Biodegradation of low-density polyethylene film by two bacteria isolated from plastic debris in coastal beach.

Low-density polyethylene (LDPE) conduces massive environmental accumulation due to its high production and recalcitrance to environment. In this study, We successfully enriched and isolated two strains, Nitratireductor sp. Z-1 and Gordonia sp. Z-2, from coastal plastic debris capable of degrading LDPE film. After a 30-day incubation at 30 ℃, strains Z-1 and Z-2 decreased the weight of branched-LDPE (BLDPE) film by 2.59 % and 10.27 % respectively. Furthermore, high temperature gel permeation chromatography (HT-GPC) analysis revealed molecular weight reductions of 7.69 % (Z-1) and 23.22 % (Z-2) in the BLDPE film. Scanning electron microscope (SEM) image showed the presence of microbial colonization and perforations on the film's surface. Fourier transform infrared spectroscopy (FTIR) analysis indicated novel functional groups, such as carbonyl and carbon-carbon double bonds in LDPE films. During LDPE degradation, both strains produced extracellular reactive oxygen species (ROS). GC-MS analysis revealed the degradation products included short-chain alkanes, alkanols, fatty acids, and esters. Genomic analysis identified numerous extracellular enzymes potentially involved in LDPE chain scission. A model was proposed suggesting a coordinated role between ROS and extracellular enzymes in the biodegradation of LDPE. This indicates strains Z-1 and Z-2 can degrade LDPE, providing a basis for deeper exploration of biodegradation mechanisms.

Cysteine Radical and Glutamate Collaboratively Enable C-H Bond Activation and C-N Bond Cleavage in a Glycyl Radical Enzyme HplG.

Hydroxyprolines are abundant in nature and widely utilized by many living organisms. Isomerization of trans-4-hydroxy-d-proline (t4D-HP) to generate 2-amino-4-ketopentanoate has been found to need a glycyl radical enzyme HplG, which catalyzes the cleavage of the C-N bond, while dehydration of trans-4-hydroxy-l-proline involves a homologous enzyme of HplG. Herein, molecular dynamics simulations and quantum mechanics/molecular mechanics (QM/MM) calculations are employed to understand the reaction mechanism of HplG. Two possible reaction pathways of HplG have been explored to decipher the origin of its chemoselectivity. The QM/MM calculations reveal that the isomerization proceeds via an initial hydrogen shift from the Cγ site of t4D-HP to a catalytic cysteine radical, followed by cleavage of the Cδ-N bond in t4D-HP to form a radical intermediate that captures a hydrogen atom from the cysteine. Activation of the Cδ-H bond in t4D-HP to bring about dehydration of t4D-HP possesses an extremely high energy barrier, thus rendering the dehydration pathway implausible in HplG. On the basis of the current calculations, conserved residue Glu429 plays a pivotal role in the isomerization pathway: the hydrogen bonding between it and t4D-HP weakens the hydroxyalkyl Cγ-Hγ bond, and it acts as a proton acceptor to trigger the cleavage of the C-N bond in t4D-HP. Our current QM/MM calculations rationalize the origin of the experimentally observed chemoselectivity of HplG and propose an H-bond-assisted bond activation strategy in radical-containing enzymes. These findings have general implications on radical-mediated enzymatic catalysis and expand our understanding of how nature wisely and selectively activates the C-H bond to modulate catalytic selectivity.

Detection of monkeypox virus based on a convenient and sensitive single-step RPA-CRISPR/Cas12a strategy.

The global outbreak of monkeypox virus (MPXV) has highlighted the need for rapid molecular diagnostics techniques. In this study, a single-step recombinase polymerase amplification (RPA)-CRISPR/Cas12a system was developed for rapid and sensitive detection of MPXV. The limit of detection of this assay was 1 copy per µL of extracted nucleic acids. A heating lysis method was integrated to further simplify the sample processing workflow and shorten the assay time to 40 min from sample to result. The reaction mixture can be lyophilized to improve its accessibility in resource-limited settings. The analysis results of the proposed single-step RPA-CRISPR/Cas12a assay for clinical MPXV positive and negative samples were 100% consistent with standard PCR assay. These results demonstrate the feasibility and efficiency of this method for rapid and accurate MPXV detection in real-world settings, showcasing its potential utility in urgent and practical settings.

