Tris(2,3-dibromopropyl) Isocyanurate Research Articles

Reprotoxic Effect of Tris(2,3-Dibromopropyl) Isocyanurate (TBC) on Spermatogenic Cells In Vitro

Tris(2,3-dibromopropyl) isocyanurate (TBC) belongs to the class of novel brominated flame retardants (NFBRs) that are widely used in industry. It has commonly been found in the environment, and its presence has been discovered in living organisms as well. TBC is also described as an endocrine disruptor that is able to affect male reproductive processes through the estrogen receptors (ERs) engaged in the male reproductive processes. With the worsening problem of male infertility in humans, a mechanism is being sought to explain such reproductive difficulties. However, so far, little is known about the mechanism of action of TBC in male reproductive models in vitro. Therefore, the aim of the study was to evaluate the effect of TBC alone and in cotreatment with BHPI (estrogen receptor antagonist), 17β-estradiol (E2), and letrozole on the basic metabolic parameters in mouse spermatogenic cells (GC-1 spg) in vitro, as well as the effect of TBC on mRNA expression (Ki67, p53, Pparγ, Ahr, and Esr1). The presented results show the cytotoxic and apoptotic effects of high micromolar concentrations of TBC on mouse spermatogenic cells. Moreover, an increase in Pparγ mRNA levels and a decrease in Ahr and Esr1 gene expression were observed in GS-1spg cells cotreated with E2. These results suggest the significant involvement of TBC in the dysregulation of the steroid-based pathway in the male reproductive cell models in vitro and may be the cause of the currently observed deterioration of male fertility. However, more research is needed to reveal the full mechanism of TBC engagement in this phenomenon.

In situ localization of tris(2,3-dibromopropyl) isocyanurate in mouse organs by MALDI-IMS with auxiliary matrix strategy

Tris(2,3-dibromopropyl) isocyanurate (TBC) is one of the novel brominated flame retardants that has been widely used in consumer goods. Humans may be exposed to TBC daily. Studies showed that TBC can induce significant toxicity. However, there is currently no report on its in situ localization in organs. In this study, we aimed to develop a reliable and reproductive method to determine the in situ localization of TBC in mouse organs by matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS). As commercially available matrices were not able to detect TBC in tissue section, we then developed a novel MALDI-IMS method based on 1,5-diaminonaphthalene hydrochloride and silver trifluoromethanesulfonate (NDA/AgOTf) as the matrix for the in situ localization of TBC. AgOTf used as the auxiliary matrix in the negative-ion mode showed an excellent MS signal of TBC. The detection limit of [2AgOTf + Br]- was at the μg/mL level. The developed MALDI-IMS method was successfully employed to obtain the TBC spatial distribution in the mouse organs collected from mice exposed to 160 mg/kg/day of TBC for 30 days. High-pressure liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS) was also used to evaluate the accumulation of TBC in liver, kidney, heart, and brain. The combination of MALDI-IMS and HPLC-MS/MS showed that TBC can accumulate in mice organs and it is mainly distributed in the renal parenchyma. In summary, an innovative method was developed for the analysis of TBC spatial distribution by MALDI-IMS using a novel NDA/AgOTf matrix, extending the application of MALDI-IMS in environmental pollutants.

Anti-estrogenic activity of tris(2,3-dibromopropyl) isocyanurate through disruption of co-activator recruitment: experimental and computational studies

