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This work demonstrates facile synthesis of Tb-doped ZnO nanoparticles and investigates their structural, optical, electrochemical, photocatalytic, and antibacterial performance. XRD patterns of undoped and doped ZnO nanoparticles confirm a hexagonal wurtzite structure. TEM and SAED reveals that the particle size is 14–38 nm. SEM images show that ZnO and Tb-doped ZnO nanoparticles have smooth surfaces, and elemental composition was confirmed by EDX analysis. UV–Visible spectrophotometry studies, reveals that the band gap narrows with increasing Tb concentration. Photoluminescence spectra at room temperature showed a band at 538 nm, indicating zinc vacancies and green emission. Tb-doped ZnO with x = 0.075 exhibited the highest photocatalytic activity for degrading Rose Bengal dye compared to other photocatalysts. The electrochemical behaviour of Catechol (CC), Hydroquinone (HQ), and Bisphenol-A (BPA) at Tb–ZnO/MCPE was studied. The modified electrode process for CC and BPA was adsorption-controlled, and simultaneous recognition of CC, HQ, and BPA was achieved, showing an increase in current. Electro polymerization of poly (Congo red) on Tb–ZnO/MCPE confirmed clean deposition on the surface, enhancing electrocatalytic activity. The antibacterial efficacy was tested using the traditional disc diffusion method, showing effective inactivation of bacterial strains, including pathogens such as S. aureus (G+) and E. coli (G-). [Display omitted] • This work demonstrates the facile synthesis of ZnO and Tb doped nanoparticles via chemical co-precipitation process. • The XRD pattern appearance hexagonal wurtzite structure. TEM and SAED reveal particle sizes of 14–38 nm. SEM and EDX confirm morphology and elemental composition. • Higher Tb doping exhibit the highest photocatalytic activity in degrading Rose Bengal dye. And the antibacterial activity, tested via disc diffusion, effectively inactivates S. aureus (G+) and E. coli (G−) bacterium. • The sweep rate confirms that the modified electrode process of CC and BPA at the PCRTZO/MCPE was adsorption controlled. Tb–ZnO/MCPE electrode simultaneously detects CC, HQ and BPA with distinct current increases. • Electro polymerization of poly (Congo red) on Tb–ZnO/MCPE confirms Congo red deposition on the electrode surface. [ABSTRACT FROM AUTHOR]

Hydroquinone (HQ), one of the phenolic metabolites of benzene, is widely recognized as an important participant in benzene-induced hematotoxicity. However, there are few relevant proteomics in HQ-induced hematotoxicity and the mechanism hasn't been fully understood yet. In this study, we treated K562 cells with 40 μmol/L HQ for 72 h, examined and validated protein expression changes by Label-free proteomic analysis and Parallel reaction monitoring (PRM), and performed bioinformatics analysis to identify interaction networks. One hundred and eighty-seven upregulated differentially expressed proteins (DEPs) and 279 downregulated DEPs were identified in HQ-exposed K562 cells, which were involved in neutrophil-mediated immunity, blood microparticle, and other GO terms, as well as the lysosome, metabolic, cell cycle, and cellular senescence-related pathways. Focusing on the 23 DEGs and 5 DEPs in erythroid differentiation-related pathways, we constructed the network of protein interactions and determined 6 DEPs (STAT1, STAT3, CASP3, KIT, STAT5B, and VEGFA) as main hub proteins with the most interactions, among which STATs made a central impact and may be potential biomarkers of HQ-induced hematotoxicity. Our work reinforced the use of proteomics and bioinformatic approaches to advance knowledge on molecular mechanisms of HQ-induced hematotoxicity at the protein level and provide a valuable basis for further clarification. [ABSTRACT FROM AUTHOR]

Melasma is a chronic hypermelanosis of the skin that affects approximately 1% of the global population, predominantly affects women, and is more prevalent in skin of color. Melasma is a common driver for patients with skin of color to seek out a dermatologist for treatment, and ensuring the right approach for these patients is important because some treatments may be associated with adverse side effects. Because of the chronicity of the disease and established psychosocial and emotional impacts, there is a large need to ensure care follows the best available evidence on the treatment of patients with melasma. Here, we summarized current available topical treatments for melasma with considerations dermatologists should have for their patients with skin of color. Steering committee consensus on clinical best practices. We describe a flexible and focused treatment algorithm that reflects both treatment and maintenance periods that is a consensus of our extensive clinical experience. Use of real-world evidence and potential for individual practice bias. Melasma can be challenging to treat, particularly in patients with skin of color, and our recommendations for best practices for patients in the United States are an important step toward standardizing care. [ABSTRACT FROM AUTHOR]

Platelet activation plays an essential role in the pathogenesis of thrombotic events in different diseases (e.g., cancer, type 2 diabetes, Alzheimer's, and cardiovascular diseases, and even in patients diagnosed with coronavirus disease 2019). Therefore, antiplatelet therapy is essential to reduce thrombus formation. However, the utility of current antiplatelet drugs is limited. Therefore, identifying novel antiplatelet compounds is very important in developing new drugs. In this context, the involvement of mitochondrial function as an efficient energy source required for platelet activation is currently accepted; however, its contribution as an antiplatelet target still has little been exploited. Regarding this, the intramolecular hydrogen bonding of hydroquinone derivatives has been described as a structural motif that allows the reach of small molecules at mitochondria, which can exert antiplatelet activity, among others. In this review, we describe the role of mitochondrial function in platelet activation and how hydroquinone derivatives exert antiplatelet activity through mitochondrial regulation. • Platelet activation plays an essential role in the pathogenesis of thrombotic events. • Identifying novel antiplatelet compounds is very important in developing new drugs. • Mitochondrial function is an efficient energy source required for platelet activation. • Hydroquinone derivatives exert antiplatelet activity through mitochondrial regulation. [ABSTRACT FROM AUTHOR]

