Immobilization of Cu3(btc)2 on graphene oxide-chitosan hybrid composite for the adsorption and photocatalytic degradation of methylene blue

Synthesis and characterization of three-dimensional graphene oxide-chitosan/ glutaraldehyde nanocomposites: Towards adsorption of crocin from saffron

Despite the unique properties of graphene oxide (GO) as a green adsorbent, its low structural stability presents a drawback. This study aimed to modify the properties of GO through its functionalization with chitosan (CH), cross-linked with glutaraldehyde (GLU), and synthesized via the freeze-drying method (GO-CH/GLU). Microscopic analysis illustrated that covering the GO sheets with CH and nanoparticles (NPs) resulted in a 15.8 % increase in d-spacing and a 600 % increase in sheet thickness. The GO-CH/GLU composite was utilized for the separation/purification of crocin from saffron extract under varying pH (5-9), temperature (298-318 K), stirring rate (100-300 rpm), and crocin concentration (25-200 mg/mL). The Freundlich isotherm and pseudo-second-order kinetic models provided a good fit for crocin adsorption. Thermodynamic analysis revealed that the process was endothermic, spontaneous, and physical. Optimal adsorption conditions in batch mode were pH 7, a stirring rate of 300 rpm, a temperature of 318 K, and a crocin concentration of 100 mg/mL. These conditions were applied in a continuous system, resulting in a crocin separation efficiency of 94.17 % at 180 mL/h. Additionally, HPLC data indicated that the purity of separated crocin exceeded 90 %. So, the GO-CH/GLU composite is a promising and economical adsorbent for the food industry.

Development of nanocomposite-selenium filter for water disinfection and bioremediation of wastewater from Hg and AgNPs

Selenium nanoparticles (SeNPs) are used in several sectors as antitumor, antimicrobial, and environmental adsorbents. Thus, the present research objective was the production of bacterial-SeNPs as an active and environmentally-friendly antibacterial and adsorbent agents and application into novel nanocomposite filter. From a total of 25 samples (soil, wastewater, and water) obtained from different locations in Egypt, 60 selenium-resistant bacterial isolates were obtained (on a mineral salt medium supplemented with selenium ions). After screening (based on the conversion of selenium from ionic form to nanoform), a superior bacterial isolate for SeNPs formation was obtained and molecular identified as Bacillus pumilus isolate OR431753. The high yield of SeNPs was noted after optimization (glucose as carbon source, pH 9 at 30 °C). The produced SeNPs were characterized as approximately 15 nm-diameter spherical nanoparticles, in addition to the presence of organic substances around these particles like polysaccharides and aromatic amines (protein residues). Also, they have antibacterial activity increased after formation of nanocomposite with nano-chitosan (SeNPs/NCh) against several pathogens. The antibacterial activity (expressed as a diameter of the inhibitory zone) averaged between 2.1 and 4.3, 2.7 and 4.8 cm for SeNPs and SeNPs/NCh, respectively compared with 1.1 to 1.8 cm for Amoxicillin. The produced nanoselenium/chitosan was used as a biofilter to remove mercury (Hg) and AgNPs as model chemicals with serious toxicity and potential pollutant for water bodies in many industries. The new SeNPs/NCh biofilter has proven highly effective in individually removing mercury and AgNPs from their synthetic wastewaters, with an efficiency of up to 99%. Moreover, the removal efficiency of AgNPs stabilized at 99% after treating them with the syringe filter-Se nanocomposite for 4 cycles of treatment (5 min each).

Bimetal Cu/Ni-BTC@SiO2 metal-organic framework as high performance photocatalyst for degradation of azo dyes under visible light irradiation

There has been significant attention on the efficient degradation of pollutants in wastewater using metal-organic frameworks (MOFs) photocatalytic methods over the past decade. Herein, we examined the elimination of two different types of water-contaminating dyes, specifically cationic dye methylene blue (MB) and anionic dye methyl orange (MO), through the application of bimetal Cu/Ni-BTC@SiO2 MOF as high performance photocatalyst. The bimetal Cu/Ni-BTC@SiO2 photocatalyst was synthesized and characterized by XRD, FTIR, SEM, TEM, TGA, BET, DRS, and VSM techniques. The examination of the impact of different operational factors on the elimination of pollutants involved a comprehensive analysis of variables including the photocatalyst type, initial pollutant concentration, quantity of photocatalyst, and pH levels. The highest removal efficiency for MO and MB dyes by the photocatalyst was found to be 98 and 71%, respectively, within 60 min. In the fifth reaction stage, degradation efficiency for MO and MB was 76 and 56% respectively. Kinetic investigations demonstrated that, in the context of the uptake of MB and MO dyes, the interparticle diffusion, and pseudo-second-order models emerged as possessing the most robust correlation coefficients with the experimental data, registering values of 0.988 and 0.961, respectively. The examination of isotherms reveals that the isotherm models proposed by BET, and Anderson (V) demonstrate the highest level of conformity with the empirical data for the decomposition of MB and MO dyes, correspondingly. The TOC levels decreased significantly from 51 to 14 and 47 to 3 mg/L for MB and MO dyes, indicating the effective mineralization process using Cu/Ni-BTC@SiO2.

Sustainable chitosan-based materials as heterogeneous catalyst for application in wastewater treatment and water purification: An up-to-date review

Water pollution is one of serious environmental issues due to the rapid development of industrial and agricultural sectors, and clean water resources have been receiving increasing attention. Recently, more and more studies have witnessed significant development of catalysts (metal oxides, metal sulfides, metal-organic frameworks, zero-valent metal, etc.) for wastewater treatment and water purification. Sustainable and clean catalysts immobilized into chitosan-based materials (Cat@CSbMs) are considered one of the most appealing subclasses of functional materials due to their high catalytic activity, high adsorption capacities, non-toxicity and relative stability. This review provides a summary of various upgrading renewable Cat@CSbMs (such as cocatalyst, photocatalyst, and Fenton-like reagent, etc.). As for engineering applications, further researches of Cat@CSbMs should focus on treating complex wastewater containing both heavy metals and organic pollutants, as well as developing continuous flow treatment methods for industrial wastewater using Cat@CSbMs. In conclusion, this review abridges the gap between different approaches for upgrading renewable and clean Cat@CSbMs and their future applications. This will contribute to the development of cleaner and sustainable Cat@CSbMs for wastewater treatment and water purification.