Efficacy and safety of pelvic floor magnetic stimulation combined with mirabegron in female patients with refractory overactive bladder: a prospective study.

Objective: To observe the efficacy and safety of pelvic floor magnetic stimulation (PFMS) combined with mirabegron in female patients with refractory overactive bladder (OAB) symptoms. Patients and methods: A total of 160 female patients with refractory OAB symptoms were prospectively randomized into two groups. Eighty cases in the combination group accepted PFMS and mirabegron therapy and 80 cases as control only accepted mirabegron therapy (The clinical trial registry number: ChiCTR2200070171). The lower urinary tract symptoms, OAB questionnaire (OAB-q) health-related quality of life (HRQol), symptom bother score and OABSS between two groups were compared at the 1st, 2nd and 4th week ends. Results: All of 160 patients were randomly assigned to two groups, of which 80 patients were included in the combination group and 80 in the mirabegron group. The incidences of LUTS, including urgency, frequent urination, and incontinence episodes, in the 2nd week and the 4th week after combination treatment were significantly lower than those in the mirabegron group (p < 0.05). The incidence of drug-related adverse events between two groups was similar, and there was no statistically significant difference (p > 0.05). With respect to secondary variables, the OAB-q HRQol score in the combination group was statistically superior in comparison with that in the mirabegron group between the 2nd week and the 4th week (p < 0.05). This was consistent with the primary outcome. Meanwhile, from the second to fourth week, the OAB-q symptom bother score and OABSS in the combination group were both lower than in the mirabegron group (p < 0.05). Conclusion: Combination therapy of PFMS and mirabegron demonstrated significant improvements over mirabegron monotherapy in reducing refractory OAB symptoms for female patients, and providing a higher quality of life without increasing bothersome adverse effects. Clinical Trial Registration: https://www.chictr.org.cn/, ChiCTR-INR-22013524.

Exploring the Cooperation of the Redox Non-innocent Ligand and Di-Cobalt Center for the Water Oxidation Reaction Catalyzed by a Binuclear Complex.

Water oxidation is a crucial reaction in the artificial photosynthesis system. In the present work, density functional calculations were employed to decipher the mechanism of water oxidation catalyzed by a binuclear cobalt complex, which was disclosed to be a homogeneous water oxidation catalyst in pH=7 phosphate buffer. The calculations showed that the catalytic cycle starts from the CoIII,III-OH2 species. Then, a proton-coupled electron transfer followed by a one-electron transfer process leads to the generation of the formal CoIV,IV-OH intermediate. The subsequent PCET produces the active species, namely the formal CoIV,V=O intermediate (4). The oxidation processes mainly occur on the ligand moiety, including the coordinated water moiety, implying a redox non-innocent behavior. Two cobalt centers keep their oxidation states and provide one catalytic center for water activation during the oxidation process. 4 triggers the O-O bond formation via the water nucleophilic attack pathway, in which the phosphate buffer ion functions as the proton acceptor. The O-O bond formation is the rate-limiting step with a calculated total barrier of 17.7 kcal/mol. The last electron oxidation process coupled with an intramolecular electron transfer results in the generation of O2.

Ultrasensitive single-step CRISPR detection of monkeypox virus in minutes with a vest-pocket diagnostic device.