Cytochrome bc1 catalyzes electron transfer from quinol (QH2) to cytochrome c in reactions coupled to proton translocation across the energy-conserving membrane. Energetic efficiency of the catalytic cycle is secured by a two-electron and two-proton bifurcation reaction leading to oxidation of QH2 and reduction of the Rieske cluster and heme bL. The proton paths associated with this reaction remain elusive. Here, we used site-directed mutagenesis and quantum mechanical calculations to analyze the contribution of protonable side chains located at the heme bL side of the QH2 oxidation site in Rhodobacter capsulatus cytochrome bc1. We observe that the proton path is effectively switched off when H276 and E295 are simultaneously mutated to the nonprotonable residues in the H276F/E295V double mutant. The two single mutants, H276F or E295V, are less efficient but still transfer protons at functionally relevant rates. Natural selection exposed two single mutations, N279S and M154T, that restored the functional proton transfers in H276F/E295V. Quantum mechanical calculations indicated that H276F/E295V traps the side chain of Y147 in a position distant from QH2, whereas either N279S or M154T induce local changes releasing Y147 from that position. This shortens the distance between the protonable groups of Y147 and D278 and/or increases mobility of the Y147 side chain, which makes Y147 efficient in transferring protons from QH2 toward D278 in H276F/E295V. Overall, our study identified an extended hydrogen bonding network, build up by E295, H276, D278, and Y147, involved in efficient proton removal from QH2 at the heme bL side of QH2 oxidation site. [ABSTRACT FROM AUTHOR]

NADH-ubiquinone (UQ) oxidoreductase (complex I) couples electron transfer from NADH to UQ with proton translocation in its membrane part. The UQ reduction step is key to triggering proton translocation. Structural studies have identified a long, narrow, tunnel-like cavity within complex I, through which UQ may access a deep reaction site. To elucidate the physiological relevance of this UQ-accessing tunnel, we previously investigated whether a series of oversized UQs (OS-UQs), whose tail moiety is too large to enter and transit the narrow tunnel, can be catalytically reduced by complex I using the native enzyme in bovine heart submitochondrial particles (SMPs) and the isolated enzyme reconstituted into liposomes. Nevertheless, the physiological relevance remained unclear because some amphiphilic OS-UQs were reduced in SMPs but not in proteoliposomes, and investigation of extremely hydrophobic OS-UQs was not possible in SMPs. To uniformly assess the electron transfer activities of all OS-UQs with the native complex I, here we present a new assay system using SMPs, which were fused with liposomes incorporating OS-UQ and supplemented with a parasitic quinol oxidase to recycle reduced OS-UQ. In this system, all OS-UQs tested were reduced by the native enzyme, and the reduction was coupled with proton translocation. This finding does not support the canonical tunnel model. We propose that the UQ reaction cavity is flexibly open in the native enzyme to allow OS-UQs to access the reaction site, but their access is obstructed in the isolated enzyme as the cavity is altered by detergentsolubilizing from the mitochondrial membrane. [ABSTRACT FROM AUTHOR]

Among the various components of the protozoan Plasmodium mitochondrial respiratory chain, only Complex III is a validated cellular target for antimalarial drugs. The compound CK-2-68 was developed to specifically target the alternate NADH dehydrogenase of the malaria parasite respiratory chain, but the true target for its antimalarial activity has been controversial. Here, we report the cryo-EM structure of mammalian mitochondrial Complex III bound with CK-2-68 and examine the structure-function relationships of the inhibitor's selective action on Plasmodium. We show that CK-2-68 binds specifically to the quinol oxidation site of Complex III, arresting the motion of the iron-sulfur protein subunit, which suggests an inhibition mechanism similar to that of Pf-type Complex III inhibitors such as atovaquone, stigmatellin, and UHDBT. Our results shed light on the mechanisms of observed resistance conferred by mutations, elucidate the molecular basis of the wide therapeutic window of CK-2-68 for selective action of Plasmodium vs. host cytochrome bc1, and provide guidance for future development of antimalarials targeting Complex III. [ABSTRACT FROM AUTHOR]

We have investigated the equilibrium properties and rapidreaction kinetics of the isolated butyryl-CoA dehydrogenase (bcd) component of the electron-bifurcating crotonyl-CoAdependent NADH:ferredoxin oxidoreductase (EtfAB-bcd) from Megasphaera elsdenii. We find that a neutral FADH- semiquinone accumulates transiently during both reduction with sodium dithionite and with NADH in the presence of catalytic concentrations of EtfAB. In both cases full reduction of bcd to the hydroquinone is eventually observed, but the accumulation of FADH- indicates that a substantial portion of reduction occurs in sequential one-electron processes rather than a single two-electron event. In rapid-reaction experiments following the reaction of reduced bcd with crotonyl-CoA and oxidized bcd with butyryl-CoA, long-wavelength-absorbing intermediates are observed that are assigned to bcdred:crotonyl-CoA and bcdox:butyryl-CoA charge-transfer complexes, demonstrating their kinetic competence in the course of the reaction. In the presence of crotonyl-CoA there is an accumulation of semiquinone that is unequivocally the anionic FAD--rather than the neutral FADH- seen in the absence of substrate, indicating that binding of substrate/product results in ionization of the bcd semiquinone. In addition to fully characterizing the rapid-reaction kinetics of both the oxidative and reductive half-reactions, our results demonstrate that oneelectron processes play an important role in the reduction of bcd in EtfAB-bcd. [ABSTRACT FROM AUTHOR]

Diatomite-modified wood ceramics (DMWCs) were successfully prepared to remove hydroquinone from wastewater. The adsorption kinetics and adsorption thermodynamics of DMWCs on hydroquinone were comprehensively studied. The results indicate that the prepared DMWCs with the porous structure are composed of quartz and crystalline graphite. When the hydroquinone dosage is 200 mg and the pH is 7, the removal rate and adsorption capacity of DMWCs reach 76.8% and 12.31 mg/g, respectively. Among the fitting parameters under different pH conditions, the correlation coefficient (R 2 = 0.99) of the pseudo-second-order kinetic model is larger than the fitting results of other models, displaying a better fitting effect on the adsorption process of hydroquinone. At different temperatures, the Freundlich equation, Redlich-Peterson equation and Koble-Corrigan equation are all well fitted to the adsorption isotherm data with the correlation coefficients R 2 higher than 0.93. The regeneration test shows that the elimination rate of hydroquinone remains above 73% after reuse for 11 times. This study provides a newly available adsorbent of DMWCs to remove hydroquinone from wastewater effectively. [ABSTRACT FROM AUTHOR]

