Carla Santos Riccardi

Solanum lycopersicum converts Fe³⁺ into Fe²⁺, the form absorbed by plants. The Fe²⁺ present in the growth medium can be absorbed in excess by the plants, causing phytotoxicity. Magnetite has an isocratic balance of Fe³⁺/Fe²⁺, which enables the release of Fe²⁺ in the culture medium. The literature reports that high availability of Fe²⁺ can cause oxidative damage and a reduction in dry mass, whereas the application of maghemite nanoparticles, which release only Fe³⁺, can promote an increase in biomass. Thus, we investigated the influence of iron oxides (magnetite and maghemite) on photosynthesis, leaf carbohydrate profile and the enzymatic antioxidant system of Solanum lycopersicum “cv Micro-Tom”. Our results indicated that application of iron oxide nanoparticles provided sufficient iron to reverse the element’s deficiency, restoring the photochemical apparatus. However, the supply of magnetite resulted in reduced root dry mass, an accumulation of reducing sugars, and increased antioxidant enzyme activity. Maghemite may have contributed to a greater allocation of photoassimilates to reproductive organs, such as flowers, which showed a higher percentage distribution of dry mass, indicating its potential for use in plant cultivation.

In plant tissues, nanoparticles can stimulate the production of reactive oxygen species (ROS), which, in excess, cause cellular toxicity by damaging membranes, chloroplasts, and DNA. However, they can also activate antioxidant mechanisms, aiding metabolic recovery under oxidative stress. In agriculture, iron oxide (nFe) nanoparticles stand out for their gradual release of the nutrient, preventing leaching and increasing productivity. This study aims to investigate whether iron oxide nanoparticles are effective alternatives for overcoming iron deficiencies, mitigating oxidative stress and restoring metabolic functions, while maintaining photosynthesis. The high H₂O₂ concentration observed in nFe 500 mg L⁻¹ (nFe 500) suggests that Fe, after being transported by the nanoparticles to the leaves, may have acted as a cofactor for antioxidant enzymes involved in H₂O₂ decomposition, reducing malondialdehyde concentration (MDA). Maintaining low oxidative stress suggests that H₂O₂ may function not only as a stress indicator but also as a signaling molecule in intracellular processes. nFe 500 suggests the ability of plants to utilize released Fe²⁺/Fe³⁺, restoring photosynthetic function in iron-deficient plants.

Novos métodos alternativos para a experimentação animal têm sido priorizados na avaliação toxicológica de medicamentos, cosméticos, nanomateriais, entre outras aplicações. Entre esses métodos, podem ser destacados os modelos in vitro de cultivo celular 2D e 3D. O objetivo desta pesquisa foi realizar um rastreamento da bioimpressão 3D como uma tecnologia disruptiva no desenvolvimento de modelos de equivalentes de pele em testes de toxicidade. A metodologia envolveu a prospecção científica pela busca nas bases de dados Scopus, Science Direct, Periódicos Capes, Pubmed e Google Scholar; a prospecção tecnológica pelas plataformas Patentscope WIPO, Espacenet e INPI; e a avaliação dos líderes de mercado pelos boletins Mordor Intelligence, IMARC Group e Grand View Research. Os resultados, no período de janeiro de 2009 a abril de 2024, apontaram uma expansão da tecnologia desde 2015, atingindo 14 patentes em 2023. Entende-se que o Brasil tem um grande potencial para criar e desenvolver métodos inovadores na área de bioimpressão de tecidos.

Methicillin-resistant Staphylococcus aureus (MRSA) often cause infections with high mortality rates. Antimicrobial peptides are a source of molecules for developing antimicrobials; one such peptide is melittin, a fraction from the venom of the Apis mellifera bee. This study aimed to evaluate the antibacterial and antibiofilm activities of melittin and its association with oxacillin (mel+oxa) against MRSA isolates, and to investigate the mechanisms of action of the treatments on MRSA. Minimum inhibitory concentrations (MICs) were determined, and synergistic effects of melittin with oxacillin and cephalothin were assessed. Antibiofilm and cytotoxic activities, as well as their impact on the cell membrane, were evaluated for melittin, oxacillin, and mel+oxa. Proteomics evaluated the effects of the treatments on MRSA. Melittin mean MICs for MRSA was 4.7 μg/mL and 12 μg/mL for oxacillin. Mel+oxa exhibited synergistic effects, reducing biofilm formation, and causing leakage of proteins, nucleic acids, potassium, and phosphate ions, indicating action on cell membrane. Melittin and mel+oxa, at MIC values, did not induce hemolysis and apoptosis in HaCaT cells. The treatments resulted in differential expression of proteins associated with protein synthesis and energy metabolism. Mel+oxa demonstrated antibacterial activity against MRSA, suggesting a potential as a candidate for the development of new antibacterial agents against MRSA.

The literature has shown that there is no consensus regarding the best resin composite photoactivation protocol. This study evaluated the efficiency of the conventional, soft-start, pulse-delay and exponential protocols for photoactivation of resin composites in reducing the shrinkage stress and temperature variation during the photopolymerisation. The photoactivation processes were performed using a photocuring unit and a smartphone app developed to control the irradiance according each photoactivation protocol. These photoactivation methods were evaluated applying photoactivation energies recommended by the resins manufactures. Three brands of resin composites were analysed: Z-250, Charisma and Ultrafill. The cure effectiveness was evaluated through depth of cure experiments. All results were statistically evaluated using one-way and multi-factor analysis of variance (ANOVA). The use of exponential and pulse-delay methods resulted in a significant reduction of the shrinkage stress for all evaluated resins; however, the pulse-delay method required too long a photoactivation time. The increases on the temperature were lower when the exponential photoactivation was applied; however, the temperature variation for all photoactivation protocols was not enough to cause damage in the restoration area. The evaluation of the depth of cure showed that all photoactivation protocols resulted in cured resins with equivalent hardness, indicating that the choice of an alternative photoactivation protocol did not harm the polymerisation. In this way, the results showed the exponential protocol as the best photoactivation technique for practical applications.

