Novel mesoporous organosilica nanoparticles with ferrocene group for efficient removal of contaminants from wastewater

Copper nanoclusters-doped novel carrier with synergistic adsorption-catalytic active sites to enable high-performance dye removal

Enhancing the synergistic interplay between adsorption and catalytic oxidation to amplify Fenton-like effects remains a pivotal challenge in advancing water pollution remediation strategies. In this study, a suite of novel carriers (SH) composed of silica (SiO2) and hydroxyapatite (HAp) in different ratios were synthesized through an amalgamation of the sol-gel and co-precipitation techniques. Notably, various forms of copper (Cu) species, including Cu2+ ions and Cu nanoclusters (Cu NCs), could be stably incorporated onto the SH surface via meticulous loading and doping techniques. This approach has engendered a new class of Fenton-like catalysts (Cu NCs-SH1-5) characterized by robust acid-base tolerance stability and remarkable recyclability. Compared with the previously reported Cu NCs-HAp, this catalyst with lower Cu species content could achieve better performance in adsorbing and degrading dyes under the aid of hydrogen peroxide (H2O2). The catalyst's dual action sites, specifically the adsorption sites (SiOH, POH, slit pores) and catalytic centers (multivalent Cu species), had clear division of labor and collaborate with each other. Further, reactive oxygen species (ROS) identification and astute electrochemical testing have unveiled the mechanism underpinning the cooperative degradation of dyes by three types of ROS, spawned through electron transfer between the Fenton-like catalyst (Cu NCs-SH) and H2O2. From these insights, the mechanism of synergistic adsorption-catalytic removal was proposed.

Utilization and value-adding of waste: Fabrication of porous material from chitosan for phosphate capture and energy storage

Efficient removal and recycling of phosphorus from complex water matrices using environmentally friendly and sustainable materials is essential yet challenging. To this end, a novel bio-based adsorbent (DX-FcA-CS) was developed by coupling oxidized dextran-crosslinked chitosan with ferrocene carboxylic acid (FcA). Detailed characterization revealed that the incorporation of FcA reduced the total pore area of DX-FcA-CS to 7.21 m2·g-1, one-third of ferrocene-free DX-CS (21.71 m2·g-1), while enhancing thermal stability and PO43- adsorption performance. Adsorption kinetics and isotherm studies demonstrated that the interaction between DX-FcA-CS and PO43- followed a pseudo-second-order kinetic model and Langmuir model, indicating chemical and monolayered adsorption mechanisms, respectively. Moreover, DX-FcA-CS exhibited excellent anti-interference properties against concentrated co-existing inorganic ions and humic acid, along with high recyclability. The maximum adsorption capacity reached 1285.35 mg·g-1 (∼428.45 mg P g-1), three times that of DX-CS and surpassing many other adsorbents. PO43--loaded DX-FcA-CS could be further carbonized into electrode material due to its rich content of phosphorus and nitrogen, transforming waste into a valuable resource. These outstanding characteristics position DX-FcA-CS as a promising alternative for phosphate capture and recycling. Overall, this study presents a viable approach to designing environmentally friendly, recyclable, and cost-effective biomaterial for wastewater phosphate removal and value-added applications.

Greening the pathways: a comprehensive review of sustainable synthesis strategies for silica nanoparticles and their diverse applications