Benzene is a known hematotoxic and leukemogenic chemical. Exposure to benzene cause inhibition of hematopoietic cells. However, the mechanism of how the hematopoietic cells inhibited by benzene undergo malignant proliferation is unknown. The cells carrying leukemia-associated fusion genes are present in healthy individuals and predispose the carriers to the development of leukemia. To identify the effects of benzene on hematopoietic cells, preleukemic bone marrow (PBM) cells derived from transgenic mice carrying the Mll – Af9 fusion gene were treated with benzene metabolite hydroquinone in serial replating of colony-forming unit (CFU) assay. RNA sequencing was further employed to identify the potential key genes that contributed to benzene-initiated self-renewal and proliferation. We found that hydroquinone induced a significant increase in colony formation in PBM cells. Peroxisome proliferator-activated receptor gamma (Ppar-γ) pathway, which plays a critical role in carcinogenesis in multiple tumors, was significantly activated after hydroquinone treatment. Notably, the increased numbers of the CFUs and total PBM cells induced by hydroquinone were significantly reduced by a specific Ppar-γ inhibitor (GW9662). These findings indicated that hydroquinone can enhance self-renewal and proliferation of preleukemic cells by activating the Ppar-γ pathway. Our results provide insight into the missing link between premalignant status and development of benzene-induced leukemia, which can be intervened and prevented. • Benzene metabolite hydroquinone (HQ) affected preleukemic bone marrow (PBM) cells. • HQ enhanced proliferation and self-renewal in PBM cells with the Mll – Af9 fusion gene. • The Ppar-γ pathway was induced in PBM cells treated with HQ. • A specific inhibitor of Ppar-γ inhibited colony formation induced by HQ. • Results suggest a novel role for HQ and the Ppar-γ pathway in leukemia induction. [ABSTRACT FROM AUTHOR]

Recovery of heavy metals, heavy rare earth elements, and phenolic compounds from industrial water has attracted attention due to their ecological toxicity and their larger demand for advanced technologies. We herein synthesize a novel EDTA-cross-linked MXene polymer composite for the removal of lead (II), holmium (III), and hydroquinone. The structure, morphology, and sorption performance of the EDTA-cross-linked MXene polymer composite were explored comprehensively. The correlation coefficients (R2) of the PSO kinetic model for lead (II), Ho (III), and hydroquinone were 0.9999 and greater than those of the PFO kinetic model when comparing the R2 derived by fitting the two kinetic models. EDTA-cross-linked MXene polymer composite rapidly removed the heavy metals, heavy rare earth metals, and phenolic compounds, such as lead (II), holmium (III), and hydroquinone within 5, 8, and 10 min, respectively. The sorption isotherm of lead (II), holmium (III), and hydroquinone might be explained well by the Langmuir model, and the maximum sorption capabilities (qmax) were derived as 893.92 mg/g for lead (II), 809.37 mg/g for Ho, and 754.09 mg/g for HQ, respectively. The adsorbed composite could easily be regenerated and can be utilized 19 times without a significant impact on its sorption performance. The synthesized adsorbent also exhibits remarkable sorption performance for other heavy metals (Cd, Cr, Ca, Mg, Ba, and Ni), rare earth metals (Eu, Yb, Er, Lu, Tm, and Y), and phenolic compounds (catechol and resorcinol). This research work provides a new EDTA-cross-linked MXene polymer composite for the excellent elimination of lead, holmium (III), and hydroquinone. [Display omitted] • Composite was prepared for adsorption of the Pb, Ho, and HQ. • The prepared composite was characterized by SEM, XRD, EDX, XPS, and TEM. • After five reusability experiments, the sorption capacities were still high. [ABSTRACT FROM AUTHOR]

Bifurcating electron transferring flavoproteins (Bf-ETFs) tune chemically identical flavins to two contrasting roles. To understand how, we used hybrid quantum mechanical molecular mechanical calculations to characterize noncovalent interactions applied to each flavin by the protein. Our computations replicated the differences between the reactivities of the flavins: the electron transferring flavin (ETflavin) was calculated to stabilize anionic semiquinone (ASQ) as needed to execute its single-electron transfers, whereas the Bf flavin (Bfflavin) was found to disfavor the ASQ state more than does free flavin and to be less susceptible to reduction. The stability of ETflavin ASQ was attributed in part to H-bond donation to the flavin O2 from a nearby His side chain, via comparison of models employing different tautomers of His. This H-bond between O2 and the ET site was uniquely strong in the ASQ state, whereas reduction of ETflavin to the anionic hydroquinone (AHQ) was associated with side chain reorientation, backbone displacement, and reorganization of its H-bond network including a Tyr from the other domain and subunit of the ETF. The Bf site was less responsive overall, but formation of the Bfflavin AHQ allowed a nearby Arg side chain to adopt an alternative rotamer that can H-bond to the Bfflavin O4. This would stabilize the anionic Bfflavin and rationalize effects of mutation at this position. Thus, our computations provide insights on states and conformations that have not been possible to characterize experimentally, offering explanations for observed residue conservation and raising possibilities that can now be tested. [ABSTRACT FROM AUTHOR]

[Display omitted] A series of new bis(pyrimidines) with p- hydroquinone linker was prepared and evaluated as AMPA receptor modulators. Both positive and negative modulators were found among the investigated compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] Melasma is a common hyperpigmented skin condition that occurs on the face and other areas prone to light exposure, seriously affecting people's quality of life. Microneedle, a new type of transdermal drug delivery device, can significantly improve skin permeability. In this study, we designed and fabricated a polymer microneedle roller (PMR) using a mold hot pressing method, and established a mouse model of melasma induced by ultraviolet radiation. The dynamometer and insertion test of MNs into parafilm and skin of mice indicates that the MNs have sufficient mechanical properties to insert parafilm and skin of mice. The two methods (apply hydroquinone cream (HQC) directly and pre-treat with PMR before applying HQC) were used to treat melasma. From the results of skin surface observation, determination of superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in skin and liver tissues, histological observation, and skin Optical coherence tomography (OCT), we confirmed both the two methods had a therapeutic effect while the PMR pretreatment group exhibited a better therapeutic effect. In addition, there were statistical differences between the UV group (P < 0.05). Together these results indicated that the MNs may be promising in future clinical applications in improving the UV irradiation-induced pigmentation like melisma. [ABSTRACT FROM AUTHOR]

