Mechanisms of Alveolar Type 2 Epithelial Cell Death During Acute Lung Injury.

Diffuse alveolar epithelial cell (AEC) death occurs extensively during acute lung injury (ALI). Due to the limited proliferative capacity of alveolar type 1 epithelial (AT1) cells, the differentiation and regenerative capacity of alveolar type 2 epithelial (AT2) cells are required to restore the barrier function of AECs. However, during lung injury, AT1 cells are particularly susceptible to injury, and ATII cells die in the presence of severe or certain types of injury. This disruption ultimately results in a hindrance to the ability of AT2 cells to proliferate and differentiate into AT1 cells in time to repair the extensively damaged AECs. Therefore, understanding the mechanism of injury death of AT2 cells may be beneficial to reverse the above situation. This article reviews the main death modes of AT2 cells, including apoptosis, necrosis, necroptosis, pyroptosis, autophagic cell death, and ferroptosis. It compares the various forms of death, showing that various cell injury death modes have unique action mechanisms and partially overlapping pathways. Studying the mechanism of AT2 cell death is helpful in screening and analyzing the target pathway of AEC barrier function recovery. It opens up new ideas and strategies for preventing and treating ALI.

Self-Supported WO3@RuO2 Nanowires for Electrocatalytic Acidic Water Oxidation.

Developing catalysts with high catalytic activity and stability in acidic media is crucial for advancing hydrogen production in proton exchange membrane water electrolyzers (PEMWEs). To this end, a self-supported WO3@RuO2 nanowire structure was grown in situ on a titanium mesh using hydrothermal and ion-exchange methods. Despite a Ru loading of only 0.098 wt %, it achieves an overpotential of 246 mV for the oxygen evolution reaction (OER) at a current density of 10 mA·cm-2 in acidic 0.5 M H2SO4 while maintaining excellent stability over 50 h, much better than that of the commercial RuO2. After the establishment of the WO3@RuO2 heterostructure, a reduced overpotential of the rate-determining step from M-O* to M-OOH* is confirmed by the DFT calculation. Meanwhile, its enhanced OER kinetics are also greatly improved by this self-supported system in the absence of the organic binder, leading to a reduced interface resistance between active sites and electrolytes. This work presents a promising approach to minimize the use of noble metals for large-scale PEMWE applications.

Mechanistic Insights into the Proton Transfer and Substitution Dynamics of N-Atom Center Reactions: A Study of CH3O- with NH2Cl.

Bimolecular substitution reactions involving N as the central atom have continuously improved our understanding of substitution dynamics. This work used chemical dynamics simulations to investigate the dynamics of NH2Cl with N as the central atom and the multiatomic nucleophile CH3O- and compared these results with the F- + NH2Cl reaction. The most noteworthy difference is in the competition between proton transfer (PT) and the SN2 pathways. Our results demonstrate that, for the CH3O- + NH2Cl system, the PT pathway is considerably more favorable than the SN2 pathway. In contrast, no PT pathway was observed for the F- + NH2Cl system at room temperature. This can be attributed to the exothermic reaction of the PT pathway for the CH3O- + NH2Cl reaction and is coupled with a more stable transition state compared to the substitution pathway. Furthermore, the bulky nature of the CH3O- group impedes its participation in SN2 reactions, which enhances both the thermodynamic and the dynamic advantages of the PT reaction. Interestingly, the atomic mechanism reveals that the PT pathway is primarily governed by indirect mechanisms, similar to the SN2 pathway, with trajectories commonly trapped in the entrance channel being a prominent feature. These trajectories are often accompanied by prolonged and frequent proton exchange or proton abstraction processes. This current work provides insights into the dynamics of N-centered PT reactions, which are useful in gaining a comprehensive understanding of the dynamics behavior of similar reactions.

Ligand Defect Density Regulation in Metal-Organic Frameworks by Functional Group Engineering on Linkers.