Performance evaluation of facile synthesized CA-PVA-GO composite for the mitigation of Cr(Ⅲ) and C.I. acid violet 54 dye from tannery wastewater

Untreated tannery wastewater contains a large amount of toxic metals, dyes, and other pollutants, which pose adverse effects on the ecosystem and public health. In this work, a calcium alginate-poly vinyl alcohol-graphene oxide (CA-PVA-GO) composite was prepared to remove metals and dyes, particularly Cr(Ⅲ) and CI acid violet 54 (AV54) dye, from tannery wastewater. FESEM, FTIR, and XRD analyses were applied to characterize the GO and CA-PVA-GO. Different operational variables, viz. pH (3.0-5.5 for Cr(III) and 2-7 for dye), dosage (0.164-2.46 g/L), contact time (10-60 min), initial concentration (39, 65, 98, and 201 ppm for Cr(III) and 21.5, 38.5, 54.5, and 61.75 ppm for dye), and temperature (298, 308, 318, and 328 K) were studied to evaluate the efficiency of the CA-PVA-GO composite. The optimum conditions for Cr(Ⅲ) and AV54 dye adsorption were found to be pH (5.0 and 3.0), dosage (0.82 g/L for both), and time (45 and 60 min), respectively, with 35.35 ± 1.43% and 84.63 ± 2.54% removal efficiency. The experimental data was analyzed through the Langmuir and Freundlich isotherms. The maximum adsorption capacity (qm) was observed at 173.01 and 74.68 mg/g for Cr(Ⅲ) and AV54 dye, respectively. The pseudo-second-order kinetic model was fitted better (R2 = 0.981, 0.995, 0.92, and 0.995) than first-order for AV54 dye adsorption. Thermodynamic analyses revealed that the Cr(Ⅲ) and AV54 dye adsorption processes were spontaneous and exothermic. The value of Gibbs free energy (ΔG) for Cr(III) adsorption was obtained at -7.433, -4.508, -2.626, and -1.311 kJ/mol, whereas it was -5.178, -4.867, -4.628, and -4.555 kJ/mol for dye. The values of ΔH and ΔS were -67.257 and -0.198 kJ/mol for Cr(III) and -10.852 and -0.019 kJ/mol for the dye removal. The regenerated CA-PVA-GO composite was reused successfully. Different physicochemical parameters, viz., concentration, pH, TDS, EC, BOD5, and COD of chrome tanning and dyeing effluents, were analyzed before and after the adsorption. The results of chromium and dye removal from tannery wastewater were 53.18% and 93.91%, revealing that the developed eco-friendly CA-PVA-GO composite could be an operative adsorbent for tannery wastewater treatment and possibly scaled up to an industrial level.

Non-viral systems for intracellular delivery of genome editing tools

A hallmark of the last decades is an extensive development of genome editing systems and technologies propelling genetic engineering to the next level. Specific and efficient delivery of genome editing tools to target cells is one of the key elements of such technologies. Conventional vectors are not always suitable for this purpose due to a limited cargo volume, risks related to cancer and immune reactions, toxicity, a need for high-purity viral material and quality control, as well as a possibility of integration of the virus into the host genome leading to overexpression of the vector components and safety problems. Therefore, the search for novel approaches to delivering proteins and nucleic acids into cells is a relevant priority. This work reviews abiotic vectors and systems for delivering genome editing tools into target cells, including liposomes and solid lipid particles, other membrane-based vesicles, cell-penetrating peptides, micelles, dendrimers, carbon nanotubes, inorganic, polymer, metal and other nanoparticles. It considers advantages, drawbacks and preferred applications of such systems as well as suitability thereof for the delivery of genome editing systems. A particular emphasis is placed on metal-organic frameworks (MOFs) and their potential in the targeted intracellular delivery of proteins and polynucleotides. It has been concluded that further development of MOF-based vectors and technologies, as well as combining MOFs with other carriers can result in safe and efficient delivery systems, which would be able to circulate in the body for a long time while recognizing target cells and ensuring cell-specific delivery and release of intact cargoes and, thereby, improving the genome editing outcome.

Investigation of ternary Zn-Co-Fe layered double hydroxide as a multifunctional 2D layered adsorbent for moxifloxacin and antifungal disinfection

Layered double hydroxides have recently gained wide interest as promising multifunctional nanomaterials. In this work, a multifunctional ternary Zn-Co-Fe LDH was prepared and characterized using XRD, FTIR, BET, TEM, SEM, and EDX. This LDH showed a typical XRD pattern with a crystallite size of 3.52 nm and a BET surface area of 155.9 m2/g. This LDH was investigated, for the first time, as an adsorbent for moxifloxacin, a common fluoroquinolones antibiotic, showing a maximum removal efficiency and equilibrium time of 217.81 mg/g and 60 min, respectively. Its antifungal activity, for the first time, was investigated against Penicillium notatum, Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, and Mucor fungi at various concentrations (1000-1.95 µg/mL). This LDH was found to be effective against a variety of fungal strains, particularly Penicillium and Mucor species and showed zones of inhibition of 19.3 and 21.6 mm for Penicillium and Mucor, respectively, with an inhibition of 85% for Penicillium species and 68.3% for Mucormycosis. The highest antifungal efficacy results were obtained at very low MIC concentrations (33.3 and 62 µg/ml) against Penicillium and Mucor, respectively. The results of this study suggest a promising multifunctional potential of this LDH for water and wastewater treatment and disinfection applications.

