Photocatalytic and antifouling performance of titania-coated alumina membranes produced using a facile sol-gel dip-coating approach.

Photocatalytic membranes (PM) have been investigated as an antifouling strategy for membrane separation processes. Coating ceramic membranes with photocatalytic layers can provide a highly active surface capable of degrading foulants and smaller molecules improving the membrane's performance when the surface is irradiated by a suitable light. Nevertheless, the coating process often leads to pore blockage due to the formation or deposition of thick layers of photocatalyst on membrane surfaces, which modifies the original membranes' average pore size and reduces membrane permeability. A facile sol-gel dip coating process was used to produce PM without modifying the original surface morphology of alumina microfiltration membranes. A 3.7-fold increase in permeate volume after 90 minutes of permeation of an acetaminophen solution in continuous filtration mode under UV light (λ = 365 nm LED, 10W) using titania as photocatalyst compared to the bare alumina membrane without irradiation. Furthermore, fouling modeling proved a reduction in the fouling constant, while fouling mechanisms were not modified. Raman analysis showed 100% anatase formed on the membrane surface. Although membranes could remove up to 87% TOC for oily wastewater filtration, antifouling capabilities for this type of effluent were not observed for the photocatalytic membranes mainly due to fouling inside the pores and light attenuation due to the thick fouling layer on the membrane surface.

Tutorial review on the processing and performance of fabrics with antipathogenic inorganic agents.

Functionalized textiles have been increasingly used for enhancing antimicrobial or antiviral (antipathogenic) action. Those pathogens can cause recurring diseases by direct or indirect transmission. Particularly, airborne microorganisms may cause respiratory diseases or skin infections like allergies and acne and the use of inorganic agents such as metal and metal oxides has proven effective in antipathogen applications. This review is a tutorial on how to obtain functional fabric with processes easily applied for industrial scale. Also, this paper summarizes relevant textiles and respective incorporated inorganic agents, including their antipathogenic mechanism of action. In addition, the processing methods and functional finishing, on a laboratory and industrial scale, to obtain a functional textile are shown. Characterization techniques, including antipathogenic activity and durability, mechanical properties, safety, and environmental issues, are presented. Challenges and perspectives on the broader use of antipathogenic fabrics are discussed.

Colorimetric detection of Pseudomonas aeruginosa by aptamer-functionalized gold nanoparticles.

Novel rapid methodologies for the detection of bacteria have been recently investigated and applied. In hospital environments, infections by pathogens are very common and can cause serious health problems. Pseudomonas aeruginosa is one of the most common bacteria, which can grow in hospital equipment such as catheters and respirators. Even at low concentrations, it can cause severe infections as it is resistant to antibiotics and other treatments. Based on this subject's relevance, this work aimed to develop a colorimetric biosensor using aptamer-functionalized gold nanoparticles for identifying P. aeruginosa. The detection mechanism is based on the color change of gold nanoparticles (AuNPs) from red to blue-purple through NaCl induction after bacteria incubation and aptamer-target binding. First, AuNPs were synthesized and characterized. The influence of aptamer and sodium chloride concentration on the agglomeration of AuNPs was investigated. Optimization of aptamer concentration and salt addition were performed. The best condition for detection was 5 µM aptamers and 200 mM of NaCl. In this case, P. aeruginosa was detected after 5 h for concentrations from 108 to 105 CFU mL-1, being 105 and 104 CFU mL-1 the detection limit for color change by the naked eye and UV-Vis spectrometry, respectively. In addition, other bacteria such as E. coli, S. typhimurium, and Enterobacteriaceae bacterium were also detected with color changing from red to gray. Finally, it was confirmed that the salt incubation time can be 2 h, and that the ideal aptamer concentration is 5 µM. Thus, the colorimetric analysis can be a simple and fast detection method for P. aeruginosa in the range of 108 to 105 CFU mL-1 to the naked eye. KEY POINTS: • A new method for rapid detection of Pseudomonas aeruginosa • Aptamers conjugated with gold nanoparticles allow pathogen detection by colorimetry • No need for previous surface modification of nanoparticles.

Conversion of fruit waste-derived biomass to highly microporous activated carbon for enhanced CO2 capture.