Defects in solid materials vitally determine their physicochemical properties; however, facile regulation of the defect density is still a challenge. Herein, we demonstrate that the ligand defect density of metal-organic frameworks (MOFs) with a UiO-66 structural prototype is precisely regulated by tuning the linker groups (X = OMe, Me, H, F). Detailed analyses reveal that the ligand defect concentration is positively correlated with the electronegativity of linker groups, and Ce-UiO-66-F, constructed by F-containing ligands and Ce-oxo nodes, possesses the superior ligand defect density (>25%) and identifiable irregular periodicity. The increase in ligand defect density results in the reduction of the valence state and the coordination number of Ce sites in Ce-UiO-66-X, and this merit further validates the relationship between the defective structure and catalytic performance of CO2 cycloaddition reaction. This facile, efficient, and reliable strategy may also be applicable to precisely constructing the defect density of porous materials in the future.

Atomically Dispersed Dual Metal Sites Boost the Efficiency of Olefins Epoxidation in Tandem with CO2 Cycloaddition.

Tandem catalysis provides an economical and energy-efficient process for the production of fine chemicals. In this work, we demonstrate that a rationally synthesized carbon-based catalyst with atomically dispersed dual Fe-Al sites (ADD-Fe-Al) achieves superior catalytic activity for the one-pot oxidative carboxylation of olefins (conversion ∼97%, selectivity ∼91%), where the yield of target product over ADD-Fe-Al is at least 62% higher than that of monometallic counterparts. The kinetic results reveal that the excellent catalytic performance arises from the synergistic effect between Fe (oxidation site) and Al sites (cycloaddition site), where the efficient CO2 cycloaddition with epoxides in the presence of Al sites (3.91 wt %) positively shifts the oxidation equilibrium to olefin epoxidation over Fe sites (0.89 wt %). This work not only offers an advanced catalyst for oxidative carboxylation of olefins but also opens up an avenue for the rational design of multifunctional catalysts for tandem catalytic reactions in the future.

Brusatol sensitizes endometrial hyperplasia and cancer to progestin by suppressing NRF2-TET1-AKR1C1-mediated progestin metabolism.

Progestin resistance is the main obstacle for the conservative therapy to maintain fertility in women with endometrial cancer. Brusatol was identified as an inhibitor of the NRF2 pathway; however, its impact on progestin resistance and the underlying mechanism remains unclear. Here, we found that brusatol sensitized endometrial cancer to progestin by suppressing NRF2-TET1-AKR1C1-mediated progestin metabolism. Brusatol transcriptionally suppressed AKR1C1 via modifying the hydroxymethylation status in its promoter region through TET1 inhibition. Suppression of AKR1C1 by brusatol resulted in decreased progesterone catabolism and maintained potent progesterone to inhibit endometrial cancer growth. This inhibition pattern has also been found in the established xenograft mouse and organoid models. Aberrant overexpression of AKR1C1 was found in paired endometrial hyperplasia and cancer samples from the same individuals with progestin resistance, whereas attenuated or loss of AKR1C1 was observed in post-treatment samples with well progestin response as compared with paired pre-treatment tissues. Our findings suggest that AKR1C1 expression pattern may serve as an important biomarker of progestin resistance in endometrial cancer.

The mutation features and geographical distributions of the surface glycoprotein (S gene) in SARS-CoV-2 strains: A comparative analysis of the early and current strains.

The surface glycoprotein (S protein) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was used to develop coronavirus disease 2019 (COVID-19) vaccines. However, SARS-CoV-2, especially the S protein, has undergone rapid evolution and mutation, which has remained to be determined. Here, we analyzed and compared the early (12 237) and the current (more than 10 million) SARS-CoV-2 strains to identify the mutation features and geographical distribution of the S gene and S protein. Results showed that in the early strains, most of the loci were with relative low mutation frequency except S: 23403 (4486 strains), while in the current strains, there was a surge in the mutation strains and frequency, with S: 23403 constantly being the highest one, but tremendously increased to approximately 1050 times. Furthermore, D614 (S: 23403) was one of the most highly frequent mutations in the S protein of Omicron as of March 2022, and most of the mutant strains were still from the United States, and the United Kingdom. Further analysis demonstrated that in the receptor-binding domain, most of the loci with low mutation frequency in the early strains, while S: 22995 was nowadays the most prevalent loci with 3 122 491 strains in the current strains. Overall, we compare the mutation features of the S region in SARS-CoV-2 strains between the early and the current stains, providing insight into further studies in concert with emerging SARS-CoV-2 variants for COVID-19 vaccines.

