Structure of a unique PSII-Pcb tetrameric megacomplex in a chlorophyll d-containing cyanobacterium.

Acaryochloris marina is a unique cyanobacterium using chlorophyll d (Chl d) as its major pigment and thus can use far-red light for photosynthesis. Photosystem II (PSII) of A. marina associates with a number of prochlorophyte Chl-binding (Pcb) proteins to act as the light-harvesting system. We report here the cryo-electron microscopic structure of a PSII-Pcb megacomplex from A. marina at a 3.6-angstrom overall resolution and a 3.3-angstrom local resolution. The megacomplex is organized as a tetramer consisting of two PSII core dimers flanked by sixteen symmetrically related Pcb proteins, with a total molecular weight of 1.9 megadaltons. The structure reveals the detailed organization of PSII core consisting of 15 known protein subunits and an unknown subunit, the assembly of 4 Pcb antennas within each PSII monomer, and possible pathways of energy transfer within the megacomplex, providing deep insights into energy transfer and dissipation mechanisms within the PSII-Pcb megacomplex involved in far-red light utilization.

Cyclometalated gold(III)-hydride under oriented external electric fields: a new strategy to modulate its reactivity?

Selected gold complexes have been regarded as promising anti-cancer agents because they can bind with protein targets containing thiol or selenol moieties, but their clinical applications were hindered by the unbiased binding towards off-target thiol-proteins. Recently, a novel gold(III)-hydride complex (abbreviated as 1) with visible light-induced thiol reactivity has been reported as potent photo-activated anticancer agents (Angew. Chem. Int. Ed., 2020, 132, 11139). To explore new strategies to stimuli this potential antitumor drug, the effect of oriented external electric fields (OEEFs) on its geometric structure, electronic properties, and chemical reactivity was systematically investigated. Results reveal that imposing external electric fields along the Au-H bond of 1 can effectively activate this bond, which is conducive to its dissociation and the binding of Au site to potential targets. Hence, this study provides a new OEEF-strategy to activate this reported gold(III)-hydride, revealing its potential application in electrochemical therapy. We anticipate this work could promote the development of more electric field-activated anticancer agents. However, further experimental research should be conducted to verify the conclusions obtained in this work.

Survival nomograms for simultaneous resection of primary and hepatic lesions without neoadjuvant chemotherapy in patients with resectable colorectal liver metastasis.

Background: No well-performing nomogram has been developed specifically to predict individual-patient cancer-specific survival (CSS) and overall survival (OS) among patients with resectable colorectal liver metastasis (CRLM) who undergo simultaneous resection of primary and hepatic lesions without neoadjuvant chemotherapy (NAC). We aim to investigate the prognosis of patients with resectable CRLM undergoing simultaneous resection of primary and hepatic lesions without NAC. Methods: Data of patients with CRLM in the Surveillance, Epidemiology and End Results Program (cohort, n = 225) were collected as the training set, and data of patients with CRLM treated at the National Cancer Center (cohort, n = 180) were collected as the validation set. The prognostic value of the clinicopathological parameters in the training cohort was assessed using Kaplan‒Meier curves and univariate and multivariate Cox proportional hazards models, and OS and CSS nomograms integrated with the prognostic variables were constructed. Calibration analyses, receiver operating characteristic (ROC) curves, and decision curve analyses (DCAs) were then performed to evaluate the performance of the nomograms. Results: There was no collinearity among the collected variables. Three factors were associated with OS and CSS: the pretreatment carcinoembryonic antigen (CEA) concentration, pathologic N (pN) stage, and adjuvant chemotherapy (each p < 0.05). OS and CSS nomograms were constructed using these three parameters. The calibration plots revealed favorable agreement between the predicted and observed outcomes. The areas under the ROC curves were approximately 0.7. The DCA plots revealed that both nomograms had satisfactory clinical benefits. The ROC curves and DCAs also confirmed that the nomogram surpassed the tumor, node, and metastasis staging system. Conclusion: The herein-described nomograms containing the pretreatment CEA concentration, pN stage, and adjuvant chemotherapy may be effective models for predicting postoperative survival in patients with CRLM.

Theoretical prediction of superatom WSi12-based catalysts for CO oxidation by N2O.