Silica nanoparticles (SiNPs) have emerged as a multipurpose solution with wide-ranging applications in various industries such as medicine, agriculture, construction, cosmetics, and food production. In 1961, Stöber introduced a ground-breaking sol-gel method for synthesizing SiNPs, which carried a new era of exploration both in academia and industry, uncovering numerous possibilities for these simple yet multifaceted particles. Inspite of numerous reported literature with wide applicability, the synthesis of these nanoparticles with the desired size and functionalities poses considerable challenges. Over time, researchers have strived to optimize the synthetic route, particularly by developing greener approaches that minimize environmental impact. By reducing hazardous chemicals, energy consumption, and waste generation, these greener synthesis methods have become an important focus in the field. This review aims to provide a comprehensive analysis of the various synthetic approaches available for different types of SiNPs. Starting from the Stöber' method, we analyze other methods as well to synthesis different types of SiNPs including mesoporous, core-shell and functionalized nanoparticles. With increasing concerns with the chemical methods associated for environmental issues, we aim to assist readers in identifying suitable greener synthesis methods tailored to their specific requirements. By highlighting the advancements in reaction time optimization, waste reduction, and environmentally friendly precursors, we offer insights into the latest techniques that contribute to greener and more sustainable SiNPs synthesis. Additionally, we briefly discuss the diverse applications of SiNPs, demonstrating their relevance and potential impact in fields such as medicine, agriculture, and cosmetics. By emphasizing the greener synthesis methods and economical aspects, this review aims to inspire researchers and industry professionals to adopt environmentally conscious practices while harnessing the immense capabilities of SiNPs.

Nanotechnology Approaches for the Remediation of Agricultural Polluted Soils

Soil pollution from various anthropogenic and natural activities poses a significant threat to the environment and human health. This study explored the sources and types of soil pollution and emphasized the need for innovative remediation approaches. Nanotechnology, including the use of nanoparticles, is a promising approach for remediation. Diverse types of nanomaterials, including nanobiosorbents and nanobiosurfactants, have shown great potential in soil remediation processes. Nanotechnology approaches to soil pollution remediation are multifaceted. Reduction reactions and immobilization techniques demonstrate the versatility of nanomaterials in mitigating soil pollution. Nanomicrobial-based bioremediation further enhances the efficiency of pollutant degradation in agricultural soils. A literature-based screening was conducted using different search engines, including PubMed, Web of Science, and Google Scholar, from 2010 to 2023. Keywords such as "soil pollution, nanotechnology, nanoremediation, heavy metal remediation, soil remediation" and combinations of these were used. The remediation of heavy metals using nanotechnology has demonstrated promising results and offers an eco-friendly and sustainable solution to address this critical issue. Nanobioremediation is a robust strategy for combatting organic contamination in soils, including pesticides and herbicides. The use of nanophytoremediation, in which nanomaterials assist plants in extracting and detoxifying pollutants, represents a cutting-edge and environmentally friendly approach for tackling soil pollution.

Contemporary Developments in Ferrocene Chemistry: Physical, Chemical, Biological and Industrial Aspects

Ferrocenyl-based compounds have many applications in diverse scientific disciplines, including in polymer chemistry as redox dynamic polymers and dendrimers, in materials science as bioreceptors, and in pharmacology, biochemistry, electrochemistry, and nonlinear optics. Considering the horizon of ferrocene chemistry, we attempted to condense the neoteric advancements in the synthesis and applications of ferrocene derivatives reported in the literature from 2016 to date. This paper presents data on the progression of the synthesis of diverse classes of organic compounds having ferrocene scaffolds and recent developments in applications of ferrocene-based organometallic compounds, with a special focus on their biological, medicinal, bio-sensing, chemosensing, asymmetric catalysis, material, and industrial applications.

Dendritic Mesoporous Organosilica Nanoparticles with Photosensitizers for Cell Imaging, siRNA Delivery and Protein Loading

Dendritic mesoporous organosilica nanoparticles (DMON) are a new class of biodegradable nanoparticles suitable for biomolecule delivery. We studied the photochemical internalization (PCI) and photodynamic therapy (PDT) of DMON to investigate new ways for DMON to escape from the endosomes-lysosomes and deliver biomolecules into the cytoplasm of cells. We added photosensitizers in the framework of DMON and found that DMON were loaded with siRNA or FVIII factor protein. We made four formulations with four different photosensitizers. The photosensitizers allowed us to perform imaging of DMON in cancer cells, but the presence of the tetrasulfide bond in the framework of DMON quenched the formation of singlet oxygen. Fortunately, one formulation allowed us to efficiently deliver proapoptotic siRNA in MCF-7 cancer cells leading to 31% of cancer cell death, without irradiation. As for FVIII protein, it was loaded in two formulations with drug-loading capacities (DLC) up to 25%. In conclusion, DMON are versatile nanoparticles capable of loading siRNA and delivering it into cancer cells, and also loading FVIII protein with good DLC. Due to the presence of tetrasulfide, it was not possible to perform PDT or PCI.