Multiphasic bioceramic scaffolds has been enhanced for dental and orthopedic applications. In this perspective, the laser surface texturing of metallic surfaces combined to bioactive calcium phosphate coatings have shown to be promising and economically feasible for biomaterial clinical applications. Ti-15Mo alloy samples were irradiated by pulsed Yb: YAG laser beam. The formation of HA and other calcium phosphates phases by biomimetic method should occur in the presence of Ca2+, PO43-, Mg2+, HCO3-, K+ and Na+. The modified surfaces were submitted to thermal treatment at 380 and 580°C. The results showed the processes of fusion and fast solidification from the laser beam irradiation, inducing the formation of stoichiometric α-Ti, TiO2 and non-stoichiometric titanium oxides, Ti3O and Ti6O with different oxide percentages depending on applied fluency (fluency of 0.023, 0.033, 0.040 and 0.048 J/mm2). The morphological and physicochemical properties have indicated the formation of a multiphase bioceramic coatings. It was observed the formation of amorphous calcium phosphate (ACP), octacalcium phosphate (OCP), and magnesium phosphate (Mg3(PO4)2) phases at 380°C, whereas β-TCP (tricalcium phosphate), OCP, and substituted β-TCP with Ca2,589Mg0,41(PO4)2 were obtained at 580°C. Therefore, the multiphasic bioceramic modified Ti-15Mo surface could enhance osteointegration for bone regeneration.

With the ever-progressing urbanization of human society comes lingering public issues, primarily those related to human health and the need to provide environments where the population can be routinely frequent. Also, the effects of climatic changes tend to aggravate such public health issues, mainly respiratory and cardiac symptoms. As such, analyzing and studying those environments can be crucial for public administrations in the decision-making processes. One such method of analysis involves using an air enthalpy index to profile and provide a picture of stress situations, helping expedite preventive measures and hospital logistics. With that, this study used the enthalpy index as a tool to create a picture of the effect of seasonality on chronic health issues, such as respiratory and cardiac symptoms, for the city of Botucatu, a city with a characteristic tropical altitude climate. It was possible to determine that the air enthalpy profile is consistent throughout the year near the estimated thermal comfort boundaries, with peaks outside in hotter months. The hospitalizations tend to be more numerous during the transition from hot to cold seasons. Simple correlation analysis, along with a t test, provided further insight into the issue, showing strong correlation for pneumonia with the maximum enthalpy variation, which can relate to the heat amount variation in a given location. Also, an agreement was observed between enthalpy and an established thermal sensation index, the heat index, meaning that air enthalpy can be a reliable and simple index for environmental thermal comfort analysis. That being said, further studies are necessary to confirm these findings, considering a longer time frame, more diverse hospitalization data, and other meteorological parameters, like wind speed and precipitation.

Ti-15Mo alloy samples were irradiated by pulsed Yb: YAG laser beam under air and atmospheric pressure. Calcium phosphate coatings were deposited on the irradiated surfaces by the sol–gel method. The sol was prepared from the precursors Ca (NO₃)₂.4H₂ O and H₃ PO₄. The modified surfaces were submitted to heat treatment conditions at 350 and 600 °C. The results showed that the two conditions established have a sufficient energy to promote ablation on the laser beam irradiated surfaces. Likewise, it has been demonstrated the processes of fusion and fast solidification from the laser beam irradiation, under ambient atmosphere, inducing the formation of stoichiometric TiO₂ and non-stoichiometric titanium oxides, including Ti₃O₅, TiO, Ti₃O and Ti₆O with different oxide percentages depending on the fluency used. Besides that, laser modification has allowed a clean and reproducible process, providing no traces of contamination, an important feature for clinical applications. The physico-chemical and morphological properties indicated the formation of a mixture of phases: calcium pyrophosphate, hydroxyapatite and β-TCP for the procedure (PA: calcination temperature), whereas HA (hydroxyapatite) and β-TCP (tricalcium phosphate) were obtained by the procedure (PB: calcination temperature). Therefore, it was possible to obtain a Ti-15Mo alloy surface consisted on calcium phosphate ceramics of biological interest using the procedure (PB). Thus, the laser beam irradiation associated to bioactive coatings of calcium phosphates of biological interest have shown to be promising and economically feasible for use in dental and orthopedic implants.

The electrochemical behavior of the enzyme peroxidase (HRP) was investigated using the hydrogen peroxide as enzymatic substrate and the 5-aminosalicylic acid (5-ASA) as mediator of electrons on graphite electrodes. Several parameters were optimized, namely, the applied potential to the amperometric technique fixed in -0.125V, the 0.1 mol L-1 phosphate-citrate buffer at pH 5.0 as supporting electrolyte and the proportion between the 5-ASA and H2O2 in 1:7, among others. It was observed the catalysis of the oxidation reaction of the H2O2 in the presence of the enzyme HRP and 5-ASA. The oxidation product was reduced in the electrode surface, evidencing a significant increase in the intensity of the cathodic current.