Amine-modified Mesoporous Silica Research Articles

Leaf on a Film: Mesoporous Silica-Based Epoxy Composites with Superhydrophobic Biomimetic Surface Structure as Anti-Corrosion and Anti-Biofilm Coatings.

In this study, a series of amine-modified mesoporous silica (AMS)-based epoxy composites with superhydrophobic biomimetic structure surface of Xanthosoma sagittifolium leaves (XSLs) were prepared and applied as anti-corrosion and anti-biofilm coatings. Initially, the AMS was synthesized by the base-catalyzed sol-gel reaction of tetraethoxysilane (TEOS) and triethoxysilane (APTES) through a non-surfactant templating route. Subsequently, a series of AMS-based epoxy composites were prepared by performing the ring-opening polymerization of DGEBA with T-403 in the presence of AMS spheres, followed by characterization through FTIR, TEM, and CA. Furthermore, a nano-casting technique with polydimethylsiloxane (PDMS) as the soft template was utilized to transfer the surface pattern of natural XSLs to AMS-based epoxy composites, leading to the formation of AMS-based epoxy composites with biomimetic structure. From a hydrophilic CA of 69°, the surface of non-biomimetic epoxy significantly increased to 152° upon introducing XSL surface structure to the AMS-based epoxy composites. Based on the standard electrochemical anti-corrosion and anti-biofilm measurements, the superhydrophobic BEAMS3 composite was found to exhibit a remarkable anti-corrosion efficiency of ~99% and antimicrobial efficacy of 82% as compared to that of hydrophilic epoxy coatings.

Extraction of heavy metals from wastewater using amine-modified mesoporous silica.

Presence of heavy metals in wastewater is a critical environmental issue, and efficient extraction of the metals remains a challenging task. In this study, the adsorption behavior of Ce(III), Hg(II), and Cu(II) metal ions using MCM-48 material modified with acid and base functional groups was examined. The modified materials were characterized using various techniques, including XRD, BET, FT-IR, NMR, and SEM, which revealed that the materials' properties remained unchanged after modification. The adsorption capacity of the modified materials for metal ions was then evaluated and was found that the amine-modified MCM-48 material exhibited the highest adsorption efficiency. Precisely, the amine-modified material achieved an adsorption capacity of 97% for Ce(III), 98% for Hg(II), and 90% for Cu(II) after 180min of adsorption. These results highlight the effectiveness of amine functionalization in enhancing the adsorption capacity of silica material for heavy metals.

Microneedle Patches with Antimicrobial and Immunomodulating Properties for Infected Wound Healing.

Treatment of infected wounds remains a challenge owing to antibiotic resistance; thus, developing smart biomaterials for the healing of infected wounds is urgently needed. In this study, a microneedle (MN) patch system with antimicrobial and immunomodulatory properties is developed to promote and accelerate infected wound healing. In the MN patch (termed PFG/M MNs), a nanoparticle with polydopamine (PDA)-loaded iron oxide is grafted with glucose oxidase (GOx) and hyaluronic acid (HA) and then integrated into the tips, and amine-modified mesoporous silica nanoparticles (AP-MSNs) are incorporated into the bases. Results show that PFG/M MNs eradicate bacterial infections and modulate the immune microenvironment, combining the advantages of chemodynamic therapy, photothermal therapy, and M2 macrophage polarization from Fe/PDA@GOx@HA in the tips as well as anti-inflammatory effect of AP-MSNs from the MN bases. Thus, the PFG/M MN system is a promising clinical candidate for promoting infected wound healing.

Synthesis of Mesoporous Silica Adsorbent Modified with Mercapto–Amine Groups for Selective Adsorption of Cu2+ Ion from Aqueous Solution

In a sol–gel co-condensation, a mesoporous silica hybrid integrated with (3-mercaptopropyl)trimethoxysilane (TMPSH) was prepared and then reacted with allylamine via a post-surface functionalization approach. Approximately 15 mol% of TMSPSH was introduced into the mesoporous silica pore walls along with tetraethyl orthosilicate. The mercapto ligands in the prepared mesoporous silica pore walls were then reacted with allylamine (AM) to form the mercapto–amine-modified mesoporous silica adsorbent (MSH@MA). The MSH@MA NPs demonstrate highly selective adsorption of copper (Cu2+) ions (~190 mg/g) with a fast equilibrium adsorption time (30 min). The prepared adsorbent shows at least a five times more efficient recyclable stability. The MSH@MA NPs adsorbent is useful for selective adsorption of Cu2+ ions.

