Nanozymes with Peroxidase-like Activity for Ferroptosis-Driven Biocatalytic Nanotherapeutics of Glioblastoma Cancer: 2D and 3D Spheroids Models.

Glioblastoma (GBM) is the most common primary brain cancer in adults. Despite the remarkable advancements in recent years in the realm of cancer diagnosis and therapy, regrettably, GBM remains the most lethal form of brain cancer. In this view, the fascinating area of nanotechnology has emerged as an innovative strategy for developing novel nanomaterials for cancer nanomedicine, such as artificial enzymes, termed nanozymes, with intrinsic enzyme-like activities. Therefore, this study reports for the first time the design, synthesis, and extensive characterization of innovative colloidal nanostructures made of cobalt-doped iron oxide nanoparticles chemically stabilized by a carboxymethylcellulose capping ligand (i.e., Co-MION), creating a peroxidase-like (POD) nanozyme for biocatalytically killing GBM cancer cells. These nanoconjugates were produced using a strictly green aqueous process under mild conditions to create non-toxic bioengineered nanotherapeutics against GBM cells. The nanozyme (Co-MION) showed a magnetite inorganic crystalline core with a uniform spherical morphology (diameter, 2R = 6-7 nm) stabilized by the CMC biopolymer, producing a hydrodynamic diameter (HD) of 41-52 nm and a negatively charged surface (ZP~-50 mV). Thus, we created supramolecular water-dispersible colloidal nanostructures composed of an inorganic core (Cox-MION) and a surrounding biopolymer shell (CMC). The nanozymes confirmed the cytotoxicity evaluated by an MTT bioassay using a 2D culture in vitro of U87 brain cancer cells, which was concentration-dependent and boosted by increasing the cobalt-doping content in the nanosystems. Additionally, the results confirmed that the lethality of U87 brain cancer cells was predominantly caused by the production of toxic cell-damaging reactive oxygen species (ROS) through the in situ generation of hydroxyl radicals (·OH) by the peroxidase-like activity displayed by nanozymes. Thus, the nanozymes induced apoptosis (i.e., programmed cell death) and ferroptosis (i.e., lipid peroxidation) pathways by intracellular biocatalytic enzyme-like activity. More importantly, based on the 3D spheroids model, these nanozymes inhibited tumor growth and remarkably reduced the malignant tumor volume after the nanotherapeutic treatment (ΔV~40%). The kinetics of the anticancer activity of these novel nanotherapeutic agents decreased with the time of incubation of the GBM 3D models, indicating a similar trend commonly observed in tumor microenvironments (TMEs). Furthermore, the results demonstrated that the 2D in vitro model overestimated the relative efficiency of the anticancer agents (i.e., nanozymes and the DOX drug) compared to the 3D spheroid models. These findings are notable as they evidenced that the 3D spheroid model resembles more precisely the TME of "real" brain cancer tumors in patients than 2D cell cultures. Thus, based on our groundwork, 3D tumor spheroid models might be able to offer transitional systems between conventional 2D cell cultures and complex biological in vivo models for evaluating anticancer agents more precisely. These nanotherapeutics offer a wide avenue of opportunities to develop innovative nanomedicines for fighting against cancerous tumors and reducing the frequency of severe side effects in conventionally applied chemotherapy-based treatments.

Photophysical, photobiological, and biomolecule-binding properties of new tri-cationic meso-tri(2-thienyl)corroles with Pt(II) and Pd(II) polypyridyl derivatives.

We report the synthesis and characterization of new tri-cationic corrole derivatives, containing Pt(II) or Pd(II) complexes attached at the peripheral position of thienyl moieties. Corrole derivatives were characterized through microanalysis, electrochemical, spectrometry and spectroscopy analysis. Singlet and triplet excited-states are investigated by photophysical/theoretical calculation methods and photobiological parameters were also evaluated spectroscopic techniques (UV-Vis and EPR). Also, the binding capacity of each corrole derivative with nucleic acids (DNA) and human serum albumin (HSA) was determined by UV-Vis, steady-state, and time-resolved fluorescence spectroscopy, combined with molecular docking analysis. Moreover, the new corroles containing peripheral complexes improve their interactions with biomacromolecules, generate reactive oxygen species under light source irradiation studied and has potential for application in photodynamic therapeutic processes.