UiO-66-NH2/guanidine-functionalized chitosan: A new bio-based reusable bifunctional adsorbent for removal of methylene blue from aqueous media

Methylene Blue (MB) is a common pollutant found in industrial wastewater, and its removal is crucial to ensure environmental sustainability. Due to MOFs have high surface area, tunable pore size distribution, and excellent adsorption capacity, in the current study, Uio-66-NH2@Cs-ISo-Gu nanohybrid was prepared through soluthermal method and then was used to remove MB dye. The results displayed that dye optimal adsorption by Uio-66-NH2@Cs-ISo-Gu nanohybrid occurred in the first 40 min, pH = 8, and low dye concentrations. Also, with increasing temperature, the amount of adsorption has decreased, which indicated the adsorption process would be exothermic. Based on the results, the Uio-66-NH2@Cs-ISo-Gu nanohybrid has a surface area of 120.9 m2.g-1 and a type IV isotherm. Also, the Freundlich isotherm and pseudo-second order models had the best agreement with the experimental data. The maximum adsorption capacity for this nanohybrid was 178.571, 153.846, and 135.135 mg.g-1 at 25 °C, 45 °C, and 65 °C temperatures, respectively, which could be successfully used as an excellent adsorbent in treatment of wastewater. However, further research is needed to understand the underlying adsorption mechanism and optimize the process for efficient removal of MB from contaminated water sources.

A novel approach to environmental pollution management/remediation techniques using derived advanced materials

The carbon dioxide (CO2) crisis is one of the world's most urgent issues. Meeting the worldwide targets set for CO2 capture and storage (CCS) is crucial. Because it may significantly reduce energy consumption compared to traditional amine-based adsorption capture, adsorption dependant CO2 capture is regarded as one of the most hopeful techniques in this paradigm. The expansion of unique, critical edge adsorbent materials has received most of the research attention to date, with the main objective of improving adsorption capacity and lifespan while lowering the temperature of adsorption, thereby lowering the energy demand of sorbent revival. There are specific materials needed for each step of the carbon cycle, including capture, regeneration, and conversion. The potential and efficiency of metal-organic frameworks (MOFs) in overcoming this obstacle have recently been proven through research. In this study, we pinpoint MOFs' precise structural and chemical characteristics that have contributed to their high capture capacity, effective regeneration and separation processes, and efficient catalytic conversions. As prospective materials for the next generation of energy storage and conversion applications, carbon-based compounds like graphene, carbon nanotubes, and fullerenes are receiving a lot of interest. Their distinctive physicochemical characteristics make them suitable for these popular study topics, including structural stability and flexibility, high porosity, and customizable physicochemical traits. It is possible to precisely design the interior of MOFs to include coordinatively unsaturated metal sites, certain heteroatoms, covalent functionalization, various building unit interactions, and integrated nanoscale metal catalysts. This is essential for the creation of MOFs with improved performance. Utilizing the accuracy of MOF chemistry, more complicated materials must be built to handle selectivity, capacity, and conversion all at once to achieve a comprehensive solution. This review summarizes, the most recent developments in adsorption-based CO2 combustion capture, the CO2 adsorption capacities of various classes of solid sorbents, and the significance of advanced carbon nanomaterials for environmental remediation and energy conversion. This review also addresses the difficulties and potential of developing carbon-based electrodes for energy conversion and storage applications.

Porous material based on modified carbon and the effect of pore size distribution on the adsorption of methylene blue dye from an aqueous solution

Carbon porous materials obtained through KOH activation of a furfural + hydroquinone + urotropine mixture were applied as adsorbent for the remediation of methylene blue (MB). The impact of porous structure with special attention to pore size distribution along with well-known pore volume and specific surface area on the remediation of MB was well investigated and elucidated. Findings obtained revealed that pore size distribution plays a crucial role in the liquid-phase adsorption of organic dyes like MB. By varying the synthesis mode parameters, in particular, the activating agent/precursor mass ratio, with the composition and initial components ratios remaining unchanged, samples with different pore size distribution were obtained. It was found that the material predominantly containing pores with an average equivalent diameter of ~ 3.5 nm appears to be the efficient MB adsorbent. The resulting highly porous carbon materials demonstrated high MB adsorption capacity (up to 2555 mg/g). Furthermore, to fully elucidate the adsorption mechanisms occurring on the obtained materials, a comprehensive mathematical processing of experimental data was performed out using the known kinetic and diffusion models (pseudo-first- and pseudo-second order, and intraparticle diffusion), as well as adsorption equilibrium isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich).It can be concluded that the porous carbon materials obtained and described in the present work are effective adsorbents for the removal of MB and may possess great potential for the treatment of dye-containing wastewater.

Graphene-Based Metal-Organic Framework Hybrids for Applications in Catalysis, Environmental, and Energy Technologies

Current energy and environmental challenges demand the development and design of multifunctional porous materials with tunable properties for catalysis, water purification, and energy conversion and storage. Because of their amenability to de novo reticular chemistry, metal-organic frameworks (MOFs) have become key materials in this area. However, their usefulness is often limited by low chemical stability, conductivity and inappropriate pore sizes. Conductive two-dimensional (2D) materials with robust structural skeletons and/or functionalized surfaces can form stabilizing interactions with MOF components, enabling the fabrication of MOF nanocomposites with tunable pore characteristics. Graphene and its functional derivatives are the largest class of 2D materials and possess remarkable compositional versatility, structural diversity, and controllable surface chemistry. Here, we critically review current knowledge concerning the growth, structure, and properties of graphene derivatives, MOFs, and their graphene@MOF composites as well as the associated structure-property-performance relationships. Synthetic strategies for preparing graphene@MOF composites and tuning their properties are also comprehensively reviewed together with their applications in gas storage/separation, water purification, catalysis (organo-, electro-, and photocatalysis), and electrochemical energy storage and conversion. Current challenges in the development of graphene@MOF hybrids and their practical applications are addressed, revealing areas for future investigation. We hope that this review will inspire further exploration of new graphene@MOF hybrids for energy, electronic, biomedical, and photocatalysis applications as well as studies on previously unreported properties of known hybrids to reveal potential "diamonds in the rough".

