Search Results (115)

Background: Psidium guajava L. (Psidium guajava) is an edible plant; its parts are widely used to cure and prevent many health disorders. Psidium guajava leaves contain a wide array of polyphenols that inhibit peroxidation and may play a role in the prevention and treatment of common, degenerative chronic disorders such as diabetes, cardiovascular disease, and cancer. Colon cancer is the third most common type of cancer diagnosed and the second most common cause of cancer-related deaths globally. In contrast, prostate cancer is the second most diagnosed cancer and the fifth leading cause of cancer-related death worldwide. This study aims to evaluate the pharmacological potential of the Psidium guajava plants cultivated in Romania on colon and prostate cancer cell lines. Methods: Phenolic compounds extraction was made using an average sample of all nine Psidium guajava varieties. Analyses were carried out using a HP-1200 liquid chromatograph. The effect of the alcoholic extract of Psidium guajava leaves was tested on two colon cancer and one prostate cancer cell line as in vitro models. Results: The Psidium guajava leaf extract exhibited anticancer activity against the tested cell lines, with decreased proliferation, increased apoptosis, and cell cycle arrest. The extract reduced the cancer cell line’s migration and invasion capacity, demonstrating greater selectivity for the colon cancer cell line than for the prostate cancer cell lines. Conclusions: This study provides further proof of the Psidium guajava plant’s anticancer properties against colon cancer cell lines. Further studies are needed to confirm its use either alone or in conjunction with conventional cancer treatments as an alternate treatment for certain kinds of malignancies. Full article

Geopolymers have gained relevance in environmental applications, and in recent years they have been studied as sustainable adsorbent materials. Increasing their porosity remains one of the main challenges. Various methodologies have been applied for the synthesis of porous geopolymers; however, energy efficiency and environmental considerations associated with the synthesis process must be considered. This study compares two synthesis routes for porous metakaolin-based geopolymers using hydrogen peroxide as a foaming agent and two curing methods: conventional oven curing and microwave-assisted curing. Structural, physical, and chemical properties were evaluated using XRD, FT-IR, SEM/EDS, TGA, and density–porosity analyses. Additionally, a quantitative environmental assessment based on the 12 principles of green chemistry was conducted using the DOZN^TM software version 2.0. The results confirmed that the addition of H₂O₂ did not alter the geopolymeric structure, as evidenced by FT-IR and XRD, regardless of curing method. Porosity increased significantly with the foaming agent, reaching up to ~65% for conventionally cured samples and a maximum of 67% for microwave-cured geopolymers at 3 wt% H₂O₂, with a minimum bulk density of 0.79 g/cm³. High-power microwave-assisted curing reduced the synthesis time to 5 min (≈80% reduction) while promoting a more developed and interconnected macroporous structure, as observed by SEM and supported by enhanced water retention behavior in TGA analyses. The green chemistry assessment demonstrated that microwave curing presents a lower overall impact within the DOZN^TM framework, primarily associated with improved energy efficiency (GCP-6), while acknowledging that this assessment does not constitute a full life cycle analysis. Overall, microwave-assisted synthesis emerges as a more sustainable and efficient route for producing highly porous, hydrophilic geopolymers with strong potential for the adsorption of aqueous pollutants in environmental applications. Full article