Amine-modified mesoporous silica for quantitative adsorption and release of hydroxytyrosol and other phenolic compounds from olive mill wastewater

Abstract A series of synthesized and commercial adsorbents were used for the treatment of olive mill wastewater (OMW). SBA-15 and P-10 silicas functionalized by post-synthesis grafting with 3-trimethoxysilylpropyl diethylenetriamine (TRI) and commercially available activated carbon (AC) were used for the removal and recovery of phenolic compounds from actual olive mill wastewater. Using UV spectrophotometric and HPLC analyses, the concentrations of total phenols, hydroxytyrosol and tyrosol in OMW were found to be 8.21 g L–1, 2.14 g L–1 and 0.50 g L–1, respectively. The recovery of phenolic compounds after adsorption was performed by solvent extraction using 0.1 M HCl in ethanol. Under otherwise the same conditions, all three adsorbents removed hydroxytyrosol quantitatively, but activated carbon showed the highest uptake of total phenols, i.e. 87% versus 75% and 67% for TRI-SBA-15 and TRI-P-10. The overall efficiencies for adsorption and recovery of hydroxytyrosol were 100%, 91% and 37% for TRI-SBA-15, TRI-P-10 and AC, respectively. Recycling experiments revealed that no loss of efficiency occurred after three consecutive adsorption–regeneration cycles. Furthermore, triamine-functionalized SBA-15 gave the highest discoloration percentage of 61% compared to the other materials.

Direct Air Capture of CO2 by Physisorbent Materials.

Sequestration of CO2, either from gas mixtures or directly from air (direct air capture, DAC), could mitigate carbon emissions. Here five materials are investigated for their ability to adsorb CO2 directly from air and other gas mixtures. The sorbents studied are benchmark materials that encompass four types of porous material, one chemisorbent, TEPA-SBA-15 (amine-modified mesoporous silica) and four physisorbents: Zeolite 13X (inorganic); HKUST-1 and Mg-MOF-74/Mg-dobdc (metal-organic frameworks, MOFs); SIFSIX-3-Ni, (hybrid ultramicroporous material). Temperature-programmed desorption (TPD) experiments afforded information about the contents of each sorbent under equilibrium conditions and their ease of recycling. Accelerated stability tests addressed projected shelf-life of the five sorbents. The four physisorbents were found to be capable of carbon capture from CO2-rich gas mixtures, but competition and reaction with atmospheric moisture significantly reduced their DAC performance.

Nitric oxide- and cisplatin-releasing silica nanoparticles for use against non-small cell lung cancer

Nitric oxide (NO) and cisplatin releasing wrinkle-structured amine-modified mesoporous silica (AMS) nanoparticles have been developed for the treatment of non-small cell lung cancer (NSCLC). The AMS and NO- and cisplatin-loaded AMS materials were characterized using TEM, BET surface area, FTIR and ICP–MS, and tested in cell culture. The results show that for NSCLC cell lines (i.e., H596 and A549), the toxicity of NO- and cisplatin-loaded silica nanoparticles (NO-Si-DETA-cisplatin-AMS) is significantly higher than that of silica nanoparticles loaded with only cisplatin (Si-DETA-cisplatin-AMS). In contrast, the toxicity of NO-Si-DETA-cisplatin-AMS toward normal lung cell lines is not significantly different from that of Si-DETA-cisplatin-AMS (normal lung fibroblast cells WI-38) or is even lower than that of Si-DETA-cisplatin-AMS (normal lung epithelial cells BEAS-2B). The NO-induced sensitization of tumor cell death demonstrates that NO is a promising enhancer of platinum-based lung cancer therapy.

Fluorescent mesoporous silica nanoparticles functionalized graphene oxide: A facile FRET-based ratiometric probe for Hg2+

This paper reported a facile method for fabricating a functionalized fluorescent graphene oxide (GO) by covalently grafting the amine-modified mesoporous silica nanoparticles (MSNs) containing poly(p-phenylenevinylene) (PPV) and lactam of Rhodamine 6G (SRh6G) inside the channel of MSNs. The resulted GO-PPV@MSN-NH2@SRh6G fluorescent hybrid nanoparticles had a good dispersion and strong green fluorescence in aqueous solution. This hybrid material can be used as a fluorescent ratiometric probe to detect Hg2+ in the water through fluorescence resonance energy transfer (FRET). Upon the addition of only Hg2+ ions, the mission corresponding to the ring-opened form of rhodamine appeared at 550nm with a simultaneous emission quenching of PPV at 494nm. This ratiometric fluorescence change indicated that an FRET from the PPV to rhodamine was triggered by Hg2+ ions. The hybrid nanoparticles of GO-PPV@MSN-NH2@SRh6G could be used as a novel fluorescent probe to carry out the quantitative detection of Hg2+ with a detection limit of 7.1×10−8M.