Different Bonding Defects on Dual-Metal Single-Atom Electrocatalyst CoZnN6 (OH) for Oxygen Reduction Reaction.

Since dual-metal single-atom catalyst (CoZnN/C) has been experimentally synthesized by atomically arching CoZn on N-doped carbon nanofibers and exhibited potential electrocatalysis activity towards oxygen reduction reaction (ORR), we perform first-principles calculations to identify the highly active sites at different defects by comparing the four-step ORR processes on the constructed four CoZnN6 models on graphene. The corresponding N-edge effect, dopant effect, and C-edge ring-closing effect are evaluated with the ORR evolution on different bonding environments, including pristine CoZnN6 (OH), nanoribbon (NR) along zigzag direction, substitution of carbon/oxygen (C/O substitution), and C-edge ring-closing configurations. OH-ligand is shown to significantly improve the ORR activities for all the considered structures. Especially, C-substituted CoZnN6 (OH), NR-CoZnN5 O(OH) and CoZnN6 (OH) with C-edge-effect exhibit obviously reduced overpotentials (ηlim =0.28, 0.48 and 0.41 V) of rate-determining steps among all the considered nine candidates. By plotting the relationship between the limiting potentials (Ulim ) and free energies of intermediate *OH (ΔGOH* ), two prior catalysts of pristine-CoZnN5 C(OH) and defect-CoZnN6 CH(OH) are located near the top of the volcano curve with higher Ulim =0.95 and 0.82 V than Pt(111) (Ulim =0.80 V), implying that C-substitution could facilitate ORR performance in pristine- and defect-CoZnN6 (OH) bonding situation.

Theoretical Screening of Transition Metal Doped Defective MoS2 as Efficient Electrocatalyst for CO Conversion to CH4.

CO is a key intermediate during electrochemical CO2 conversion. The deep reduction of CO to value-added chemical products is a crucial strategy for effective carbon utilization. Single transition metal atoms supported by two-dimensional material present a novel paragon for various catalytic reactions. Herein, we employ first principle theory to study a series of single 3d-transition metal atoms supported by monolayered MoS2 with S vacancy as efficient electrocatalyst for CO electroreduction to CH4 . The screening result indicates that Cr doped defective MoS2 (labeled as Cr/Sv -MoS2 ) is beneficial to electroreduction of CO to CH4 , with even less negative limiting potential (-0.32 V) than Cu that has been widely studied as the most promising electrocatalyst in experiment. The outstanding activity is derived from the regulation of the d-band-center of doped Cr and Mo atoms exposed on the surface. This discovery provides a theoretical basis for the preparation of future electrocatalysts for CORR.

Assessing the depression risk in the U.S. adults using nomogram.

