Non-toxic Conditions Research Articles

Degradation Behavior of Medical MgZZC-1 in Various Simulated Body Fluids.

Magnesium-based biodegradable metal bone implants exhibit superior mechanical properties compared to biodegradable polymers for orthopedic and cardiovascular stents. In this study, MgZZC-x (x = 1, 1.2) alloys were screened by in vitro biocompatibility tests in three simulated body fluids under nontoxic conditions. The MgZZC-1 alloys with better biocompatibility were selected to predict the days required for complete degradation. The evolution of degradation products was analyzed, and the mechanism of formation of the product film was inferred. A degradation kinetic model was established to investigate the effect of MEM components on the degradation of the alloys. The results demonstrate that the proteins in MEM can greatly retard the degradation progress by attaching to the surface of MgZZC-1 alloys, which are predicted to degrade completely within 341 days. The carbonate and phosphate buffers were adjusted to pH in MEM solution, delaying the degradation of magnesium alloys. This process in MEM more accurately reflects the actual degradation in the body and is superior to that in Hanks and SBF solutions. This study will promote the application of biodegradable materials in clinical medicine.

Asiatic acid inhibits osteosarcoma cell migration and invasion via the AKT/Sp1/MMP1 axis.

Osteosarcoma is a malignant bone tumor affecting adolescents and children. No effective treatment is currently available. Asiatic acid (AA), a triterpenoid compound found in Centella asiatica, possesses anti-tumor, anti-inflammatory, and anti-oxidant properties in various types of tumor cells. This study aims to determine whether AA exerts antitumor effects in human osteosarcoma cells. Our results indicate that AA does not influence the viability, proliferative rate, or cell cycle phase of human osteosarcoma cells under non-toxic conditions. AA suppressed osteosarcoma cell migration and invasion by down-regulating matrix metalloproteinase 1 (MMP1) expression. Data in the TNMplot database suggested MMP1 expression was higher in osteosarcoma than in normal tissues, with associated clinical significance observed in osteosarcoma patients. Overexpression of MMP1 in osteosarcoma cells reversed the AA-induced suppression of cell migration and invasion. AA treatment decreased the expression of specificity protein 1 (Sp1), while Sp1 overexpression abolished the effect of AA on MMP1 expression and cell migration and invasion. AA inhibited AKT phosphorylation, and treatment with a PI3K inhibitor (wortmannin) increased the anti-invasive effect of AA on osteosarcoma cells via the p-AKT/Sp1/MMP1 axis. Thus, AA exhibits the potential for use as an anticancer drug against human osteosarcoma.

Triplet Energy Transfer Mechanism in Copper Photocatalytic N- and O-Methylation.

Methylation reactions are chemically simple but challenging to perform under mild and non-toxic conditions. A photochemical energy transfer strategy was merged with copper catalysis to enable fast reaction times of minutes and broad applicability to N-heterocycles, (hetero-)aromatic carboxylic acids, and drug-like molecules in high yields and good functional group tolerance. Detailed mechanistic investigations, using kinetic analysis, aprotic MS, UV/Vis, and luminescence quenching experiments revealed a triplet-triplet energy transfer mechanism between hypervalent iodine(III) reagents and readily available photosensitizers.

Transcriptome analysis of cultured human vascular endothelial cells after γ-ray irradiation and correlation analysis with ATP, ADP, and adenosine as secondary soluble factors.

Vascular endothelial cells serve as barriers between blood components and subendothelial tissue and regulate the blood coagulation-fibrinolytic system. Ionizing radiation is a common physical stimulant that induces a bystander effect whereby irradiated cells influence neighboring cells through signalings, including purinergic receptor signaling, activated by adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and adenosine as secondary soluble factors. Human vascular endothelial EA.hy926 cells were cultured and irradiated with γ-rays or treated with ATP, ADP, or adenosine under non-toxic conditions. RNA-seq, gene ontology, and hierarchical clustering analyses were performed. The transcriptome analysis of differentially expressed genes in vascular endothelial cells after γ-ray irradiations suggests that the change of gene expression by γ-irradiation is mediated by ATP and ADP. In addition, the expression and activity of the proteins related to blood coagulation and fibrinolysis systems appear to be secondarily regulated by ATP and ADP in vascular endothelial cells after exposure to γ-irradiation. Although it is unclear whether the changes of the gene expression related to blood coagulation and fibrinolysis systems by γ-irradiation affected the increased hemorrhagic tendency through the exposure to γ-irradiation or the negative feedback to the activated blood coagulation system, the present data indicate that toxicity associated with γ-irradiation involves the dysfunction of vascular endothelial cells related to the blood coagulation-fibrinolytic system, which is mediated by the signalings, including purinergic receptor signaling, activated by ATP and ADP.