Post-synthetic modification of aluminum trimesate and copper trimesate with TiO2 nanoparticles for photocatalytic applications.

Organic pollutants have been a significant source of concern in recent years due to their facile dissemination and harmful effects. In this work, two different metal-organic frameworks (MOFs) were initially prepared by hydrothermal treatment, namely aluminum trimesate (MIL-100(Al)) and copper trimesate (HKUST-1). These materials were subsequently submitted to a post-synthetic modification step to grow titania nanoparticles on their surface. Anatase nanoparticles with sizes around 5 nm were successfully anchored on MIL-100(Al), and the concentration of TiO2 in this sample was about 68 wt.%. This is the first time that this composite (TiO2@MIL-100(Al)) is reported in the literature. It showed an improved photocatalytic activity, removing 90% of methylene blue (k app = 1.29 h-1), 55% of sodium diclofenac (k app = 0.21 h-1), and 62% of ibuprofen (k app = 0.37 h-1) after four hours of illumination with UV-A light. A significant concentration (14 µM) of reactive oxygen species (ROS) was detected for this composite. HKUST-1 showed a structural collapse during its post-synthetic modification, leading to a non-porous material and providing fewer sites for the heterogeneous nucleation of titania. This behavior led to a low concentration of rutile nanoparticles on HKUST-1 (9 wt.%). However, the obtained composite (TiO2@HKUST) also showed an improved photoactivity compared to HKUST-1, increasing the photodegradation rates evaluated for methylene blue (0.05 h-1 vs. 0.29 h-1), sodium diclofenac (negligible vs. 0.03 h-1), and ibuprofen (0.01 h-1 vs. 0.02 h-1). This work brings new insights concerning the preparation of photocatalysts by growing semiconductor nanoparticles on trimesate-based MOFs.

Detection of singlet oxygen by EPR: The instability of the nitroxyl radicals.

The use of spin traps and redox probes coupled with electron paramagnetic resonance (EPR) is a method frequently applied in the evaluation of the efficiency of photosensitizers and photocatalysts in phototherapeutic and photocatalytic processes that involve reactive oxygen species. In this way, the method helps to clarify the mechanism behind photo-induced reactions. Hydroxy-TEMP is a very specific redox probe for selectively identifying and quantifying singlet oxygen (1O2). In this work, the kinetics of radical generated by the oxidation products of the Hydroxy-TEMP redox probe was analyzed from EPR spectra in aqueous solutions of several water-soluble porphyrins ([H2T4MPyP](OTs)4, Na4[H2T4SPP], [H2T2MPyP](OTs)4, [ZnT4MyPyP](OTs)4, [MnT4MyPyP](OTs)5, H2T4CPP, and [H2T4TriMAPP](OTs)4) under white light illumination. Different factors such as the concentration of the redox probe, pH of the medium, and photostability of the porphyrins were evaluated. A systematic study was carried out to reveal the factors associated with stable radical degradation (TEMPOL) by illumination in the visible spectral region in systems containing photosensitizer (porphyrin) and redox probe (Hydroxy-TEMP). With the aid of EPR and gas chromatography coupled with mass spectroscopy (GC-MS) techniques, the mechanism of the radical degradation and the photobleaching of porphyrins were investigated. After successive interactions with the porphyrin in its excited state, in alkaline aqueous solution (pH > 10), the free radical TEMPOL is transformed into TEMPONE until the final diamagnetic product Phorone. A protocol was elaborated to identify and quantify the generation of 1O2 by Hydroxy-TEMP reliably, to avoid possible errors in the interpretation of efficiency of photosensitizers.

Hybrid polymer aerogels containing porphyrins as catalysts for efficient photodegradation of pharmaceuticals in water.

Polymer aerogels of poly(acrylic acid)/poly(vinyl alcohol) (labeled as CPA) were prepared and tested as support materials for different cationic porphyrin organocatalysts (denoted as TMPyP, TMPyPZn, or TMPyPMn). The hybrid aerogels were characterized by various techniques, while their catalytic activity was investigated towards the photodegradation of amoxicillin (AMX), caffeine (CAF), and naproxen (NPX) under artificial visible light. Photodegradation experiments revealed that the CPA-TMPyPMn aerogel shows superior catalytic potential when compared to the others aerogels or the "free" TMPyPMn porphyrin. All pharmaceuticals were quickly degraded (before 60 min) and high COD removal rates (greater than95%) were achieved at pH 7.0 and room temperature. The CG-MS data confirm the complete degradation of all tested pharmaceuticals catalyzed by CPA-TMPyPMn. Recycling experiments revealed that this hybrid aerogel keeps its photocatalytic efficiency for at least 15 reuse runs. In short, this original photocatalytic system is promising to mediate the removal of pharmaceutical contaminants from the aqueous medium.