Benzene is a frequent component of environmental pollution and is abundant in petrochemicals, decorative materials, motor vehicle exhaust and cigarette smoke. Benzene is a well-known carcinogen in humans and animals, but the molecular mechanism has not yet been elucidated. Our earlier research indicated that hydroquinone (HQ), one of the main reactive metabolites of benzene, could activate aryl hydrocarbon receptor (AhR), which is essential for HQ-induced toxicity, including apoptosis and DNA damage. Since AhR is an important regulator of the immune system that integrates the environmental stimulus and immune response, we examined whether and how HQ-induced AhR activity could lead to NLRP3 inflammasome-dependent pyroptosis in JHP cells. Our results showed that HQ could cause inflammation process and resultant pyroptosis. In JHP cells, HQ also induced endoplasmic reticulum stress (ERS) by releasing excessive reactive oxygen species (ROS). The activation of pyroptosis induced by HQ treatment was reversed by an antioxidant (NAC) and an ERS inhibitor (4-PBA). Interestingly, the treatment of CH223191, an AhR inhibitor, reversed HQ-induced oxidative stress, ERS and pyroptosis. These data suggested that AhR-mediated HQ-induced ERS, ROS and inflammasome activation may play vital roles in the toxic effects of benzene. This work provides insights and prospective strategies into potential mechanisms for reducing benzene-induced hematotoxicity. [Display omitted] • Hydroquinone (HQ) induced inflammation process and resultant pyroptosis. • HQ induced endoplasmic reticulum stress (ERS) through excessive reactive oxygen species (ROS) release. • ROS scavenger (NAC) and the ERS inhibitor (4-PBA) reversed HQ induced pyroptosis. • AhR inhibition blocked HQ-induced oxidative stress, ERS and pyroptosis. [ABSTRACT FROM AUTHOR]

Owing to their potentially elevated catalytic activity, diverse morphology and abundant active sites, cobalt phosphides (Co 2 P, CoP etc.) have garnered important interest in modified materials for electrochemical sensors. Nevertheless, their low intrinsic conductivity still restrained and limited their electrochemical application. Herein, a solid-state gas-steamed metal-organic-framework strategy was designed to construct carbon-encapsulated cobalt phosphide nanoparticles and N doped carbon substrates (denoted as CoP/Co 2 P@NC) composites using ZIF-67 as the MOFs precursor. The resultant catalyst exhibited excellent the electrocatalytic activity for the detection of catechol (CC) and hydroquinone (HQ) due to the composites with the large surface area, high stability and enhanced conductivity. The CoP/Co 2 P@NC-modified electrode facilitated a quasi-reversible redox reaction for CC and HQ, characterized by a significant oxidation current response. Under the optimum electrochemical conditions, the CoP/Co 2 P@NC was stable, reproducible and demonstrated wide ranges (0.05–80 μM and 0.05–80 μM) and low detection limits (20 nM and 30 nM) for HQ and CC. Furthermore, the CoP/Co 2 P@NC modified electrode was successfully developed a cost-effective electrochemical environmental monitoring sensor. [Display omitted] • The CoP/Co 2 P@NC composites were fabricated by a green gas-steamed MOF approach. • The CoP/Co 2 P@NC composites sensor was firstly developed. • The outstanding performances of composites sensor was shown. [ABSTRACT FROM AUTHOR]

Hydroquinone (HQ), a phenolic compound, poses substantial risks to human health due to its low degradability and high toxicity. Consequently, developing sensitive, accurate, and portable approaches for monitoring HQ is of significant importance. Herein, M-substituted (M=Cu, Mn, Ni, and La) Co 3 O 4 nanocube (Co 3 O 4 NC) was developed for improving the peroxidase-like activity of Co 3 O 4 NC. Among these, Cu-substituted Co 3 O 4 NC (Cu 0.4 Co 2.6 O 4 NC) exhibited optimal peroxidase-like performance. Investigation into the catalytic mechanism revealed that the generation of hydroxyl radical and the increase of superoxide anion significantly enhanced the catalytic activity of Cu 0.4 Co 2.6 O 4 NC. Cu 0.4 Co 2.6 O 4 NC could catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) with H 2 O 2 to form a blue-color product. In the existence of HQ, the chromogenic reaction of TMB was inhibited due to the competition between HQ and TMB for the reactive oxygen species in the catalytic system. Additionally, a smartphone-mediated portable hydrogel sensor was integrated with color change to facilitate on-site detection. Furthermore, Cu 0.4 Co 2.6 O 4 NC served as an electrocatalyst for electrochemical analysis of HQ. Considering these findings, we proposed a colorimetrical, hydrogel, and electrochemical multi-mode sensor for detecting HQ, showing wide linear ranges and low detection limits. The multi-mode sensor features self-verification for more reliable results and is suitable for various analysis conditions. It successfully determined HQ in real water samples, accompanied by consistent results with HPLC. This work not only provides an efficient pathway for developing nanozymes with superior catalytic properties but also demonstrates application potential in environmental protection. • Cu 0.4 Co 2.6 O 4 NC exhibited superior peroxidase-like activity than that of Co 3 O 4 NC. • Cu 0.4 Co 2.6 O 4 NC could be used as a bifunctional nanomaterial. • A multi-mode sensor based on Cu 0.4 Co 2.6 O 4 NC was proposed for detecting HQ. • A smartphone-based hydrogel sensor facilitated on-site detection. • The proposed strategy can be successfully applied in actual samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful fabrication of thymol blue film modified electrode for electrochemical sensor application. • Simultaneous and interference free detection of catechol (CC) and hydroquinone (HQ) in a binary mixture. • The density functional theory was used to investigate the interaction of analytes with the modified electrode surface. • The reason behind the deviation of the redox behavior of CC and HQ from an ideal reversible process was simulated. • The electrochemical and theoretical evidences were analyzed to understand the sensing mechanism. Herein, simultaneous detection of catechol (CC) and hydroquinone (HQ) at a poly(thymol blue) (PTB) modified carbon paste electrode (CPE) was investigated. Electrochemical characterization of the bare CPE (BCPE) and the PTB modified CPE (PTB/CPE) in 1 mM K 4 Fe(CN) 6 redox probe showed that PTB/CPE possessed a higher electrocatalytic activity toward the redox reaction of the redox probe as well as a better electronic conductivity than the BCPE. The density functional theory (DFT) calculations were efficiently utilized to investigate the interaction of thymol blue with the BCPE. The limit of detection (LOD) of CC and HQ at PTB/CPE were obtained as 4.90 μM and 5.60 μM over the corresponding linear range of 20–80 μM and 10–80 μM, respectively. Electroanalysis of water samples spiked with CC and HQ at PTB/CPE gave percentage recoveries of 97.60–99.46 % and 98.13–98.20 %, respectively. PTB/CPE retained about 90 % and 92 % of its initial anodic peak current (I pa) after 22 days of the corresponding CC and HQ electroanalysis at 7 days interval. [ABSTRACT FROM AUTHOR]