Phytoreactor for Arsenic Biodetoxification: An Integrated Sequential Process of Phytoremediation Involving Multi-Kingdom Organisms

Phytoremediation of polluted environments has received attention and developed rapidly in recent decades. Plant performance assessment is conducted around the effectiveness and efficiency of reducing the concentration of pollutants and certain plant-associated organisms. While supporting these advances, this paper aims to develop integrated phytoremediation as a pollutant treatment reactor involving all processes and multi-kingdoms of organisms, referred to as phytoreactor. The data collected comes from the results of previous studies related to various kinds of phytoremediation processes. Screening and selection of data were based on criteria for differences in plant processes, involvement of various plant-associated organisms, and aesthetics. An arsenic pollutant, one of the most toxic metalloids and ubiquitous, the kingdom’s involvement of plant-associated organisms between aboveground and belowground plant parts. A new perspective in phytoremediation is creating a phytoreactor that integrates three sequential processes. Starting with the containment of toxic pollutants, followed by a primary process consisting of physicochemical and biological processes, and completed by a secondary process in plants, which produces nontoxic environmental media conditions. The primary biological processes are carried out in the rhizosphere and phyllosphere. The involvement of the plant-associated organism kingdom is different in the rhizosphere and phyllosphere due to the suitability of the habitat, the type of pollutant, and the aesthetics of the application of the phytoreactor. Phytoreactor for the remediation of polluted environments involves synergistic multi-kingdoms of plant-associated organisms for specific types of pollutants in the rhizosphere and phyllosphere.

L. pneumophila resists its self-harming metabolite HGA via secreted factors and collective peroxide scavenging.

Before environmental opportunistic pathogens can infect humans, they must first successfully grow and compete with other microbes in nature, often via secreted antimicrobials. We previously discovered that the bacterium Legionella pneumophila, the causative agent of Legionnaires' disease, can compete with other microbes via a secreted molecule called HGA. Curiously, L. pneumophila strains that produce HGA is not wholly immune to its toxicity, making it a mystery how these bacteria can withstand the "friendly fire" of potentially self-targeting antimicrobials during inter-bacterial battles. Here, we identify several strategies that allow the high-density bacterial populations that secrete HGA to tolerate its effects. Our study clarifies how HGA works. It also points to some explanations of why it is difficult to disinfect L. pneumophila from the built environment and prevent disease outbreaks.

Activation of Diazo Compounds by Fluorinated Triarylborane Catalysts

AbstractThe diverse applicability of diazo compounds as versatile reagents has enlarged the chemical toolbox in organic synthesis. Over the past few decades, transition-metal-catalyzed diazo compound activation has ignited the classical synthetic methodology via utilizing highly reactive metal carbenoid species. Many reviews have also appeared in the literature that show the advantages and disadvantages of metal-catalyzed activation of diazo compounds. Recently, tris(pentafluorophenyl)borane-mediated diazo activation reactions has remodeled this research area due to the potential for mild, environmentally friendly, metal-free, nontoxic reaction conditions, and the diverse reactivity patterns of boranes towards diazo compounds. In this review, we discuss the reactivity of the boron–diazo precursor adducts with compounds using catalytic and stoichiometric halogenated triarylboranes and, the mechanism of N2 release from the diazo reagent. This generates the reactive carbene species as a key intermediate which can further be exploited for O–H, N–H, S–H, and C–H insertions, azide insertion, carbonate transfer, C–C and C=C bond forming reactions, [2+2] or [2+4] cascade cyclization reactions, annulation reactions, etc.1 Introduction2 Diazo Activation Using Stoichiometric Boranes3 Diazo Activation Using Catalytic B(C6F5)3 4 B(C6F5)3-Catalyzed Diazo Activation Reactions5 Conclusions

Biosynthesis of Nicotinamide Mononucleotide: Current Metabolic Engineering Strategies, Challenges, and Prospects