BACKGROUND: Depression has received a lot of attention as a common and serious illness. However, people are rarely aware of their current depression risk probabilities. We aimed to develop and validate a predictive model applicable to the risk of depression in US adults. METHODS: This study was conducted using the database of the National Health and Nutrition Examination Survey (NHANES, 2017-2012). In particular, NHANES (2007-2010) was used as the training cohort (n = 6015) for prediction model construction and NHANES (2011-2012) was used as the validation cohort (n = 2812) to test the model. Depression was assessed (defined as a binary variable) by the Patient Health Questionnaire (PHQ-9). Socio-demographic characteristics, sleep time, illicit drug use and anxious days were assessed using a self-report questionnaire. Logistic regression analysis was used to evaluate independent risk factors for depression. The nomogram has the advantage of being able to visualize complex statistical prediction models as risk estimates of individualized disease probabilities. Then, we developed two depression risk nomograms based on the results of logistic regression. Finally, several validation methods were used to evaluate the prediction performance of nomograms. RESULTS: The predictors of model 1 included gender, age, income, education, marital status, sleep time and illicit drug use, and model 2, furthermore, included anxious days. Both model 1 and model 2 showed good discrimination ability, with a bootstrap-corrected C index of 0.71 (95% CI, 0.69-0.73) and 0.85 (95% CI, 0.83-0.86), and an externally validated C index of 0.71 (95% CI, 0.68-0.74) and 0.83 (95% CI, 0.81-0.86), respectively, and had well-fitted calibration curves. The area under the receiver operating characteristic curve (AUC) values of the models with 1000 different weighted random sampling and depression scores of 10-17 threshold range were higher than 0.7 and 0.8, respectively. Calculated net reclassification improvement (NRI) and integrated discrimination improvement (IDI) showed the discrimination or accuracy of the prediction models. Decision curve analysis (DCA) demonstrated that the depression models were practically useful. The network calculators work for participants to make personalized predictions. CONCLUSIONS: This study presents two prediction models of depression, which can effectively and accurately predict the probability of depression as well as helping the U.S. civilian non-institutionalized population to make optimal treatment decisions.

Laser-assisted hatching zona thinning does not improve the pregnancy outcomes of poor-quality blastocysts in frozen-thawed embryo transfer cycle: a retrospective cohort study.

It had been suggested, after facilitating the hatching process, improved pregnancy outcomes could be attained in embryos with thick and hard zona. This study aimed to determine the effect of zona thinning on pregnancy outcomes in poor-quality frozen-thawed blastocysts. This retrospective study included 230 women (≤ 40 years) who underwent frozen embryo transfer of poor-quality blastocysts (scored < 3BB). In total, 105 patients were in the assisted hatching group in which the zona was thinned by laser before transfer and 125 patients were in the control group in which the blastocysts were non-manipulated. Patients' demographics, cycle characteristics, and pregnancy outcomes were compared between the assisted hatching group and the control group. Further, regression analysis was applied to test the correlation between assisted hatching and live birth. All parameters in the patients' demographic characteristics and the cycle's characteristics were not significantly different between two groups. As for pregnancy outcomes, the second trimester pregnancy loss was significantly higher in the assisted hatching group (P = 0.035). Other pregnancy outcomes, including implantation rate, clinical pregnancy rate, biochemical miscarriage rate, the first trimester pregnancy loss, ongoing pregnancy rate, and live birth rate were comparable between two groups. The logistic regression analysis demonstrated no association between live birth and assisted hatching (univariate, OR = 0.787, P > 0.05; multivariate, OR = 0.652, P > 0.05), and the area under the receiver operating characteristic curve of the regression model was almost 0.7. It suggested that zona thinning may not be supposed to perform on poor-quality, frozen-thawed blastocysts. The indications of assisted hatching were still needed to further investigate.

Identification and Localisation Algorithm for Sugarcane Stem Nodes by Combining YOLOv3 and Traditional Methods of Computer Vision.

Sugarcane stem node identification is the core technology required for the intelligence and mechanization of the sugarcane industry. However, detecting stem nodes quickly and accurately is still a significant challenge. In this paper, in order to solve this problem, a new algorithm combining YOLOv3 and traditional methods of computer vision is proposed, which can improve the identification rate during automated cutting. First, the input image is preprocessed, during which affine transformation is used to correct the posture of the sugarcane and a rotation matrix is established to obtain the region of interest of the sugarcane. Then, a dataset is built to train the YOLOv3 network model and the position of the stem nodes is initially determined using the YOLOv3 model. Finally, the position of the stem nodes is further located accurately. In this step, a new gradient operator is proposed to extract the edge of the image after YOLOv3 recognition. Then, a local threshold determination method is proposed, which is used to binarize the image after edge extraction. Finally, a localization algorithm for stem nodes is designed to accurately determine the number and location of the stem nodes. The experimental results show that the precision rate, recall rate, and harmonic mean of the stem node recognition algorithm in this paper are 99.68%, 100%, and 99.84%, respectively. Compared to the YOLOv3 network, the precision rate and the harmonic mean are improved by 2.28% and 1.13%, respectively. Compared to other methods introduced in this paper, this algorithm has the highest recognition rate.