Catalytic conversion of N2O and CO into nonharmful gases is of great significance to reduce their adverse impact on the environment. The potential of the WSi12 superatom to serve as a new cluster catalyst for CO oxidation by N2O is examined for the first time. It is found that WSi12 prefers to adsorb the N2O molecule rather than the CO molecule, and the charge transfer from WSi12 to N2O results in the full activation of N2O into a physically absorbed N2 molecule and an activated oxygen atom that is attached to an edge of the hexagonal prism structure of WSi12. After the release of N2, the remaining oxygen atom can oxidize one CO molecule via overcoming a rate-limiting barrier of 28.19 kcal mol-1. By replacing the central W atom with Cr and Mo, the resulting MSi12 (M = Cr and Mo) superatoms exhibit catalytic performance for CO oxidation comparable to the parent WSi12. In particular, the catalytic ability of WSi12 for CO oxidation is well maintained when it is extended into tube-like WnSi6(n+1) (n = 2, 4, and 6) clusters with energy barriers of 25.63-29.50 kcal mol-1. Moreover, all these studied MSi12 (M = Cr, Mo, and W) and WnSi6(n+1) (n = 2, 4, and 6) species have high structural stability and can absorb sunlight to drive the catalytic process. This study not only opens a new door for the atomically precise design of new silicon-based nanoscale catalysts for various chemical reactions but also provides useful atomic-scale insights into the size effect of such catalysts in heterogeneous catalysis.

Computational screening of metalloporphyrin-based drug carriers for antitumor drug 5-fluorouracil.

Developing novel nanoscale carriers for drug delivery is of great significance for improving treatment efficiency and reducing side effects of antitumor drugs. In view of the good biocompatibility and special affinity of porphyrin (PP) molecule to cancer cells, it was used to construct a series of metal-doped M@PP (M = Ca âˆ¼ Zn) materials for the delivery of anticancer drug 5-fluorouracil (5-Fu) in this work. Our results reveal that 5-Fu is tightly adsorbed on M@PP (M = Ca âˆ¼ V, Mn âˆ¼ Co, and Zn) by chemisorption, but is physically adsorbed by M@PP (M = Cr, Ni, and Cu). The calculated electronic properties show that all these 5-Fu@[M@PP] (M = Ca âˆ¼ Zn) complexes have both high stability and solubility. Among these 5-Fu@[M@PP] complexes, the chemical bond formed between 5-Fu and Ti@PP has the strongest covalent characteristic, resulting in the largest adsorption energy of -19.93 kcal/mol for 5-Fu@[Ti@PP]. In particular, 5-Fu@[Ti@PP] has the proper recovery time under the near-infrared light at body temperature, which further suggests that Ti@PP is the best drug carrier for 5-Fu. This study not only reveals the interaction strength and nature between 5-Fu and M@PP, but also confirmed the intriguing potential of Ti@PP as nano-carrier for drug delivery. However, further experimental research should be conducted to verify the conclusion obtained in this work.

The regularity of anatomical variations of dominant pulmonary segments in the right upper lobe.

BACKGROUND: Anatomical variations often pose challenges to pulmonary surgery. Previous studies have mainly described the frequencies of bronchovascular anatomical variations in pulmonary segments, but did not determine the differences between pulmonary segments and the regularity behind these anatomical variations. Here, we attempted to investigate the regularity of bronchovascular anatomical variations in different pulmonary segments. METHODS: Thin-slice enhanced computed tomography data of 800 cases from our center were included in this study. Digitalized three-dimensional virtual lung segmentation was done, the dominant and inferior lung segments of the right upper lobe were defined, and the regularity of anatomical variations was explored. RESULTS: The mean volume ratio of the anterior segment of the right upper lobe (39.6 ± 8.6%) was highest, and that of the posterior segment (28.6 ± 7.9%) was lowest. Therefore, the dominant-type segment (DS + SDS) was dominant in the anterior segment, accounting for 74.6% (597/800), and the inferior-type segment (SIS + IS) was dominant in the posterior segment of the right upper lobe, accounting for 71.5% of cases (573/800). During the transformation of dominant and inferior lung segments, the corresponding regularity of anatomical variations could be displayed. For example, with an increase in the volume of the anterior segment of the right upper lobe, the occurrence rate of the bifurcated type of bronchus (B1 + 2, B3), the "central vein type" and the involvement of the trunk inferior and ascending artery in the blood supply of anterior segment gradually increased. CONCLUSIONS: The existence of dominant segments will increase the diversity of anatomical variations and the complexity of pulmonary segmentectomy.

On the possibility of using the Ti@Si16 superatom as a novel drug delivery carrier for different drugs: A DFT study.