Enhanced photodegradation of methylene blue from aqueous solution using Al-doped ZnS nanoparticles

The post-transition semiconducting material of pure zinc sulfide (ZnS) and various concentrations of aluminum (Al) (2.5 wt%, 5.0% wt, 7.5 wt%, and 10% calcined at 200 °C) doped ZnS nanoparticles (NPs) were synthesized by sol-gel procedure. The crystal-like nature and phase structure of the product were examined by powder XRD analysis. This analysis shows that the pure ZnS nanoparticle does not form any secondary phase. The functional group of synthesized materials was analyzed by FTIR examination. The energy gap of the materials is calculated using electro-optic analysis and the Kubelka-Munk equation varies from 3.04 nm to 3.63 nm. The photoluminescence studies show the wide emissions (blue to green) for pure ZnS and Al-doped ZnS nanomaterials. The SEM images show the spherical structure and the agglomerated nanostructures. The presence of Zn, S, and Al are confirmed by EDAX spectra. From HR-TEM studies, pure ZnS and Al-doped ZnS nanoparticles exhibit uniform particle sizes. The rate of degradation was observed using MB dye. MB dye has maximum wavelength (λ_max) of 664 nm. The dye degradation efficiency was improved as the dye ratio increased. Photocatalytic activities studies show the intensity of photocatalytic activities decreased for the maximum time interval. Doping of Al in ZnS boosts the photocatalytic activity. Hence, Al-doped ZnS appears to be better decomposing MB dye when exposed to visible light.

Graphene-based nanocomposites and nanohybrids for the abatement of agro-industrial pollutants in aqueous environments

Incessant release of a large spectrum of agro-industrial pollutants into environmental matrices remains a serious concern due to their potential health risks to humans and aquatic animals. Existing remediation techniques are unable to remove these pollutants, necessitating the development of novel treatment approaches. Due to its unique structure, physicochemical properties, and broad application potential, graphene has attracted a lot of attention as a new type of two-dimensional nanostructure. Given its chemical stability, large surface area, electron mobility, superior thermal conductivity, and two-dimensional structure, tremendous research has been conducted on graphene and its derived composites for environmental remediation and pollution mitigation. Various methods for graphene functionalization have facilitated the development of different graphene derivatives such as graphene oxide (GO), functional reduced graphene oxide (frGO), and reduced graphene oxide (rGO) with novel attributes for multiple applications. This review provides a comprehensive read on the recent progress of multifunctional graphene-based nanocomposites and nanohybrids as a promising way of removing emerging contaminants from aqueous environments. First, a succinct overview of the fundamental structure, fabrication techniques, and features of graphene-based composites is presented. Following that, graphene and GO functionalization, i.e., covalent bonding, non-covalent, and elemental doping, are discussed. Finally, the environmental potentials of a plethora of graphene-based hybrid nanocomposites for the abatement of organic and inorganic contaminants are thoroughly covered.

A Review on Green Synthesis of Nanoparticles and Their Diverse Biomedical and Environmental Applications

In recent times, metal oxide nanoparticles (NPs) have been regarded as having important commercial utility. However, the potential toxicity of these nanomaterials has also been a crucial research concern. In this regard, an important solution for ensuring lower toxicity levels and thereby facilitating an unhindered application in human consumer products is the green synthesis of these particles. Although a naïve approach, the biological synthesis of metal oxide NPs using microorganisms and plant extracts opens up immense prospects for the production of biocompatible and cost-effective particles with potential applications in the healthcare sector. An important area that calls for attention is cancer therapy and the intervention of nanotechnology to improve existing therapeutic practices. Metal oxide NPs have been identified as therapeutic agents with an extended half-life and therapeutic index and have also been reported to have lesser immunogenic properties. Currently, biosynthesized metal oxide NPs are the subject of considerable research and analysis for the early detection and treatment of tumors, but their performance in clinical experiments is yet to be determined. The present review provides a comprehensive account of recent research on the biosynthesis of metal oxide NPs, including mechanistic insights into biological production machinery, the latest reports on biogenesis, the properties of biosynthesized NPs, and directions for further improvement. In particular, scientific reports on the properties and applications of nanoparticles of the oxides of titanium, cerium, selenium, zinc, iron, and copper have been highlighted. This review discusses the significance of the green synthesis of metal oxide nanoparticles, with respect to therapeutically based pharmaceutical applications as well as energy and environmental applications, using various novel approaches including one-minute sonochemical synthesis that are capable of responding to various stimuli such as radiation, heat, and pH. This study will provide new insight into novel methods that are cost-effective and pollution free, assisted by the biodegradation of biomass.

Dye Removal Ability of Pure and Doped Graphitic Carbon Nitride

Background:

Rapid escalation in textile, paper, pesticides, pharmaceuticals and several other chemical based manufacturing industries due to amplification in human requirements have proportionately contributed to the extreme contamination of water ecosystem, resulted from the discharge of toxic pollutants from industries. Effluents from textile industries are comprised of coloured dyes like Rhodamine B, Methyl Orange, Methylene Blue and phenolic compounds which deserve special mention owing to their non-biodegradable, carcinogenic and severe detrimental nature. Urgent needs to ameliorate this fast declining environmental situation are of immense necessity in current scenario.

