Carlucio Roberto Alves

Objetivo: Este estudo desenvolveu um bioinseticida formulado a partir do extrato aquoso de folhas desidratadas de nim (Azadirachta indica), suplementado com líquido da casca do coco verde (LCCV) como adjuvante. Método: A eficácia inseticida foi avaliada contra os insetos sugadores Aphis gossypii e Dactylopius coccus em culturas de limão e berinjela, juntamente com a avaliação da sensibilidade foliar. Formulações do bioinseticida compostas por 10, 20, 50, 80 e 90% de extrato de nim combinados, respectivamente, com 90, 80, 50, 20 e 10% de LCCV foram pulverizadas sobre plantas infestadas. Sete dias após a aplicação, foram avaliadas a integridade foliar, a fitotoxicidade e as taxas de mortalidade dos insetos. Resultados: O bioinseticida apresentou forte efeito inibitório sobre a função gastrointestinal dos insetos, comprometendo o desenvolvimento, o crescimento, a fertilidade, a fecundidade e, por fim, induzindo a mortalidade. A formulação contendo 90% de extrato de nim e 10% de LCCV demonstrou a maior eficácia. A caracterização química revelou maior teor de proteínas no extrato puro de nim em comparação à formulação combinada, refletindo a influência de taninos, compostos fenólicos e metabólitos secundários provenientes do LCCV. Os níveis de carboidratos solúveis diminuíram no bioinseticida misto; entretanto, uma quantidade substancial foi mantida, indicando a preservação do potencial biológico. A espectroscopia no infravermelho confirmou os perfis químicos dos extratos e sugeriu a formação de um novo composto complexado. Conclusão: De modo geral, a integração do extrato de nim com o LCCV resultou em um bioinseticida com atividade inseticida satisfatória, sustentando seu potencial como ferramenta biotecnológica para o manejo sustentável de pragas agrícolas.

Oligosaccharides occur naturally in many foods and can also be sourced from industrial solid waste. To enhance their value, two oligosaccharides, raffinose and melezitose, have been reacted with toluene diisocyanate (TDI) to produce polyurethanes. The resulting products vary in form—liquid, gel, or solid gel—depending on the stoichiometric ratio of the starting materials. Both conventional and microwave heating have been employed in the synthesis, with microwave heating proving effective in reducing reaction time compared to conventional heating. The resulting polymers have been characterized using ¹³C NMR, FT‐IR, TGA, and DSC to confirm their structural and thermal properties. Additionally, the feasibility of incorporating a second polymer into the oligosaccharide‐based polyurethane, thereby creating a semi‐interpenetrating polymer network, has been demonstrated. Examples include the successful embedding of poly(lactic acid) and poly(vinyl pyrrolidone) within the polyurethane matrix. The newly developed materials reported in this work may be used as bioplastics and potential replacements for petroleum‐based materials.

In this work, we report the observation of uncatalyzed ene reactions between several phenylpropanoid compounds and diethyl azodicarboxylate (DEAD). For allylbenzene, the reaction produces the ene product at molar ratios of up to 1:2 of allylbenzene to DEAD. At higher levels of DEAD, more complex reactions are observed. For the reaction between methyl eugenol and DEAD, similar ene reaction products have been found. However, the reaction of eugenol with DEAD is more complex; in addition to the ene reaction, other reactions happen at the same time. Most of the structures of the resulting products have been elucidated using NMR spectroscopy (¹H, ¹³C, and 2D), and the findings have been further corroborated by FTIR analysis. Interestingly, these products appear to undergo molecular aggregation, which results in self-thickening in their neat form. However, the viscosity significantly decreases upon dilution with a solvent. This self-thickening property suggests their potential use as thickening agents in organic solvent formulations.

Carbon dots in biosensing have advanced significantly, adding improvements to different detection techniques. In this study, an amperometric immunosensor for Salmonella Thyphimurium was designed using antibodies labeled with carbon dots (Cdots) from pequi almond (Caryocar brasiliensis). Cdots were synthesized by pyrolysis and characterized by FTIR, UV/fluorescence, electrochemistry, zeta potential, and transmission electron microscopy (TEM). A particle size of 6.80 ± 2.13 nm was estimated, and the zeta potential was − 47.4 mV, indicating the preponderant presence of acidic groups, as confirmed by FTIR. The impedance evaluation of the response of biosensors assembled for live (Rct = 13.4 kΩ) and dead (Rct = 499.7 Ω) Salmonella showed a significant difference in their values, in agreement with chronoamperometric analyses, which had their current values drastically reduced from − 2.2 mA (live) to 0 mA (dead). An analytical curve for Salmonella was established with the limit of detection lower than 1 CFU/mL. This electrochemical biosensor using pequi carbon dots for antibody labeling showed promising results for detecting the pathogen. Thus, carbon dots can be used as substitutes for enzymes in labeling antibodies used in the design and production of sensors.

