Immobilization of growing cells by polyethyleneimine-modified alginate

A unique polymer matrix that is suitable for immobilizing growing cells has been developed. Alginate was chemically modified with polyethyleneimine (PEI), and the resultant polymer aggregate was evaluated as a cell carrier. Our method of immobilization depends on reversible gelation of the PEI-modified alginate. Our hypothesis is that immobilized cells grow by dissolving the surrounding gel matrix; the dissolved polymer adduct is displaced peripherally and gelled again by the influx of calcium ion from the surrounding fermentation broth, retaining both cells and carrier polymer in the gel beads. Thus, the immobilized cells gain space for growth by expanding the carrier matrix. The PEI modification offers the following advantages: (1) improved mechanical strength; (2) improved cell retention; (3) increased catalyst life; (4) ease of pelletization; and (5) an apparent bacteriostatic capability. When immobilized yeast cells were applied to a continuous ethanol fermentation, 94% theoretical conversion of glucose to ethanol was observed, with a reactor productivity of 15–30 g/L/h in a nonsterile reactor. A 3-mo catalyst life and minimal cell washout were observed.     

Relationship between flavonoid structure and inhibition of farnesyl protein transferase

Flavonoids are well-known phytochemicals that are produced by various plants in high quantities. The chemopreventive activity of flavonoids is dependent on their structural features. The studies of structure-FPTase inhibitory activity indicated that the number, position and substitution of hydroxyl groups of the A and B rings of flavonoid, and unsaturation of the C2-C3 bond are important factors affecting inhibition on FPTase by flavonoids. A couple of flavonoids inhibited FPTase and also the growth of human tumor cell lines, especially butein, which strongly inhibited the growth of colon cancer cell line (HCT116). However, flavanones and flavanols did not inhibit FPTase nor the growth of tumor cells.     

Sonication treatment of CdTe/CdS semiconductor nanocrystals and their bio-application

Ultrasonic irradiation of core/shell structures was shown to lead to low toxicity and high quantum yields relative to thermal methods for bio-application.     

Synthesis of 3‐Aryl‐2,5‐Dihydro‐1‐Benzoxepines from Phenol via Ring‐Closing Metathesis

In this paper, the synthesis of 3‐aryl‐2,5‐dihydro‐1‐benzoxepines is described. While the reaction was started from phenol and based on the sequential reactions such as Claisen rearrangement, O‐alkylation, Wittig reaction, and ring‐closing metathesis (RCM), a series of new 3‐aryl‐1‐benzoxepines were prepared in good overall yields.     

Inhibition of LPS-induced cyclooxygenase 2 and nitric oxide production by transduced PEP-1-PTEN fusion protein in Raw 264.7 macrophage cells

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor suppressor. Although it is well known to have various physiological roles in cancer, its inhibitory effect on inflammation remains poorly understood. In the present study, a human PTEN gene was fused with PEP-1 peptide in a bacterial expression vector to produce a genetic in-frame PEP-1-PTEN fusion protein. The expressed and purified PEP-1-PTEN fusion protein were transduced efficiently into macrophage Raw 264.7 cells in a time- and dose-dependent manner when added exogenously in culture media. Once inside the cells, the transduced PEP-1-PTEN protein was stable for 24 h. Transduced PEP-1-PTEN fusion protein inhibited the LPS-induced cyclooxygenase 2 (COX-2) and iNOS expression levels in a dose-dependent manner. Furthermore, transduced PEP-1-PTEN fusion protein inhibited the activation of NF-κB induced by LPS. These results suggest that the PEP-1-PTEN fusion protein can be used in protein therapy for inflammatory disorders.     

Benzimidazole-based receptor for Zn2+ recognition in a biological system: a chemosensor operated by retarding the excited state proton transfer

A new benzimidazole-based receptor was developed with potential functional groups for excited state proton transfer (ESPT) through keto–enol tautomerism. The enol form of the receptor selectively recognizes Zn²⁺, allowing it to be used as a ratiometric fluorescence sensor in DMSO/CH₃CN (1:9, v/v). The binding event triggers a blue-shifted band through the modulation of charge transfer transitions. The sensor is applicable for recognizing Zn²⁺ in the cytoplasm of Saccharomyces cerevisiae.     

Expression and Immunogenicity of a Recombinant Chimeric Protein of Human Colorectal Cancer Antigen GA733-2 and an Fc Antibody Fragment in Stably Transformed Drosophila melanogaster S2 Cells

Human colorectal cancer antigen GA733-2 fused to the immunoglobin Fc fragment (GA733-2-Fc) was expressed in stably transformed Drosophila melanogaster S2 cells, and the immunogenicity of recombinant GA733-2-Fc was investigated in mice. Recombinant GA733-2-Fc was secreted into a culture medium with a molecular mass of approximately 65 kDa. Recombinant GA733-2-Fc was purified to homogeneity using affinity fractionation with Protein A sepharose 4 Fast Flow. Recombinant GA733-2-Fc proteins elicited production of specific antibodies against recombinant GA733-2 by immunization through an intraperitoneal route. Recombinant GA733-2-Fc-induced antibodies showed a binding activity to human colorectal carcinoma HCT-116 cells. Secretory recombinant GA733-2-Fc from Drosophila S2 cell systems can be used as an effective experimental antigen for research in cancer vaccine development.     

One pot synthesis of RGO/PbS nanocomposite and its near infrared photoresponse study

We report the synthesis and characterization of lead sulfide (PbS) decorated reduced graphene oxide (RGO) nanocomposite materials. The materials were synthesized in a one-step solvothermal reaction where the reduction of graphene oxide, synthesis of PbS nanoparticle and decoration of PbS onto RGO were done simultaneously. Structural characterizations reveal that PbS nanoparticles are highly crystalline and a strong interaction exists between RGO and PbS. We also demonstrate fabrication of a near infrared (NIR) photo detector using RGO/PbS nanocomposite film.     

An organometallic approach for ultrathin SnO(x)Fe(y)S(z) plates and their graphene composites as stable anode materials for high performance lithium ion batteries

Through an organometallic approach, ultrathin SnO(x)Fe(y)S(z) plates with ~2 nm single layer-thicknesses were obtained and their graphene composites showed very promising discharge capacities of up to 736 mA h g(-1) and excellent stabilities as anode materials in lithium ion batteries.