Effects of tumor necrosis factor-α-induced exosomes on the endothelial cellular behavior, metabolism and bioenergetics.

OBJECTIVE: To investigate the effects of TNF-α-induced exosomes release on the biological behavior, metabolism, and bioenergetics of HUVECs. METHODS: Exosomes were isolated from conditioned media of HUVECs by ultracentrifugation after treatment with or without TNF-α. HUVECs were treated with or without TNF-α, or different concentrations of exosomes isolated from conditioned media with or without TNF-α induction (TExo and CExo , respectively). RESULTS: The results showed that TNF-α significantly inhibited migration, tube formation, and increased apoptosis rate of HUVECs compared with controls. Furthermore, TNF-α-induced exosomes (TExo ) rather than CExo , indicated similar effects to inhibit migration, tube formation and promote endothelial apoptosis. Although TNF-α treatment did not show a statistical difference, TExo significantly inhibited extracellular OCR compared with controls. TExo could significantly inhibited intracellular OCR in a hypoxia condition. TNF-α significantly increased L-ECA compared with control cells, and TExo showed similar stimulative effect on L-ECA. CONCLUSIONS: TNF-α-induced exosomes could significantly (a) change migration, tube formation, and apoptosis; (b) inhibit endothelial extracellular OCR and intracellular OCR (hypoxia); (c) increase glycolysis rate of the endothelial cells. These data provide new evidence for exploring endothelial behavior regulation using exosomes and their effects on endothelial metabolism and bioenergetics.

Surface Modifications of Ti2 CO2 for Obtaining High Hydrogen Evolution Reaction Activity and Conductivity: A Computational Approach.

The identification of hydrogen evolution reaction (HER) catalysts with high conductivity and high activity is the top priority in the development of renewable energy. Oxygen-terminated Ti2 C (Ti2 CO2 ), as one of the typical MXenes, shows good HER Gibbs free energy (ΔGH ) at low hydrogen coverage, whereas the large band gap of approximately 1.0 eV limits its conductivity capability. By doping phosphor (P) or sulfur (S) to partially substitute the surficial O, the average free energy (ΔGHa ) at various hydrogen coverages has been draggd to approach zero, and the conductivity is also significantly improved by narrowing the band gap to lower than 0.3 eV. Partial charge analysis indicates that doping P or S on the surface induces the diffusion of electrons on oxygen from O 2px to O 2pz , resulting in O 2pz reaction with H 1s. The facial overlapping of H 1s with O 2pz will strengthen the binding strength, hence lowering ΔGH . The energy shift toward Fermi level of Ti 3d after P or S doping contributes to the reduced band gap and high conductivity. Surficial O or P vacancies are created to evaluate the vacancy effect on HER performance, which not only improves ΔGHa and conductivity but also leads to a low reaction barrier of H2 O splitting (<0.2 eV). The armchair nanoribbon (ANR) displays improved HER activity by P-doping at 50% ratio. Our research shows that modification of end-group in MXenes can effectively improve HER catalytic activity and conductivity, which is expected to promote their potential applications in electrocatalysis and energy conversion.

Crystal structure of the multidrug transporter P-glycoprotein from Caenorhabditis elegans.