While the effects of formulation variables of a rubber compound are well established for conventional rubber manufacturing techniques, their role in extrusion-based additive manufacturing remains underexplored. This study explores the impact of different base rubbers (NBR and EPDM) and curing agents (sulfur and peroxide) on processability and final part characteristics in material extrusion additive manufacturing applications. Under identical printing conditions, sulfur-cured NBR exhibits greater post-print shrinkage (12%) than sulfur-cured EPDM (7%). However, sulfur-cured NBR achieves a higher degree of adhesion between printed layers than sulfur-cured EPDM, as suggested by the % retention of the bulk materials’ ultimate stress by the printed parts (84–100% and 51–62%, respectively). Additionally, a peroxide-cured NBR formulation was compared against the same sulfur-cured NBR formulation. Printed parts from the peroxide-cured NBR formulation showed higher shrinkage (16%) and lower % retention of the bulk materials’ ultimate stress (26–33%) than the sulfur-cured NBR formulation. Additionally, the tensile behavior of all three rubber compounds was found to be strongly dependent on printing orientation, showing the anisotropic behavior typical of extrusion-based additive manufacturing. Sulfur-cured NBR showed the least anisotropy for stress at break (0.82) and strain at break (0.90), whereas peroxide-cured NBR showed the highest anisotropy in stress (0.74) and strain (0.82). The anisotropy ratios for sulfur-cured NBR and EPDM compounds were very similar for stress (0.82 vs. 0.82) and comparable for strain (0.90 vs. 0.87). Notably, the peroxide cure system provided almost twice as much available printing time as the sulfur cure system. This report on the effects of base rubber and curing agents on 3D printability and part properties provides a background to guide future efforts to design rubber compounds for 3D printing applications. Full article

Dual-cure composite cements are an important element of modern dental prosthetics, enabling a stable and long-lasting bond between prosthetic restorations and tooth tissues. Thanks to the combined mechanism of chemical- and light-curing polymerization, they are characterized by high clinical versatility. Despite their wide application, the impact of storage/pre-conditioning temperature on the mechanical properties of dual-cure composite cements remains unclear. The study evaluated the shear bond strength (SBS) of the bond between four dual cements—Bifix Hybrid Abutment (VOCO GmbH, Cuxhaven, Germany), MaxCem Elite (Kerr Corporation, Orange, CA, USA), EnaCem HF (Micerium, Avegno, Italy), and Multilink Automix (Ivoclar Vivadent, Schaan, Lichtenstein)—and dentin depending on their storage temperature (25 °C or 50 °C) and curing method. The tests were carried out on extracted human permanent teeth. The cements were divided into two temperature groups—stored for 7 days at 25 °C or stored for 7 days at 50 °C—and then each of these two temperature groups was divided into two groups—light- and chemically cured (dual-cured, LC) and chemically cured only (CC). Dual-cured cements showed higher shear bond strength at 25 °C. Storage at 50 °C lowered the SBS values, especially for the purely chemically bound cements. LC Bifix Hybrid Abutment achieved the highest SBS at 25 °C, but at 50 °C its properties deteriorated. EnaCem HF showed higher strength at a lower temperature; MaxCem Elite was stable at both temperatures, whereas Multilink Automix showed lower SBS at 50 °C. The study showed that the chemical composition of cements, especially the presence of a benzoyl peroxide (BPO) initiating system, can play a key role in their SBS when bonded to teeth tissue and stability at different storage temperatures. MaxCem Elite showed the best resistance to temperature changes—it achieved the highest temperature stability in both temperature groups. Full article

Novel initiation systems for the production of poly(methyl methacrylate) (PMMA) bone cements based on low-toxicity tertiary amine initiators and hydroxyapatite nanoparticles were investigated. Bicomponent systems formed by a solid component containing PMMA and benzoyl peroxide (BPO) and a liquid component containing methylmethacrylate and low-toxicity aliphatic (dimethylamino-ethoxy-ethane) (DMEE) and aromatic (dimethylamino-benzaldehyde) (DMAB) tertiary amines were tested at two amine concentrations (0.75 and 3.75 wt%) and compared with the standard tertiary amine dimethyl-p-toluidine (DMT). The components were mixed in a 2:1 ratio (solid/liquid) for 60 s. Nanocomposites were prepared using nano-hydroxyapatite inserted into the PMMA-based polymer matrix at various concentrations between 1.0 and 3.75 wt%, aiming to increase the biocompatibility of bone cements applied in cranioplasty. The concentration of tertiary amines directly affects the reaction rate, and increasing the concentration accelerates the curing reaction. Thermal analyses (DSC and TGA) revealed that the produced polymers did not show significant changes in glass transition temperature (113 °C and 115 °C), nor in onset (150–158 °C) or peak degradation temperatures (353 °C and 355 °C). The reaction with the aliphatic amine proved to be slow, as no polymerization occurred within the time period stipulated in the study. However, drastic changes did take place when the cure occurred in the presence of nano-hydroxyapatite. The cure with DMAB (3.75 wt%) that presented an exothermic peak at 37 min (53 °C) showed a peak at 16 min (70 °C), and the cure with DMEE (3.75 wt%) a peak at 11 min (62.5 °C) after the addition of nano-hydroxyapatite. In conclusion, addition of nano-hydroxyapatite significantly influenced both the time and the temperature of cure reaction in all amines studied, expanding the possibility of using new initiators in polymerization systems for cranioplasty flaps. Full article