The potential application of an experimentally synthesized superatom Ti@Si16 as a novel drug carrier for cisplatin (DDP), isoniazid (INH), acetylsalicylic acid (ASA), 5-fluorouracil (5-Fu), and favipiravir (FPV) has been explored by density functional theory. It is observed that the Pt atom of DDP can be effectively absorbed on Ti@Si16 via a "donation-back donation" electron transfer mechanism, resulting in a moderate adsorption energy of -19.95 kcal/mol for DDP@[Ti@Si16]. As for INH, it prefers to combine with Ti@Si16 via the N atom of pyridine ring by forming a strongly polar N-Si bond. Differently, the interaction between Ti@Si16 and the ASA, 5-Fu, and FPV drugs is dominated by the Van der Waals interaction. Our results reveal that DDP@[Ti@Si16] possesses a moderate recovery time under body temperature, which benefits the desorption of DDP from Ti@Si16. More importantly, the release of DDP drug from the Ti@Si16 surface can be effectively controlled by exerting small orientation external electric fields on the DDP@[Ti@Si16] complex. Therefore, this study demonstrates that Ti@Si16 can serve as a promising drug carrier for DDP, and thus will further expand its practical applications in the biomedical field.

Cryo-electron microscopy structure of the intact photosynthetic light-harvesting antenna-reaction center complex from a green sulfur bacterium.

The photosynthetic reaction center complex (RCC) of green sulfur bacteria (GSB) consists of the membrane-imbedded RC core and the peripheric energy transmitting proteins called Fenna-Matthews-Olson (FMO). Functionally, FMO transfers the absorbed energy from a huge peripheral light-harvesting antenna named chlorosome to the RC core where charge separation occurs. In vivo, one RC was found to bind two FMOs, however, the intact structure of RCC as well as the energy transfer mechanism within RCC remain to be clarified. Here we report a structure of intact RCC which contains a RC core and two FMO trimers from a thermophilic green sulfur bacterium Chlorobaculum tepidum at 2.9 Å resolution by cryo-electron microscopy. The second FMO trimer is attached at the cytoplasmic side asymmetrically relative to the first FMO trimer reported previously. We also observed two new subunits (PscE and PscF) and the N-terminal transmembrane domain of a cytochrome-containing subunit (PscC) in the structure. These two novel subunits possibly function to facilitate the binding of FMOs to RC core and to stabilize the whole complex. A new bacteriochlorophyll (numbered as 816) was identified at the interspace between PscF and PscA-1, causing an asymmetrical energy transfer from the two FMO trimers to RC core. Based on the structure, we propose an energy transfer network within this photosynthetic apparatus.

Oncological outcomes of neoadjuvant chemotherapy in patients with resectable synchronous colorectal liver metastasis: A result from a propensity score matching study.

Background: The efficacy and safety of neoadjuvant chemotherapy (NAC) in treating resectable synchronous colorectal liver metastases (CRLM) remain controversial. Methods: Data from CRLM patients who underwent simultaneous liver resection between January 2015 and December 2019 were collected from the Surveillance, Epidemiology, and End Results (SEER) database (SEER cohort, n=305) and a single Chinese Cancer Center (NCC cohort, n=268). Using a 1:2 ratio of propensity score matching (PSM), the prognostic impact of NAC for patients who underwent NAC before surgical treatment and patients who underwent surgical treatment alone was evaluated. Results: After PSM, there was no significant difference in overall survival (OS) between patients receiving NAC prior to CRLM resection and those undergoing surgery only, in both the NCC and SEER cohorts (each P > 0.05). Age was an independent predictor of OS only in the SEER cohort (P = 0.040), while the pN stage was an independent predictor for OS only in the NCC cohort (P = 0.002). Furthermore, Disease-free survival (DFS) was comparable between the two groups in the NCC cohort. In a subgroup analysis, the DFS and OS in the NAC- group were significantly worse than those in the NAC+ group for patients with more than two liver metastases in the NCC cohort (P < 0.05 for both). Conclusion: NAC did not have a significant prognostic impact in patients with resectable synchronous CRLM. However, patients with more than two liver metastases could be good candidates for receiving NAC.

Oncologic Benefit of Adjuvant Therapy in Lateral Pelvic Lymph Node Metastasis following Neoadjuvant Chemoradiotherapy and Lateral Pelvic Lymph Node Dissection.