Anestesia intravenosa contínua com cetamina racêmica ou dextrocetamina e detomidina em cadelas / [Continuous intravenous anesthesia with racemic ketamine or dextroketamine and detomidine in female dogs]

Objetivou-se com este estudo comparar a associação de detomidina e cetamina ou dextrocetamina, por via intravenosa contínua, em oito cadelas submetidas a dois protocolos: GCD - indução anestésica com 5mg/kg e infusão intravenosa contínua de 20mg/kg/h de cetamina; e GDD - indução com 3,5mg/kg e infusão de 14mg/kg/h de dextrocetamina. Associou-se detomidina, 30µg/kg/h, em ambos os grupos. Registraram-se frequência cardíaca (FC), pressão arterial (PA), frequência respiratória (f), temperatura (TC), miorrelaxamento, analgesia, hemogasometria e eletrocardiograma, antes e 15 minutos após a MPA (Mbasal e Mmpa); após o início da infusão (Mic); a cada 10 minutos até 90 minutos (M10, M20, M30, M40, M50, M60, M70, M80 e M90); e 30 minutos após o fim da infusão (M120). Foi observada bradicardia em Mmpa no GCD e de Mmpa a M10 no GDD. Ocorreu hipotensão em Mmpa e hipertensão a partir de Mic. A f diminuiu de M10 a M30. Foram observados: onda T de alta amplitude, bloqueios atrioventriculares e parada sinusal. Ocorreu acidose respiratória. O período de recuperação foi de 219,6±72,3 minutos no GCD e de 234,1±96,8 minutos no GDD. A cetamina e a dextrocetamina, associadas à detomidina por infusão contínua, causam efeitos cardiorrespiratórios e anestésicos similares.(AU)

The combination of detomidine and ketamine or dextrocetamine for continuous intravenous infusion was compared in eight female dogs submitted to two protocols: GCD - 5mg/kg of anesthetic induction and continuous intravenous infusion of ketamine 20mg/kg/h; and GDD - induction with 3.5mg/kg and infusion of 14mg/kg/h of dextrocetamine. Detomidine, 30µg/kg/h was associated in both groups. Heart rate (HR), blood pressure (BP), respiratory rate (RR), temperature (CT), myorelaxation, analgesia, blood gas analysis and electrocardiogram were recorded before and 15 minutes after MPA (Mbasal and Mmpa); after the start of infusion (Mic); every 10 minutes to 90 minutes (M10, M20, M30, M40, M50, M60, M70, M80 and M90); and 30 minutes after the end of infusion (M120). Bradycardia was observed in Mmpa in GCD and from Mmpa to M10 in GDD. There was hypotension in Mmpa and hypertension from Mic. The RR decreased from M10 to M30. High amplitude T wave, atrioventricular blocks and sinus arrest were observed. Respiratory acidosis occurred. The recovery period was 219.6±72.3 minutes in GCD and 234.1±96.8 minutes in GDD. Ketamine and S+ ketamine associated with detomidine for continuous infusion cause cardiorespiratory and similar anesthetic effects.(AU)

Amoxicillin photodegradation under visible light catalyzed by metal-free carbon nitride: An investigation of the influence of the structural defects.

Herein, the structural defects of metal-free polymeric carbon nitrides were controlled by making use of different precursors in their syntheses, i.e. melamine (CN-M) and thiourea (CN-T), as well as a 1:1 mixture of them (CN-1M:1 T). By controlling the structural defects, the electronic, morphological and chemical properties were modified. Additionally, the activities of synthesized PCNs were evaluated for amoxicillin photodegradation under visible light irradiation (16 mW cm-2). The results of photocatalytic tests showed that CN-T material has better efficiency (100 % removal within 48 h), which is directly related to the greater number of defects present in its structure with consequent improvement of electron-hole pairs separation efficiency. The CN-T material showed excellent stability with only 13 % decrease in its photocatalytic activity after the third cycle. A mechanism for amoxicillin degradation by CN-T was proposed based on the ESI-MS and the in situ EPR allied with spin trapping method investigations.