[Display omitted] • A sensitive electrochemical biosensor for cTnI analysis was developed. • The simple synthesized Pd@PdPtCo MNPs were utilized as signal amplifiers. • Compared with previous methods, this biosensor exhibited a wider linear range. • The prepared biosensor performed well in complex serum environment. Cardiac troponin I (cTnI) has been widely used in clinical diagnosis of acute myocardial infarction (AMI). Herein, a sensitive electrochemical biosensor for cTnI analysis was designed, in which the simple synthesized Pd@PdPtCo mesoporous nanopolyhedras (MNPs) were utilized as signal amplifiers. The mesoporous polyhedral structure of Pd@PdPtCo MNPs endows them with more specific surface area and more active sites, as well as the synergistic effect between multiple metal elements, all of which increase the electrocatalytic performance of Pd@PdPtCo MNPs in efficiently oxidizing hydroquinone (HQ) to benzoquinone (BQ). Experimental results showed that Pd@PdPtCo MNPs had better performance in oxidation of HQ to BQ compared with their corresponding monometallic and bimetallic nanomaterials. With the aid of the interaction between antigens and antibodies, the peak current of HQ to BQ showed an upward trend with increasing concentration of cTnI, thus the quantitative detection of cTnI could be achieved. Under optimal conditions, the biosensor prepared in this work has a wider linear range (1.0 × 10−4–200 ng mL−1) and a lower detection limit (0.031 pg mL−1) than other sensors reported in literatures, coupled by good stability and high sensitivity. More importantly, it also performed well in complex serum environment, proving that the electrochemical sensor has a practical application potential in this field. [ABSTRACT FROM AUTHOR]

[Display omitted] • COP (SNW1)-derived carbon showed best performance in adsorption of hydroquinone. • However, the carbon showed poor performance in adsorption of resorcinol and catechol. • Relative adsorption (hydroquinone≫catechol > resorcinol) was explained. • The adsorption mechanism was explained through H-bond and π-π interactions. Urbanization and modernization through intense industrial activity led to the disposal of harmful and non-biodegradable organic substances including dihydroxybenzene isomers such as hydroquinone, catechol, and resorcinol. A covalent-organic polymer Schiff-based network-1, SNW1 was synthesized, pyrolyzed, and subsequently carbonized again, after mixing with KOH, at 800 °C. The obtained carbon, prepared in two-step-carbonization (named as SNW1-2DC), was applied to the adsorption of dihydroxybenzene isomers; showed remarkable performance in hydroquinone adsorption with the maximum adsorption capacity (Q 0) of 1060 mg/g at neutral conditions. This Q 0 is 6.0 and 5.5 times that of activated carbon and the carbon obtained from the simple pyrolysis of SNW1, respectively; of note, this value represents the highest compared to any previously reported findings. Moreover, the regenerated adsorbent, with simple ethanol washing, performed well for up to 5 cycles. This material could be suggested as a promising adsorbent in hydroquinone removal from water. The adsorption mechanism, including hydrogen bonding, could be suggested. Interestingly, the performance of SNW1-2DC in the adsorptive removal of catechol and resorcinol was very low in comparison with that of hydroquinone. The relative adsorption performances of SNW1-2DC for dihydroxybenzene isomers could be explained with density functional theory calculation and thermodynamic parameters. The most favorable hydroquinone adsorption (among the three dihydroxybenzene isomers) over SNW1-2DC might be because of less endothermic adsorption and more effective H-boning interaction between hydroquinone and SNW1-2DC than that between catechol or resorcinol and the adsorbent. [ABSTRACT FROM AUTHOR]

With more and more attention to health, developing a simple and effective method for detecting phenolic compounds is an urgent and challenging task. In this context, Mn-doped CoP (referred to as Mn-CoP) with a nanocage interior architecture has been successfully constructed. The formation of a hollow structure exposes more active sites, while the incorporation of Mn ion reduces the charge transfer resistance and accelerates the charge transfer. Consequently, Mn-CoP effectively provides electrons to activate H 2 O 2 and O 2 producing OH• and O 2 • , demonstrating excellent peroxidase-like and oxidase-like activities. Given its strong oxidase-like activity, Mn-CoP enables a straightforward colorimetric assay for detecting hydroquinone using 3,3′,5,5′-tetramethyl benzidine (TMB) as colorimetric substrate. Interestingly, the developed colorimetric detection method exhibits a broad linear range and a low limit of detection (LOD) for hydroquinone, showing good potential for application even in real samples. Detailed analyses reveal that the doped Mn ions serve as Lewis acid sites directly reacting with the amino functional group in TMB. The Lewis acid-base reaction between Mn-CoP and TMB is crucial for the chromogenic reaction of TMB. Moreover, doping Mn ion to enhance the oxidase-like activity of the nanozyme is a simple and feasible modification strategy with universal applicability. This work provides a valuable reference for designing nanozymes with oxidase-like activity. [Display omitted] • Introduction of Lewis acid site can improve oxidase-like activity of nanozyme. • Lewis acid-base reaction plays an important role in colorimetric sensing system. • The reaction mechanism of colorimetric sensing system is well clarified. • A colorimetric assay for detecting hydroquinone with a low LOD is established. • A universal strategy for boosting the oxidase-like activity of nanozyme is proposed. [ABSTRACT FROM AUTHOR]

