Improved Performance of Recombinant Protein A Immobilized on Agarose Beads by Site-Specific Conjugation

Protein A affinity adsorbent with high antibody-binding capacity plays a prominent part in the purification of biopharmaceuticals to decrease the manufacturing costs. We describe a site-specific covalent conjugation strategy for protein A to immobilize on agarose beads. Recombinant protein A, which has one cysteine introduced at the C terminus through genetic engineering technology, was immobilized site-specifically on maleimide-functionalized agarose beads by the thiol–maleimide reaction. As a comparison, the recombinant protein A was randomly immobilized on the aldehyde-functionalized agarose beads via free amino groups on the protein surface. The site-specific conjugation of recombinant protein A on the agarose beads was validated through the assay of free SH groups on the adsorbents using the Ellman’s reagent. Adsorbents containing various amounts of protein A were used to adsorb antibody from human plasma. Analysis of immunoturbidimetry showed that the adsorbed fractions contained the 90.1% IgG, 4.2% IgA, and 5.7% IgM. The maximal antibodies-binding capacities with static adsorption and dynamic adsorption were approximately 64 and 50 mg, respectively, per swollen gram for site-specifically conjugated adsorbent and 31 and 26 mg for randomly conjugated adsorbent. Remarkably, the high antibody-binding capacity for site-specifically conjugated adsorbent outperformed the existing commercial protein A Sepharose (approximately 30 mg/g). The orientation of a protein is crucial for its activity after immobilization, and these results demonstrate that the site-specifically conjugated protein molecule is in a functionally active form to interact with the antibody with weak steric hindrance. The proposed approach may be an attractive strategy to synthesize affinity adsorbents with high-binding capacity

Toluene catalytic oxidation over gold catalysts supported on cerium-based high-entropy oxides

A series of cerium-based high-entropy oxide catalysts (the ratio of CeO2 and HEO is 1:1) was prepared by a solid-state reaction method, which exploit their unique structural and performance advantages. The Ce-HEO-T samples can achieve 100% toluene conversion rate above 328 oC when they were used as catalysts directly. Subsequently, the Ce-HEO-500 exhibited the lowest temperature for toluene oxidation was used as a support to deposit different amounts of Au for a further performance improvement. Among all of prepared samples, Au/Ce-HEO-500 with a moderate content of Au (0.5 wt%) exhibited the lowest temperature for complete combustion of toluene (260 oC)，which decreased nearly 70 oC compared with Ce-HEO-500 support. Moreover, it also showed excellent stability for 60 h with 98% toluene conversion rate. Most importantly, under the condition of 5 vol.% H2O vapor, the toluene conversion rate remained unchanged and even increased slightly compared with that in dry air, exhibiting excellent water resistance. Combined with the characterizations of XRD, SEM, TEM, BET, Raman, H2-TPR and XPS, it was found that the high dispersion of active Au NPs, the special high-entropy structure and the synergistic effect between Au and Ce, Co, Cu are the key factors when improving the catalytic performance in the Au/Ce-HEO-500 catalyst.</p

Kinetics and Mechanism of Direct Reaction between CO₂ and Ca(OH)₂ in Micro Fluidized Bed

Even at present it is still difficult to characterize the reaction between CO₂ and Ca­(OH)₂ at high temperature and atmospheric pressure using traditional instruments such as thermogravimetric analyzer and differential scanning calorimeter. This study was devoted to characterizing such a reaction in a newly developed micro fluidized bed reaction analyzer (MFBRA) under isothermal conditions in the temperature range of 773–1023 K. The results indicated that the MFBRA has not only a good adaptability for characterizing the above-mentioned reaction but enables as well a new insight into the mechanism of the reaction. An obvious time delay was identified for the release of the formed steam (H₂O) in comparison with the onset of its CO₂ absorption, which might be attributed to the formation of an unstable intermediate product Ca­(HCO₃)₂ in the reaction process between CO₂ and Ca­(OH)₂. The activation energy for forming Ca­(HCO₃)₂ was found to be about 40 kJ/mol, which is much lower than that of the reaction between CO₂ and CaO

Synthesis of Mono‑<i>O</i>‑alkylated Homo­oxa­calix­[3]­arene and a Protection–Deprotection Strategy for Homo­oxa­calix­[3]­arene

The regioselective synthesis of mono-<i>O</i>-alkylated homo­oxacalix­[3]­arene is accomplished for the first time. The synthetic route relies on two key steps: (i) a facile protection of two OH groups at the lower rim of the homo­oxacalix­[3]­arene and (ii) the deprotection of 9-anthrylmethyl groups via the Pd/C-catalyzed hydrogenation under atmospheric hydrogen. An efficient protection–deprotection strategy for the functionalization of homo­oxacalix­[3]­arene is presented

Synthesis of Mono‑<i>O</i>‑alkylated Homo­oxa­calix­[3]­arene and a Protection–Deprotection Strategy for Homo­oxa­calix­[3]­arene