Oxidized dextran-crosslinked ferrocene-chitosan-PEI composite porous material integrating adsorption and degradation to malachite green

Treating wastewater containing malachite green (MG) using porous materials with both adsorption and degradation functions have become a major challenge in achieving the carbon neutrality goal. Herein by incorporating the ferrocene (Fc) group as a Fenton active center, a novel composite porous material (DFc-CS-PEI) was prepared using chitosan (CS) and polyethyleneimine (PEI) as skeletons and oxidized dextran as a crosslinker. DFc-CS-PEI not only possesses satisfactory adsorption performance to MG but also excellent degradability in the presence of a minor amount of H₂O₂ (3.5 mmol/L) without any additional assistance, due to high specific surface area and active Fc group. The maximum adsorption capacity is ca. 177.73 ± 3.11 mg/g, outperforming most CS-based adsorbents. The removal efficiency of MG is significantly enhanced from 20 % to 90 % as DFc-CS-PEI and H₂O₂ coexist, due to ^·OH-dominated Fenton reaction, and remained in a wide pH range (2.0-7.0). Cl^- exhibits notable suppression on the degradation of MG because of quenching effects. Note that DFc-CS-PEI has a very small iron leaching (0.2 ± 0.015 mg/L), and can be rapidly recycled by simple water-washing, without any harmful chemicals and potential second pollution. Such versatility, high stability, and green recyclability make the as-prepared DFc-CS-PEI a promising porous material for the treatment of organic wastewater.

Bio-templated synthesis of porous silica nano adsorbents to wastewater treatment inspired by a circular economy

Water is an indispensable substance in human life activities. However, due to industrial discharge problems, water resources are polluted, so there is an urgent need for material and technology for wastewater treatment. This paper presents an innovative synthesis of porous silica microspheres (PSM) from a biomass template material (fish skin collagen) to treat protein from wastewater. The collagen from the biomass template was rich in amino, carboxyl, and hydroxyl groups that effectively controlled the hydrolysis rate of tetraethyl orthosilicate (TEOS) and promoted the synthesis of structured PSM. X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), nitrogen sorption isotherms measurements, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to characterize the chemical composition, crystalline structure, and pore architecture of the synthesized PSM. The characterization results confirmed that the PSM were spherical with the microporous and mesoporous structure in shape and approximately 400 nm in size. Moreover, the pore size could be tuned by addition of mesitylene (TMB). The large number of silicon hydroxyl groups on the PSM surface effectively bound proteins in wastewater and greatly improved the overall absorption rate. The PSM adsorption capacity for lysozyme (LZ) was 49.5 mg/g, and the adsorption behavior was well described by a pseudo-second-order kinetic model and the Langmuir model. Most importantly, the PSM effectively removed protein from actual industrial wastewater, thereby realizing a high value-added utilization of wastewater pollutants.

Acid resistant functionalised magnetic nanoparticles for radionuclide and heavy metal adsorption

Coating superparamagnetic iron oxide NPs with SiO₂ has been established in order to confer stability in acidic media. Acid stability tests were carried out between pH 1 and pH 7 to determine the effectiveness of the SiO₂ passivating layer to protect the magnetic Fe₃O₄ core. Transmission Electron Microscopy (TEM) and zeta potential measurements have shown that uncoated Fe₃O₄ NPs exhibit rapid agglomeration and dissolution when exposed to acidic media, moving from a zeta potential of - 26 mV to a zeta potential of + 3 mV. In contrast, the SiO₂ coating of the Fe₃O₄ NPs shows a very high degree of stability for over 14 months and the zeta potential of these NPs remained at ∼- 39 mV throughout the acid exposure and they showed no loss in magnetisaton. Due to the use of these NPs as a potential tool for heavy metal extraction, the stability of the surface functionalisation (in this case a phosphate complex) was also assessed. With a constant zeta potential of ∼ - 29 mV for PO_x-SiO₂@Fe₃O₄ NP complex, the phosphate functionality was shown to be highly stable in the acidic conditions simulating the environment of certain nuclear wastes. ATR-FTIR was conducted after acid exposure confirming that the phosphate complex on the surface of the NPs remained present. Finally, preliminary sorption experiments were carried out with Pb(II), where the NP complexes shown complete removal of the heavy metals at pH 3 and pH 5.