Nicotinamide mononucleotide (NMN) is an essential precursor of nicotinamide adenine dinucleotide (NAD+), which is widely applied in the pharmaceutical and biotech industries. The biosynthesis of NMN is currently attracting much attention because it has non-toxic reaction conditions and low amounts of isomers, whereas chemical synthesis has low yields and is not environmentally friendly. This review systematically describes the two biosynthetic pathways of NMN in detail for the first time and introduces the latest studies on NMN production through different pathways using metabolic engineering strategies. NMN accumulation can be improved by optimizing the activity of key enzymes, enhancing the supply of precursors and co-factors, inhibiting the synthesis of byproducts, and promoting product export. Finally, we also discuss the current challenges of producing NMN and possible solutions for the future.

Controlled Release of Drug-Encapsulated Protein Films with Various Sodium Dodecyl Sulfate Concentrations.

Protein-based drug carriers are ideal drug-delivery platforms because of their biocompatibility, biodegradability, and low toxicity. Many types and shapes of protein-based platforms, including nanoparticles, hydrogels, films, and minipellets, have been prepared to deliver drug molecules. In this study, protein films containing the desired amounts of doxorubicin (DOX) as cancer drugs were developed using a simple mixing method. The release ratio and rate of DOXs were dependent on the surfactant concentration. The drug release ratio was controlled within the range of 20-90% depending on the amount of the surfactant used. The protein film surface was analyzed using a microscope before and after drug release, and the relationship between the degree of film swelling and the drug release ratio was discussed. Moreover, the effects of cationic surfactants on the protein film were investigated. Non-toxic conditions of the protein films were confirmed in normal cells, while the toxicity of the drug-encapsulated protein film was confirmed in cancer cells. Remarkably, it was observed that the drug-encapsulated protein film could eliminate 10-70% of cancer cells, with the extent of efficacy varying based on the surfactant amount.

Trans‐metallated chlorophyllin by copper supported on silica‐coated magnetic nanoparticles as an efficient and green catalyst for the synthesis of furan‐2(5H)‐ones

In recent years, an unprecedented increase in environmental pollution as a result of the rapid industrialization of the world has attracted a lot of attention to green chemistry. Chlorophyllin copper complex (Chln‐Cu) is one of the most vital compounds derived from natural chlorophyll that can be used as an environmental, sustainable, and green catalyst in industrial processes. In the current paper, chlorophyll was first extracted from spinach leaves, hydrolyzed, and trans‐metallated to chlorophyllin copper (II) complex. The fixation of Chln‐Cu on functionalized magnetic nanoparticles was performed using a green mechanical method. This mechanical solvent‐free reaction was done in a planetary ball mill with 60 zirconia balls (diameter = 3 mm) and the rotation speed 200 rpm at 12 h. In conclusion, an efficient and reusable Fe3O4@SiO2‐NH2‐Chln‐Cu catalyst was obtained. To characterize the synthesized catalyst, several analytical techniques were used such as UV–Vis, FT‐IR, 1H‐NMR, and 13C‐NMR spectra as well as TG, ICP‐OES, XRD, FE‐SEM, elemental mapping, VSM, and XPS analyses. The conducted analyses showed that the catalyst was successfully synthesized. The efficiency of the catalyst was checked in the preparation of 3,4,5‐trisubstituted furan‐2(5H)‐one derivatives at room temperature in propylene carbonate as a green solvent. Moreover, the effect of time, temperature, and solvent on the reaction yield was thoroughly investigated. Excellent performance at mild, environmentally friendly, and nontoxic conditions showed that Fe3O4@Si‐Chln‐Cu not only is an excellent catalyst for this process but also it can be an outstanding catalyst for other catalytic reactions.

Impact of buffer composition on biochemical, morphological and mechanical parameters: A tare before dielectrophoretic cell separation and isolation