The emerging monkeypox virus (MPXV) has raised global health concern, thereby highlighting the need for rapid, sensitive, and easy-to-use diagnostics. Here, we develop a single-step CRISPR-based diagnostic platform, termed SCOPE (Streamlined CRISPR On Pod Evaluation platform), for field-deployable ultrasensitive detection of MPXV in resource-limited settings. The viral nucleic acids are rapidly released from the rash fluid swab, oral swab, saliva, and urine samples in 2 min via a streamlined viral lysis protocol, followed by a 10-min single-step recombinase polymerase amplification (RPA)-CRISPR/Cas13a reaction. A pod-shaped vest-pocket analysis device achieves the whole process for reaction execution, signal acquisition, and result interpretation. SCOPE can detect as low as 0.5 copies/µL (2.5 copies/reaction) of MPXV within 15 min from the sample input to the answer. We validate the developed assay on 102 clinical samples from male patients / volunteers, and the testing results are 100% concordant with the real-time PCR. SCOPE achieves a single-molecular level sensitivity in minutes with a simplified procedure performed on a miniaturized wireless device, which is expected to spur substantial progress to enable the practice application of CRISPR-based diagnostics techniques in a point-of-care setting.

Compression Therapy after Thermal Ablation of Varicose Veins: A Meta-Analysis.

OBJECTIVE: To investigate whether compression therapy after thermal ablation of varicose veins can improve the prognosis of patients. METHODS: Systematic research were applied for Chinese and English electronic databases(PubMed, Web of Science, Cochrane Library, CNKI, Wanfang, VIP Databases). Eligible prospective studies that comparing the efficacy of compression therapy and non-compression therapy on patients after thermal ablation of varicose veins were included. The interest outcome such as pain, quality of life (QOL), venous clinical severity score (VCSS), time to return to work and complications were analyzed. RESULTS: 10 studies were of high quality, and randomized controlled trials involving 1,545 patients met the inclusion criteria for this study. At the same time, the meta-analysis showed that the application of compression therapy improved pain (SMD: -0.51, 95% CI: -0.95, -0.07) but exhibited no statistically significant effect on QOL (SMD: 0.04, 95% CI: -0.08, 0.16), VCSS (MD: -0.05, 95% CI: -1.19, 1.09), time to return to work (MD: -0.43, 95% CI: -0.90, 0.03), total complications (RR: 0.54, 95% CI: 0.27, 1.09), and thrombosis (RR: 0.71, 95% CI: 0.31, 1.62). CONCLUSION: Compression therapy after thermal ablation of varicose veins can slightly relieve pain, but it has not been found to be associated with improvement in other outcomes.

Cobalt-Catalyzed Acceptorless Dehydrogenation of Primary Amines to Nitriles.

The direct double dehydrogenation from primary amines to nitriles without an oxidant or hydrogen acceptor is both intriguing and challenging. In this paper, we describe a non-noble metal catalyst capable of realizing such a transformation with high efficiency. A cobalt-centered N,N-bidentate complex was designed and employed as a metal-ligand cooperative dehydrogenation catalyst. Detailed kinetic studies, control experiments, and DFT calculations revealed the crucial hydride transfer, proton transfer, and hydrogen evolution processes. Finally, a tandem outer-sphere/inner-sphere mechanism was proposed for the dehydrogenation of amines to nitriles through an imine intermediate.

Photocatalytic selective oxidation of toluene under encapsulated air conditions.

Benzaldehydes are indispensable building blocks in chemistry. However, the selective oxidation of toluene to benzaldehyde remains an ongoing challenge due to the low oxidation potential of benzaldehyde compared to toluene. We report herein a mild protocol that combines hydrogen atom transfer (HAT) with encapsulated air conditions and suitable catalyst loading for selective oxidation of toluene with high selectivity as well as good functional-group tolerance and a broad substrate scope for the synthesis of various high-value aromatic aldehydes. Moreover, the compatibility of this reaction with toluene derivatives of bioactive molecules further demonstrated the practicality of this approach. Mechanism studies have demonstrated that the collaboration between the oxygen quantity and the HAT catalytic system has a major impact on the high selectivity of the reaction. This study not only showcases the effectiveness of HAT strategies toward selective oxidation of toluene to benzaldehyde, but also provides an approach to controlling the selectivity of HAT reactions.

