivery capability, triggered by acidosis, holding great promise for cancer therapy, wound healing, and infection treatment.

Three-Dimensional Graphene-RGD Peptide Nanoisland Composites That Enhance the Osteogenesis of Human Adipose-Derived Mesenchymal Stem Cells.

Graphene derivatives have immense potential in stem cell research. Here, we report a three-dimensional graphene/arginine-glycine-aspartic acid (RGD) peptide nanoisland composite effective in guiding the osteogenesis of human adipose-derived mesenchymal stem cells (ADSCs). Amine-modified silica nanoparticles (SiNPs) were uniformly coated onto an indium tin oxide electrode (ITO), followed by graphene oxide (GO) encapsulation and electrochemical deposition of gold nanoparticles. A RGD–MAP–C peptide, with a triple-branched repeating RGD sequence and a terminal cysteine, was self-assembled onto the gold nanoparticles, generating the final three-dimensional graphene–RGD peptide nanoisland composite. We generated substrates with various gold nanoparticle–RGD peptide cluster densities, and found that the platform with the maximal number of clusters was most suitable for ADSC adhesion and spreading. Remarkably, the same platform was also highly efficient at guiding ADSC osteogenesis compared with other substrates, based on gene expression (alkaline phosphatase (ALP), runt-related transcription factor 2), enzyme activity (ALP), and calcium deposition. ADSCs induced to differentiate into osteoblasts showed higher calcium accumulations after 14–21 days than when grown on typical GO-SiNP complexes, suggesting that the platform can accelerate ADSC osteoblastic differentiation. The results demonstrate that a three-dimensional graphene–RGD peptide nanoisland composite can efficiently derive osteoblasts from mesenchymal stem cells.

Preparation of organic-inorganic hybrid nanocomposites from chemically modified epoxy and novolac resins and silica-attached carbon nanotubes by sol-gel process: Investigation of thermal degradation and stability

Abstract Hear, three hybrid composites with high char yield and thermal stability were prepared form tetraethyl orthosilicate (TEOS)-modified epoxy resin (MER), (3-glycidyloxypropyl) trimethoxysilane (GPTES)-modified novolac resin (MNR), epoxidized novolac resin (ENR), and silica-grafted carbon nanotube (SFCNT) by a sol-gel method. The first class was prepared from MER and SFCNT. The second class was prepared from MER, MNR, and SFCNT. And the third class was prepared from MNR, ENR, and SFCNT. TEOS was used as covalent coupling agent in the sol-gel process. Results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed successful modification of epoxy and novolac resins, modification of silica nanoparticles with (3-Aminopropyl)triethoxysilane (APTES), and also functionalization of CNT with amine-modified silica nanoparticles. Results of thermogravimetric analysis confirmed that the hybrid composite containing 4 wt% of SFCNT, MNR, and ENR shows the highest char yield of 58.4%. The hybrid composite containing 4 wt% of SFCNT and MER shows the highest degradation temperature of 442.7 °C. Finally, the hybrid composite formed from 4 wt% of SFCNT, MER, and MNR shows degradation temperature of 439.0 °C and char yield of 47.2%. Microscopic images and X-ray diffraction results confirmed attachment of silica particles at the surface of CNT by chemical bonding.

Synthesis and characterization of ibandronate-loaded silica nanoparticles and collagen nanocomposites.

Non-porous bare silica nanoparticles, amine modified silica nanoparticles and mesoporous particles, were evaluated as carriers for sodium ibandronate. The synthesized nanoparticles were characterized by SEM, TEM, DLS and porosity. Then, their capacity to incorporate a bisphosphonate drug (sodium ibandronate) and the in vitro release behavior was analyzed by capillary electrophoresis. Mesoporous and amine-modified particles showed higher levels of drug incorporation, 44.68 mg g(-1) and 28.90 mg g(-1), respectively. The release kinetics from the two types of particles was similar following a first order kinetics. However, when these particles were included into collagen hydrogels only mesoporous nanoparticles had a sustained release for over 10 days. The biocompatibility of mesoporous particles towards Saos-2 cells was also evaluated by the MTT assay observing an increase in cell viability for concentrations lower than 0.6 mg ml(-1) of particles and a decrease for concentrations over 1.2 mg ml(-1). Furthermore, when these particles were incubated with mesenchymal cells it was observed that they had the capacity to promote the differentiation of the cells with a significant increase in the alkaline phosphatase activity.

Evaluation of Photodynamic Efficacy of Chlorin p 6 Bound to Amine-Modified Silica Nanoparticles in Colon and Oral Cancer Cell Lines

We report results of our studies on cellular uptake and phototoxicity of free chlorin p6 (Cp6) and Cp6 bound to amine-modified silica nanoparticles (Cp6-SiNP) in colon (Colo-205) and oral cancer (Nt8e) cell lines. Fluorescence spectroscopy-based measurement of cellular uptake showed no significant difference in the amount of free Cp6 and Cp6-SiNP localized in cells. Measurements on phototoxicity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that the Cp6-SiNP was more effective as compared with free Cp6. Fluorescence-correlation spectroscopy performed on the free drug and drug-SiNP complex in serum media confirmed that the drug remains preferentially bound to SiNP. The rate of photobleaching was much lower in case of Cp6-SiNP complex as compared with the free drug in serum media. These results suggest that the observed increase in photodynamic activity of Cp6-SiNP complex may arise because of an increase in the photostability of Cp6 when bound to SiNP.