Activated carbons were prepared from different Amazonian fruit waste-derived biomass residues from the Amazon to store CO2 at low pressure. The samples were carbonized in under flowing N2 flow atmosphere and activated with KOH. The carbon materials obtained were physically and structurally characterized by the analysis of N2 isotherms for textural characterization, X-ray fluorescence (XRF), ash content, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and applied for CO2 adsorption. Temperature programmed desorption (TPD), the isosteric heat were also calculated. The values of the specific surface area (SBET) ranged from 1824 to 2004 m2/g, and the total pore volume varied between 0.68 and 0.79 cm3/g. These results confirm that the obtained activated carbons are microporous materials. The highest CO2 adsorption under the pressure of 1 bar was achieved in activated carbon derived from andiroba seeds ANKO1, the adsorption of carbon dioxide at 1 bar was being 7.18 and 4.81 mmol/g at 273 K and 298 K, respectively. As a result, the most important factor in the preparation of activated carbon for CO2 capture is primarily rich in extremely the high amount of small micropores.

Chitosan/ß-TCP composites scaffolds coated with silk fibroin: a bone tissue engineering approach.

Bone regeneration and natural repair are long-standing processes that can lead to uneven new tissue growth. By introducing scaffolds that can be autografts and/or allografts, tissue engineering provides new approaches to manage the major burdens involved in this process. Polymeric scaffolds allow the incorporation of bioactive agents that improve their biological and mechanical performance, making them suitable materials for bone regeneration solutions. The present work aimed to create chitosan/beta-tricalcium phosphate-based scaffolds coated with silk fibroin and evaluate their potential for bone tissue engineering. Results showed that the obtained scaffolds have porosities up to 86%, interconnectivity up to 96%, pore sizes in the range of 60-170 µm, and a stiffness ranging from 1 to 2 MPa. Furthermore, when cultured with MC3T3 cells, the scaffolds were able to form apatite crystals after 21 d; and they were able to support cell growth and proliferation up to 14 d of culture. Besides, cellular proliferation was higher on the scaffolds coated with silk. These outcomes further demonstrate that the developed structures are suitable candidates to enhance bone tissue engineering.

Chitosan as a matrix of nanocomposites: A review on nanostructures, processes, properties, and applications.

Chitosan is a biopolymer that is natural, biodegradable, and relatively low price. Chitosan has been attracting interest as a matrix of nanocomposites due to new properties for various applications. This study presents a comprehensive overview of common and recent advances using chitosan as a nanocomposite matrix. The focus is to present alternative processes to produce embedded or coated nanoparticles, and the shaping techniques that have been employed (3D printing, electrospinning), as well as the nanocomposites emerging applications in medicine, tissue engineering, wastewater treatment, corrosion inhibition, among others. There are several reviews about single chitosan material and derivatives for diverse applications. However, there is not a study that focuses on chitosan as a nanocomposite matrix, explaining the possibility of nanomaterial additions, the interaction of the attached species, and the applications possibility following the techniques to combine chitosan with nanostructures. Finally, future directions are presented for expanding the applications of chitosan nanocomposites.

Lipase immobilization on ceramic supports: An overview on techniques and materials.

Enzyme immobilization is a well-known technique that allows the reuse of the biocatalyst and generally improves its stability. These improved characteristics are of fundamental importance to turn industrial biocatalysis into viable and competitive processes. The immobilization of enzymes can occur through several physical or chemical techniques. When the increase or retention of the catalytic activity is the main purpose, physical methods should be used because they cause fewer changes in the enzymatic structure. When the reuse and stability are the main targets, a chemical method should be chosen to guarantee stronger enzyme-support interaction. Several materials can be applied for the immobilization of enzymes, either organic or inorganic. Inorganic materials have some advantages, such as high mechanical, thermal and chemical resistance, which are important for the process economy. Among the inorganic materials, ceramics stand out due to their longer shelf life, pore size control during the manufacturing, and novel applications in several industrial processes. Due to the high versatility of lipases and broad range of relevant applications, they are the focus of this review. Lipases are known to have a high affinity with hydrophobic substrates (such as polymers), so there is a lack of studies regarding general aspects of their immobilization in hydrophilic materials as ceramics. Thus, the objective of this work is to provide an overview of the main techniques of enzyme immobilization in ceramic supports highlighting the immobilization of lipases. A general overview of the key parameters to be considered to obtain immobilized enzymes that can be used on a large scale is also presented.

An overview and future prospects on aptamers for food safety.