Objectives:

Objectives: In this regard, graphitic carbon nitride (GCN) is a distinguished material for water purification-based applications because of its exclusive characteristics making it highly prospective for degradation of toxic dyes from water by catalysis and adsorption techniques. GCN has been a material of conspicuous interest in recent times owing to its two dimensional sheets like structure with favourable surface area, and cost-effective synthesis approaches along with high production yield. This article presents a detail study of different aspects of GCN as a material of potential for water purification. Through extensive literature survey it has been shown that GCN is an effective material to be used in the fields of application. Several effective procedures like catalysis or adsorption for removal of dyes from water have been discussed with their basic science behind.

Conclusions:

This systematic effort shows that GCN can be considered to be one of the most efficient water purifier with further advantages arising from its easy and cost effective large scale synthesis.

In Situ Growth of MOFs Crystals to Synthesis Graphene Oxide /ZIF-7 Gel with Enhanced Adsorption Capacity for Methylene Blue

Graphene oxide gel containing ZIF-7 (Zx@GoG) was synthesized by immersing graphene oxide gel (GoG) in DMF solution of Zn2+ and DMF solution of organic ligands, respectively, and characterized by powder...

Clean approach for chromium removal in aqueous environments and role of nanomaterials in bioremediation: Present research and future perspective

Chromium is an insidious ecological pollutant that is of huge value for its toxicity. The existing ecological objective to lower the heights of toxic materials in marine systems and to stimulate the existing water to recycle after suitable treatment of wastewater. Chromium is a hazard element that appears in discharges of numerous industries that must be diminished to accomplish the goals. Nearly all of the findings described in the literature related to the usage of various materials such as fungal, algal, bacterial biomass, and nanomaterials for chromium adsorption. The current work evaluates the findings of research commenced in the preceding on the use of a variety of adsorbents to decrease chromium concentrations in contaminated waters. This review article focuses on the issue of chromium contamination, its chemistry, causes, consequences, biological agent remediation techniques, and the detailed process of chromium detoxification in microbial cells. It also lists a description of the in situ and ex situ chromium bioremediation methods used. This can help design more effective Cr(VI) removal methods, thus bridging the difference between laboratory discoveries and industrial chromium remediation applications.

Detection, Contamination, Toxicity, and Prevention Methods of Ochratoxins: An Update Review

Ochratoxins (OTs) with nephrotoxic, immunosuppressive, teratogenic, and carcinogenic properties are thermostable fungal subordinate metabolites. OTs contamination can occur before or after harvesting, during the processing, packing, distribution, and storage of food. Mold development and mycotoxin contamination can occur in any crop or cereal that has not been stored properly for long periods of time and is subjected to high levels of humidity and temperature. Ochratoxin A (OTA) presents a significant health threat to creatures and individuals. There is also a concern of how human interaction with OTA will also express the remains of OTA from feedstuffs into animal-derived items. Numerous approaches have been studied for the reduction of the OTA content in agronomic products. These methods can be classified into two major classes: inhibition of OTA adulteration and decontamination or detoxification of food. A description of the various mycotoxins, the organism responsible for the development of mycotoxins, and their adverse effects are given. In the current paper, the incidence of OTA in various fodder and food materials is discussed, which is accompanied by a brief overview of the OTA mode of synthesis, physicochemical properties, toxic effects of various types of ochratoxins, and OTA decontamination adaptation methods. To our knowledge, we are the first to report on the structure of many naturally accessible OTAs and OTA metabolism. Finally, this paper seeks to be insightful and draw attention to dangerous OTA, which is too frequently neglected and overlooked in farm duplication from the list of discrepancy studies.

Photocatalytic degradation of congo red dye using nickel-titanium dioxide nanoflakes synthesized by Mukia madrasapatna leaf extract

Semiconductor photocatalysts are efficient degraders of organic and inorganic waste water pollutants. Herein, we synthesized nickel-titanium dioxide (Ni-TiO₂) nanoflakes using Mukia maderaspatana leafs with the aim of analyzing their photocatalytic degradation potential. Morphological analyses revealed that the nanoflakes were highly agglomerated with an average size of 100 nm. Further, elemental analysis confirmed the presence of Ti, O, and Ni, whereas Fourier transform infrared spectroscopy and X-ray diffraction established the presence of TiO₂ and NiO. We found that photocatalytic degradation of congo red under UV illumination increased with increasing incubation period, demonstrating that Ni-TiO₂ nanoflakes can be used as optimal photocatalysts for the degradation of dyes in waste water.

Sustainable carbonaceous biochar adsorbents derived from agro-wastes and invasive plants for cation dye adsorption from water

This study investigated methyl orange (MO) dye adsorption using three biochars produced from agro-waste and invasive plants; the latter consisted of wattle bark (BA), mimosa (BM), and coffee husks (BC). BC had the lowest specific surface area (2.62 m²/g) compared to BA (393.15 m²/g) and BM (285.53 m²/g). The adsorption efficiency of MO was stable at pH 2-7 (95%-96%), whilst it had reduced stability at pH 7-12. Between 0 and 30 min, MO adsorption efficiency was >82%, and at 120 min, representative adsorption equilibrium had occurred. The maximum adsorption capacity of the biochars was 12.3 mg/g. The underlying adsorption mechanisms of the three biochars were governed by electrostatic adsorption and pore diffusion. There was an abundance of active sites for adsorption in BA and BM, while chemical adsorption appeared to be more vital for BC, as it contained more functional groups on its surface. The highest MO adsorption efficiency occurred with BM. BC was not recommended for MO removal, as it was observed to stain the water when a dose exceeding 5.0 g/L was utilized.