Rapid identification of A29L antibodies based on mRNA immunization and high-throughput single B cell sequencing to detect Monkeypox virus.

With the large number of atypical cases in the mpox outbreak, which was classified as a global health emergency by the World Health Organization (WHO) on 23 July 2022, rapid diagnosis of mpox and diseases with similar symptoms to mpox such as chickenpox and respiratory infectious diseases in the early stages of viral infection is key to controlling the spread of the outbreak. In this study, antibodies against the monkeypox virus A29L protein were efficiently and rapidly identified by combining rapid mRNA immunization with high-throughput sequencing of individual B cells. We obtained eight antibodies with a high affinity for A29L validated by ELISA, which were was used as the basis for developing an ultrasensitive fluorescent immunochromatographic assay based on multilayer quantum dot nanobeads (SiTQD-ICA). The SiTQD-ICA biosensor utilizing M53 and M78 antibodies showed high sensitivity and stability of detection: A29L was detected within 20 min, with a minimum detection limit of 5 pg/mL. A specificity test showed that the method was non-cross-reactive with chickenpox or common respiratory pathogens and can be used for early and rapid diagnosis of monkeypox virus infection by antigen detection. This antibody identification method can also be used for rapid acquisition of monoclonal antibodies in early outbreaks of other infectious diseases for various studies.

Bimetallic H2 Addition and Intramolecular Caryl-H Activation Mediated by an Iron-Zinc Hydride.

Heteronuclear Fe(µ-H)Zn hydride Cp*Fe(1,2-Cy2PC6H4)HZnEt (3) undergoes reversible intramolecular Caryl-H reductive elimination through coupling of the cyclometalated phosphinoaryl ligand and the hydride, giving rise to a formal Fe(0)-Zn(II) species. Addition of CO intercepts this equilibrium, affording Cp*(Cy2PPh)(CO)Fe-ZnEt that features a dative Fe-Zn bond. Significantly, this system achieves bimetallic H2 addition, as demonstrated by the transformation of the monohydride Fe(µ-H)Zn to a deuterated dihydride Fe-(µ-D)2-Zn upon reaction with D2.

CRISPR/Cas13a-based single-nucleotide polymorphism detection for reliable determination of ABO blood group genotypes.

The ABO blood group plays an important role in blood transfusion, linkage analysis, individual identification, etc. Serologic methods of blood typing are gold standards for the time being, which require stable typing antisera and fresh blood samples and are labor intensive. At present, reliable determination of ABO blood group genotypes based on single-nucleotide polymorphisms (SNPs) among A, B, and O alleles remains necessary. Thus, in this work, CRISPR/Cas13a-mediated genotyping for the ABO blood group by detecting SNPs between different alleles was proposed. The ABO*O.01.01(c.261delG) allele (G for the A/B allele and del for the O allele) and ABO*B.01(c.796C > A) allele (C for the A/O allele and A for the B allele) were selected to determine the six genotypes (AA, AO, BB, BO, OO, and AB) of the ABO blood group. Multiplex PCR was adapted to simultaneously amplify the two loci. CRISPR/Cas13a was then used to specifically differentiate ABO*O.01.01(c.261delG) and ABO*B.01(c.796C > A) of A, B, and O alleles. Highly accurate determination of different genotypes was achieved with a limit of detection of 50 pg per reaction within 60 min. The reliability of this method was further validated based on its applicability in detecting buccal swab samples with six genotypes. The results were compared with those of serological and sequencing methods, with 100% accuracy. Thus, the CRISPR/Cas13a-mediated assay shows great application potential in the reliable identification of ABO blood group genotypes in a wide range of samples, eliminating the need to collect fresh blood samples in the traditional method.

RIRS with FV-UAS vs. MPCNL for 2-3-cm upper urinary tract stones: a prospective study.