Background: It remains controversial whether the addition of adjuvant chemotherapy (ACT) to total mesorectal excision (TME) plus lateral pelvic lymph node dissection (LLND) can provide a survival benefit after neoadjuvant chemoradiotherapy (nCRT) in patients with clinically suspected lateral pelvic lymph node metastasis (LPNM). We aim to investigate the effectiveness of ACT after nCRT with TME plus LLND for patients with clinically suspected LPNM. Methods: From January 2015 to December 2021, 138 patients with clinically suspected LPNM who were treated with nCRT followed by TME plus LLND at three institutions were enrolled in this study. The patients were categorized into the ACT group (n = 95) and the non-ACT group (n = 43). Results: The mean follow-up period was 37 months. The 3-year disease-free survival (DFS) rate for the entire cohort was 74.8%. Ninety-five patients (68.8%) received ACT, without any oncologic benefit (3-year DFS rates for the ACT and non-ACT groups were 67.0% and 80.5%, respectively, P = 0.130). Additionally, multivariate analysis showed that lymphatic invasion (hazard ratio [HR]: 6.26, P = 0.005) was an independent risk factor for DFS. Subgroup analyses revealed that for patients ≥ 64 years and those with ypStage 0, the distribution of 95% confidence interval (CI) values tended to focus on the non-ACT strategy. Conclusion: The efficacy of the addition of ACT to TME plus LLND after nCRT in LARC patients with clinically suspected LPNM was not confirmed in this study. Moreover, patients with age ≥ 64 years and those with ypStage 0 may not receive benefit from ACT after nCRT followed by TME plus LLND.

Investigation on the incidence and risk factors of lung cancer among Chinese hospital employees.

OBJECTIVE: In recent years, the lung cancer incidence has grown and the population is younger. We intend to find out the true detection rate of pulmonary nodules and the incidence of lung cancer in the population and search for the risk factors. METHOD: Hospital employees ≥40 years old who underwent low-dose computed tomography (CT) lung cancer screening from January 2019 to March 2022 were selected to record CT-imaging characteristics, pathology, staging, and questionnaires to investigate past history, smoking history, diet, mental health, etc. PM2.5 and radiation intake in radiation-related occupation received monitoring in hospital. RESULT: The detection rate of suspicious pulmonary nodules was 9.1% (233/2552), and the incidence rate of lung cancer (including adenocarcinoma in situ) was 4.0% (103/2552). Morbidity among doctors, nurses, technicians, administers, and logistics was no difference (p = 0.184), but higher in women than in men (4.7% vs 2.4% p = 0.002). The invasiveness increased with age and CT density of nodules (p = 0.018). The relationship between lung cancer morbidity and PM2.5 was not clear (p = 0.543); and no lung cancer has been found in employees related ionizing radiation. CONCLUSION: The high screening rate has brought about a high incidence of lung cancer. At present, the risk factor analysis of lung cancer based on small samples cannot find the direct cause. Most of the ground glass opacity (GGO)s detected by LDCT screening are indolent, but there are also rapidly progressive lung cancer. A predictive model to identify active and indolent GGO is necessary.

Designing an alkali-metal-like superatom Ca3B for ambient nitrogen reduction to ammonia.

Converting earth-abundant nitrogen (N2) gas into ammonia (NH3) under mild conditions is one of the most important issues and a long-standing challenge in chemistry. Herein, a new superatom Ca3B was theoretically designed and characterized to reveal its catalytic performance in converting N2 into NH3 by means of density functional theory (DFT) computations. The alkali-metal-like identity of this cluster is verified by its lower vertical ionization energy (VIE, 4.29 eV) than that of potassium (4.34 eV), while its high stability was guaranteed by the large HOMO-LUMO gap and binding energy per atom (Eb). More importantly, this well-designed superatom possesses unique geometric and electronic features, which can fully activate N2via a "double-electron transfer" mechanism, and then convert the activated N2 into NH3 through a distal reaction pathway with a small energy barrier of 0.71 eV. It is optimistically hoped that this work could intrigue more endeavors to design specific superatoms as excellent catalysts for the chemical adsorption and reduction of N2 to NH3.

BRCA1 Expression and Outcome in Patients With EGFR-Mutant NSCLC Treated With Gefitinib Alone or in Combination With Olaparib.

