Patrícia Bulegon Brondani’s research while affiliated with Universidade Federal de Santa Catarina and other places

Cotton is one of the most used fibers in the textile sector but is highly prone to microbial growth. Surface functionalization of cotton fabric is an alternative to overcome this problem and grant new properties to this product. This work aimed to develop a new methodology for the surface functionalization of cotton fabric, carrying out bio-oxidation catalyzed by laccases followed by the covalent incorporation of chitosan nanoparticles (CHINPs) containing eucalyptus or lavender essential oil to obtain fabrics with antibacterial properties. The cellulose bio-oxidation process was optimized considering the types of laccase and mediator used. The optimal conditions consisted of using laccase from Pleurotus ostreatus, TEMPO as a mediator, and a post-treatment with 1 mol L−1 of a NaOH solution. CHINPs were synthesized using the oil-in-water emulsification method followed by ionic gelation. The characterization of the CHINPs confirmed the formation of spherical nanoparticles with diameters ranging from 12 to 40 nm and the presence of encapsulated lavender (12.5%) or eucalyptus essential oil (31.2%). The CHINPs were incorporated into the fabric by reacting the NH2 groups of chitosan with the COOH groups of the bio-oxidized cellulose, generating a covalent bond. The antibacterial assay with E. coli and S. aureus indicated a reduction in bacterial growth in fabrics functionalized with nanoparticles compared to the non-functionalized one. Furthermore, the CHINPs and essential oils remained on the cotton surface even after at least five washing cycles, showing the effectiveness of the binding of the nanoparticles to the fiber surface.

Polyamide (PA) has notable physical and chemical properties and is one of the most versatile synthetic materials in the industrial sector. However, its hydrophobicity creates significant challenges in its beneficiation and modification. Modifications of PA with chitosan nanoparticles (CNPs) can improve its undesired properties but are rarely found in the literature due to the weak interaction between the chemical groups of both structures. Surface hydrolysis mediated by enzymes can mildly improve the PA properties and create reactive sites. These sites can react with CNPs to confer enhanced properties to the fabrics, such as antimicrobial activity and flame retardancy. This study investigated the action of 14 hydrolases in the surface hydrolysis of 100% polyamide 6 (PA 6) fabric. Such an extensive study applying several enzymes for this process is uncommon. Under the optimum conditions, the hydrolyzed fabric was covalently bonded to the CNPs, generating material with reduced bacterial proliferation and flame retardancy properties. The uncommon covalent bond attachment achieved high material durability, even after five washing cycles.

Neste estudo são apresentadas abordagens temáticas na área de Química Têxtil a partir de Estudo de Caso com o objetivo de ampliar a visão dos estudantes a respeito da importância da Química na sociedade. Foram produzidos três casos investigativos acompanhados dos guias de resolução para auxiliar o docente na implementação do recurso didático em aulas de Química na Educação Básica e adaptado para o Ensino Superior. Os casos versam sobre a composição dos tecidos utilizados em camisas esportivas e roupas íntimas, discutindo a sua natureza química a partir de conteúdos como ligações químicas, funções orgânicas e polaridade. O material foi desenvolvido em uma plataforma interativa para que os estudantes e o docente possam acessá-los digitalmente. Como possibilidades futuras considera-se que novos trabalhos possam ser publicados com os resultados das aplicações dos casos por professores da educação básica, bem como a validação de docentes frente ao material didático elaborado.

Few works present effective or viable alternatives to the problem of the electroreduction of acetophenone which usually leads to the pinacol dimer as a primary product in addition to 1‐phenylethanol. Here, various lipases were applied in acetophenone electroreduction. The optimized reaction conditions are tin/lead (63 : 37) combined working electrode coated with Nafion film modified with lipase from Thermomyces lanuginosus, a platinum counter electrode, applied potential of −2.0 V vs. Ag/AgCl (KCl 3.0 mol L⁻¹), acetate buffer (0.1 mol L⁻¹) pH 5.0 in 4 hours, and led to the formation of 87.8 % of 1‐phenylethanol. The same working electrode was used five times over five days, and the conversion remained constant. A voltammetric study indicates an alteration of the electroreduction mechanism in the presence of the cited lipase. Adding lipase from Thermomyces lanuginosus directly in the medium immobilized in a clay mineral or in silica gel (Lipolase 100T) resulted in even higher conversions (93.2–93.9 %). The modified electrode improved the methodology regarding enzyme stability, process reproducibility, and material reusability.