To observe the efficacy and safety of retrograde intrarenal surgery (RIRS) combined with flexible vacuum-assisted ureteral access sheath (FV-UAS) and minimally invasive percutaneous nephrolithotomy (MPCNL) in patients with 2-3 cm upper urinary tract stones. A total of 160 patients with 2-3 cm upper urinary tract stones were prospectively randomized into 2 groups-80 in the FV-UAS group and 80 cases as control in the MPCNL group. The stone-free rates (SFRs) at different times (postoperative 1st day and 4th week) were considered as the primary outcome of the study. The secondary end points were operative time, hemoglobin decrease, postoperative hospital stay, and operation-related complications. There was no obvious difference between the two groups in patient's demographics and preoperative clinical characteristics (all P > 0.05). Postoperative data showed that mean decrease in hemoglobin level was less in FV-UAS group than that in MPCNL group (5.3 vs. 10.8 g/L, P < 0.001). Postoperative hospital stay in FV-UAS group was more shorten than that in MPCNL group (2.7 vs. 4.9 days, P < 0.001). There was no statistical significance between the two groups in SFRs during postoperative 1st day and 4th week (both P > 0.05). However, in terms of the rates of bleeding and pain, MPCNL group were both significantly higher than FV-UAS group (6.2 vs. 0.0%, P = 0.023; 16.2 vs. 2.5%, P = 0.003; respectively). Our study showed that RIRS with FV-UAS, a new partnership to treat 2-3 cm upper urinary tract stones, was satisfying as it achieved a high SFR rate and a low rate of complications. This method was safe and reproducible in clinical practice.

Accessing ladder-shape azetidine-fused indoline pentacycles through intermolecular regiodivergent aza-Paternò-Büchi reactions.

Small molecules with conformationally rigid, three-dimensional geometry are highly desirable in drug development, toward which a direct, simple-to-complexity synthetic logic is still of considerable challenges. Here, we report intermolecular aza-[2 + 2] photocycloaddition (the aza-Paternò-Büchi reaction) of indole that facilely assembles planar building blocks into ladder-shape azetidine-fused indoline pentacycles with contiguous quaternary carbons, divergent head-to-head/head-to-tail regioselectivity, and absolute exo stereoselectivity. These products exhibit marked three-dimensionality, many of which possess 3D score values distributed in the highest 0.5% region with reference to structures from DrugBank database. Mechanistic studies elucidated the origin of the observed regio- and stereoselectivities, which arise from distortion-controlled C-N coupling scenarios. This study expands the synthetic repertoire of energy transfer catalysis for accessing structurally intriguing architectures with high molecular complexity and underexplored topological chemical space.

Associated factors of depression in primiparas with hypothyroidism during pregnancy.

This cross-sectional study aimed to explore the associated factors of depression in primiparas with hypothyroidism during pregnancy. The research subjects were 200 primiparas with hypothyroidism during pregnancy who were admitted to our hospital between December 2016 and December 2019. Self-rating depression scale scores were used to evaluate the depression, and the incidence of depression were examined. The data from all the subjects were collected to compare the differences between primiparas with hypothyroidism during pregnancy with and without depression. A logistic regression equation was used to analyze the influencing factors of depression in these patients. Of the 200 primiparas who took part in this study, 27 suffered from depression, accounting for 13.50%. There were differences in age, education level, economic income, sleep quality, and conjugal relations between the depressed and the nondepressed participants. When the above factors were included in the logistic regression equation, it was found that the odds ratio values for these factors were all >1, which indicated that they had an influence on maternal depression in primiparas with hypothyroidism during pregnancy. This study demonstrated that pregnancy-associated hypothyroidism in primiparas is affected by age, education level, economic income, sleep quality, and conjugal relations, all of which increase the incidence of depression. Relevant preventive measures should be provided in clinical practice to avoid the occurrence of depression.

Pivotal Role of Geometry Regulation on O-O Bond Formation Mechanism of Bimetallic Water Oxidation Catalysts.