Synthesis of a copper (II) metal-organic framework for photocatalytic degradation of rhodamine B dye in water

The Cu(II) metal-organic frameworks (MOFs) based on 1,3,5-benzenetricarboxylic acid (Cu₃(BTC)₂) was synthesized by the hydrothermal method. The synthesized Cu₃(BTC)₂ exhibited pyramid-shaped morphology and showing an average specific area of 32.16 m² g^-1. The Cu₃(BTC)₂ photocatalysts were characterized using Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), field emission scanning electron microscopy-energy-dispersive X-ray spectroscopy (FESEM-EDX), UV-Vis diffusive reflectance spectra, and Brunauer-Emmett-Teller (BET). The photocatalytic activity of Cu₃(BTC)₂ was examined on Rhodamine B (RhB) degradation under visible light irradiation. The outcomes displayed exceedingly enhanced photocatalytic activity under visible light. In addition, its recyclability was also confirmed for multiple cycles. The easiness of construction and high photocatalytic performance of Cu₃(BTC)₂ photocatalysts can be capable in environmental applications to treat water contamination.

Recent technologies for nutrient removal and recovery from wastewaters: A review

Water scarcity and its pollution has become a concern in recent times. The disposal of nutrient-rich (nitrogen and phosphorous) wastewater is also one of the main cause of water pollution through eutrophication, reduced dissolved oxygen that poses threat to aquatic ecosystems. As a result, nutrient removal has become a mandate apart from the removal of organics. However, the removal of nutrients from sewage is a challenging task. Conversely, conventional biological treatment processes provide little relief in nutrient removal. The treated effluents from conventional biological processes do not achieve the stringent nutrient removal disposal standard limits and become primary cause of pollution in the receiving water bodies. This has stressed upon the need for eco-friendly, low-energy and cost-efficient nutrient removal treatment technologies. Various biological treatment combinations or variants are in use for the efficient removal of nutrients. The biological processes in itself or in combination with chemical processes are preferred over technologies based solely on physico-chemical processes for its treatment performance at lower cost. This review summarizes the existing treatment processes and their possible up-gradation with the aim to accomplish the marked effluent standards for the nutrients. The concept of conventional systems and advanced systems for nutrients (nitrogen and phosphorous) removal which are already developed or under development are deeply discussed. Further, the challenges of each treatment systems are abridged. Finally, the possible suggestions for the modification/retrofitting of existing treatment systems for achieving stringent disposal standards are pointed out.

Graphene-Based Materials Immobilized within Chitosan: Applications as Adsorbents for the Removal of Aquatic Pollutants

Graphene and its derivatives, especially graphene oxide (GO), are attracting considerable interest in the fabrication of new adsorbents that have the potential to remove various pollutants that have escaped into the aquatic environment. Herein, the development of GO/chitosan (GO/CS) composites as adsorbent materials is described and reviewed. This combination is interesting as the addition of graphene to chitosan enhances its mechanical properties, while the chitosan hydrogel serves as an immobilization matrix for graphene. Following a brief description of both graphene and chitosan as independent adsorbent materials, the emerging GO/CS composites are introduced. The additional materials that have been added to the GO/CS composites, including magnetic iron oxides, chelating agents, cyclodextrins, additional adsorbents and polymeric blends, are then described and discussed. The performance of these materials in the removal of heavy metal ions, dyes and other organic molecules are discussed followed by the introduction of strategies employed in the regeneration of the GO/CS adsorbents. It is clear that, while some challenges exist, including cost, regeneration and selectivity in the adsorption process, the GO/CS composites are emerging as promising adsorbent materials.

Immobilization of cellulase enzymes on nano and micro-materials for breakdown of cellulose for biofuel production-a narrative review

Cellulose is a very abundant polymer that is found in nature. Cellulose has been used as a raw material for production of biofuels for many years. However, there are multiple processing steps that are required so that cellulose can be used as a raw material for biofuel production. One of the most important steps is the breakdown of cellulose into intermediate sugars which can then be a viable substrate for biofuel production. Cellulases are enzymes which play a role in the catalysis of the breakdown of cellulose into glucose. Nanomaterials and micromaterials have been gaining a lot of attention over the past few years for its potential in immobilizing enzymes for industrial procedures. Immobilization of enzymes on these nanomaterials has been observed to be of great value due to the improvement in thermal stability, pH stability, regenerative capacity, increase in activity and the reusability of enzymes. Similarly, there have been multiple reports of cellulase enzymes being immobilized on various nanoparticles. The immobilization of these cellulase enzymes have resulted in very efficient processing and provide a great and economic solution for the processing of cellulose for biofuel production. Hence in this paper, we review and discuss the various advantages and disadvantages of enzymes on various available nanomaterials.

Mechanisms of halosulfuron methyl pesticide biosorption onto neem seeds powder

The current investigation was designed to remove halosulfuron methyl from aqueous media by means of neem seed powder (NSP) in batch modes. Characterizations of NSP were carried out by using EDX, SEM, FTIR, point of zero charge and surface analysis. Optimum operation conditions were scrutinized by studying the influence of different factors like solution pH, dose of NSP, contact time, initial halosulfuron methyl concentration and temperature. Result indicates the dependency of the removal of halosulfuron methyl on solution pH and maximal removal (54%) was achieved in acidic medium (i.e. pH 3.0). To identify the chemical surface of NSP, point of zero charge of NSP was determined and was found to be 6.5 which imply that the surface of NSP is positively charged below pH 6.6 and favored the anionic sorption. Kinetics of halosulfuron methyl were demonstrated well by pseudo second order due to highest R2 (0.99) owing to the nearness between experimental and calculated sorption capacities. Isotherm results imply that Langmuir was found to the principal model to explain the removal of halosulfuron methyl and maximum monolayer sorption capacity was determined to be 200 mg g-1. Thermodynamic parameters like ΔH°, ΔG° and ΔS° were calculated from van't Hoff plot and were found negative which suggest that removal of halosulfuron methyl is exothermic and spontaneous at low temperature. These outcomes insinuate that neem seed power may be a valuable, inexpensive and ecofriendly biosorbent for the removal of pesticides.