The aim of this study was to produce a carbohydrate gel based on genipap and banana and analyze its physico-chemical, rheological, and sensory quality, as well as its proximate composition and antioxidant activity. Three gel samples were formulated containing different concentrations of genipap and clarified banana juice. The formulated samples followed the minimum parameters required and were subjected to analyses of their pH, soluble solids, titratable acidity, moisture, ash, lipids, proteins, glucose, fructose, sucrose, polyphenols, antioxidant activity, and rheology. Commercial carbohydrate gel was used as a control sample. It can be concluded that the gel formulations were formulated following the minimum parameters required, with a moderate sensory acceptance. The physico-chemical parameters and proximate composition the developed gels were similar to the commercial gel, while their glucose, sucrose, fructose, polyphenol, and antioxidant activity contents were higher and their rheological properties were within the expected range for this category of commonly marketed products. In the two blocks of analysis mentioned above, data variability was mostly explained by PC1–PC3 at almost 100%. Rheologically, the commercial gel is considered to be a Newtonian fluid, and the developed formulations can be considered as pseudoplastic fluids due to the insoluble solids still present.

Pequi oil presents high levels of unsaturated fatty acids and beta-carotene and has been used for nutraceutical purposes. Microcapsules can improve the protection of bioactive compounds in pequi oil and mask the inherent smell and taste for food applications. However, the stability of the microencapsulated oil and its influence on the product characteristics need to be investigated. This work evaluated the impact of pequi oil microcapsules on the physicochemical characteristics of fermented milk and other aspects of stability, digestion, and bioaccessibility via the analysis of beta-carotene present in the oil. During 28 days of storage, the pH values decreased from 4.5 to 4.32 for all fermented milk. Syneresis values decreased (<50%) due to water retention caused by the biopolymers on the microcapsules. Microencapsulation promoted an improvement in oil stability and a gradual release for 120 min, which allowed a better condition for beta-carotene quantification in the micellar phase and resulted in better bioaccessibility. Thus, the microcapsules positively influenced the physicochemical properties of the fermented milk and improved oil bioaccessibility aspects.

The electrosynthesis of polyaniline (PAni) and cashew gum (CG) composite was successfully performed by electrochemical methods (potential scanning and constant potential) in terms of pH, aniline (Ani), and polyelectrolyte concentrations. Study aim was to investigate the performance of a polyaniline-based ammonia sensor under different concentrations of ammonium gas, evidencing a color change from green to blue as in the presence of gas in a sensitive and reversible process. Films grown by cyclic voltammetry and chronoamperometry showed a cauliflower-like morphology, and a visual analysis detected a limit of 0.015 and 0.010 mol l⁻¹, respectively. The sensor demonstrated a fast response time of 20 s, a low detection limit, with a short regeneration time of less than 1 min at room temperature. This polyaniline-based sensor is shown as a portable, sensitive, dimensionally flexible, and cost-effective alternative for food packaging and other devices. The findings of this study contribute to the development of advanced ammonia detection technology.

The combination of a biopolymer and a conductive polymer can produce new materials with improved physico-chemical and morphological properties that enhance their use as sensors. Magnetite nanoparticles (MN) can be further introduced to these new matrices to improve the analytical performance. This study aimed to evaluate the electrocatalytic response of nanocomposites formed by the introduction of MN to polypyrrole (PPy) doped in the presence of cashew gum polysaccharide (CGP) and in the presence of carboxymethylated cashew gum polysaccharide (CCGP). Characterization of the nanocomposites was carried out via transmission electron microscopy (TEM) and infrared spectroscopy (FTIR) and showed that the absorption band of the blend was shifted to a higher frequency in the nanocomposites, indicating the intermolecular interaction between the blend and nanoparticles. The electrocatalytic performance of the nanocomposites was evaluated by applying a constant potential of −0.7 V with successive additions of H₂O₂ (1 mmol L⁻¹) in 10 mmol L⁻¹ phosphate buffer under agitation at pH 7.5. The nanocomposite formed by the introduction of MN to polypyrrole doped with cashew gum polysaccharide (PPy(cgp)–MN) displayed excellent electrocatalytic surface properties, with high H₂O₂ specificity, a linear response (R2 = 0.99), high sensitivity (0.28 µmol L⁻¹), and a low H₂O₂ detection limit (0.072 mmol L⁻¹).