Tailored Synthesis of Core-Shell Mesoporous Silica Particles-Optimization of Dye Sorption Properties

Water-dispersable photoreactors based on core-shell mesoporous silica particles

Robust solid-core silica particles with submicrometer size and anthracene-containing mesoporous shell were obtained and studied as model water-dispersable photoreactors. An anthracene derivative containing a triethoxysilyl group was synthesized and co-condensed with tetraethoxysilane in various ratios to form a photoactive mesoporous shell with a thickness up to approximately 80 nm on previously prepared solid silica particles. Mesopores of as-synthesized particles, without a commonly applied removal of the micellar templates, offered a confined space for solubilization of hydrophobic molecules. Efficient excitation energy transfer from anthracene chromophores to both hydrophobic (perylene) and hydrophilic (fluoresceine) encapsulated acceptors was observed in an aqueous dispersion of the particles. Photosensitized oxidation of encapsulated perylene was shown to proceed efficiently in such systems serving as water-dispersable photoreactors. Importantly, the designed core-shell systems were found to be stable for a long time (at least 24 months) and robust enough, thanks to the presence of solid cores, to be handled by centrifugation in aqueous dispersions. All these features make them promising candidates for reusable systems for the photosensitized degradation of water pollutants, especially hydrophobic pollutants.

Resource Recycling Utilization of Distillers Grains for Preparing Cationic Quaternary Ammonium—Ammonium Material and Adsorption of Acid Yellow 11

Using distillers grains (DG) as raw material after pre-treatment with sodium hydroxide (NaOH) and modified with cationic etherification agent 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC), cationic quaternary ammonium distillers grains adsorption material (CDG) was successfully prepared. The optimal adsorption conditions were an adsorption temperature of 25 °C, adsorption time of 180 min, amount of adsorbent at 8.5 g/L, initial dye concentration of 100 mg/L, and pH of dye solution 7.0. The structure of CDG was characterized by FTIR, EDS, SEM, BET, ultraviolet spectrum analysis, and analysis of the zeta potential, while the adsorption mechanism was studied by adsorption kinetics, isotherms, and thermodynamics. The results showed that CHPTAC modified the distillers grains successfully and induced the formation of CDG with a large number of pore structures and good adsorption effect. The highest adsorption yield was above 98%, while after eight rounds of adsorption–desorption experiments, the adsorption rate was 81.80%. The adsorption mechanism showed that the adsorption process of acid yellow 11 (AY11) by CDG conforms to the pseudo-second-order kinetic model, mainly with chemical and physical adsorption such as pore adsorption and electrostatic adsorption. Thermodynamics conforms to the Freundlich isothermal model, and the adsorption process is a spontaneous, endothermic and entropy-increasing process.

Silicon nanoparticles (SiNPs) in sustainable agriculture: major emphasis on the practicality, efficacy and concerns

Silicon (Si), a beneficial element for plants, is known for its prophylactic effect under stress conditions. Many studies have documented the role of biogenic silica (bulk-Si) in alleviating biotic and abiotic stresses in plants. The scarce amount of the plant-available form of Si (monosilicic acid) in most of the cultivated soil and the limited efficacy of silicate fertilizers (bulk-Si) are the major concerns for the exploration of Si-derived benefits. In this regard, recent advances in nanotechnology have opened up new avenues for crop improvement, where plants can derive benefits associated with Si nanoparticles (SiNPs). Most of the studies have shown the positive effect of SiNPs on the growth and development of plants specifically under stress conditions. In contrast, a few studies have also reported their toxic effects on some plant species. Hence, there is a pertinent need for elaborative research to explore the utility of SiNPs in agriculture. The present review summarizes SiNP synthesis, application, uptake, and role in stimulating plant growth and development. The advantages of SiNPs over conventional bulk-Si fertilizers in agriculture, their efficacy in different plant species, and safety concerns have also been discussed. The gaps in our understanding of various aspects of SiNPs in relation to plants have also been highlighted, which will guide future research in this area. The increased attention towards SiNP-related research will help to realize the true potential of SiNPs in agriculture.

Bi-functionalized aminoguanidine-PEGylated periodic mesoporous organosilica nanoparticles: a promising nanocarrier for delivery of Cas9-sgRNA ribonucleoproteine

BACKGROUND

There is a great interest in the efficient intracellular delivery of Cas9-sgRNA ribonucleoprotein complex (RNP) and its possible applications for in vivo CRISPR-based gene editing. In this study, a nanoporous mediated gene-editing approach has been successfully performed using a bi-functionalized aminoguanidine-PEGylated periodic mesoporous organosilica (PMO) nanoparticles (RNP@AGu@PEG1500-PMO) as a potent and biocompatible nanocarrier for RNP delivery.