P-glycoprotein (P-gp) is an ATP-binding cassette transporter that confers multidrug resistance in cancer cells. It also affects the absorption, distribution and clearance of cancer-unrelated drugs and xenobiotics. For these reasons, the structure and function of P-gp have been studied extensively for decades. Here we present biochemical characterization of P-gp from Caenorhabditis elegans and its crystal structure at a resolution of 3.4 ångströms. We find that the apparent affinities of P-gp for anticancer drugs actinomycin D and paclitaxel are approximately 4,000 and 100 times higher, respectively, in the membrane bilayer than in detergent. This affinity enhancement highlights the importance of membrane partitioning when a drug accesses the transporter in the membrane. Furthermore, the transporter in the crystal structure opens its drug pathway at the level of the membrane's inner leaflet. In the helices flanking the opening to the membrane, we observe extended loops that may mediate drug binding, function as hinges to gate the pathway or both. We also find that the interface between the transmembrane and nucleotide-binding domains, which couples ATP hydrolysis to transport, contains a ball-and-socket joint and salt bridges similar to the ATP-binding cassette importers, suggesting that ATP-binding cassette exporters and importers may use similar mechanisms to achieve alternating access for transport. Finally, a model of human P-gp derived from the structure of C. elegans P-gp not only is compatible with decades of biochemical analysis, but also helps to explain perplexing functional data regarding the Phe335Ala mutant. These results increase our understanding of the structure and function of this important molecule.

New Particle Filter Based on GA for Equipment Remaining Useful Life Prediction.

Remaining useful life (RUL) prediction of equipment has important significance for guaranteeing production efficiency, reducing maintenance cost, and improving plant safety. This paper proposes a novel method based on an new particle filter (PF) for predicting equipment RUL. Genetic algorithm (GA) is employed to improve the particle leanness problem that arises in traditional PF algorithms, and a time-varying auto regressive (TVAR) model and Akaike Information Criterion (AIC) are integrated to establish the dynamic model for PF. Moreover, starting prediction time (SPT) detection method based on hypothesis testing theory is presented, by which SPT of equipment RUL can be adaptively detected. In order to verify the effectiveness of the methods proposed in this study, a simulation test and the accelerating fatigue test of a rolling element bearing are designed for RUL prediction. The test results show the methods proposed in this study can accurately predict the RUL of the rolling element bearing, and it performs better than the traditional PF algorithm and support vector machine (SVM) in the RUL prediction.

Effect of Milk Powder Supplementation with Different Calcium Contents on Bone Mineral Density of Postmenopausal Women in Northern China: A Randomized Controlled Double-Blind Trial.

The objective of this study is to examine the effect of milk powder supplementation with different calcium contents on bone mineral density (BMD) in postmenopausal Chinese women, and to determine a more appropriate dose of calcium supplementation. A 2-year, randomized controlled double-blind trial. Postmenopausal women (n = 210) aged 50-65 years were recruited and assigned randomly into three calcium supplementation groups. All participants received milk powder supplementation with different calcium contents (300, 600, and 900 mg per day for groups A, B, and C, respectively) and all groups received 800 IU of vitamin D per day. During the follow-up period, BMD of the left hip and lumbar spine (as the main indicator) was measured using dual-energy X-ray absorptiometry at the baseline, 1 and 2 years. Both three BMD measures and the changes of BMD over 2 years were used to analyze. Before adjusting for covariates, BMD in group A of the lumbar spine and groups A and B of greater trochanter decreased significantly from the baseline over time but increased significantly in the rest groups of the lumbar spine and greater trochanter and in three groups of Ward's triangle. There were significant differences across the three groups for changes of BMD in the greater trochanter and Ward's triangle. When adjusting for covariates, there were significant decreases with time in group A of the spine (P = 0.001), groups A and B of greater trochanter (P = 0.0002 and P = 0.04, respectively) and increases in groups B and C of Ward's triangle (P = 0.03 and P = 0.004, respectively). BMD change in the greater trochanter was significantly different among three groups. For healthy postmenopausal women, high calcium milk powder supplementation was better in retarding bone loss than medium and low calcium in the greater trochanter. Considering the dietary calcium intake of postmenopausal women in north of China, a dose of 900 mg/day is considered as the most appropriate calcium supplementation for greater trochanter but not for other sites.