Low-Intensity Focused Ultrasound-Augmented Multifunctional Nanoparticles for Integrating Ultrasound Imaging and Synergistic Therapy of Metastatic Breast Cancer

The metastasis of breast cancer is believed to have a negative effect on its prognosis. Benefiting from the remarkable deep-penetrating and noninvasive characteristics, sonodynamic therapy (SDT) demonstrates a whole series of potential leading to cancer treatment. To relieve the limitation of monotherapy, a multifunctional nanoplatform has been explored to realize the synergistic treatment efficiency. Herein, we establish a novel multifunctional nano-system which encapsulates chlorin e6 (Ce6, for SDT), perfluoropentane (PFP, for ultrasound imaging), and docetaxel (DTX, for chemotherapy) in a well-designed PLGA core-shell structure. The synergistic Ce6/PFP/DTX/PLGA nanoparticles (CPDP NPs) featured with excellent biocompatibility and stability primarily enable its further application. Upon low-intensity focused ultrasound (LIFU) irradiation, the enhanced ultrasound imaging could be revealed both in vitro and in vivo. More importantly, combined with LIFU, the nanoparticles exhibit intriguing antitumor capability through Ce6-induced cytotoxic reactive oxygen species as well as DTX releasing to generate a concerted therapeutic efficiency. Furthermore, this treating strategy actives a strong anti-metastasis capability by which lung metastatic nodules have been significantly reduced. The results indicate that the SDT-oriented nanoplatform combined with chemotherapy could be provided as a promising approach in elevating effective synergistic therapy and suppressing lung metastasis of breast cancer.

In vitro evaluation of curcumin-loaded chitosan-coated hydroxyapatite nanocarriers as a potential system for effective treatment of cancer

Nanotechnology has many potential applications in cancer treatment. For example, nano-drug delivery systems (NDDS) with high bioavailability, biodegradability, and biocompatibility have been developed, in order to increase the therapeutic effects of anticancer drugs. Among these NDDS, high-performance hydroxyapatite (HA) nanoparticles are rapidly advancing in the targeted cancer treatment due to their numerous benefits. Curcumin is an herbal metabolite that acts as a chemical inhibitor through the inhibition of tumor cells and the progression of many cancers. However, the poor bioavailability of curcumin is the most important challenge in using this substance. In this study, HA nanoparticles coated by chitosan were used as a pH-sensitive biopolymer to improve the efficiency and bioavailability of curcumin. For this purpose, HA nanoparticles were first synthesized by the sol-gel method. Then, a layer of chitosan was coated on it, and the curcumin drug was encapsulated in the nanocarrier, under controlled conditions. Techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the nanocarriers. In the second part, nano-drugs prepared by various bioassays were examined. For this purpose, the rate of cytotoxicity by the methyl-thiazol-tetrazolium (MTT) assay and the rate of apoptosis induction by the acridine orange and ethidium bromide (AO/EB) staining method on the brain carcinoma U87MG cell line were investigated.

Graphene Oxide-Doped MgO Nanostructures for Highly Efficient Dye Degradation and Bactericidal Action

Various concentrations (0.01, 0.03 and 0.05 wt ratios) of graphene oxide (GO) nanosheets were doped into magnesium oxide (MgO) nanostructures using chemical precipitation technique. The objective was to study the effect of GO dopant concentrations on the catalytic and antibacterial behavior of fixed amount of MgO. XRD technique revealed cubic phase of MgO, while its crystalline nature was confirmed through SAED profiles. Functional groups presence and Mg-O (443 cm-1) in fingerprint region was evident with FTIR spectroscopy. Optical properties were recorded via UV-visible spectroscopy with redshift pointing to a decrease in band gap energy from 5.0 to 4.8 eV upon doping. Electron-hole recombination behavior was examined through photoluminescence (PL) spectroscopy. Raman spectra exhibited D band (1338 cm-1) and G band (1598 cm-1) evident to GO doping. Formation of nanostructure with cubic and hexagon morphology was confirmed with TEM, whereas interlayer average d-spacing of 0.23 nm was assessed using HR-TEM. Dopants existence and evaluation of elemental constitution Mg, O were corroborated using EDS technique. Catalytic activity against methyl blue ciprofloxacin (MBCF) was significantly reduced (45%) for higher GO dopant concentration (0.05), whereas bactericidal activity of MgO against E. coli was improved significantly (4.85 mm inhibition zone) upon doping with higher concentration (0.05) of GO, owing to the formation of nanorods.

Facile synthesis of reduced graphene oxide using Acalypha indica and Raphanus sativus extracts and their in vitro cytotoxicity activity against human breast (MCF-7) and lung (A549) cancer cell lines

In the present study, an eco-friendly approach is adapted for the synthesis of reduced graphene oxide (rGO's) by a simple hydrothermal reaction using two plant extracts namely Acalypha indica and Raphanus sativus. After the hydrothermal reaction, GO turns into a black color from brown color, which indicates the successful reduction of graphene oxide. Further, various characterization techniques such as UV-Vis spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction is used to confirm the physicochemical properties of synthesized rGO's. Raman analysis confirms the reduction of GO by noticing an increase in the I_D/I_G ratio significantly. Field emission scanning electron microscopy and transmission electron microscopy clearly show the morphology and crystalline nature of rGO's. FT-IR spectrum confirms that the bioactive molecules of the plant extract (i.e. polyphenols, flavonoids, terpenoids, etc.) playing a key role in the elimination of oxygen groups from the GO surface. Further, the synthesized rGO's are tested for their potential against human lung and breast cancer cell lines. A significant cancer cell inhibition activity is obtained even in the less concentration of rGO's with IC₅₀ values for lung cancer cell lines are 38.46 µg/mL and 26.69 µg/mL for AIrGO and RSrGO, respectively. Similarly, IC₅₀ values for breast cancer cell lines are 35.97 µg/mL and 33.22 µg/mL for AIrGO and RSrGO, respectively.