RESULTS

The bi-functionalized MSN-based nanomaterials have been fully characterized using electron microscopy (TEM and SEM), nitrogen adsorption measurements, thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and dynamic light scattering (DLS). The results confirm that AGu@PEG1500-PMO can be applied for gene-editing with an efficiency of about 40% as measured by GFP gene knockdown of HT1080-GFP cells with no notable change in the morphology of the cells.

CONCLUSIONS

Due to the high stability and biocompatibility, simple synthesis, and cost-effectiveness, the developed bi-functionalized PMO-based nano-network introduces a tailored nanocarrier that has remarkable potential as a promising trajectory for biomedical and RNP delivery applications.

Uptake and in vitro anticancer activity of oleic acid delivered in nanocapsules stabilized by amphiphilic derivatives of hyaluronic acid and chitosan

The nanoemulsion-based delivery systems have gained particular attention due to effective encapsulation and protection of hydrophobic active compounds. However, several features like limited stability, cellular uptake or release of payloads still need to be addressed. We investigated the uptake of the nanocapsules based on the amphiphilic derivative of hyaluronate with oleic acid cores (oil-in-water nanoemulsion) and their anticancer activity in vitro. The core-shell nanocapsules exhibiting long term stability in dispersion showed an enhanced uptake by cancer cells and effectively killed them only if composed of hyaluronate-based shells and oleic acid cores - the anionic chitosan-based shells and/or corn oil cores were used for control experiments. We concluded that the nanocapsules stabilized by the amphiphilic derivative of hyaluronic acid may serve as very stable and efficient delivery systems for oil-soluble compounds without necessity of application of low molecular weight (co)surfactants. The in vitro studies indicated anticancer activity of such delivered oleic acid and crucial role of hyaluronate shell of the nanocapsules in its efficient delivery and enzyme-triggered disintegration inside cells. Corn oil was shown as a nutrient that can serve as an inert vehicle in the studied nanoemulsion that exhibit application potential in food, dietary supplement industry and medicine.

Thermoresponsive Polymer Gating System on Mesoporous Shells of Silica Particles Serving as Smart Nanocontainers

Spherical silica nanoparticles with solid cores and mesoporous shells (SCMS) were decorated with thermoresponsive polymer brushes that were shown to serve as macromolecular valves to control loading and unloading of a model dye within the mesopores. Thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) brushes were grafted from the surfaces of both solid core (SC) and SCMS particles of similar size using surface-initiated atom transfer radical polymerization. Both systems based on porous (SCMS-PNIPAM) and nonporous (SC-PNIPAM) particles were characterized using cryo-TEM, thermogravimetry and elemental analysis to determine the structure and composition of the decorated nanoparticles. The grafted PNIPAM brushes were found to be responsive to temperature changes enabling temperature-controlled gating of the pores. The processes of loading and unloading in the obtained systems were examined using a model fluorescent dye-rhodamine 6G. Polymer brushes in SCMS-PNIPAM systems were shown to serve as molecular valves enabling significant adsorption (loading) of the dye inside the pores with respect to the SC-PNIPAM (no pores) and SCMS (no valves) systems. The effective unloading of the fluorescent cargo molecules from the decorated nanoparticles was achieved in a water/methanol solution. The obtained SCMS-PNIPAM particles may be used as smart nanocontainers or nanoreactors offering also facile isolation from the suspension due to the presence of dense cores.

Antioxidant Nanomaterial Based on Core⁻Shell Silica Nanospheres with Surface-Bound Caffeic Acid: A Promising Vehicle for Oxidation-Sensitive Drugs

The design of efficient, biocompatible, and easily prepared vehicles for drug delivery is a subject of great interest for medicine and pharmaceutical sciences. To achieve the above goals, surface functionalization is critical. Here, we report a hybrid nanocarrier consisting of core⁻shell silica nanospheres and the antioxidant caffeic acid linked to the surface, to evaluate their in vitro antioxidant capacity, their capability to protect oxidation-sensitive compounds incorporated in nanoparticles, and to study the interaction with bovine serum albumin protein. The results show that the radical-scavenging activity of immobilized caffeic acid is attenuated in the silica nanospheres; however, other antioxidant properties such as Fe2+-chelating activity and singlet oxygen quenching are enhanced. In addition, caffeic acid is protected from binding to proteins by the nanoparticle, suggesting that this nanosystem is more likely to maintain the antioxidant activity of caffeic acid in biological media. Finally, the natural antioxidant barrier on the nanocarrier is able to delay the degradation of a compound incorporated into this nanovehicle. Considering all findings, this work proposes a suitable tool for pharmaceutical and cosmetic industries as an antioxidant nanocarrier for oxidation-sensitive drugs.