Investigation on the interaction of cefpirome sulfate with lysozyme by fluorescence quenching spectroscopy and synchronous fluorescence spectroscopy.

The reaction mechanism of cefpirome sulfate with lysozyme at different temperatures (298, 310 and 318 K) was investigated using fluorescence quenching and synchronous fluorescence spectroscopy under simulated physiological conditions. The results clearly demonstrated that cefpirome sulfate caused strong quenching of the fluorescence of lysozyme by a static quenching mechanism. The binding constants obtained using the above methods were of the same order of magnitude and very similar. Static electric forces played a key role in the interaction between cefpirome sulfate and lysozyme, and the number of binding sites in the interaction was close to 1. The values of Hill's coefficients were > 1, indicating that drugs or proteins showed a very weakly positive cooperativity in the system. In addition, the conclusions obtained from the two methods using the same equation were consistent. The results indicated that synchronous fluorescence spectrometry could be used to study the binding mechanism between drug and protein, and was a useful supplement to the fluorescence quenching method. In addition, the effect of cefpirome sulfate on the secondary structure of lysozyme was analyzed using circular dichroism spectroscopy.

Investigation on the effect of fluorescence quenching of bovine serum albumin by cefoxitin sodium using fluorescence spectroscopy and synchronous fluorescence spectroscopy.

The reaction mechanism of cefoxitin sodium with bovine serum albumin was investigated using fluorescence spectroscopy and synchronous fluorescence spectroscopy at different temperatures. The results showed that the change of binding constant of the synchronous fluorescence method with increasing temperature could be used to estimate the types of quenching mechanisms of drugs with protein and was consistent with one of fluorescence quenching method. In addition, the number of binding sites, type of interaction force, cooperativity between drug and protein and energy-transfer parameters of cefoxitin sodium and bovine serum albumin obtained from two methods using the same equation were consistent. Electrostatic force played a major role in the conjugation reaction between bovine serum albumin and cefoxitin sodium, and the type of quenching was static quenching. The primary binding site for cefoxitin sodium was sub-hydrophobic domain IIA, and the number of binding sites was 1. The value of Hill's coefficients (nH ) was approximately equal to 1, which suggested no cooperativity in the bovine serum albumin-cefoxitin sodium system. The donor-to-acceptor distance r < 7 nm indicated that static fluorescence quenching of bovine serum albumin by cefoxitin sodium was also a non-radiation energy-transfer process. The results indicated that synchronous fluorescence spectrometry could be used to study the reaction mechanism between drug and protein, and was a useful supplement to the conventional method. Copyright © 2015 John Wiley & Sons, Ltd.

Using resonance light scattering and UV/vis absorption spectroscopy to study the interaction between gliclazide and bovine serum albumin.

At different temperatures (298, 310 and 318 K), the interaction between gliclazide and bovine serum albumin (BSA) was investigated using fluorescence quenching spectroscopy, resonance light scattering spectroscopy and UV/vis absorption spectroscopy. The first method studied changes in the fluorescence of BSA on addition of gliclazide, and the latter two methods studied the spectral change in gliclazide while BSA was being added. The results indicated that the quenching mechanism between BSA and gliclazide was static. The binding constant (Ka ), number of binding sites (n), thermodynamic parameters, binding forces and Hill's coefficient were calculated at three temperatures. Values for the binding constant obtained using resonance light scattering and UV/vis absorption spectroscopy were much greater than those obtained from fluorescence quenching spectroscopy, indicating that methods monitoring gliclazide were more accurate and reasonable. In addition, the results suggest that other residues are involved in the reaction and the mode 'point to surface' existed in the interaction between BSA and gliclazide. Copyright © 2015 John Wiley & Sons, Ltd.