In this study, we highlight the impact of catalyst geometry on the formation of O-O bonds in Cu2 and Fe2 catalysts. A series of Cu2 complexes with diverse linkers are designed as electrocatalysts for water oxidation. Interestingly, the catalytic performance of these Cu2 complexes is enhanced as their molecular skeletons become more rigid, which contrasts with the behavior observed in our previous investigation with Fe2 analogs. Moreover, mechanistic studies reveal that the reactivity of the bridging O atom results in distinct pathways for O-O bond formation in Cu2 and Fe2 catalysts. In Cu2 systems, the coupling takes place between a terminal CuIII -OH and a bridging µ-O⋅ radical. Whereas in Fe2 systems, it involves the coupling of two terminal Fe-oxo entities. Furthermore, an in-depth structure-activity analysis uncovers the spatial geometric prerequisites for the coupling of the terminal OH with the bridging µ-O⋅ radical, ultimately leading to the O-O bond formation. Overall, this study emphasizes the critical role of precisely adjusting the spatial geometry of catalysts to align with the O-O bonding pathway.

Effect of electroacupuncture on Nrf2/NLRP3/Caspase-1 pathway mediated-pyroptosis in mice with Parkinson's disease. / ç”µé’ˆå¯¹å¸•é‡‘æ£®ç— å°é¼ Nrf2/NLRP3/Caspase-1通路介导的细胞焦亡的影响.

OBJECTIVES: To observe the effect of electroacupuncture (EA) on nuclear transcription factor E2 related factor 2 (Nrf2)/NOD-like receptor family pyrin domain-containing protein 3 (NLRP3)/cysteine aspartic acid specific protease-1 (Caspase-1) pathway in the substantia nigra (SN) of mice with Parkinson's disease (PD), so as to explore the neuroprotective mechanism of EA. METHODS: Forty C57BL/6 male mice were randomly divided into 4 groups, namely, control, PD model, EA and sham-EA groups, with 10 mice in each group. The PD mouse model was established by gavage of rotenone for 4 weeks. Mice in the EA group were given EA stimulation (1 mA, 2 Hz) at "Fengfu" (GV36), bilateral "Taichong" (LR3) and "Zusanli" (ST36) for 30 min, once daily for 2 consecutive weeks. And mice in the sham-EA group were given acupuncture at the subcutaneous areas of the same acupoints without EA stimulation. The open-field test was used for assessment of mouse behavior. The levels of interleukin-1ß (IL-1ß) and interleukin-18 (IL-18) in the serum were detected by enzyme-linked immunosorbent assay . The positive expression of tyrosine hydroxylase (TH) in SN was determined by immunohistochemistry. The mRNA expression levels of Nrf2, NLRP3, Caspase-1, gasdermin D(GSDMD), IL-1ß, IL-18 and the protein expression levels of Nrf2, NLRP3, Caspase-1 and GSDMD in the SN were detected by quantitative real-time PCR and Western blot, separately. RESULTS: After modeling, compared with the control group, the behavioral score was increased (P<0.01), the total exercise time, the total distance and the average speed were decreased (P<0.01), and the positive expression of TH and the mRNA and protein expression levels of Nrf2 in the SN were decreased (P<0.01), while the contents of IL-1ß and IL-18 in serum, the mRNA and protein expression levels of NLRP3, Caspase-1 and GSDMD and the mRNA expression levels of IL-1ß and IL-18 in the SN were up-regulated (P<0.01) in the PD model group. Following EA intervention, the behavioral score was decreased(P<0.01), the total exercise time, total distance and average speed were increased (P<0.01), the positive expression of TH and the mRNA and protein expressions of Nrf2 in SN were up-regulated (P<0.01, P<0.05), while the contents of IL-1ß and IL-18 in serum, the mRNA and protein expression levels of NLRP3, Caspase-1 and GSDMD as well as the mRNA expression levels of IL-1ß and IL-18 in the SN were down-regulated (P<0.01, P<0.05) in the EA group relative to the PD model and sham-EA groups. There were no significant differences in the above indicators between the PD model and sham-EA groups. CONCLUSIONS: EA stimulation of GV36, LR3 and ST36 can improve motor deficits, reduce the loss of dopamine neurons in the SN, and inhibit neuroinflammatory responses in mice with PD, which may be related to its effects in regulating the Nrf2/NLRP3/Caspase-1 pathway mediated pyroptosis.