Dielectrophoresis (DEP) represents an electrokinetic approach for discriminating and separating suspended cells based on their intrinsic dielectric characteristics without the need for labeling procedure. A good practice, beyond the physical and engineering components, is the selection of a buffer that does not hinder cellular and biochemical parameters as well as cell recovery. In the present work the impact of four buffers on biochemical, morphological, and mechanical parameters was evaluated in two different cancer cell lines (Caco-2 and K562). Specifically, MTT ([3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]) assay along with flow cytometry analysis were used to evaluate the occurring changes in terms of cell viability, morphology, and granulocyte stress formation, all factors directly influencing DEP sorting capability. Quantitative real-time PCR (qRT-PCR) was instead employed to evaluate the gene expression levels of interleukin-6 (IL-6) and inducible nitric oxide synthase (iNOS), two well-known markers of inflammation and oxidative stress, respectively. An additional marker representing an index of cellular metabolic status, i.e. the expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene, was also evaluated. Among the four buffers considered, two resulted satisfactory in terms of cell viability and growth recovery (24 h), with no significant changes in cell morphology for up to 1 h in suspension. Of note, gene expression analysis showed that in both cell lines the apparently non-cytotoxic buffers significantly modulated IL-6, iNOS, and GAPDH markers, underlining the importance to deeply investigate the molecular and biochemical changes occurring during the analysis, even at apparently non-toxic conditions. The selection of a useful buffer for the separation and analysis of cells without labeling procedures, preserving cell status, represents a key factor for DEP analysis, giving the opportunity to further use cells for additional analysis.

Aneuploidy Rate and Stemness in Low-Level Mosaic Human Embryonic Stem Cells in the Presence/Absence of Bortezomib, Paclitaxel, and Lapatinib

Human embryonic stem cells (hESCs) are predisposed to aneuploidy through continual passages. Some reports indicate more sensitivity of aneuploid hESCs cells to anticancer drugs. The present study was designed to investigate the cytotoxicity of three anticancer drugs (including bortezomib, paclitaxel, and lapatinib) and their effect on aneuploidy rate in hESCs. To create a low-level mosaic cell line, normal hESCs (80%) and trisomic hESCs for chromosomes 12 and 17 (20%) were mixed. The effect of the 3 mentioned anticancer drugs on the chromosomal status was assessed by metaphase spread analysis after selection of the nontoxic conditions. Expression of pluripotency genes was analyzed, and an alkaline phosphatase test was performed to assess pluripotency preservation. Our data showed that treatment with bortezomib, paclitaxel, and lapatinib was nontoxic at 0.01, 0.01, and 0.2 μ<sc>M</sc> concentrations, respectively. Alkaline phosphatase and pluripotency gene expression analyses revealed maintenance of pluripotency following treatment with above-noted nontoxic concentrations. Aneuploid cells were dominant in treated and control groups with a minimum abundance of 70%, with no significant differences between groups. Drug treatments had no negative effect on pluripotency. Insensitivity of aneuploid cells in treatment groups could be related to the specific characteristics of each cell line in response to the drug and the proliferative superiority of cells with trisomies 12 and 17.

Ecological risk assessment of priority PAHs pollutants in crude oil contaminated soil and its impacts on soil biological properties

Polycyclic aromatic hydrocarbons (PAHs) are one of the major toxic constituents of crude oil and therefore, an understanding on PAHs associated risks and their relationship with soil biological parameters are necessary for adopting effective risk-based and site specific remediation strategies in the contaminated soil. Here, risks evaluation of eight detected PAHs in terms of toxic equivalent concentration (TEQC), benzo(a)pyrene equivalent (BaPeq), contamination factor (CF), pollution load index (PLI), hazard quotient (HQ), hazard index (HI), toxic unit for individual PAHs (TU) and PAHs mixture (TUm) have been evaluated. Besides, the effect of PAHs contamination on soil biological properties has also been investigated and correlated with PAHs concentrations. The TEQc of eight PAHs was recorded in the range of 0.06–5.0 mg kg−1 soil, whereas the BaPeq value was 25.3 mg kg−1 soil which exceed the permissible limit. Similarly, CF (85.5–1668.2), PLI (322.8), HQ (311.7–8340.9), HI (26,443.8), TU (227.9–3821.6) and TUm(7916.2) also exceed the permissible values for non-toxic conditions indicating carcinogenic risk for humans. Besides, activities of soil dehydrogenase, urease, alkaline-phosphatase, catalase, amylase and cellulase were decreased by 1.5–2.3 folds in the contaminated soil than control. The results of Pearson’s correlation matrix also established negative impact of PAHs on the soil's biological properties.

Construction of multi-substituted pyrazoles via potassium carbonate-mediated [3 + 2] cycloaddition of in situ generated nitrile imines with cinnamic aldehydes.