In systemic diseases, controlling oral bacteria and cancer is an important issue. As biomaterials, recently, carbon dots (DSs) are the focus of a variety of studies owing to their extensive applicability in life sciences. In this study, the effectiveness of carbon dots (CDs) for the elimination of both oral bacteria and oral cancer in vitro was assessed using a dental light-curing unit (LCU) as a light source. CDs were synthesized using an amino acid. The absorbance of CDs and the emission spectrum of the LCU were measured. The production of reactive oxygen species (ROS) was evaluated spectroscopically. Changes in glutathione (GSH) content were evaluated. Using oral bacteria and cancer cells, in vitro antibacterial and antitumor capabilities of CDs were evaluated under light irradiation. Confocal microscopy was used to observe live/dead cells and intracellular lipid peroxidation (LPO). The emission spectrum of the LCU fully matched the absorbance of CDs. After CD treatment, the initial peak absorbances of the p-nitrosodimethylaniline-imidazole (for singlet oxygen assay) and nitroblue tetrazolium (for superoxide oxide assay) solutions changed under light irradiation. The initial peak absorbance of the GSH assay solution decreased during and after light irradiation. Both CD-treated oral bacteria and oral cancer cells were near totally eliminated at 50 and 200 μg/mL concentrations, respectively, after light irradiation. In the live/dead cell and C11-BODIPY^581/591 dye assays, red and green fluorescent spots were, respectively, observed in the CD-treated and light-irradiated cells. Accordingly, CDs effectively eliminated both oral bacteria and cancer cells in vitro in conjunction with dental LCU with less damage to normal cells through ROS-induced or ROS-initiated GSH depletion-induced intracellular LPO. Dental LCU plays a crucial role in ROS production through CD photoexcitation. Dental LUC has the potential to be used as a light source in dentistry for the treatment of oral bacteria and cancer cells. Full article

An experimental investigation was conducted to study the effect of initiator content and polymerization temperature on the mechanical and bonding properties of polyacrylate mortar. Initiator content was controlled in 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0% and polymerization temperature was set at −20, 0, 20, 40, and 60 °C in aggregation process, respectively. The mixture of butyl methacrylate (BMA), benzoyl peroxide (BPO) and N, N-dimethylaniline (DMA) was added to the aggregate composed of quartz sand and silica fume (SF) according to the ratio of monomer to aggregate of 1:4. Results showed that compressive, flexural, tensile, and bonding strengths of polyacrylate mortar decreased with increasing temperature but increased with higher initiator content. The optimal initiator content was 0.6%. Although the highest strength was observed at −20 °C, this curing condition is not easy to achieve in practice and should be considered as laboratory optimization. According to the room temperature, 20 °C can be selected as the best polymerization temperature. SEM observations indicated that the polyacrylate cementitious material cross-linked to form a film, with a dense polymer distribution at the interface that improved interfacial continuity. These findings provide mechanistic insight for optimizing initiator content and curing conditions to enhance the mechanical and bonding performance of polyacrylate-based cementitious composites. Full article