• UV222 outperformed UV254 in photolyzing chlorophenols. • UV222 improved the dechlorination of chlorophenols to 95 % compared to 60 % by UV254. • Radical promotion may not compensate for UV-absorption inhibition by sensitizers. • Introducing •OH -sensitizer decreased toxic intermediates and detoxified the system. The KrCl-excimer lamp, emitting far-UVC light at 222 nm (UV222), offers a promising alternative to conventional UVC light at 254 nm (UV254) for the photolysis of organic pollutants and the activation of radical sensitizers. This study was aimed to investigate the efficiencies of UV222 in the treatment of halogenated aromatics, focusing on its performance in degradation, dechlorination and detoxification. Chlorophenols, representative recalcitrant and toxic halogenated aromatics, were used as target pollutants. The pathways of direct photolysis, photooxidation and photoreduction under UV222 illumination were compared. UV222 outperformed UV254 in photolyzing chlorophenols (1.4−34.1 times faster), especially protonated chlorophenols, due to substantially higher UV absorption (17.1−108.0 times) and quantum yields (2.1−3.4 times). The quantum yields of chlorophenols were influenced by the inducive electron-withdrawing effect of Cl-substitutes. Moreover, UV222 improved the dechlorination of chlorophenols to 95 % compared to 60 % by UV254. The introduction of radical sensitizer (e.g., H 2 O 2 , nitrate, and sulfite) reduced 4-chlorophenol photolysis by competing for UV222 absorption, though the sensitizers partially increased radical oxidation via generating •OH or e aq −. UV222 photolysis of 4-chlorophenol increased the toxicity by 88.6 times through forming toxic intermediates (e.g., hydroquinone and resorcinol). Notably, •OH and e aq − (i.e., UV222/H 2 O 2 and UV222/sulfite) increased the dechlorination and •OH (i.e., UV222/H 2 O 2) detoxified the mixture solution. Moreover, UV222 photolysis remained effective for 4-chlorophenol removal in real paper-mill wastewater, indicating the potential application of KrCl* lamp UV222. [Display omitted] [ABSTRACT FROM AUTHOR]

The aerobic electron transfer chain builds a proton gradient by proton coupled electron transfer reactions through a series of proteins. Complex I is the first enzyme in the sequence. Here transfer of two electrons from NADH to quinone yields four protons pumped from the membrane N- (negative, higher pH) side to the P- (positive, lower pH) side. Protons move through three linear antiporter paths, with a few amino acids and waters providing the route; and through the E -channel, a complex of competing paths, with clusters of interconnected protonatable residues. Proton loading sites (PLS) transiently bind protons as they are transported from N- to P-compartments. PLS can be individual residues or extended clusters of residues. The program MCCE uses Monte Carlos sampling to analyze the E -channel proton binding in equilibrium with individual Molecular Dynamics snapshots from trajectories of Thermus thermuphillus Complex I in the apo, quinone and quinol bound states. At pH 7, the five E -channel subunits (Nqo4, Nqo7, Nqo8, Nqo10, and Nqo11) take >25,000 protonation microstates, each with different residues protonated. The microstate explosion is tamed by analyzing interconnected clusters of residues along the proton transfer paths. A proton is bound and released from a cluster of five coupled residues on the protein N-side and to six coupled residues in the protein center. Loaded microstates bind protons to sites closer to the P-side in the forward pumping direction. MCCE microstate analysis identifies strongly coupled proton binding amongst individual residues in the two PLS clusters. • MCCE calculates protonation states in Complex I using MD trajectory snapshots. • Two proton loading sites (PLS) were identified in Complex I E -channel. • A proton binds to five residues N-side and six in center, forming two PLS. • MCCE microstates show proton binding in PLS clusters with strong residue coupling. • Center PLS loads protons with quinone; N-side loads more in apo or MQH 2. [ABSTRACT FROM AUTHOR]

This study introduces an innovative approach for quantifying isomeric pollutants utilizing an amperometric sensor. The determination of the isomers hydroquinone and catechol is based on the use of a glassy carbon electrode modified with Cu@PtPd/C nanoparticles (Cu@PtPd/C/GCE) in core-shell form, showing significant electrocatalytic activity in the oxidation of the later compounds. The determination was carried out at two different potentials: one at which where only hydroquinone is oxidized, and another in which where both hydroquinone and catechol are oxidized. Using these potentials, two calibration curves were built, one for the quantification of hydroquinone and the other for both isomers. Subsequently, the quantification of catechol was performed using a strategy based on the calculation of a difference using the information collected in the first step. The experiments using hydrogen peroxide as a redox probe demonstrate a clear synergistic effect in the catalytic reduction of hydrogen peroxide at −0.100 V, when Pt, Pd and Cu are incorporated into the core-shell nanostructure. The best performance was achieved with Cu@PtPd/C/GCE 1.00 mg mL−1. For the selected sensor, the analytical parameters are very competitive compared to similar devices reported in recent years for hydroquinone and catechol, with comparable linearity ranges of 0.010–0.200 mmol L−1 (hydroquinone) and 0.005–0.500 mmol L−1 (catechol), low limits of detection (LODs) of 14.0 nmol L−1 (S/N = 3.3) and 1.75 nmol L−1 (S/N = 3.3) for hydroquinone and catechol. The resulting sensor platform has been successfully applied for the quantification of hydroquinone and catechol in river and tap water and could be a promising candidate for environmental monitoring and drinking water safety. [Display omitted] • A novel strategy for the quantification of isomeric pollutants by electrochemical detection. • Amperometric sensor for the simultaneous determination of hydroquinone (HQ) and catechol (CC). • The Cu@PtPd/C in core-shell form are used as amplifiers for the electrochemical detection of HQ and CC. • Analysis of real samples for environmental monitoring was successfully performed. [ABSTRACT FROM AUTHOR]