Comments on: A Comparative Study of Diamine-Modified and Amine-Modified Silica Nanoparticles as Pseudo-Stationary Phases for CE Separation by Li-Juan Hui and Yong Ma

Comments on: A Comparative Study of Diamine-Modified and Amine-Modified Silica Nanoparticles as Pseudo-Stationary Phases for CE Separation by Li-Juan Hui and Yong Ma

A Comparative Study of Diamine-Modified and Amine-Modified Silica Nanoparticles as Pseudo-Stationary Phases for CE Separation

The use of silica nanoparticles with surface modification in different applications is a topic of growing interest. This article provides a systematic comparison of diamine-modified and amine-modified silica nanoparticles as pseudo-stationary phases (PSPs) in capillary electrophoresis. The different electrophoretic behavior of these PSPs was evaluated by analysis of four auxins, indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), 2,4-dichlorophenoxyacetic acid (dCPAA), and 2-(1-naphthyl)acetic acid (NAA). As expected, fast separation of the auxins was achieved, because they migrate in the same direction as the electro-osmotic flow under the optimum experimental conditions. However, the two nanoparticles had different selectivity and efficiency in the separation of the auxins, which could be related to the primary and secondary amines in their structures. The results indicated that even slight structural changes of the functional groups of the nanoparticles have pronounced effect on the interactions between the pseudo-stationary phase and the analytes.

Synthesis of Stable Silica-Dye Hybrid Nanomaterial as DNA Carrier

A new method is proposed for the fabrication of fluorescence-labeled and amine-modified silica nanoparticles for application as nonviral vectors in gene delivery. Highly monodisperse, stable fluorescent silica nanoparticles were prepared using 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene and the water-in-oil microemulsion method. The green-fluorescent-protein gene can be easily combined onto the positively charged surfaces of nanoparticles to form a nanoparticle-DNA complex. The nanoparticle-DNA complex successfully passed through various barriers into the HeLa and HEK 293 K cells. The cytotoxicity of the PEI-coated and BBOT-encapsulated silica nanoparticles on both the HeLa and HEK 293T cell lines was found to be at an acceptable level for use as gene carriers when the particle concentration was below 125 microg/ml. The fluorescence intracellular images confirm the successful delivery of the nanoparticle-DNA complex and gene expression. The present work suggests the potential use of dye-incorporated silica nanoparticles in nonviral gene delivery.

Tunable Wetting of Nanoparticle-Decorated Polymer Films

In this paper, amine-modified silica nanoparticles (NPs) with diameters (d) from 15 to 230 nm are covalently linked to poly(styrene-random-acrylic acid) (P(S-ran-AA)) films, and wettability is studied as a function of diameter and NP surface coverage. During attachment, films swell and exhibit long and short scale roughness, consisting of a ridged, honeycomb structure, approximately 1 mum wide and 45-50 nm deep, which encircles nanoscale features 10-15 nm high and approximately 50 nm apart. A maximum NP coverage of approximately 70% was achieved for d less than or nearly equal to the nanoscale roughness induced by surface swelling. For d several times greater than this nanoscale roughness, the maximum coverage was limited by interparticle repulsion and reached only approximately 30%. For NPs with diameters of 15-106 nm, the water contact angle increased from 75 degrees to 120 degrees as NP coverage increased from 0 to 70%. At low and high NP coverage, the Wenzel and Cassie models, respectively, accurately describe the data. However, at intermediate NP coverage, neither model is satisfactory. An increase in surface roughness alone cannot account for this discrepancy. Atomic force microscopy (AFM) studies show that the NPs partially embed into the swollen P(S-ran-AA) surface, suggesting that the amine-coated NPs are wet by the copolymer, exposing low surface energy styrene. These studies demonstrate that control over surface properties of coatings, such as wetting, can be achieved by selecting NP sizes that complement film roughness.

Optimization of the methods for introduction of amine groups onto the silica nanoparticle surface

The luminescent silica nanoparticle has attracted the researchers' concentration in bioanalysis recently. Its extensive application is based on the immobilization of various biomolecules such as deoxyribonucleic acid, antibody, and so forth onto the surface. By comparing different introduction methods of amine groups, it was confirmed that the "two-step" route is more preferable by adding tetraethyl orthosilicate and 3-aminopropyl-(triethoxyl)silane in sequence, to attain ideal amine-modified silica nanoparticles. On this basis, carboxyl groups were derived from amine groups on the nanoparticle surface and then were activated by 1-ethyl-3-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxy-succinimide. Finally, mouse monoclonal antihuman CD71 antibody (McAb CD71) and transferrin were effectively linked with the carboxyl groups and successfully labeled the receptors in the membrane of fibroblast cells, respectively.

Surface modification of silica nanoparticles to reduce aggregation and nonspecific binding.

In this article, a systematic study of the design and development of surface-modification schemes for silica nanoparticles is presented. The nanoparticle surface design involves an optimum balance of the use of inert and active surface functional groups to achieve minimal nanoparticle aggregation and reduce nanoparticle nonspecific binding. Silica nanoparticles were prepared in a water-in-oil microemulsion and subsequently surface modified via cohydrolysis with tetraethyl orthosilicate (TEOS) and various organosilane reagents. Nanoparticles with different functional groups, including carboxylate, amine, amine/phosphonate, poly(ethylene glycol), octadecyl, and carboxylate/octadecyl groups, were produced. Aggregation studies using SEM, dynamic light scattering, and zeta potential analysis indicate that severe aggregation among amine-modified silica nanoparticles can be reduced by adding inert functional groups, such as methyl phosphonate, to the surface. To determine the effect of various surface-modification schemes on nanoparticle nonspecific binding, the interaction between functionalized silica nanoparticles and a DNA chip was also studied using confocal imaging/fluorescence microscopy. Dye-doped silica nanoparticles functionalized with octadecyl and carboxylate groups showed minimal nonspecific binding. Using these surface-modification schemes, fluorescent dye-doped silica nanoparticles can be more readily conjugated with biomolecules and used as highly fluorescent, sensitive, and reproducible labels in bioanalytical applications.