INTRODUCTION: DNA repair capacity, as exemplified by BRCA1 gene expression, is related with outcome to EGFR tyrosine kinase inhibitors in patients with EGFR-mutant NSCLC. Olaparib, a PARP inhibitor, reduces BRCA1 expression. Olaparib was tested in combination with gefitinib versus gefitinib single agent, as a first-line therapy for patients with EGFR-mutant NSCLC in the GOAL study (trial registration: NCT01513174). Here, we report the results of the biomarker-related prespecified secondary objectives of the GOAL study. METHODS: We evaluated the impact of BRCA1 mRNA expression in 91 patients with EGFR-mutant NSCLC. Of those 91 patients, 51 were randomized to treatment with gefitinib and 40 were randomized to treatment with gefitinib plus olaparib. We explored in vitro whether BRCA1 mRNA levels are related with outcome to gefitinib plus olaparib. The expression levels of 53BP1, CtIP, and AXL were also explored and correlated with the treatment outcome. RESULTS: Overall, as what happened in the GOAL study, no statistically significant difference was observed in median progression-free survival (PFS) between the two treatment arms, for the 91 patients of the present study (p = 0.2419). For patients with high BRCA1 mRNA expression (BRCA1-high group), median PFS was 12.9 months in the gefitinib plus olaparib arm, compared with 9.2 months in the gefitinib arm (p = 0.0449). In the gefitinib arm, median PFS was 9.1 months for the BRCA1-high group and 10.2 months for the BRCA1-low group (p = 0.0193). We observed a more pronounced synergism of gefitinib plus olaparib in cells with higher BRCA1 compared with those with low BRCA1 mRNA expression. CONCLUSIONS: High BRCA1 mRNA expression identified patients with NSCLC who benefited from gefitinib plus olaparib in the GOAL phase 2 clinical trial.

A unique photosystem I reaction center from a chlorophyll d-containing cyanobacterium Acaryochloris marina.

Photosystem I (PSI) is a large protein supercomplex that catalyzes the light-dependent oxidation of plastocyanin (or cytochrome c6 ) and the reduction of ferredoxin. This catalytic reaction is realized by a transmembrane electron transfer chain consisting of primary electron donor (a special chlorophyll (Chl) pair) and electron acceptors A0 , A1 , and three Fe4 S4 clusters, FX , FA , and FB . Here we report the PSI structure from a Chl d-dominated cyanobacterium Acaryochloris marina at 3.3 Å resolution obtained by single-particle cryo-electron microscopy. The A. marina PSI exists as a trimer with three identical monomers. Surprisingly, the structure reveals a unique composition of electron transfer chain in which the primary electron acceptor A0 is composed of two pheophytin a rather than Chl a found in any other well-known PSI structures. A novel subunit Psa27 is observed in the A. marina PSI structure. In addition, 77 Chls, 13 α-carotenes, two phylloquinones, three Fe-S clusters, two phosphatidyl glycerols, and one monogalactosyl-diglyceride were identified in each PSI monomer. Our results provide a structural basis for deciphering the mechanism of photosynthesis in a PSI complex with Chl d as the dominating pigments and absorbing far-red light.

Timing and Origins of Local and Distant Metastases in Lung Cancer.

INTRODUCTION: Metastasis is the primary cause of lung cancer-related death. Nevertheless, the underlying molecular mechanisms and evolutionary patterns of lung cancer metastases are still elusive. METHODS: We performed whole-exome sequencing for 40 primary tumors (PTs) and 61 metastases from 47 patients with lung cancer, of which 40 patients had paired PTs and metastases. The PT-metastasis genomic divergence, metastatic drivers, timing of metastatic dissemination, and evolutionary origins were analyzed using appropriate statistical tools and mathematical models. RESULTS: There were various degrees of genomic heterogeneity when comparing the paired primary and metastatic lesions or comparing metastases of different sites. Multiple metastasis-selected/enriched genetic alterations were found, such as MYC amplification, NKX2-1 amplification, RICTOR amplification, arm 20p gain, and arm 11p loss, and these results were were also featured in a meta-analysis cross-validated using an independent cohort from Memorial Sloan-Kettering Cancer Center database. To elucidate the metastatic seeding time, we applied a metastatic model and found 61.1% of the tumors were late dissemination, in which the metastatic seeding happened approximately 2.74 years before clinical detection. One exception was lymph node metastases whose dissemination time was relatively early. By analyzing the evolutionary origins, we reported that nonlymph node metastases were mainly seeded by the PT (87.5%) rather than the earlier colonized lymph node metastases. CONCLUSIONS: Our results shed light on the molecular features that potentially drive lung cancer metastases. The distinct temporospatial pattern of disease progression revealed that lung cancer was susceptible to either late dissemination or indolent early lymph node metastases, leaving a potential time window to minimize metastases by early cancer detection.

DFT study on the adsorption of 5-fluorouracil on B40, B39M, and M@B40 (M = Mg, Al, Si, Mn, Cu, Zn).