Conjugation of PPV functionalized mesoporous silica nanoparticles with graphene oxide for facile and sensitive fluorescence detection of TNT in water through FRET

This paper reported a convenient method to prepare water-soluble graphene oxide (GO) functionalized by amine-modified mesoporous silica nanoparticles (MSNs) containing poly(p-phenylenevinylene) via covalent bonds. The resulted GO–PPV@MSN hybrid materials had a good dispersion and strong green fluorescence in aqueous solution. The structure, morphology and optical properties of the resulting hybrid materials were characterized. The GO-PPV@MSN can be used as a novel and effective fluorescent sensing platform for detection of 2,4,6-trinitrotoluene (TNT) in aqueous solution by fluorescence resonance energy transfer (FRET). Upon the addition of TNT, the amino groups on the surface of PPV@MSN can bind TNT molecules from solution by forming Meisenheimer complex, and this complex can absorb the green part of visible light, and strongly suppress the fluorescence emission of GO-PPV@MSN through FRET. The observed linear fluorescence intensity change allowed the quantitative detection of TNT with a detection limit down to 1.3 × 10−7 M.

Development of Amine-Modified Solid Sorbents for Postcombustion CO2 Capture

Amine-modified solid sorbents are potentially good candidates for postcombustion CO2 capture. We synthesized a series of amine-modified mesoporous silica sorbents, and measured their CO2 adsorption capacities. Among them, mesoporous silica MSU-H modified with (3-trimethoxysilylpropyl)diethylenetriamine, denoted by TA/MSU-H(II), showed high CO2 adsorption capacity of 3.08 mmol/g-sorbent at 60°C with 15kPa of CO2, 12kPa of H2O vapor and 74kPa of N2 as similar as the postcombustion CO2 capture condition. Furthermore, we confirmed that the CO2 adsorption capacity of TA/MSU-H(II) after 30 cycles of the adsorption at 60°C and the desorption at 120°C was 2.98 mmol/g-sorbent.

Dual-tuned drug release by nanofibrous scaffolds of chitosan and mesoporous silica microspheres

A sustained drug release with an initial burst release followed by a linear release to optimally maintain the drug concentration in the therapeutic region is highly desirable for medicine administration. This study describes a method for the preparation of chitosan and chitosan–silica scaffolds and assesses their use for sustained release of curcumin. Porous chitosans with nanofibrous or sheet-like morphologies are fabricated from aqueous curcumin–chitosan solutions by a freeze-drying approach. The pore morphology can influence the release rate; curcumin was released much faster from the nanofibers than from the macroporous scaffolds. Amine-modified mesoporous silica microspheres are added into chitosan as another control; the release rate decreases due to the interaction of amine groups on silica and curcumin with chitosan. The silica microspheres with tuneable loading of curcumin are further incorporated into the curcumin–chitosan scaffold. The curcumin release into phosphate buffer solutions at 37 °C shows a two-stage release profile with distinctly different release rates. The high permeability and hydrophilic property of chitosan result in the initial burst release. The slow near-linear release at the 2nd stage results from the loaded silica microspheres. Loading of curcumin, concentration of chitosan, and content of silica microspheres in the composites are investigated and the effects on the release profiles are demonstrated. The present method is further adapted to prepare thin films with reasonable strength and flexibility by air drying and freeze drying. The tuneable sustained release of curcumin is also shown for the films.

Preparation and CO 2 separation properties of amine-modified mesoporous silica membranes

Mesoporous silica membranes were prepared on porous alumina supports by both hydrothermal and sol–gel spin-coating methods. SEM images showed that these techniques deposited dense mesoporous silica layers of 200 and 500 nm, respectively, on the alumina supports. TEM and XRD observations showed that these membranes have a highly ordered cubic structure with a pore diameter of 2 nm. Gas permeation properties of these mesoporous silica membranes were governed by the Kundsen diffusion mechanism. Surface modification of the pore walls of mesoporous silica membranes by grafting amino-silane greatly improved the CO 2 permselectivities. The amine-modified mesoporous silica membranes showed high CO 2/N 2 separation properties for a mixture of 20% CO 2 and 80% N 2 at 373 K. The CO 2/N 2 selectivities of the membranes prepared using hydrothermal and sol–gel spin-coating methods were 50 and 800, respectively.