Peroxidation and photo-peroxidation of pantoprazole in aqueous solution using silver molybdate as catalyst.

In this study, silver molybdate was used as a catalyst in different oxidation processes to degrade pantoprazole (PAN) from aqueous suspension. The catalyst was synthesized using a controlled precipitation method and characterized by XRD, FTIR spectroscopy, BET analysis, Zeta potential, FEG-SEM/EDS, DRS and EPR. The α- and ß-phases of Ag2MoO4 were identified as crystalline structure of the butterfly-shaped particles. The metastable α-phase could be completely converted into ß-Ag2MoO4 by thermal treatment at 300 °C. The band gap energy of ß-Ag2MoO4 (Eg = 3.25 eV) is slightly higher than for as-prepared catalyst (α-Ag2MoO4 + ß-Ag2MoO4) (Eg = 3.09 eV), suggesting that as-prepared catalyst should be active under visible light. PAN is sensible to UV light irradiation, and the addition of H2O2 as electron acceptor enhanced the mineralization rate. In the catalytic UV-based reactions, high PAN oxidation efficiencies were obtained (>85%) but with low mineralization (32-64%). Catalytic peroxidation and photo-catalytic peroxidation under visible light showed the highest PAN oxidation efficiency, leading to its almost complete mineralization (>95%), even under dark conditions (98% in 120 min). Several degradation byproducts were identified and three mechanistic routes of PAN decomposition were proposed. The identified byproducts are less toxic than the parent compound. EPR coupled with the spin trapping method identified •OH radicals as the main ROS species in both photocatalytic and catalytic peroxidation reactions. Ag2MoO4 showed to be a promising catalyst to promote the decomposition of hydrogen peroxide into ROS.1.

Photophysical and electrochemical properties of two trans-A2B-corroles: differences between phenyl or pyrenyl groups at the meso-10 position.

The present study reports on the optical and photophysical properties of trans-A2B-corroles possessing pyrenyl units attached at the meso-10-position and compares them with those of model trans-A2B-corroles having phenyl substituents at that position. In contrast to the model meso-substituted corrole, the new pyrenyl-corrole shows slightly red-shifted absorption bands and blue-shifted emission, slightly higher fluorescence quantum yield, and more importantly, it shows better photo-stability under white-light illumination. Theoretical calculations were used to determine the electronic transitions and geometries of the singlet and triplet excited states (TD-DFT and NTO). Moreover, we demonstrate that the pyrenyl-corrole in analogy to previously studied model corroles is able to generate reactive oxygen species (ROS) under visible light using photo-degradation of 1,3-diphenylisobenzofuran (DBPF), a singlet oxygen quencher, and EPR spectroscopy allied with the spin-trapping method is used for identifying singlet oxygen species. The results show that the pyrenyl unit attached at the meso-10-position of the corrole increases the photo-stability and efficiency in ROS generation compared to the phenyl substituent.

Photophysical, photodynamical, redox properties and BSA interactions of novel isomeric tetracationic peripheral palladium(II)-bipyridyl porphyrins.

New isomeric tetra-cationic porphyrins containing peripheral [Pd(bpy)Cl]+ units attached to pyridyl substituents were synthesized and fully characterized. The porphyrins present an intense Soret band located in the blue spectral region and an additional four weaker red-shifted Q bands in the visible spectral region (about 500-700 nm). The obtained Strickler-Berg parameters indicate fully spin and symmetry allowed transitions for all the observed absorption bands. Both porphyrins present two fluorescence emission bands, an intense one located around 650 nm and an additional weak red-shifted emission at ∼710 nm. Fluorescence decay time profiles were obtained showing bi-exponential decay. The interaction of the porphyrins with bovine serum albumin (BSA) was studied in detail by a fluorescence quenching method and molecular docking analysis. In addition, the photodynamical activity of the porphyrins in the photooxidation of BSA was determined and compared with the light-induced formation of reactive oxygen species (ROS) by electron paramagnetic resonance (EPR) allied with the spin trapping method. The results show that the Pd(ii)-bypyridyl tetra-cationic porphyrins are promising candidates for the photooxidation of biological substrates used in photodynamic therapy (PDT).