Regioselective Diels-Alder Reactions of Anthracenes with Olefins via Visible Light Photocatalysis in a Homogeneous Solution.

Diels-Alder cycloaddition of anthracene with olefin is achieved in a homogeneous solution via energy transfer under visible light. A series of substrates including electroneutral styrene derivatives can be successfully converted into the corresponding cycloadducts in a head-to-head orientation with high to excellent yields. The high ortho-regioselectivity, mild condition, and broad substrate scope enable promising advances in organic transformation.

Efficient magnetic enrichment cascade single-step RPA-CRISPR/Cas12a assay for rapid and ultrasensitive detection of Staphylococcus aureus in food samples.

Staphylococcus aureus (S. aureus) is a prevalent foodborne pathogen that could cause severe food poisoning. Thus, rapid, efficient, and ultrasensitive detection of S. aureus in food samples is urgently needed. Here, we report an efficient magnetic enrichment cascade single-step recombinase polymerase amplification (RPA)-CRISPR/Cas12a assay for the ultrasensitive detection of S. aureus. Magnetic beads (MBs) functionalized with S. aureus-specific antibodies were initially used for S. aureus enrichment from the complex matrix, with 98% capture efficiency in 5 min and 100-fold sensitivity improvement compared with unenriched S. aureus. Next, a single-step RPA-CRISPR/Cas12a-based diagnostic system with optimized extraction-free bacteria lysis was constructed. This assay could detect as low as 1 copy/µL (five copies/reaction) of extracted DNA template and 10 CFU/mL of S. aureus within 40 min. Furthermore, the assay could effectively detect S. aureus in real food samples such as lake water, orange juice, pork, and lettuce, with concordant results to qPCR assays. The proposed cascade signal-amplification assay eliminates the need for lengthy bacterial culture and complex sample preparation steps. Hence, the proposed assay shows great application potential for rapid, efficient, and ultrasensitive detection of pathogens in real food samples.

Mechanism of photocatalytic CO2 reduction to HCO2H by a robust multifunctional iridium complex.

The tetradentate PNNP-type IrIII complex Mes-IrPCY2 ([Cl-IrIII-H]+) is reported to be an efficient catalyst for the reduction of CO2 to formate with excellent selectivity under visible light irradiation. Density functional calculations have been carried out to elucidate the mechanism and the origin of selectivity in the present work. Calculations suggest that the double-reduced complex 1-H (1[IrI-H]0) demonstrates higher activity than the single-reduced complex 2-H (2[IrIII(L˙-)-H]+), possibly owing to the higher hydride donor ability of the former compared to the latter; thus 1-H functions as the active species in the overall CO2 reduction reaction. In the HCOO- formation pathway, the hydride of 1-H performs a nucleophilic attack on CO2via an outer-sphere fashion to generate species 1-OCHO (1[IrI-OCHO]0), which then releases HCOO- to produce an IrI intermediate. A subsequent protonation and chloride coordination of the Ir center leads to the regeneration of catalyst 1[Cl-IrIII-H]+. For the CO production, a nucleophilic attack on CO2 takes place by the Ir atom of 1-Hvia an inner-sphere manner to afford complex O2C-3-H (1[O2C-IrIII-H]0), followed by a two-proton-one-electron reduction to furnish the OC-2-H complex (2[OC-IrIII(L˙-)-H]+) after liberating a H2O. Ultimately, CO is released to form 2-H. The stronger nucleophilicity as well as smaller steric hindrance of the hydride than the Ir atom of the active species 1-H (1[IrI-H]0) is found to account for the favoring of formate formation over CO formation. Meanwhile, the CO2 reduction reaction is calculated to be preferred over the hydrogen evolution reaction, and this is consistent with the experimental product distributions.