Inspired by the iron porphyrin structure of natural horseradish peroxidase (HRP), an efficient carbon-based nanozyme was fabricated using nitrogen-doped graphene quantum dots (NGQDs) and iron ion (Fe3+) nanocomposite, enabling selective distinguishment of hydroquinone (HQ) from its isomers. NGQDs with good dispersibility and uniform size were synthesized via a one-step hydrothermal process. NGQDs lacked peroxidase-like activity but the formed nanocomposite (Fe3+-NGQDs) upon Fe3+ addition possessed high peroxidase-like activity. Fe3+-NGQDs nanocomposite exhibited shuttle-shaped structure (∼30 nm), the lattice structure of NGQDs and electron transfer between Fe3+ and NGQDs. The Fe3+-NGQDs nanocomposite can catalyze the production of superoxide radicals (•O 2 −) from H 2 O 2. The Michaelis constant (K m) of Fe3+-NGQDs (0.115 mM) was lower than that of natural HRP (0.434 mM) with 3,3′,5,5′-tetramethylbenzidine (TMB) as the substrate and the maximum initial reaction rate (V max , 16.47 × 10−8 M/s) was nearly 4 times higher than that of HRP using H 2 O 2 substrate. HQ, unlike its isomers catechol (CC) and resorcinol (RE), could consume •O 2 − generated from the decomposition of H 2 O 2 catalyzed by Fe3+-NGQDs nanocomposite, reducing the oxidation of TMB. This principle enabled selective colorimetric determination of HQ ranged from 1 μM to 70 μM and a limit of detection (LOD) of 0.2 μM. Successful determination of HQ in pond water was also realized. [Display omitted] • Nitrogen-doped graphene quantum dots (NGQDs) were one-step synthesized with high yield. • NGQDs formed nanocomposite (Fe3+-NGQDs) upon Fe3+ addition. • Fe3+-NGQDs nanocomposite possessed high peroxidase-like activity. • Selective colorimetric detection of hydroquinone (HQ) from its isomers using Fe3+-NGQDs nanozyme. [ABSTRACT FROM AUTHOR]

Alternative complex III (ACIII) is a multi-subunit quinol:electron acceptor oxidoreductase that couples quinol oxidation with transmembrane proton translocation in bacterial respiratory and photosynthetic electron transport chains. Four ACIII cryoelectron microscopy (cryo-EM) structures are known. However, the effects of cryo-EM versus X-ray crystallography structure determination on ACIII structure are unclear. Here, we report a 3.25 Å crystal structure of photosynthetic ACIII from Chloroflexus aurantiacus (Ca ACIIIp), revealing eight subunits (ActA–G and I) with four iron-sulfur clusters and six c -type hemes, a menaquinol-binding site, and two proton translocation passages. Structural comparisons with the previously reported cryo-EM structures reveal slight local conformational changes in the solvent-exposed regions of ActB, ActD, ActG, and the transmembrane (TM) helix of subunit I. The regions conferring structural flexibility possess low sequence conservation across species. However, the core functional modules containing the menaquinol-binding pocket, redox centers, and proton translocation passages remain unchanged, preserving the enzyme's activity. [Display omitted] • The crystal structure of Ca ACIIIp was determined at 3.25 Å resolution • Conformational stability of the core functional modules is maintained in Ca ACIIIp • Regions displaying local conformational flexibility are less conserved The quinol acceptor oxidoreductase ACIII is involved in bacterial respiratory and photosynthetic electron transport chains. Wu et al. determined the crystal structure of Chloroflexus aurantiacus ACIII. The core functional modules are very similar in the crystal and previously determined cryo-EM structures, whereas small conformational changes are observed in solvent-exposed regions. [ABSTRACT FROM AUTHOR]

Peanut allergy has garnered worldwide attention due to its high incidence rate and severe symptoms, stimulating the demand for the ultrasensitive detection method of peanut allergen. Herein, we successfully developed a novel electrochemical aptasensor for ultrasensitive detection Ara h1, a major allergenic protein present in peanuts. A conductive nickel atoms Anchored Hydrogen-Bonded Organic Frameworks (PFC-73-Ni) were utilized as excellent electrocatalysts toward hydroquinone (HQ) oxidation to generate a readable current signal. The developed electrochemical aptasensor offers wide linear range (1–120 nM) and low detection limit (0.26 nM) for Ara h1. This method demonstrated a recovery rate ranging from 95.00% to 107.42% in standard addition detection of non-peanut food samples. Additionally, the developed electrochemical method was validated with actual samples and demonstrated good consistency with the results obtained from a commercial ELISA kit. This indicates that the established Ara h1 detection method is a promising tool for peanut allergy prevention. • A novel biosensor was constructed using aptamers and HOF for Ara h1 detection. • This sensor offers low detection limit (0.26 nM) and wide linear range (1–120 nM). • Method was used to test 45 actual samples with good accuracy. [ABSTRACT FROM AUTHOR]

