Access to 4-Alkenylated Coumarins via Ruthenium-Catalyzed Olefinic C-H Alkenylation of Coumarins with Modifiable and Removable Directing Groups.

The ruthenium-catalyzed activation of the C4 position of coumarins for coupling with acrylates was described using modifiable ketone as a directing group. The alkenylation reaction provided a direct approach to prepare previously inaccessible 4-alkenylated coumarins with operational simplicity and high atom-economy. This protocol also worked well with coumarin-3-carboxylic acids to unveil a rare instance of a tandem alkenylation/decarboxylation reaction. The potential value of this approach was further highlighted by the efficient synthesis of several heterocyclic fused coumarin derivatives.

Colorimetric determination of the early biomarker hypoxia-inducible factor-1 alpha (HIF-1α) in circulating exosomes by using a gold seed-coated with aptamer-functionalized Au@Au core-shell peroxidase mimic.

An ultra-sensitive method is described here for the determination of HIF-1α (an early biomarker for myocardial infarction) in circulating exosomes in serum. Gold nanospheres were functionalized with a HIF-1α-binding aptamer via sulfydryl chemistry. The apt-AuNP-coated gold seeds were grown by seed-mediated growth, and this significantly increased the peroxidase-mimicking property the nanoparticles. A chromogenic system composed of 3,3'5,5'-tetramethylbenzidine and hydrogen peroxide was used. Absorbance at 652 nm increases linearly in the 0.3 to 200 ng L-1 HIF-1α concentration range, and the limit of detection is 0.2 ng L-1. The method was tested by analyzing rat serum from isoproterenol (ISO)-induced myocardial infarction. It allows HIF-1α to be directly determined in a 25 µL sample without preconcentration. The assay is not interfered by the polydispersity of exosomes released under either health and disease conditions. Graphical abstractGold nanospheres were functionalized with a HIF-1α-binding aptamer via sulfydryl chemistry. Nanosized gold seed particles were then modified with the functionalized gold nanospheres, and this strongly increases the peroxidase-mimicking activity of the nanomaterial. By using the tetramethylbenzidine/H2O2 chromogenic system, the absorbance at 652 nm increases linearly in the 0.3 to 200 ng L-1 HIF-1α concentration range.

Competitive Protein Binding Assay of Naproxen by Human Serum Albumin Functionalized Silicon Dioxide Nanoparticles.

We have developed a new competitive protein binding assay (CPBA) based on human serum albumin functionalized silicon dioxide nanoparticles (nano-SiO2-HSA) that can be used for naproxen determination in urine. Compared with a conventional multi-well reaction plate, nano-SiO2 with a high surface-area-to-volume ratio could be introduced as a stationary phase, markedly improving the analytical performance. Nano-SiO2-HSA and horseradish peroxidase-labeled-naproxen (HRP-naproxen) were prepared for the present CPBA method. In this study, a direct competitive binding to nano-SiO2-HSAwas performed between the free naproxen in the sample and HRP-naproxen. Thus, the catalytic color reactions were investigated on an HRP/3,3'5,5'-tetramethylbenzidine (TMB)/H2O2 system by the HRP-naproxen/nano-SiO2-HSA composite for quantitative measurement via an ultraviolet spectrophotometer. A series of validation experiments indicated that our proposed methods can be applied satisfactorily to the determination of naproxen in urine samples. As a proof of principle, the newly developed nano-CPBA method for the quantification of naproxen in urine can be expected to have the advantages of low costs, fast speed, high accuracy, and relatively simple instrument requirements. Our method could be capable of expanding the analytical applications of nanomaterials and of determining other small-molecule compounds from various biological samples.

An efficient direct competitive nano-ELISA for residual BSA determination in vaccines.

A simple, fast, and highly sensitive direct competitive enzyme-linked immunosorbent assay (ELISA) based on bovine serum albumin (BSA) antigen labeled amine-terminated silicon dioxide (SiO2-NH-BSA) nanoparticles was developed to determine residual BSA in vaccines. As nano-ELISA using nanomaterials with a very high surface-to-volume ratio has emerged as a promising strategy, SiO2-NH-BSA nanoparticles were prepared in this study by the coupling of BSA to SiO2 nanoparticles modified with amidogen, followed by the quantification of BSA via a direct competitive binding of BSA-antigen-labeled SiO2 nanoparticles to anti-BSA antibody conjugated with horseradish peroxidase. The validation study showed that the linear range of this method was from 1 to 90 ng/mL (r = 0.998) and the limit of detection was 0.67 ng/mL. The intra-assay and interassay coefficients of variation were less than 10% at three concentrations (10, 40, and 70 ng/mL), and the recovery was 92.4%, indicating good specificity. As a proof of principle, this new method was applied in the analysis of residual BSA in five different vaccines. Bland-Altman plots revealed that there was no significant difference in the accuracy and precision between our new method and the most commonly used sandwich ELISA. From the results taken together, the new method developed in this study is more sensitive and facile with lower cost and thus demonstrated potential to be applied in the quality control of biological products. Graphical Abstract Illustration of the procedures of the direct competitive enzyme immunoassay.