Based on density functional theory, the adsorption behavior of 5-fluorouracil (5-Fu) on B40 and its derivatives has been explored. It was observed that 5-Fu prefers to combine with the corner boron atom of the B40 cage via one of its oxygen atoms, forming a strong polar covalent B-O bond. The adsorption energy of 5-Fu on B40 was calculated to be -11.15 kcal mol-1, and thus, it can be duly released from B40 by protonation in the slightly acidic environment of tumor tissue, which makes for reducing the toxic and side effects of this drug. Additionally, the substituent and embedding effect of Mg, Al, Si, Mn, Cu, and Zn atoms on the drug delivery performance of B40 have been also considered. We hope this work could offer some implications for the potential application of boron-based nanomaterials, such as B40 in drug delivery.

Architecture of the photosynthetic complex from a green sulfur bacterium.

The photosynthetic apparatus of green sulfur bacteria (GSB) contains a peripheral antenna chlorosome, light-harvesting Fenna-Matthews-Olson proteins (FMO), and a reaction center (GsbRC). We used cryo-electron microscopy to determine a 2.7-angstrom structure of the FMO-GsbRC supercomplex from Chlorobaculum tepidum The GsbRC binds considerably fewer (bacterio)chlorophylls [(B)Chls] than other known type I RCs do, and the organization of (B)Chls is similar to that in photosystem II. Two BChl layers in GsbRC are not connected by Chls, as seen in other RCs, but associate with two carotenoid derivatives. Relatively long distances of 22 to 33 angstroms were observed between BChls of FMO and GsbRC, consistent with the inefficient energy transfer between these entities. The structure contains common features of both type I and type II RCs and provides insight into the evolution of photosynthetic RCs.

Numerous long single-stranded DNAs produced by dual amplification reactions for electrochemical detection of exosomal microRNAs.

Exosomal microRNAs (miRNAs) have been explored as an extremely promising biomarker of liquid biopsy for the diagnosis, treatment and prognosis of diseases such as cancer, in which sensitive and selective detection is significant. Herein, we describe the construction and testing of an electrochemical biosensor for the sensitive detection of exosomal miRNAs. It is based on synthetizing numerous long single-stranded DNAs (ssDNAs), which are produced by dual amplification reactions of target-triggered cyclic strand displacement reaction (TCSDR) and primer exchange DNA amplification reaction (PEDAR). In the first signal amplification step, target miRNAs are captured by the hairpin DNA strands (capture probes, Cp) that are immobilized on electrode. After strand unfolding with target capture, primer probes (Pp) enable to hybridize with Cp. And then target miRNAs were displaced for starting the TCSDR process that enable the introduction of numerous primers in Pp. In the second signal amplification step, the primers associated with PEDAR produce copious amounts of elongated ssDNAs. These ssDNAs absorb abundant quantities of methylene blue (MB) that enables the highly sensitive and label-free detection of exosomal miRNAs. This dual amplification process is characterized by a low limit of detection (LOD) of 3.04 aM. In addition, the electrochemical biosensor exhibits good selectivity for miR-21 detection, and shows benefits of simple operation, low cost, portability. Overall, the electrochemical biosensor provides a promising platform for the early diagnosis and screening of tumor biomarkers and the development of devices for point-of-care testing (POCT).

On the Interaction between Superatom Al12Be and DNA Nucleobases/Base Pairs: Bonding Nature and Potential Applications in O2 Activation and CO Oxidation.

The interaction between quasi-chalcogen superatom Al12Be and DNA nucleobases/base pairs has been explored by searching for the most stable Al12Be-X (X = DNA bases and base pairs) complexes. Our results reveal that Al12Be prefers to combine with guanine by two Al-O and Al-N bonds rather than the other DNA bases, no matter in free state or base pair. The formed Al-N and Al-O bonds between Al12Be and DNA bases proved to be strong polar covalent bonds by the Wiberg bond index, nature bond orbitals, atoms in molecules theory, localized molecular orbitals, and electron localization functions analyses. More importantly, it is found that the formed global minimum of Al12Be-G has the ability to activate an oxygen molecule into a peroxide dianion 1O2 2-, which can further catalyze the CO oxidation via the Eley-Rideal mechanism with a small energy barrier of 7.78 kcal/mol. We hope that this study could not only provide an in-depth understanding on the intermolecular interaction between metallic superatoms and DNA at the molecular level but also attract more interest in designing and synthesizing superatom-based heterogeneous catalysts with DNA/nucleobases as basic building blocks.