Pain is a signal of harmful stimuli generated by the nociceptive system through the activation of receptors or channels present on the surface of the nociceptors. For example, the acid-sensing ion channels (ASICs) are activated by minor pH variations related to many different disorders. Drugs that cease the stimulus (and pain) antagonize this process. The treatment of pain is a serious public health issue and because of that, there has been a huge effort to develop new antinociceptive drugs. The main objective of this article was to develop a screening test bioinspired by ASIC channels to accelerate the development of new antinociceptive drugs and reduce the number of experiments conducted in animals. For that, a micellar dispersion of polystyrene-b-poly (acrylic acid) (PS-b-PAA) was tested encapsulating p-nitrophenyl butyrate (p-NFB) in the presence of lipase isolated from Pseudomonas fluorescens. When the p-NFB is released, the lipase hydrolyses it to the corresponding phenol, which can be detected in a clear analytical response. The system was pH-responsive between pH 7.4 and 7.0, and the signal was suppressed by ibuprofen as expected for an ASICs bioinspired system. The developed system seems to be effective for screening new drugs in the physiological pH range, proved to be stable, with associated low cost, and is easy to use.

Cotton is the world’s leading fiber crop and contains natural coloring impurities which need to be removed by bleaching. The most applied bleaching methodology utilizes chemical oxidants, such as hydrogen peroxide. This method is carried out at high temperatures and under strong alkaline conditions, entailing high-energy consumption, strong alkaline effluents and severe fiber damage. The development of milder and greener bleaching processes, in which the fibers are less damaged, is a goal that has long been pursued. Another approach for cotton bleaching is the use of sodium hypochlorite as an oxidant. Several methods applying hypochlorite are known, but they face problems associated with the transport, storage and handling of unstable and hazardous chemicals. Here we present a mild methodology for in situ electrogeneration of hypochlorite from sodium chloride or potassium chloride, and its application in bleaching of cotton, thus reducing the problems associated with the transport and storage of the oxidizing reagent. Our methodology was able to bleach the cotton fibers with a comparable whiteness degree, when compared to the conventional one, and it is carried out in lower reaction times, at room temperature, with no need of addition of hazardous materials and avoiding the production of residual hypochlorite.

The wastewater that originates from the widespread usage of synthetic dyes in the industry have become a severe environmental problem. Several efforts have been made to develop new types of treatment which are capable of performing the degradation of the dyes from the environment. Within this scope, much attention has been drawn to enzymatic approaches, mainly the ones applying oxidative enzymes, such as peroxidases. A recently discovered superfamily of peroxidases, the so called dye-decolorizing peroxidases (DyPs) is a promising alternative to further improve the efficiency of these processes. In this work, two of these peroxidases (Saccharomonospora viridis (SviDyP) and Thermobifida fusca (TfuDyp)) were tested together with twelve different reactive dyes in order to evaluate the efficiency of degradation and decolorization, leading to good results. When applying the SviDyP enzyme in experiments carried out for 12 h in pH 3, the degradation efficiencies were above 80% for some dyes. The biodegradation efficiency data and cyclic voltammograms were recorded to obtain the redox potential of the chosen dyes and enzymes. In addition, an electrochemical biosensor was used to gauge the genotoxicity of the generated bioproducts. This analysis showed that bioproducts from dye degradation mostly present a lower degree of genotoxicity when compared to the control reactions.

Background In general, fungal species are characterized by their opportunistic character and can trigger various infections in immunocompromised hosts. The emergence of infections associated with high mortality rates is due to the resistance mechanisms that these species develop. Methods This phenomenon of resistance denotes the need for the development of new and effective therapeutic approaches. In this paper, we report the investigation of the antioxidant and antifungal behavior of dimeric naphthoquinones derived from lawsone whose antimicrobial and antioxidant potential has been reported in the literature. Results Seven fungal strains were tested, and the antioxidant potential was tested using the combination of the methodologies: reducing power, total antioxidant capacity and cyclic voltammetry. Molecular docking studies (PDB ID 5V5Z and 1EA1) were conducted which allowed the derivation of structureactivity relationships (SAR). Compound 1-i, derived from 3-methylfuran-2-carbaldehyde showed the highest antifungal potential with an emphasis on the inhibition of Candida albicans species (MIC = 0.5 µg/mL) and the highest antioxidant potential. Conclusion A combination of molecular modeling data and in vitro assays can help to find new solutions to this major public health problem.