As a potential endocrine disruptor, tris(2,3-dibromopropyl) isocyanurate (TBC) has previously been demonstrated to reduce expression of estrogen-dependent vitellogenin (vtg) mRNA in adult zebrafish. However, the underlying toxicity pathways and molecular mechanisms involved in TBC-induced endocrine disruption remain elusive. In the current study, E-Screen and MVLN assays were employed to explore the potential anti-estrogenic effects of TBC via the estrogen receptor α (ERα)-mediated signaling pathway. Within a dose range between 1 × 10- 9 and 1 × 10- 7M, TBC significantly inhibited 17β-estradiol (E2)-induced cell proliferation in a breast cancer cell line. The luciferase activity induced by E2 was also significantly inhibited by TBC in a dose-dependent manner. Moreover, neither TBC nor E2 affected proliferation of the ERα-negative breast cancer cell line MDA-MB-231. These experimental results confirmed that TBC has anti-estrogenic effects by affecting the ERα-mediated signaling pathway. By comparing TBC with known antagonists of ERα, we found that TBC has similar molecular structure as certain co-activator binding inhibitors. Therefore, using molecular docking and molecular dynamics simulations, TBC was further predicted to competitively occupy the surface site of ERα rather than the canonical E2-binding pocket of ERα, thus disrupt subsequent co-activator recruitment and transcription activation. Our findings elucidate the anti-estrogenic mechanism of TBC at the atomic level and highlight the biological importance of surface sites of nuclear receptors for a risk assessment of potential environmental pollutants.

Effects of tris(2,3-dibromopropyl) isocyanurate on steroidogenesis in H295R cells

Tris(2,3-dibromopropyl) isocyanurate (TBC) is widely used in polymer products. It is ubiquitously found in environmental matrices. Previous studies have shown that TBC has potential endocrine-disrupting effects on aquatic organisms. However, the effects on adrenocortical function and the underlying mechanisms are not well characterized. In present study, the H295R cell line was employed to investigate the potential endocrine-disrupting action of TBC. TBC inhibited basal and forskolin-induced sex hormone production but did not exhibit cytotoxicity. The expression of the steroidogenic genes, StAR, 3βHSD2, CYP17, CYP21, CYP19, HMGR, 17βHSD1, 17βHSD4 and CYP11A, was not changed upon TBC exposure. However, the cAMP inducer forskolin strongly induced the expression of all these genes, except for HMGR, 17βHSD1 and 17βHSD4. TBC blocked forskolin-induced StAR, 3βHSD2, CYP17, CYP21 and CYP19 mRNA expression. Our results indicate that TBC can inhibit sex hormone biosynthesis due to the interference with steroidogenic gene transcription in activated condition.

Effective Improving the Detection Limit of Tris(2,3-dibromopropyl) Isocyanurate by Bis-amino inO-phenylenediamine

A facile approach for ultrasensitively sensing tris(2,3-dibromopropyl) isocyanurate (TBC) was reported. Based on coupling molecularly imprinting with electropolymerization of ο -phenylenediamine (OPD), which is electro-active monomers, the poly-OPD film was deposited in an OPD solution by potentiodynamic cycling of potential (scan rate is 50mV/s) on a glassy carbon electrode. Using K 3 [Fe(CN) 6 ] as an electro-active marker, the properties of the TBC imprinting electrode were investigated by differential pulse voltammetry and amperometric i-t curve and exhibited an excellent imprinting effect. The results showed that a linear relationship between the value of peak current and the TBC concentration was found in the range of 1.4×10 −12 ~6.7×10 −12 mol/L and a low detection limit of 6.26×10 −13 mol/L for TBC determination.

A real-time immuno-PCR assay for the flame retardant tris(2,3-dibromopropyl) isocyanurate using a probe DNA conjugated to gold nanoparticles

We report on an improved real-time immuno-PCR assay for the flame retardand tris(2,3-dibromopropyl) isocyanurate (TBC). For establishing this immunoassay, two kinds of TBC antigen (TBC-OVA and TBC-BSA) were prepared by coupling TBC hapten to ovalbumin and to bovine serum, respectively. The anti-TBC polyclonal antibody was obtained via immunization of rabbits. Subsequently, a bio-functionalized probe was synthesized by conjugating thiol-capped DNA and goat anti-rabbit IgG to gold nanoparticles. This immunoassay involves the follow steps: (a) fixing the coating antigen (TBC-OVA) onto the surface of PCR tubes, and blocking the unbound sites; (b) adding anti-TBC antibody and sample solutions, upon which the TBC analyte in sample and TBC-OVA fixed on the tube well competitively combine with anti-TBC antibody; (c) adding bio-functionalized probe to specifically recognize anti-TBC antibody and release template DNA during PCR amplification. The fluorescence signal was detected via SYBR Green at excitation/emission wavelengths of 497/520 nm. Under optimized conditions, TBC could be detected in the 0.1 pg∙L−1 to 0.1 ng∙L−1 concentration range, with a detection limit as low as 0.97 pg∙L−1. To our knowledge, this immunoassay is the most sensitive one at present and – in our perception – has a large potential for trace detection of TBC in environmental samples.