Functionalized silica nanoparticles: classification, synthetic approaches and recent advances in adsorption applications

Nanotechnology is rapidly sweeping through all the vital fields of science and technology such as electronics, aerospace, defense, medicine, and catalysis. It involves the design, synthesis, characterization, and applications of materials and devices on the nanometer scale. At the nanoscale, physical and chemical properties differ from the properties of the individual atoms and molecules of bulk matter. In particular, the design and development of silica nanomaterials have captivated the attention of several researchers worldwide. The applications of hybrid silicas are still limited by the lack of control on the morphology and particle size. The ability to control both the size and morphology of the materials and to obtain nano-sized silica particles has broadened the spectrum of applications of mesoporous organosilicas and/or has improved their performances. On the other hand, adsorption is a widely used technique for the separation and removal of pollutants (metal ions, dyes, organics,...) from wastewater. Silica nanoparticles have specific advantages over other materials for adsorption applications due to their unique structural characteristics: a stable structure, a high specific surface area, an adjustable pore structure, the presence of silanol groups on the surface which allow easy modification, less environmental harm, simple synthesis, low cost, etc. Silica nanoparticles are potential adsorbents for pollutants. We present herein an overview of the different types of silica nanoparticles going from the definitions to properties, synthetic approaches and the mention of potential applications. We focus mainly on the recent advances in the adsorption of different target substances (metal ions, dyes and other organics).

Progress in Mesoporous Silica Nanoparticles as Drug Delivery Agents for Cancer Treatment

Cancer treatment and therapy have made significant leaps and bounds in these past decades. However, there are still cases where surgical removal is impossible, metastases are challenging, and chemotherapy and radiotherapy pose severe side effects. Therefore, a need to find more effective and specific treatments still exists. One way is through the utilization of drug delivery agents (DDA) based on nanomaterials. In 2001, mesoporous silica nanoparticles (MSNs) were first used as DDA and have gained considerable attention in this field. The popularity of MSNs is due to their unique properties such as tunable particle and pore size, high surface area and pore volume, easy functionalization and surface modification, high stability and their capability to efficiently entrap cargo molecules. This review describes the latest advancement of MSNs as DDA for cancer treatment. We focus on the fabrication of MSNs, the challenges in DDA development and how MSNs address the problems through the development of smart DDA using MSNs. Besides that, MSNs have also been applied as a multifunctional DDA where they can serve in both the diagnostic and treatment of cancer. Overall, we argue MSNs provide a bright future for both the diagnosis and treatment of cancer.

Microbial Nanotechnology for Bioremediation of Industrial Wastewater

Pollutant removal from industrial effluents is a big challenge for industries. These pollutants pose a great risk to the environment. Nanotechnology can reduce the expenditure made by industries to mitigate these pollutants through the production of eco-friendly nanomaterials. Nanomaterials are gaining attention due to their enhanced physical, chemical, and mechanical properties. Using microorganisms in the production of nanoparticles provides an even greater boost to green biotechnology as an emerging field of nanotechnology for sustainable production and cost reduction. In this mini review, efforts are made to discuss the various aspects of industrial effluent bioremediation through microbial nanotechnology integration. The use of enzymes with nanotechnology has produced higher activity and reusability of enzymes. This mini review also provides an insight into the advantages of the use of nanotechnology as compared to conventional practices in these areas.