Metal–organic frameworks/biopolymer nanocomposites: from fundamentals toward recent applications in modern technology

Bio–nanocomposite compounds based on biopolymers and MOFs have presented great potential in various applications for modern technology.

The degradation of methylene blue dye using copper-doped hydroxyapatite encapsulated into polycaprolactone nanofibrous membranes

Methylene blue is degraded under visible light irradiation in the presence of the nanofibrous membranes of PCL containing modified HAP with different contents of Cu ions.

Graphene Oxide Negatively Regulates Cell Cycle in Embryonic Fibroblast Cells

BACKGROUND

Unique properties of graphene and its derivatives make them attractive in the field of nanomedicine. However, the mass application of graphene might lead to side effects, which has not been properly addressed in previous studies, especially with regard to its effect on the cell cycle.

METHODS

The effect of two concentrations (100 and 200 μg/mL) of nano- and microsized graphene oxide (nGO and mGO) on apoptosis, cell cycle, and ROS generation was studied. The effect of both sizes on viability and genotoxicity of the embryonic fibroblast cell cycle was evaluated. MTT and flow cytometry were applied to evaluate the effects of graphene oxide (GO) nanosheets on viability of cells. Apoptosis and cell cycle were analyzed by flow cytometry.

RESULTS

The results of this study showed that GO disturbed the cell cycle and nGO impaired cell viability by inducing cell apoptosis. Interestingly, both nGO and mGO blocked the cell cycle in the S phase, which is a critical phase of the cell cycle. Upregulation of TP53-gene transcripts was also detected in both nGO- and mGO-treated cells compared to the control, especially at 200 μg/mL. DNA content of the treated cells increased; however, because of DNA degradation, its quality was decreased.

CONCLUSION

In conclusion, graphene oxide at both nano- and micro-scale damages cell physiology and increases cell population in the S phase of the cell cycle.

Zwitterion composite chitosan-epichlorohydrin/zeolite for adsorption of methylene blue and reactive red 120 dyes

In this research, an attempt to develop zwitterion composite adsorbent is conducted by modifying chitosan (CHS) with a covalent cross-linker (epichlorohydrin, ECH) and an aluminosilicate mineral (zeolite, ZL). The zwitterion composite adsorbent of chitosan-epichlorohydrin/zeolite (CHS-ECH/ZL) is performed multifunctional tasks by removing two structurally different cationic (methylene blue dye, MB), and anionic (reactive red 120 dye, RR120) dyes from aqueous solutions. The surface property, crystallinity, morphology, functionality, and charge of the CHS-ECH/ZL are analyzed using BET, XRD, SEM, FTIR, and pH_pzc, analyses, respectively. The influence of pertinent parameters namely CHS-ECH/ZL dosage (0.02-0.5 g), solution pH (4-10), temperature (303-323K), initial dye concentration (30-400 mg/L), and contact time (0-600 min) on the MB and RR120 removal are tested. The research findings revealed that the adsorption isotherm at equilibrium well explained in according to the Freundlich isotherm model, and the recorded adsorption capacities of CHS-ECH/ZL are 156.1 and 284.2 mg/g for MB and RR120 respectively at 30 °C. The mechanism of MB and RR120 adsorption onto the CHS-ECH/ZL indicates various types of interactions namely, electrostatic interaction, hydrogen bonding, and Yoshida H-bonding in addition to n-π interaction. Overall, this research introduces CHS-ECH/ZL composite as an eco-friendly zwitterion adsorbent with good applicability towards the two structurally different cationic and anionic dyes from aqueous environment.

Anti-Epcam Aptamer (Syl3c)-Functionalized Liposome for Targeted Delivery Of Doxorubicin: In Vitro And In Vivo Antitumor Studies in Mice Bearing C26 Colon Carcinoma

In this study, we have surface-functionalized PEGylated-nanoliposomal doxorubicin (DOX) with anti-EpCAM (epithelial cell adhesion molecule) aptamer via post-insertion of anti-EpCAM aptamer-conjugated DSPE-mPEG2000 into Caelyx® (ED-lip). The size, charge, release profile, and cytotoxicity and cellular uptake of formulation were determined. The characterization of the ED-lip demonstrated the slightly increase in size and PDI along with the decrease in zeta potential which indicated that post-insertion efficiently done. The results of flow cytometry and fluorescent microscopy have shown that ED-lip enhanced the rate of cell uptake on C26 cell line compared to Caelyx®. The ED-lip also had more cytotoxic effects than Caelyx® which indicated the efficacy of anti-EpCAM aptamer as targeting ligand. The pharmacokinetic and tissue biodistribution of formulations in mice bearing C26 tumors demonstrated that ED-lip did not affect the distribution profile of DOX compared to Caelyx® in animal model. In addition, ED-lip effectively improved the tumor accumulation of DOX and promoted survival of animals compared to Caelyx®. These results suggest that the functionalization of Caelyx® with anti-EpCAM aptamer is promising in cancer treatment and merits further investigation.

Water-Soluble Fullerenol with Hydroxyl Group Dependence for Efficient Two-Photon Excited Photodynamic Inactivation of Infectious Microbes

We successfully prepared water-soluble fullerenol [C₆₀(OH)₄₆] that exhibited a high singlet oxygen quantum yield and efficiently generated reactive oxygen species. Additionally, the water-soluble C₆₀(OH)₄₆ with a higher composition of exposed hydroxyl groups had superior two-photon stability and characteristics compared with that with a lower composition of such groups. Therefore, the prepared fullerenol can be an effective two-photon photosensitizer. The water-soluble C₆₀(OH)₄₆ had favorable two-photon properties. During two-photon photodynamic therapy, the water-soluble C₆₀(OH)₄₆ had substantial antimicrobial activity against Escherichia coli at an ultralow-energy level of 211.2 nJ pixel^-1 with 800 scans and a photoexcited wavelength of 760 nm.