The rheological behavior and low-temperature curing kinetics of poly(ethylene glycol fumarate)–acrylic acid systems initiated by benzoyl peroxide/N,N-dimethylaniline have been investigated for the first time with a focus on the development of thermosetting binders with controllable properties. It has been established that both composition and temperature have a significant effect on rheological behavior and kinetic parameters. Rheological studies revealed non-Newtonian flow behavior and thixotropic properties, while oscillatory tests demonstrated structural transformations during curing. Increasing the temperature was found to accelerate gelation, whereas a higher polyester content retarded the process, which is crucial for controlling the pot life of the reactive mixture. DSC analysis indicated that isothermal curing at 30–40 °C can be satisfactorily described by the Kamal autocatalytic model, whereas at 20 °C, at later stages, and at higher polyester contents, diffusion control becomes significant. The thermal behavior of cured systems was investigated using thermogravimetry. Calculations using the isoconversional Kissinger–Akahira–Sunose and Friedman methods confirmed an increase in the apparent activation energy for thermal decomposition, suggesting a stabilizing effect of poly(ethylene glycol fumarate) in the polymer structure. The studied systems are characterized by controllable kinetics, tunable viscosity, and high thermal stability, making them promising thermosetting binders for applications in composites, construction, paints and coatings, and adhesives. Full article

Consumer demand for organic and nitrite-free meat products has stimulated the search for sustainable alternatives to synthetic curing agents. Conventional nitrites are effective in stabilizing color, inhibiting lipid oxidation, and suppressing pathogens, but their use raises health concerns due to potential nitrosamine formation. This study investigated the application of Portulaca oleracea powder as a multifunctional ingredient to fully replace sodium nitrite in organic cooked frankfurters. Two formulations were produced: control frankfurters with sodium nitrite and experimental frankfurters with purslane powder 1.2%. Physicochemical, oxidative, proteomic, and antioxidant parameters were monitored during refrigerated storage. Purslane incorporation improved the lipid profile by increasing α-linolenic acid and lowering the ω-6/ω-3 ratio, while peroxide, thiobarbituric acid reactive substances (TBARS), and acid values remained significantly lower than in nitrite-containing controls after 10 days. Protein oxidation was also reduced, and SDS-PAGE profiles confirmed that the major structural muscle proteins remained stable, indicating that purslane addition did not disrupt the core proteome. Antioxidant assays showed strong ferric-reducing antioxidant power (FRAP) activity 13.7 mg GAE/g and enhanced 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity 22.3%, highlighting purslane’s contribution to oxidative stability. Although redness (a*) was lower than in nitrite controls, overall color stability (L*, b*) remained high. Taken together, purslane enhanced oxidative stability and quality attributes of nitrite-free organic frankfurters; microbiological validation is ongoing and will be reported separately. Full article

For the first time, the kinetics of isothermal curing and thermal degradation of polyethylene glycol maleate (pEGM)–based systems and their composites with mineral fillers were investigated in the presence of a benzoyl peroxide/N,N-Dimethylaniline redox-initiating system. DSC analysis revealed that the curing process at 20 °C can be described by the modified Kamal autocatalytic model; the critical degree of conversion (α_c) decreases with increasing content of the unsaturated polyester pEGM and in the presence of fillers. In particular, for unfilled systems, α_c was 0.77 for pEGM45 and 0.60 for pEGM60. TGA results demonstrated that higher pEGM content and the incorporation of fillers lead to increased thermal stability and residual mass, along with a reduction in the maximum decomposition rate (dTGₘₐₓ). Calculations using the Kissinger–Akahira–Sunose and Friedman methods also confirmed an increase in the activation energy of thermal degradation (E_a): E_KAS was 419 kJ/mol for pEGM45 and 470 kJ/mol for pEGM60, with the highest values observed for pEGM60 systems with fillers (496 kJ/mol for SiO₂ and 514 kJ/mol for CaCO₃). Rheological studies employing three-interval thixotropy tests revealed the onset of thixotropic behavior upon filler addition and an increase in structure recovery after deformation of up to 56%. These findings underscore the potential of pEGM-based systems for low-temperature curing and for the design of composite materials with improved thermal resistance. Full article