INTRODUCTION: Many bacteria are responsible for infections in humans and plants, being found in vegetables, water, and medical devices. Most bacterial detection methods are time-consuming and take days to give the result. Aptamers are a promising alternative for a quick and reliable measurement technique to detect bacteria present in food products. Selected aptamers are DNA or RNA oligonucleotides that can bind with bacteria or other molecules with affinity and specificity for the target cells by the SELEX or cell-SELEX technique. This method is based on some rounds to remove the non-ligand oligonucleotides, leaving the aptamers specific to bind to the selected bacteria. Compared with conventional methodologies, the detection approach using aptamers is a rapid, low-cost form of analysis. OBJECTIVE: This review summarizes obtention methods and applications of aptamers in the food industry and biotechnology. Besides, different techniques with aptamers are presented, which enable more effective target detection. CONCLUSION: Applications of aptamers as biosensors, or the association of aptamers with nanomaterials, may be employed in analyses by colorimetric, fluorescence, or electrical devices. Additionally, more efficient ways of sample preparation are presented, which can support food safety to provide human health, with a low-cost method for contaminant detection. Key points • Aptamers are promising for detecting contaminants outbreaks. • Studies are needed to identify aptamers for different targets.

Are TiO2 nanoparticles safe for photocatalysis in aqueous media?

Although environmental and toxicity concerns are inherently linked, catalysis using photoactive nanoparticles and their hazardous potential are usually addressed independently. A toxicological assessment under the application framework is particularly important, given the pristine nanoparticles tend to change characteristics during several processes used to incorporate them into products. Herein, an efficient TiO2-functionalized macroporous structure was developed using widely adopted immobilization procedures. The relationships between photocatalysis, catalyst release and associated potential environmental hazards were assessed using zebrafish embryonic development as a proxy. Immobilized nanoparticles demonstrated the safest approach to the environment, as the process eliminates remnant additives while preventing the release of nanoparticles. However, as acute sublethal effects were recorded in zebrafish embryos at different stages of development, a completely safe release of TiO2 nanoparticles into the aquatic environment cannot be advocated.

Avaliação da energia incorporada e da emissão de CO2 em recipientes para refrigerantes: PET versus vidro / Evaluation of energy and CO 2 emissions in soft drink containers: PET versus Glass

RESUMO Este artigo busca avaliar e comparar qual material (PET ou vidro) proporciona um ciclo de vida mais sustentável para os recipientes utilizados no envase de refrigerantes. Foram comparados quatro recipientes de vidro - três retornáveis e um descartável - com cinco recipientes em polietileno tereftalato (PET) - três descartáveis produzidos com material virgem, um descartável produzido com 20% de material reciclado e um retornável (RefPET). Utilizou-se como ferramenta o programa CES-Selector/EcoAudit, o qual considera cinco etapas principais do ciclo de vida do produto - material (obtenção de matéria-prima), produção, transporte, uso e descarte. Os indicadores resultantes foram a energia incorporada e a quantidade de CO2 emitida. Os resultados, para cada 1.000 L de refrigerante envasado, comprovam que a reutilização do recipiente é a escolha ambientalmente mais correta e mostram que, nas garrafas de PET, quanto maior a capacidade do recipiente, menor a quantidade de material de PET utilizado, menor a energia incorporada e menor a emissão de CO2. Por outro lado, para as garrafas de vidro, o resultado é oposto, ou seja, quanto maior a capacidade do recipiente, maior a quantidade de material utilizado, maior a energia incorporada e maior será a quantidade de CO2 emitida. Considerando a energia incorporada e o CO2 gerado, o resultado final mostra que, para envasar pequenos volumes (vidro de 290 mL e PET de 250 mL), os recipientes de vidro apresentam resultados melhores, enquanto, para envasar volumes maiores (acima de 600 mL), os recipientes de PET são os mais indicados.

ABSTRACT The present paper aims to assess and compare which material (PET or glass) provides a more sustainable life cycle for soft drink containers. Four glass containers, three returnable ones and one disposable were compared to five PET containers (polyethylene terephthalate), three disposable ones made from virgin material, one disposable made from 20% of recycled material and one returnable (RefPet). The CES-Selector/EcoAudit program, which considers five main stages of the product life cycle - material (obtaining raw material), production, transportation, use and disposal - , was used. The resulting indicators were the energy and the amount of CO2 emission. The results, for every 1,000 liters of soft drink bottled, prove that the reuse of containers is the most environmentally correct choice and show that in PET bottles the larger the container capacity the smaller the amount of PET material used, lower the energy and the lower the CO2 emission. On the other hand, for glass bottles, the result is opposite, that is, the larger the container capacity, the greater the amount of material used, the greater the embodied energy and the greater the CO2 emission. Considering the incorporated energy and the CO2 generated, the final result shows that glass containers present better results when filling small-volume packages (290 ml glass and 250 ml PET), while PET containers are the most suitable ones for larger volumes (above 600 ml).

Biomining of iron-containing nanoparticles from coal tailings.

