Detecting and Quantifying Polyhaloaromatic Environmental Pollutants by Chemiluminescence-Based Analytical Method

Molecular mechanism for the unusual enhancement of the second-step chemiluminescence production from the carcinogenic tetrabromohydroquinone and H2O2

We have found recently that two-step intrinsic hydroxyl radical (·OH)-dependent chemiluminescence (CL) could be produced by carcinogenic tetrahaloquinone and H2O2. However, the first-step CL was too fast to clearly detect the stepwise generation of ·OH and CL, and to distinguish the exact dividing point between the first-step and second-step CL. Here we found that, extremely clear two-step intrinsic CL could be produced by the relative slow reaction of tetrabromohydroquinone (TBHQ) with H2O2, which was directly dependent on the two-step ·OH generation. Interestingly, the second-step, but not the first-step CL production of TBHQ/H2O2 (CRET donor) was markedly enhanced by fluorescein (a typical xanthene dye, CRET acceptor) through a unique chemiluminescence resonance energy transfer (CRET) process. The novel CRET system of TBHQ/H2O2/fluorescein was successfully applied for the sensitive detection of TBHQ with the detection limit as low as 2.5 µmol/L. These findings will help to develop more sensitive and highly efficient CL or CRET systems and specific CL sensor to detect the carcinogenic haloquinones, which may have broad environmental applications.

Ferroptosis and mitochondrial dysfunction in acute central nervous system injury

Acute central nervous system injuries (ACNSI), encompassing traumatic brain injury (TBI), non-traumatic brain injury like stroke and encephalomeningitis, as well as spinal cord injuries, are linked to significant rates of disability and mortality globally. Nevertheless, effective and feasible treatment plans are still to be formulated. There are primary and secondary injuries occurred after ACNSI. Most ACNSIs exhibit comparable secondary injuries, which offer numerous potential therapeutic targets for enhancing clinical outcomes. Ferroptosis, a newly discovered form of cell death, is characterized as a lipid peroxidation process that is dependent on iron and oxidative conditions, which is also indispensable to mitochondria. Ferroptosis play a vital role in many neuropathological pathways, and ACNSIs may induce mitochondrial dysfunction, thereby indicating the essentiality of the mitochondrial connection to ferroptosis in ACNSIs. Nevertheless, there remains a lack of clarity regarding the involvement of mitochondria in the occurrence of ferroptosis as a secondary injuries of ACNSIs. In recent studies, anti-ferroptosis agents such as the ferroptosis inhibitor Ferrostain-1 and iron chelation therapy have shown potential in ameliorating the deleterious effects of ferroptosis in cases of traumatic ACNSI. The importance of this evidence is extremely significant in relation to the research and control of ACNSIs. Therefore, our review aims to provide researchers focusing on enhancing the therapeutic outcomes of ACNSIs with valuable insights by summarizing the physiopathological mechanisms of ACNSIs and exploring the correlation between ferroptosis, mitochondrial dysfunction, and ACNSIs.

Mechanistic Investigation of H2 O2 -dependent Chemiluminescence from Tetrabromo-1,4-Benzoquinone

As a H₂ O₂ -dependent bioluminescent substrate, tetrabromo-1,4-benzoquinone (TBBQ) was first isolated from acorn worm. The mechanism of chemiluminescence (CL) corresponding to the bioluminescence (BL) of acorn worm is largely unknown, let alone the mechanism of BL. In this article, we firstly studied the chemical and physical processes, and mechanism of H₂ O₂ -dependent CL from TBBQ by theoretical and experimental methods. The research results indicate: the CL process is initiated by a nucleophilic substitution reaction, which leads to the formation of an anionic dioxetane through five consecutive reactions; the anionic dioxetane decomposes to the first singlet excited state (S₁ ) via a conical interaction of the potential energy surfaces (PESs) between the ground (S₀ ) and S₁ state; the anionic S₁ -state changes to its neutral form by a proton transfer from the solvent and this neutral product is assigned as the actual luminophore. Moreover, the experimental detection of CL, ^. OH and the identifications of 2,3-dibromo maleic acid and 2-bromo malonic acid as the major final products provide direct evidence of the theoretically suggested mechanism. Finally, this study proves that the activity of the H₂ O₂ -dependent CL from TBBQ is significantly lower than the one from tetrachloro-1,4-benzoquinone (TCBQ), which is caused by the weaker electron withdrawing effect and the stronger heavy atomic effect of bromine.