Inflammatory bowel diseases (IBDs), such as ulcerative colitis, and Crohn’s disease are chronic idiopathic inflammatory diseases of the gastrointestinal system involving interaction between genetic and environmental factors mediating the occurrence of oxidative stress and inflammation. There is no permanent cure for IBD except long-term treatment or surgery (resection of the intestine), and the available agents in the long term appear unsatisfactory and elicit numerous adverse effects. To keep the disease in remission, prevent relapses and minimize adverse effects of currently used medicines, novel dietary compounds of natural origin convincingly appear to be one of the important therapeutic strategies for the pharmacological targeting of oxidative stress and inflammation. Therefore, it is imperative to investigate plant-derived dietary agents to overcome the debilitating conditions of IBD. In the present study, the effect of α-Bisabolol (BSB), a dietary bioactive monoterpene commonly found in many edible plants as well as important components of traditional medicines, was investigated in acetic acid (AA)-induced colitis model in rats. BSB was orally administered to Wistar male rats at a dose of 50 mg/kg/day either for 3 days before or 30 min after induction of IBD for 7 days through intrarectal administration of AA. The changes in body weight, macroscopic and microscopic analysis of the colon and calprotectin levels in the colon of rats from different experimental groups were observed on day 0, 2, 4, and 7. The levels of myeloperoxidase (MPO), a marker of neutrophil activation, reduced glutathione (GSH) and malondialdehyde (MDA), a marker of lipid peroxidation, and the levels of pro-inflammatory cytokines were measured. AA caused a significant reduction in body weight and induced macroscopic and microscopic ulcers, along with a significant decline of endogenous antioxidants (superoxide dismutase (SOD), catalase, and GSH), with a concomitant increase in MDA level and MPO activity. BSB significantly improved the AA-induced reduction in body weight, colonic mucosal histology, inhibited MDA formation, and restored antioxidant levels along with a reduction in MPO activity. AA also induced the release of pro-inflammatory cytokines such as interleukin-1 (IL-1), interleukin-23 (IL-23) and tumor necrosis factor-α (TNF-α). Furthermore, AA also increased levels of calprotectin, a protein released by neutrophils under inflammatory conditions of the gastrointestinal tract. BSB treatment significantly reduced the release of calprotectin and pro-inflammatory cytokines. The findings of the present study demonstrate that BSB has the potential to improve disease activity and rescue colonic tissues from damage by inhibiting oxidative stress, lipid peroxidation and inflammation. The findings are suggestive of the benefits of BSB in IBD treatment and substantiate its usefulness in colitis management, along with its gastroprotective effects in gastric ulcer. Full article

Two-component dental materials are commonly used by the dentist for various applications (cementation of indirect restorations, filling of a cavity without layering, etc.). These materials are cured by redox polymerization. The (hydro)peroxide/thiourea/copper salt redox initiator system is well established and can be found in a wide range of commercially available dental materials. The thiourea is a key component of the initiator system. This study explores the influence of the nature of the thiourea reducing agent on the reactivity and efficiency of redox initiator systems. In this work, six different thiourea structures were investigated, in combination with copper(II) acetylacetonate and cumene hydroperoxide (CHP), to understand their impact on polymerization kinetics and mechanical properties of methacrylate-based materials. Various experimental techniques, including mass spectrometry (MS) and spectroscopic analyses, were employed to elucidate the underlying mechanisms governing these redox systems. The results highlight that thiourea plays a dual role, acting both as a reducing agent and as a ligand in copper complexes, affecting radical generation and polymerization efficiency. Structural modifications of thiourea significantly influence the initiation process, demonstrating that reactivity is governed by a combination of factors rather than a single property. Self-cure dental flowable composites exhibiting excellent flexural strength (>100 MPa) and modulus (>6000 MPa) were obtained using hexanoyl thiourea, N-benzoylthiourea, or 1-(pyridin-2-yl)thiourea as a reducing agent. The adjustment of the Cu(acac)₂ enables to properly set the working time in the range of 100 to 200 s. These findings provide valuable insights into the design of the next generation of redox initiating systems for mild and safe polymerization conditions. Full article