Sulfur minerals originating from coal mining represent an important environmental problem. Turning these wastes into value-added by-products can be an interesting alternative. Biotransformation of coal tailings into iron-containing nanoparticles using Rhodococcus erythropolis ATCC 4277 free cells was studied. The influence of culture conditions (stirring rate, biomass concentration, and coal tailings ratio) in the particle size was investigated using a 23 full factorial design. Statistical analysis revealed that higher concentrations of biomass produced larger sized particles. Conversely, a more intense stirring rate of the culture medium and a higher coal tailings ratio (% w/w) led to the synthesis of smaller particles. Thus, the culture conditions that produced smaller particles (< 50 nm) were 0.5 abs of normalized biomass concentration, 150 rpm of stirring rate, and 2.5% w/w of coal tailings ratio. Composition analyses showed that the biosynthesized nanoparticles are formed by iron sulfate. Conversion ratio of the coal tailings into iron-containing nanoparticles reached 19%. The proposed biosynthesis process, using R. erythropolis ATCC 4277 free cells, seems to be a new and environmentally friendly alternative for sulfur minerals reuse.

Properties and Applications of Morinda citrifolia (Noni): A Review.

Morinda citrifolia commonly known as noni is a perennial plant originating in Southeast Asia, consumed over 2000 years. Due to its versatility of adaptation and use of the structures of the plant for different therapeutic purposes, noni attracted the attention of researchers from the pharmaceutical and food industry. Chemical and nutritional analyzes already performed in M. citrifolia reveal the existence of more than 200 phytochemical substances with bioactive properties such as acids, alcohols, phenols, saccharides, anthraquinones, carotenoids, esters, triterpenoids, flavonoids, glycosides, lactones, iridoids, ketones, lactones, lignans, nucleosides, triterpenides, sterols, and aromatic compounds. The high nutritional value of M. citrifolia may induce therapeutic effects, including antimicrobial and antioxidant properties. The main industrial products from this plant are beverages (juice drinks), powders (from dried fruits), oil (from seeds), and leaf powders. Biological and phytotherapeutic applications of M. citrifolia are promising, but more extensive studies are still required. Thus, this review aims to gather updated and comprehensive information on Morinda citrifolia, discussing its traditional use, biochemical, phytotherapics, and toxicological properties, as well as the recent advances in the processing and standardization of products derived from noni fruit.

Characterization of silver nanoparticles produced by biosynthesis mediated by Fusarium oxysporum under different processing conditions.

The goal of this study was the biosynthesis of silver nanoparticles (SNPs) mediated by the fungus Fusarium oxysporum, as well as the characterization of these nanoparticles including evaluation of the particles size and stability under different processing conditions. The results showed that the biosynthesis produced silver nanoparticles having a mean size of 34 nm and zeta potential values below -30 mV at the conditions used, characterizing the nanoparticles as being stable in suspension. Ultraviolet-visible spectroscopy and flame atomic absorption spectroscopy confirmed the formation of silver nanoparticles and Fourier transform infrared spectroscopy detected the bands corresponding to the binding vibration of amide I and II bands of proteins in addition to the presence of cyclic alkanes, cyclohexane, ethers, and aromatic hydrocarbons. Finally, field emission scanning electron microscopy and transmission electron microscopy revealed the formation of spherical and well-dispersed SNPs.

Comparative study of the adsorption of acetaminophen on activated carbons in simulated gastric fluid.

Samples of commercial activated carbons (AC) obtained from different sources: Norit E Supra USP, Norit B Test EUR, and ML (Baracoa, Cuba) were investigated. The adsorption of acetaminophen, Co = 2500 mg/L, occured in simulated gastric fluid (SGF) at pH 1.2 in contact with activated carbon for 4 h at 310 K in water bath with stirring. Residual acetaminophen was monitored by UV visible. The results were converted to scale adsorption isotherms using alternative models: Langmuir TI and TII, Freundlich, Dubinin-Radushkevich (DR) and Temkin. Linearized forms of the characteristic parameters were obtained in each case. The models that best fit the experimental data were Langmuir TI and Temkin with R(2) ≥0.98. The regression best fits followed the sequence: Langmuir TI = Temkin > DR > LangmuirTII > Freundlich. The microporosity determined by adsorption of CO2 at 273 K with a single term DR regression presented R(2) > 0.98. The adsorption of acetaminophen may occur in specific sites and also in the basal region. It was determined that the adsorption process of acetaminophen on AC in SGF is spontaneous (ΔG <0) and exothermic (-ΔHads.). Moreover, the area occupied by the acetaminophen molecule was calculated with a relative error from 7.8 to 50%.