A heterogeneous biotin–streptavidin-amplified enzyme-linked immunosorbent assay for detecting tris(2,3-dibromopropyl) isocyanurate in natural samples

Tris(2,3-dibromopropyl) isocyanurate (TBC) is a novel brominated flame retardant (BFR) that is widely used to substitute the prohibited BFRs throughout the world. With the development of research, the potential environmental and ecological harms of TBC have been revealed. For sensitive and selective detecting TBC, an indirect competitive biotin–streptavidin-amplified enzyme-linked immunosorbent assay (BA–ELISA) has been established in this study. The small molecular TBC–hapten was synthesized first; it mimicked the chemical structure of TBC and possessed a secondary amine group. The as-obtained hapten was then conjugated with carrier proteins to prepare artificial antigen. After immunization, the anti-TBC polyclonal antibody was obtained from separating rabbit serum. The procedures of this BA–ELISA were optimized. Under the optimal conditions, the limit of detection (IC10) was 0.0067ng/ml and the median inhibitory concentration (IC50) was 0.66ng/ml. Cross-reactivity values of the BA–ELISA with the tested TBC analogues were ⩽5%. This immunoassay was successfully applied to determine the TBC residue in river water samples that were collected near a BFR manufacturing plant. Satisfactory recoveries (92.1–109.2%) were obtained. The results indicated that this proposed BA–ELISA is suitable for the rapid and sensitive determining of TBC in environmental monitoring.

Influence of tris(2,3-dibromopropyl) isocyanurate on the expression of photosynthesis genes of Nannochloropsis sp.

The proteins encoded by psaA and psaB form a heterodimer, an essential compound of photosystem; while the protein encoded by psbC binds with chlorophyll a in photosystem II, serving as antennae in photosystem. Here we report that a heterocyclic brominated flame retardant, tris(2,3-dibromopropyl) isocyanurate (TBC), inhibited the expression of psaA and psbC, then leads to the decrease of Nannochloropsis sp.'s growth biomass. TBC exposure inhibited the expression of psaA and psbC at 10, 100ng/mL slightly and 1000ng/mL significantly. In addition, TBC was found to slow down the growth of Nannochloropsis sp. at concentrations ranging from 10 to 1000ng/mL. These results indicated that TBC influenced both photosynthesis and growth performance of Nannochloropsis sp.

Synthesis of haptens and development of an indirect enzyme-linked immunosorbent assay for tris(2,3-dibromopropyl) isocyanurate

A competitive indirect enzyme-linked immunosorbent assay (ciELISA) was developed for detection of tris(2,3-dibromopropyl) isocyanurate (TBC). Polyclonal antibodies against TBC were raised from synthesized haptens and then screened against various coating antigens. After optimization of the immunoassay conditions, the linear range and IC50 value of the assay were 0.30–100 and 5.17μg/L, respectively, with little cross-reactivity (⩽2%). Recovery of various samples (water, serum, soil) was tested and the values ranged from 68% to 110%. This ciELISA was also applied to determine TBC in the riverside soil of the Liuyang River, and the results were compared with the data obtained by UHPLC–MS/MS. The experimental assay results confirmed that this proposed immunoassay is a specific, sensitive, and reliable method for determination and monitoring of TBC.

Surface modification of Cu metal particles by the chemical reaction between the surface oxide layer and a halogen surfactant

Surface oxides on small (2–5μm) copper metal particles can be removed by chemical reaction with tris(2,3-dibromopropyl) isocyanurate (TIC) in diethylene glycol mono-n-hexyl ether (DGHE) solution under mild conditions where metal particles are not damaged. Surface oxides convert to copper bromide species and subsequently dissolve into the solvent. It was found that resultant surface species are resistant to re-oxidation due to remaining surface bromides. This finding opens up a possibility to create microclines based on cheap copper nanoparticles.