The increasing consumption of edible oils has resulted in a parallel rise in waste cooking oil (WCO), a harmful waste stream but one that also represents a promising raw material. In this study, oil-based binders were synthesised from WCO using various reagents: Sulfuric(VI) acid, hydrobromic acid, acetic acid, salicylic acid, glycolic acid, zinc acetate, ethanol, hydrogen peroxide, and their selected mixtures. The manufacturing process was optimised, and the composites were evaluated for physicochemical and mechanical properties, including compressive strength, bending strength, and water absorption. The best performance was observed for composites catalysed with a mixture of sulfuric(VI) acid and 20% hydrogen peroxide, cured at 240 °C, yielding compressive and bending strengths of 5.20 MPa and 1.34 MPa, respectively. Under modified curing conditions, a compressive strength of 5.70 MPa and a bending strength of 0.75 MPa were obtained. The composite modified with glycolic acid showed the lowest water absorption (3%). These findings demonstrate how catalyst type and curing parameters influence composite structure, porosity, and mechanical behaviour. The study provides new insights into the process–structure–property relationships in oil-based materials and supports the development of environmentally friendly composites from waste feedstocks. Full article

Pancreatic cancer is a highly lethal malignant tumor characterized by challenges in early diagnosis and limited therapeutic options, leading to an exceptionally low clinical cure rate. With the advent of novel cancer treatment paradigms, ferroptosis—a form of iron-dependent regulated cell death driven by lipid peroxidation—has emerged as a promising therapeutic strategy, particularly for tumors harboring RAS mutations. However, the poor bioavailability and insufficient tumor-targeting capabilities of conventional drugs constrain the efficacy of ferroptosis-based therapies. Recent advancements in nanotechnology and imaging-guided treatments offer transformative solutions through targeted drug delivery, real-time monitoring of treatment efficacy, and multimodal synergistic strategies. This article aims to elucidate the mechanisms underlying ferroptosis in pancreatic cancer and to summarize the latest identified therapeutic targets for ferroptosis in this context. Furthermore, it reviews the recent progress in nanotechnology-based ferroptosis therapy for pancreatic cancer, encompassing ferroptosis monotherapy, synergistic ferroptosis therapy, and endogenous ferroptosis therapy. Subsequently, the integration of imaging-guided nanotechnology in ferroptosis therapy is summarized. Finally, this paper discusses innovative strategies, such as stroma-targeted ferroptosis therapy, immune-ferroptosis synergy, and AI-driven nanomedicine development, offering new insights and directions for future research in pancreatic cancer treatment. Full article

Science has made significant progress in detecting reactive oxygen species (ROS) in tobacco smoke, which is an important step for precision cancer therapy. An important advance is also the understanding that superoxide can be produced by electrophilic molecules. The dual action of hydrogen peroxide, directly or via electrophilic molecules, in the development of oxidative stress allows for the identification of target proteins that can potentially stop unwanted signals in cancer development. However, despite advances in proteomics, reliable inhibitors to stop ROS-associated cancer progression have not yet been proposed for the treatment of tobacco cigarette smokers. This is likely due to an imperfect understanding of the diversity of molecular mechanisms of anti-ROS action. Fluorescent protein detection in living cells, called in-gel, offers a direct route to a better understanding of the rapid interaction of ROS and electrophilic compounds with targeted proteins. It seemed that the traditional paradigm of pharmaceutical innovation “one drug, one disease” did not solve the problem of tobacco smoking causing cancer. However, among the various therapeutic treatments for tobacco smokers, the best way to combat cancer today is smoking cessation, which fits into the “one-cure” paradigm. Full article