Polymer-modified mesoporous silica microcubes (P@MSMCs) for the synergistic oxidative entrapment of Ag(i), Ti(iv), and Zn(ii) from natural river water

Herein, we demonstrate a hydrothermal route to the one-pot synthesis of polymeric mesoporous silica microcubes (P@MSMCs) for the adsorption of heavy metal ions. During the synthesis of P@MSMCs from column silica gel, the roles and combination of the polymer and an etchant were characterized. Moreover, the porosity of P@MSMCs was tailored by adjusting the reaction temperature between 75 °C and 200 °C. The characterization through UV, FTIR, FESEM, XRD, BET, and EDX techniques exhibited that P@MSMCs have a well-ordered mesoporous structure with cubic morphology. The P@MSMCs had a diameter of 2 μm, with an average pore volume and pore size of 0.69 cm3 g-1 and 10.08 nm, respectively. The results indicated that the P@MSMCs have excellent adsorption capacity for Ag(i), Ti(iv), and Zn(ii) due to the formation of an aggregated complex. These aggregations led to affordable density difference-based separation of these metal ions through centrifugation, filtration or simple decantation. The removal efficiencies for Ag(i), Ti(iv), and Zn(ii) were observed to be 520, 720, and 850 mg g-1, respectively. The kinetic studies demonstrated that the adsorption performance fitted well to the pseudo-second-order kinetic model. The as-synthesized P@MSMCs were stable in the wide pH range of 4-8. Significantly, the recycling or reuse results displayed effective adsorption performance of these P@MSMCs for up to 5 cycles. The adsorption results obtained herein will promote the development of similar strategies for the removal of heavy metal ions from natural water.

Photo-responsive degradable hollow mesoporous organosilica nanoplatforms for drug delivery

BACKGROUND

Stimulus-responsive degradable mesoporous organosilica nanoparticles (MONs) have shown great promise as drug carriers via enhancing the efficiency of drug delivery and accelerating the degradation of nanocarriers. However, it remains a great challenge to develop novel light-enabled spatial and temporal degradable MONs with both superior responsiveness for efficient anti-cancer drug delivery and safe exocytosis.

RESULTS

We report a novel photo-responsive degradable hollow mesoporous organosilica nanoplatform (HMONs@GOQD). The platform is based on organosilica nanoparticles (HMONs) containing singlet oxygen (¹O₂)-responsive bridged organoalkoxysilanes and wrapped graphene oxide quantum dots (GOQDs). The unique hollow mesoporous structure of the HMONs guarantees an excellent drug loading and release profile. During light irradiation, ¹O₂ produced by the GOQDs leads to the degradation of the organosilica nanoparticles, resulting in enhanced local drug release.

CONCLUSIONS

We carried out in vitro and in vivo experiments using DOX as a model drug; DOX-HMONs@GOQDs exhibited high biocompatibility, accelerated degradation, and superior therapeutic efficacy during light irradiation, indicating a promising platform for clinical cancer therapy.

Supramolecular Nanopumps with Chiral Recognition for Moving Organic Pollutants from Water

Since organic pollutants in water resources have raised concerns on aquatic ecosystems and human health, mechanical machines such as a nanopump for rapid and efficient removal of pollutants from water with regeneration properties remains a challenge. Here, a pH-responsive artificial pump from left-handed porous tubules into right-handed solid fibers was presented by the self-assembly of bent-shaped aromatic amphiphiles. The bent-shaped amphiphile with a pH-sensitive segment was demonstrated in aromatic hexameric macrocycles, which could contract into dimeric disks. Such a switchable aromatic pore with superhydrophobicity was well-suited for an efficient removal and controlled release of organic pollutants from water through pulsating motion. The removal efficiency is found to be 78% for ethinyloestradiol and 82% for bisphenol. Additionally, the pumping accompanied by chiral inversion was endowed with a rapid removal and convenient regenerable ability. The inflation from right-handed solid fibers into left-handed tubules for efficient removal pollutants was remarkably promoted by (-)-acidic enantiomer of malic acid, whereas the contraction with full desorption of pollutants was incisively responsive to alkaline with (+)-conformation. The kinetically regulable porous device with a chiral recognition will provide a promising platform for the construction of rapid responsible machine for sewage treatment.