Homogeneous electrochemiluminescence immunoassay based on tris(2,3-dibromopropyl) isocyanurate using luminol luminescence and Ti/TiO2 NTs electrode

A novel homogeneous electrogenerated chemiluminescence (ECL) immunoassay for the detection of tris(2,3-dibromopropyl) isocyanurate (TBC) is developed based on a Ti/TiO2 nanotube array electrode using luminol as the luminescence label. The anti-TBC antibody is derived from immunization of rabbits for the first time. The formation of luminol-labeled hapten-antibody immunocomplex results in decrease in ECL intensity of the luminol-labeled hapten due to the steric hindrance and the decrease in diffusion coefficient of the immunocomplex. In the presence of TBC, the specific immunoreaction between TBC and the anti-TBC antibody release the luminol-hapten, leading to the recovery of the ECL signal. The TBC-resulted increase in ECL intensity is linearly dependent on the logarithm of TBC concentration in the range from 0.42 to 170 nM with a detection limit of 0.2 nM and relative standard derivation of <5.5%. The analysis of water samples in the outlet of a TBC manufacturing plant along the Liuyang River reveals that the proposed method can be applied for fast scanning of TBC in environmental samples without complicated pretreatments.

A photoelectrochemical immunosensor for tris(2,3-dibromopropyl) isocyanurate detection with a multiple hybrid CdTe/Au–TiO2 nanotube arrays

In this paper, tris(2,3-dibromopropyl) isocyanurate (TBC) is for the first time as far as we know determined by ultrasensitive photoelectrochemical (PEC) immunoassay using an antibody-modified ternary hybrid CdTe/Au-TiO2 nanotube arrays (NTAs) photoelectrode, developed by the pulse electrodeposition technique. The as-prepared hybrid shows enhanced photon absorption and photocurrent response, which subsequently increased the photoelectrical conversion efficiency in the visible region. TBC-antibody (Ab) was developed in rabbits as a result of immunization with the BSA-TBC conjugate and covalently cross-linked onto the CdTe/Au-TiO2 NTAs. Since the photocurrent is highly dependent on the TiO2 surface properties, the specific interaction between TBC and the antibody results in a sensitive change in the photocurrent, which displayed a linear range of 5.0 × 10(-11) to 5.0 × 10(-5) M and a low detection limit of 5.0 × 10(-11) M for TBC determination. This proposed strategy highlights the application of TiO2 nanotube in visible-light-activated photoelectrochemical biosensing, which could largely reduce the destructive effect of UV light on biomolecules.

Tris(2,3-dibromopropyl) Isocyanurate, Hexabromocyclododecanes, and Polybrominated Diphenyl Ethers in Mollusks from Chinese Bohai Sea

A novel brominated flame retardant (BFR), tris(2,3-dibromopropyl) isocyanurate (TBC), as well as hexabromocyclododecanes (HBCDs) and polybrominated diphenyl ethers (PBDEs), were analyzed in 11 species of mollusks collected from nine coastal cities around the Chinese Bohai Sea in 2009 and 2010. The detection frequencies were 100%, 99%, and 77% for PBDEs, HBCDs, and TBC, respectively. Concentrations of ∑HBCDs ranged from below detection limit (nd) to 28.8 ng g(-1) on a dry weight (dw) basis, followed by ∑(12)PBDE (0.01-20.4 ng g(-1) dw) and TBC (nd-12.1 ng g(-1) dw). Statistically significant linear correlations were found among the three BFRs. Positive correlations were found between BFRs concentrations and lipid content in mollusks. The concentrations tend to decrease with increasing trophic levels of the mollusks, implying trophic dilution rather than biomagnifications of the BFRs in the aquatic food chains of the sampling area. Among the 11 mollusks species, Mytilus edulis showed higher bioaccumulation capability than others and was therefore considered to be an appropriate bioindicator of contamination by the BFRs in the Chinese Bohai Sea, in agreement with its previous selection for the biomonitoring of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). A dramatic decrease in PBDE concentrations in mollusks of the area was found for the time period from 2003 to 2010, with a half-life of only 2.3 ± 1.7 years, reflecting a rapid response of mollusks to the change in pollution of the marine environment.