A highly efficient potassium carbonate-mediated [3 + 2] cycloaddition reaction of hydrazonoyl chlorides with cinnamic aldehydes to furnish multi-substituted pyrazoles under nontoxic and mild conditions has been developed. A plausible stepwise cycloaddition reaction mechanism is proposed. This protocol featured broad substrate coverage, good functional group tolerance, wide scalability, and operational simplicity, as well as conveniently constructed pyrazole scaffolds.

Hematopoietic Stem Cell Mobilization:Current Collection Approaches, Stem Cell Heterogeneity, anda Proposed New Method for Stem Cell Transplant Conditioning.

Hematopoietic stem cells naturally traffic out of their bone marrow niches into the peripheral blood. This natural trafficking process can be enhanced with numerous pharmacologic agents - a process termed "mobilization" - and the mobilized stem cells can be collected for transplantation. We review the current state of mobilization with an update on recent clinical trials and new biologic mechanisms regulating stem cell trafficking. We propose that hematopoietic mobilization can be used to answer questions regarding hematopoietic stem cell heterogeneity, can be used for non-toxic conditioning of patients receiving stem cell transplants, and can enhance gene editing and gene therapy strategies to cure genetic diseases.

The FGFR Family Inhibitor AZD4547 Exerts an Antitumor Effect in Ovarian Cancer Cells.

The dysregulation of fibroblast growth factor (FGF) signaling has been implicated in tumorigenesis, tumor progression, angiogenesis, and chemoresistance. The small-molecule AZD4547 is a potent inhibitor of FGF receptors. This study was performed to investigate the antitumor effects and determine the mechanistic details of AZD4547 in ovarian cancer cells. AZD4547 markedly inhibited the proliferation and increased the apoptosis of ovarian cancer cells. AZD4547 also suppressed the migration and invasion of ovarian cancer cells under nontoxic conditions. Furthermore, it attenuated the formation of spheroids and the self-renewal capacities of ovarian cancer stem cells and exerted an antiangiogenic effect. It also suppressed in vivo tumor growth in mice. Collectively, this study demonstrated the antitumor effect of AZD4547 in ovarian cancer cells and suggests that it is a promising agent for ovarian cancer therapy.

Soil enrichment with actinomycete mitigates the toxicity of arsenic oxide nanoparticles on wheat and maize growth and metabolism.

The use of plant growth-promoting bacteria (PGPB) to enhance plant growth and protection against heavy metal toxicity has been extensively studied. However, its potentiality to reduce arsenate toxicity, a threat to plant growth and metabolism, has been hardly investigated. Moreover, the toxic effect of arsenic oxide nanoparticles (As-NPs) on plants and possible mechanisms for its alleviation has not yet been explored. In this study, the impact of the bioactive actinomycete Streptomyces spp. on the growth, physiology and stress-related metabolites, such as sugars and proline, on As-NPs-stressed wheat and maize plants was investigated. Soil amendment with arsenic oxide nanoparticles (As-NPs) induced the uptake and accumulation of As in the plants of both species, resulting in reduced growth and photosynthesis, but less marked in maize than in wheat plants. Under As-NPs-free conditions, Streptomyces spp. treatment markedly improved growth and photosynthesis in wheat only. The application of Streptomyces spp. reduced As accumulation, recovered the As-NPs-induced growth, photosynthesis inhibition, and oxidative damage in plants of both species. Wheat plants specifically accumulated soluble sugars, while both species accumulated proline. Under As-NPs stress, the ornithine pathway of proline biosynthesis was more important in maize than in wheat plants, while the glutamine pathway was dominant in wheat ones. The addition of Streptomyces spp. further induced the accumulation of proline and starch in both plant species. Overall, despite a different response to Streptomyces spp. under nontoxic conditions, the amendment of as-contaminated soil with Streptomyces spp. induced similar metabolic responses in the two tested species, which trigger stress recovery.