Efeitos do propofol administrado por via intracelomática em cágados-de-barbicha (Phrynops geoffroanus) Schweigger, 1812 / Effects of propofol administered by intracelomatic route in Geoffroy's toadhead turtle (Phrynops geoffroanus) Schweigger, 1812

O presente estudo avaliou a influência do regime hídrico sobre efeitos do propofol em Phrynops geoffroanus, bem como a qualidade da contenção farmacológica produzida. Foram utilizados 10 animais, anestesiados em dois momentos com propofol, na dose de 35mg/kg, por via intracelomática, com intervalo de 15 dias. O grupo 1 fora retirado da água 12 horas antes do procedimento e o grupo 2 permaneceu dentro da água até o momento da indução anestésica. Foram mensuradas frequência cardíaca, pressão arterial sistólica, temperatura, frequência respiratória e saturação de oxi-hemoglobina, e avaliados duração do período de latência, período hábil, período de recuperação e qualidade da contenção farmacológica. Houve diferença significativa entre grupos apenas quanto à frequência cardíaca. No grupo 1, as médias dos períodos de latência, hábil anestésico e de recuperação foram de 16,8±8,4, 86,5±79,4 e 1,5±3,8 minutos, respectivamente. Já no grupo 2, as médias foram de 19,9±9,8, 110,9±104,7 e 28,8±58,2 minutos, respectivamente. Concluiu-se que o regime hídrico de 12 horas não influenciou os parâmetros anestésicos e fisiológicos dos animais e que a qualidade da contenção farmacológica foi considerada boa em ambos os grupos.(AU)

The present study evaluated the influence of the water regime on the effects of propofol on Phrynops geoffroanus, as well as the quality of the pharmacological containment produced. Ten animals, anesthetized at two times with propofol at a dose of 35mg / kg, were used intracelomatically with a 15 day interval. Group 1 was withdrawn from the water 12 hours prior to the procedure and Group 2 remained in the water until the time of anesthetic induction. Heart rate, systolic blood pressure, temperature, respiratory rate and oxyhemoglobin saturation were measured and the duration of the latency period, skill period, recovery period and quality of pharmacological containment were measured. There was a significant difference between groups only regarding heart rate. In Group 1, the means of the latency, skillful anesthesia and recovery periods were 16.8±8.4, 86.5±79.4 and 1.5±3.8 minutes, respectively. In Group 2, the mean values were 19.9±9.8, 110.9±104.7 and 28.8±58.2 minutes, respectively. It was concluded that the 12-hour water regime did not influence the anesthetic and physiological parameters of the animals, and the quality of the pharmacological restraint was considered good in both groups.(AU)

Avaliação biomecânica e dimensional do fio de sutura à base de quitosana / Biomechanics and dimensional evaluation of the suture based on chitosan

A resistência à tração e o diâmetro são características de grande importância na avaliação da qualidade de fios de sutura, estando relacionados à capacidade destes de suportar o estresse promovido pelas forças atuantes em determinados tecidos. Desta forma, objetivou-se com este estudo avaliar as propriedades mecânica e dimensional de fios de sutura à base de quitosana, comparando-as com as preconizadas pela norma NBR 13904/2003. Tais propriedades foram avaliadas usando-se uma máquina de ensaio universal e um micrômetro digital. Os parâmetros mecânico e dimensional analisados foram a resistência quanto à tração, a deformação, bem como o diâmetro, respectivamente. O valor médio do diâmetro dos fios de quitosana apresentou variação e observou-se resistência à tração ligeiramente abaixo da norma preconizada, com rápida deformação. O fio de quitosana, na forma em que foi produzido, apresentou variabilidade dimensional e baixa resistência à tração, havendo a necessidade de melhorias no método de fabricação dele.(AU)

Tensile strength and diameter are very important characteristics in assessing the quality of suture, being related to their ability to withstand the stress caused by forces acting in certain tissues. Thus, the aim of this study was to evaluate the mechanical and dimensional properties of chitosan-based suture, comparing them with those recommended by the NBR 13904/2003. These properties were evaluated by using a universal testing machine and a digital micrometer. The mechanical and dimensional parameters analyzed were resistance to traction, deformation and diameter, respectively. The average diameter of the chitosan showed variation and yarn tensile strength was observed slightly below the recommended standard, with rapid deformation. The chitosan yarn in the form in which it was produced, presented dimensional variability and low tensile strength, there is a need for improvements in the method of manufacturing the same.(AU)