Impaired Gas Bladder Inflation in Zebrafish Exposed to a Novel Heterocyclic Brominated Flame Retardant Tris(2,3-dibromopropyl) Isocyanurate

The teleost gas bladder is a gas-filled internal organ that processes gas exchange and controls buoyancy. Here we report that an emerging heterocyclic brominated flame retardant, tris(2,3-dibromopropyl) isocyanurate (TBC), causes defects in the inflation of the gas bladder of zebrafish larvae. This could cause impaired motility, which can ultimately lead to their death. Exposure to zebrafish embryos revealed that TBC had the most significant influence on the larvae at 72-96 h postfertilization, which coincided with the time that the gas bladder first inflates. Critical factors involved in early zebrafish gas bladder development remained at normal levels, which indicated that TBC caused defects in the inflation of the gas bladder without disrupting early organogenesis. However, the ultrastructure of the gas bladder was altered in the TBC-treated groups: the electron density of cytoplasmic vesicles was changed and the mitochondria were damaged. We deduce that TBC causes damage to mitochondria that influences the secretion of mucus-like material, resulting in defects in gas bladder inflation. For the first time, we report that the gas bladder could be a primary target organ for TBC, and assessment of the gas bladder should be included in toxicity testing protocols of zebrafish embryos.

Nitrate enhanced electrochemiluminescence determination of tris(2,3-dibromopropyl) isocyanurate with a gold nanoparticles-modified gold electrode

Tris(2,3-dibromopropyl) isocyanurate (TBC) is a heterocyclic hexabrominated flame retardant, which cannot be degraded even over a long time and may be a potential environmental pollutant. In this paper, TBC is for the first time as far as we know determined by silver nitrate-enhanced electrochemiluminescence (ECL) using a gold nanoparticles (AuNPs)-modified gold electrode. In our experiments, TBC was found to have the characteristics of increasing the ECL intensity of Ru(bpy)(3)(2+), and the ECL signal was proportional to the concentration of TBC. Based on this, we have successfully developed a novel, fast and sensitive method for the analysis of TBC. The main influencing factors including the volume ratio of acetonitrile and water, and the concentration of Ru(bpy)(3)(2+) were investigated in detail. Compared with using a bare gold electrode in MeCN without AgNO(3), the limit of detection is remarkably lowered by 20 times and the linear range is expanded by 5 times by using the AuNPs-modified gold electrode and AgNO(3). Under the optimal conditions, a limit of detection of 5.0 × 10(-8) M (S/N = 3) is achieved with a linear range of 1.0 × 10(-7) to 5.0 × 10(-5) M. The mechanism of the ECL enhancement of the system is also investigated.

Simultaneous determination of hexabromocyclododecanes and tris (2,3-dibromopropyl) isocyanurate using LC–APCI-MS/MS

Hexabromocyclododecanes (HBCDs) and tris (2,3-dibromopropyl) isocyanurate (TBC) are both brominated flame retardants, and have been used throughout the world with subsequent concern for potential environment pollution. Here we describe the development of a method for the simultaneous determination of TBC and HBCD diastereoisomers in environmental matrices by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The method recovery ranged from 81% to 93% and limits of detections (LODs) on column were 4.3 pg, 0.5 pg, 0.4 pg, 0.3 pg for TBC, α-HBCD, β-HBCD, and γ-HBCD, respectively, which showed high sensitivity compared to previous published methods. Compared to electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) was found to be a more sensitive, effective ionization mode for determination of HBCDs. This novel method was further validated by analyzing TBC and HBCDs in biotic and abiotic samples. The concentration ranges of TBC, α, β, γ-HBCD in sediment samples were 136.1–5884.6 ng/g, 9.0–1079.6 ng/g, 1.0–1161.7 ng/g, and 65.4–3964.2 ng/g, respectively. The concentration range for TBC, α-HBCD, β-HBCD, and γ-HBCD in common carp samples were 51.1–1899 ng/g, 21.6–1338 ng/g, <LOD–10.9 ng/g, and 1.4–101 ng/g, respectively.