• The N, S dual-doped rGO was obtained via hydrothermal route with ammonium sulphate. • The symmetric NSGO cell delivered an energy density of 65 Wh Kg-1 in KI-HQ/1 M H 2 SO 4. • Enhanced energy density was observed for the dual redox additives. • The NSGO modified GCE used as sensor for the detection of DNP, DNT, HQ and RC. • Simultaneous and selective detection of HQ and RC was achieved via SWV technique. The dual application-based scenario in electrochemistry has gained substantial reliability and benefits across various domains. In this study, N, S dual-doped graphene (NSGO) was synthesized via hydrothermal method and utilized for supercapacitor and electrochemical sensing applications. For electrochemical sensing, the NSGO-modified glassy carbon electrode (NSGO/GCE) was used to detect 2,4-dinitrophenol (DNP), 2,4-dinitrotoluene (DNT), hydroquinone (HQ) and resorcinol (RC). The NSGO/GCE demonstrated enhanced sensing performance with low detection limits of 16 nM (DNP), 12 nM (DNT), 0.1 µM (HQ) and 0.08 µM (RC) in a linear dynamic range from 0.1 µM to 60.0 µM (DNP, DNT) and 1.0 µM to 500.0 µM (HQ, RC). The NSGO/GCE sensor exhibited excellent reproducibility and stability, with its practical utility validated through real water sample testing. In supercapacitor applications, the NSGO electrode achieved an impressive gravimetric capacitance of 373 F g-1 in 1 M H 2 SO 4 solution at 0.5 A g-1. Symmetric supercapacitor analyses demonstrated that the NSGO cell in 0.01 M KI-0.01 HQ/1 M H 2 SO 4 achieved an enhanced energy density of 65 Wh Kg-1 at 4 A g-1, which is three times superior to 0.01 M HQ/1 M H 2 SO 4 (21.7 Wh Kg-1). [Display omitted] [ABSTRACT FROM AUTHOR]

Escherichia coli (E. coli) is a prevalent pathogen that is frequently associated with the foodborne illness. It causes various infections and poses a significant threat to human health. A rapid and sensitive assay for detecting E. coli is essential for timely diagnosis. Herein, a simple and sensitive colorimetric analysis method for detecting E. coli was developed based on the formation of Au@Ag core-shell nanoparticles facilitated by p -benzoquinone (BQ). E. coli reduced p -benzoquinone to generate hydroquinone (HQ), which could reduce the added Tollens' reagent to silver elemental and grow on the surface of gold nanoparticles (AuNPs). As the E. coli concentration increased, the silver layer thickess on the AuNPs surface growed, resulting in a stronger silver absorption peak observed at 390 nm. The color of the solution changed from red to orange, which could be used to detect E. coli by the naked eye. As a result, E. coli was detected with a linear range from 1.0 × 101 to 1.0 × 107 CFU/mL based on the absorbance intensity. In addition, this method accurately detected E. coli in real milk sample, demonstrating promising applications in foodborne pathogen detection. With satisfactory accuracy, the proposed colorimetric method holds excellent prospects in detecting pathogens in actual food samples. A simple and sensitive colorimetric analysis method for detecting Escherichia coli was proposed based on the formation of Au@Ag core-shell nanoparticles facilitated by p -benzoquinone. [Display omitted] • The color changes related to E. coli concentration were observable by the naked eye. • The colorimetric method avoided complex instruments and label procedure. • The method had a wide linear range and a low detection limit. • The method was applied in real milk samples with satisfactory accuracy. [ABSTRACT FROM AUTHOR]

Hydroquinone (HQ) and catechol (CC) are widespread environmental pollutants known for their high toxicity and poor biodegradability. Herein, we devised an electrochemical sensor for sensitive and selective detection of HQ and CC. The glassy carbon electrode (GCE) was meticulously modified by using the Ca-perovskite (CaTiO 3 /GCE), zinc-based metal-organic frameworks (Zn-MOF/GCE), and their nanocomposite with reduced graphene oxide (rGO), i.e., CaTiO 3 -Zn-MoF@rGO/GCE (CaM@rGO/GCE). The CaM@rGO/GCE sensor showed stupendous electrochemical performance due to the synergistic effects of rGO's high conductivity and Ca-perovskite's electrocatalytic activity. Furthermore, the Zn-MOF component ensures the sensor's remarkable stability. The developed sensor boasts impressive selectivity towards HQ and CC, achieving exceptionally low detection limits (0.0086 µM (S/N = 3) for HQ, 0.0115 µM (S/N = 3) for CC), and broad linear ranges (0.05–105 µM for HQ, 0.05–120 µM for CC). The sensor shows better sensitivity to hydroquinone (HQ) than catechol (CC) due to the absence of intramolecular hydrogen bonding in HQ. The sensor's real-world applicability was validated by analyzing environmental water samples, demonstrating its immense potential for practical environmental monitoring. • Development of stupendous CaTiO 3 -Zn-MoF@rGO/GCE electrochemical sensor. • Development of a method for improving electrocatalyst stability of the sensor. • Detection of HQ and CC with LOD of 0.0086 µM and 0.0115 µM. • In real-time sample analysis, the sensors were proven to be useful. [ABSTRACT FROM AUTHOR]

Key challenges in the management of pigmentary disorders such as melasma and postinflammatory hyperpigmentation are their resistance to treatment, tendency to recur after treatment, and the risk of exacerbating hyperpigmentation with many treatment modalities. The second article in this 2-part continuing medical education series on pigmentary disorders focuses on the evidence behind medical and procedural treatments of dyschromias, including photoprotection, topical lightening agents, oral agents, chemical peels, and laser therapy. [ABSTRACT FROM AUTHOR]

Disorders of hyperpigmentation are common and, depending on the extent and location of involvement, can affect the quality of life and pose a significant psychologic burden for patients. Given the similarities in presentation of the various causes of hyperpigmentation, it is often difficult to elucidate the etiology of these conditions, which is important to guide management. Furthermore, certain disorders, such as lichen planus pigmentosus and ashy dermatosis, have similar clinical and/or histologic presentations, and their classification as distinct entities has been debated upon, leading to additional confusion. In this review, the authors selected commonly encountered disorders of hyperpigmentation of the skin, subdivided into epidermal, dermal, or mixed epidermal-dermal disorders based on the location of pigment deposition, along with disorders of hyperpigmentation of the mucosa and nails. Melanocytic nevi, genetic disorders, and systemic causes of hyperpigmentation were largely excluded and considered to be outside the scope of this review. We discussed the pathogenesis of hyperpigmentation as well as the clinical and histologic features of these conditions, along with challenges encountered in their diagnosis and classification. The second article in this 2-part continuing medical education series focuses on the medical and procedural treatments of hyperpigmentation. [ABSTRACT FROM AUTHOR]