Application of serum exosomal hypoxia-inducible factor-1 alpha (HIF-1α) as potential circulating biomarker for bacterial peritonitis.

Bacterial peritonitis is a severe disease that diagnosis remains challenging for clinicians. Measuring biomarkers might be a rapid diagnostic method. The objective of this study was to analyze and evaluate the dynamic changes in HIF-1α concentration in serum exosomes during bacterial peritonitis. The pre-clinical application value of serum exosomal HIF-1α was evaluated via imipenem and cilastatin sodium (ICS) intervention in the bacterial peritonitis model. The new colorimetric method to quantitate dynamic expression changes of HIF-1α in serum exosomes during bacterial peritonitis was established by our team via using the gold seed-coated with aptamer-functionalized Au @ Au core-shell peroxidase mimic. The typical inflammatory cytokines of bacterial peritonitis were also measured. Following intramuscular administration with ICS, In-Vivo Xtreme imaging system was used to visualize abdominal infection extent. Meanwhile, HIF-1α concentration in rat serum exosomes and pro-inflammatory factors levels in serum were detected. The serum typical inflammatory cytokines levels were elevated in GFP-labeled E.coli induced bacterial peritonitis. The serum exosomal HIF-1α levels clearly increased at 12 h, reached the peak during 24-48 h, and then gradually decreased at 72 h. Following intramuscular administration with ICS, the abdominal infection extent, HIF-1α concentration in serum exosomes, and the serum pro-inflammatory factors levels were reduced at 24 h in GFP-labeled E. coli induced bacterial peritonitis model. The serum exosomal HIF-1α can be used as a biomarker in the early stage of bacterial peritonitis, which might provide the basic research in the pre-clinical for further predicting and monitoring the pathological process of bacterial peritonitis.

Astragaloside IV Derivative (LS-102) Alleviated Myocardial Ischemia Reperfusion Injury by Inhibiting Drp1Ser616 Phosphorylation-Mediated Mitochondrial Fission.

Our previous studies showed that Astragaloside IV derivative (LS-102) exhibited potent protective function against ischemia reperfusion (I/R) injury, but little is known about the mechanisms. Mitochondrial fission regulated by dynamin-related protein1 (Drp1) is a newly recognized determinant of mitochondrial function. This study aimed to investigate the protection of LS-102 on mitochondrial structure and function by regulating the activity of Drp1 using models of H9c2 cardiomyocyte injury induced by hypoxia-reperfusion (H/R), and rat heart injury induced by I/R. The results showed that LS-102 significantly decreased apoptosis, levels of ROS, CK, LDH, and calcium, upregulating MMP, and the Bax/Bcl-2 ratio in cardiomyocytes during I/R injury. Furthermore, LS-102 prevented I/R-induced mitochondrial fission by decreasing Drp1's mitochondrial localization through decreasing the phosphorylation of Drp1 at Ser616 (Drp1Ser616) and increasing the phosphorylation of Drp1 at Ser637 (Drp1Ser637) in H9c2 cells. Importantly, we also robustly confirmed Drp1Ser616 as a novel GSK-3ß phosphorylation site. GSK-3ß-mediated phosphorylation at Drp1Ser616 may be associated with mitochondrial fission during I/R of cardiomyocytes. In conclusion, LS-102 exerts cardio protection against I/R-induced injury by inhibiting mitochondrial fission via blocking GSK-3ß-mediated phosphorylation at Ser616 of Drp1.

Development of a nano-SiO2 based enzyme-linked ligand binding assay for the determination of ibuprofen in human urine.

The application domains of classic enzyme-linked ligand binding assay (ELBA) is relatively narrow due to the high cost and hardly available binding receptor. In here, we described for the first time the possibility of developing a new ELBA based on silica nanoparticles (nano-SiO2) to assess the ibuprofen in human urine. Nano-SiO2 with a large surface area was introduced as stationary phase to improve the analytical performance. In the experiment, a competitively binding procedure with human serum albumin (HSA) was performed between the ibuprofen presented in sample and horseradish peroxidase labeled ibuprofen (HRP-ibuprofen) subsequently added. After centrifugal separation, the HRP/ibuprofen/nano-SiO2 composite catalyzed the substrate solution (TMB/H2O2) with a color change from colorless to yellow for quantitative measurement via an ultraviolet spectrophotometer. As a validation of the new principle, the developed nano-ELBA method was applied in the determination of ibuprofen excreted in human urine with excellent performance. This detection range only depends on the solubility of ligand and sensitivity of UV spectrophotometer. Our results indicate that this new method demonstrated to be able to rapidly and adequately determine the concentration of components in biological samples and advocate its effectiveness for various applications.