Enhanced three-dimensional printing scaffold for osteogenesis using a mussel-inspired graphene oxide coating

For further advance a functionality of three-dimensional (3D) printing techniques using biopolymers, graphene oxide (GO) as a carbon-based nanomaterial has received much attention recently due to its superior properties. However, the ability to synergistically affect the resulting 3D-printed structures has been limited by difficulty controlling the nanomaterial ratio in which biological stability is achieved, as well as by the use of noxious solvents applied to the nanomaterials during scaffold fabrication. To address these issues, we demonstrate the use of an ecofriendly mussel-inspired GO coating for 3D-printed scaffolds to enhance the scaffold’s functionality and bioactivity. We used polydopamine for deposition using 1, 3, and 6 mg/mL GO in solution on the surface of the scaffold. By this coating method, we efficiently regulated the degree of GO deposition on the surface of scaffold strands under non-toxic conditions, which revealed by microscope. Furthermore, the surface roughness, hydrophilicity, and functional groups were increased after GO coating process. Especially, we identified that the GO coated scaffold was shown improved properties for promoting osteogenesis compared to a bare scaffold by in vitro analyses. Therefore, we suggest that the GO coated scaffold has the potential as a bone substitute for tissue engineering.

Turbo‐charging proximity labeling: directed evolution of promiscuous biotin ligase for efficient proteomic mapping in vivo

Protein interaction networks and protein compartmentalization underlie all signaling and regulatory processes in cells. Traditional biochemical approaches such as fractionation and affinity purification have contributed greatly towards our understanding of these protein networks and subcellular proteomes, however impurities from contaminant molecules and loss of material during these procedures can limit their specificity and depth of biological investigation. Enzyme-catalyzed proximity labeling (PL) has emerged as a complementary approach to study the spatial and interaction characteristics of proteins in which a PL enzyme can be genetically targeted to a subcellular region and used to tag surrounding endogenous proteins in living cells with a chemical handle that allows their identification by MS. Previous PL methods such as BioID and APEX are limited by poor catalytic efficiency or toxic substrates that limit their application in vivo. Therefore, we used yeast-display directed evolution to engineer a new proximity labeling method, called TurboID, that uses non-toxic labeling conditions and has high catalytic efficiency that allows its use in a wide variety of biological contexts, including in microbes, cultured cells, flies, worms, mice, and plants.

Comparison of in-office and at-home tooth-whitening products cytotoxicity

Introduction Bleaching teeth to have a whiter and bright smile is a popular trend and currently one can do it at home, without technical support from dentists. However, whitening products are not innocuous and the European legislation is clear limiting the content in hydrogen peroxide (H2O2), present or released, to 6%, still, products containing up to 40% of H2O2 are commercially available. In fact, the contact time of live tissues with H2O2 agents is usually small, which may restrict side effects, but on the other hand, successively applications as well as at-home careless applications may be harmful. This work aims to verify how whitening products commercialised in Portugal impact on fibroblasts viability. Materials and methods We used fibroblasts, the main cells of both pulp and gingivae that contact with whitening gels. Mouse embryo fibroblasts (NIH/3T3) were incubated with serial dilutions of Opalescence PF boost 40%, Opalescent PF 16%, Opalescent PF 10% from Ultradent (USA) and Bbryance 0.095% (France) in culture medium for 1-hour. After that period, the culture medium was removed and cell viability was determined using MTT assay. Results Our results showed a huge decrease in fibroblasts viability after exposure to both product types: containing H2O2 or carbamide peroxide. To achieve conditions considered non-toxic, i.e. showing a reduction in cell viability <30% [1], it was necessary to dilute whitening products at least 100- to 62,500-fold, down to 0.0001–0.0004% H2O2, as shown in Table 1. Table 1. Necessary dilutions to achieved non-toxic conditions (viability >70%). Utilisation Product /Whitening agent Equivalents in H2O2 in the product (%) Product dilution Predicted [H2O2] to achieve 70% viability In-office Opalescent PF boost 40%/ hydrogen peroxide 40 1/62,500 0.0001 At-home Opalescent PF 16% / carbamide peroxide 5.8 1/37,500 0.0001 Opalescent PF 10% / carbamide peroxide 3.6 >1/1500 0.0004 BBRYANCE 0.095% / hydrogen peroxide 0.095 1/100 0.0002 Discussion and conclusions Although we cannot extrapolate this effect directly to human teeth, because the concentration of H2O2 arriving at the pulp depends on diffusion through dentinal tubules, our observations are of great concern in particular for gingivae health. Moreover, the whitening products sold for at-home use are as cytotoxic as the in-office product to be applied under the supervision of the dental professional independently of the product type. Since we found that at-home products have similar toxicities, we anticipated that the BBRYANCE gel will induce less severe effects due to his lower H2O2 concentration.