The regioselective synthesis of mono-<i>O</i>-alkylated homo­oxacalix­[3]­arene is accomplished for the first time. The synthetic route relies on two key steps: (i) a facile protection of two OH groups at the lower rim of the homo­oxacalix­[3]­arene and (ii) the deprotection of 9-anthrylmethyl groups via the Pd/C-catalyzed hydrogenation under atmospheric hydrogen. An efficient protection–deprotection strategy for the functionalization of homo­oxacalix­[3]­arene is presented

A rare and exclusive endoperoxide photoproduct derived from a thiacalix[4]arene crown-shaped derivative bearing a 9,10-substituted anthracene moiety

A rare and exclusive endoperoxide photoproduct was quantitatively obtained from a thiacalix[4]arene crown-shaped derivative upon irradiation at λ=365 nm; the structure was unambiguously confirmed by ¹H/¹³C NMR spectroscopy and X-ray crystallography. The prerequisites for the formation of the endoperoxide photoproduct have also been discussed. Furthermore, the photochemical reaction rate could be greatly enhanced in the presence of the thiacalix[4]arene platform because it served as a host to capture oxygen

4‑Sulfocalix[4]arene/Cucurbit[7]uril-Based Supramolecular Assemblies through the Outer Surface Interactions of Cucurbit[<i>n</i>]uril

Upon mixing of aqueous solutions of the freely soluble building blocks cucurbit[7]­uril (Q[7]) and 4-sulfocalix[4]­arene (SC[4]­A), white microcrystals instantly separate in near-quantitative yield. The driving force for this assembly is suggested to be the outer-surface interaction of the Q­[<i>n</i>]. Dynamic light scattering, scanning electron microscopy, and NMR (diffusion-ordered NMR spectroscopy) analyses have confirmed the supramolecular aggregation of Q[7] and SC[4]­A. Titration ¹H NMR spectroscopy and isothermal titration calorimetry have shown that the interaction ratio of Q[7] and SC[4]­A is close to 3:1. Moreover, the Q[7]/SC[4]­A-based supramolecular assembly can accommodate molecules of some volatile compounds or luminescent dyes. Thus, this work offers a simple and highly efficient means of preparing adsorbent or solid fluorescent materials

Additional file 3: of Whole genome sequencing data of 1110 Mycobacterium tuberculosis isolates identifies insertions and deletions associated with drug resistance

The accession numbers of the validation data set. (XLSX 79 kb

Additional file 2: of Whole genome sequencing data of 1110 Mycobacterium tuberculosis isolates identifies insertions and deletions associated with drug resistance

Table S1. Test for the difference in IGR indel incidence rate between resistant and sensitive strains for each drug among 1110 MTB strains. Table S2. Function enrichment for genes with at-least-one-drug-resistant strain-specific FS mutations in more than two resistant strains. Table S3. Function enrichment for genes with frameshift mutations in the DR-TB, MDR-TB and XDR-TB groups of strains. Table S4. The 20 region markers identified according to adjusted chi-square and Fisher’s exact p-values. Table S5. The 20 identified region markers and corresponding strain numbers. Table S6. Overview of functions for 20 region markers. Table S7. Description of the 20 region markers. Table S8. The distribution of region markers in function categories. Table S9. The 83 identified point markers of FS mutations and IGR indels, showing adjusted p-values. Table S10. The 83 identified point markers of FS mutations and IGR indels, showing strain numbers. Table S11. The identified point markers located in the IGRs expressing sRNA. Table S12. Overview of the functions of the 83 point markers. Table S13. Descriptions of the functions of the 83 point markers. Table S14. The 6 point markers out of the 83 point markers exclusively occurring in resistant strains. Table S15. P-values after logistic regression for the associations between the 20 region markers and drug resistance. Table S16. P-values after logistic regressions for the associations between the 83 point markers and drug resistance. Table S17. Effect of mutations on DNA repair genes. Table S18. Region markers in the validation set overlapping with the 20 region markers. Table S19. Point markers in the validation set overlapping with the 83 point markers. Table S20. Point markers in the 62 samples in which no known drug resistance associated SNPs were found. Table S21. The incidence rate for region markers. Table S22. The incidence rate for point markers. (DOCX 193 kb

Giant Polarization Sensitivity <i>via</i> the Anomalous Photovoltaic Effect in a Two-Dimensional Perovskite Ferroelectric

Polarization sensitivity, which shows great potential in photoelectric detection, is expected to be significantly improved by the ferroelectric anomalous photovoltaic (APV) effect. However, it is challenging to explore new APV-active ferroelectrics due to severe polarization fatigue induced by the leakage current of photoexcited carriers. For the first time, we report a strong APV effect in a 2D hybrid perovskite ferroelectric assembled by alloying mixed organic cations, (HA)2(EA)2Pb3Br10 (1, where HA+ is n-hexylammonium and EA+ is ethylammonium), which has a large spontaneous polarization ∼3.8 μC/cm2 and high a Curie temperature ∼378 K. Its ferroelectricity allows a strong APV effect with an above-bandgap photovoltage up to 7.4 V, which exceeds its bandgap (∼2.7 eV). Most strikingly, based on the dependence on polarized-light angle, this strong APV effect renders the highest level of polarization sensitivity with a giant current ratio of ∼25, far beyond other 2D single-phase materials. This study sheds light on the exploration of APV-active ferroelectrics and inspires their future high-performance optoelectronic device applications