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We present receptor-modified carbon nanotube sensors for the highly selective and sensitive detection of acetylcholine (ACh), one kind of neurotransmitter. Here, we successfully expressed the M1 muscarinic acetylcholine receptor (M1 mAChR), a family of G protein-coupled receptors (GPCRs), in E. coli and coated single-walled carbon nanotube (swCNT)-field effect transistors (FETs) with lipid membrane including the receptor, enabling highly selective and sensitive ACh detection. Using this sensor, we could detect ACh at 100 pM concentration. Moreover, we showed that this sensor could selectively detect ACh among other neurotransmitters. This is the first demonstration of the real-time detection of ACh using specific binding between ACh and M1 mAChR, and it may lead to breakthroughs for various applications such as disease diagnosis and drug screening.

The effectiveness of silkworm hemolymph was investigated as a substitute for fetal bovine serum (FBS) in insect cell culture. Cells were adapted to grow in reduced FBS medium supplemented with silkworm hemolymph through a gradual adaptation process. FBS concentration in the medium could be reduced to 1% without decrease in cell growth rate and maximum cell concentration by adding 5% silkworm hemolymph.

In order to successfully utilize stem cells for therapeutic applications in regenerative medicine, efficient differentiation into a specific cell lineage and guidance of axons in a desired direction is crucial. Here, we used aligned multi-walled carbon nanotube (MWCNT) sheets to differentiate human mesenchymal stem cells (hMSCs) into neural cells. Human MSCs present a preferential adhesion to aligned CNT sheets with longitudinal stretch parallel to the CNT orientation direction. Cell elongation was 2-fold higher than the control and most of the cells were aligned on CNT sheets within 5° from the CNT orientation direction. Furthermore, a significant, synergistic enhancement of neural differentiation was observed in hMSCs cultured on the CNT sheets. Axon outgrowth was also controlled using nanoscale patterning of CNTs. This CNT sheet provides a new cellular scaffold platform that can regulate morphogenesis and differentiation of stem cells, which could open up a new approach for tissue and stem cell regeneration.

Background and Objectives Poor homing efficiency is one of the major limitations of current stem cell therapy. Magnetic bionanoparticles (MPs) obtained from Magnetospirillum sp. AMB-1 have a lipid bilayer membrane and ferromagnetic properties. We evaluated a novel priming strategy using MPs to enhance the homing of transplanted progenitor cells to target tissue. Materials and Methods Effects of MP on proliferation, viability, and migration of late human endothelial progenitor cells (EPCs) were examined in vitro. Additionally, effects of MP on gene and protein expression related to survival and adhesion were evaluated. Homing and angiogenic efficiency of MP transferred late EPCs was evaluated in nude mouse hindlimb ischemia model. Results Below threshold concentration, MP transfer did not influence proliferation or survival of late EPCs, but enhanced migration and trans-endothelial migration of late EPCs toward magnet. Below threshold concentration, MP transfer did not influence gene and protein expression related to survival. In the mouse hindlimb ischemia model, late EPCs treated with high dose MP (5 ug/mL) showed enhanced homing of injected late EPCs in the ischemic limb by magnet, compared to low dose MP (1 ug/mL) treated late EPCs. In addition, high dose MP transferred EPC showed significantly better improvement of perfusion in ischemic limb compared to untreated EPC. Conclusion MP transfer with magnet application can be a promising novel strategy to enhance homing efficacy and outcomes of current stem cell therapy.

Growth limiting factors influencing the high density cultivation of insect cells were studied. A stationary phase in Grace's medium was found to be due to the deprivation of the active form of FBS components. Various compounds were added in the early stationary phase to observe the recovery of cell growth. With the addition of yeastolate, final cell densities were 4-fold and 3.5-fold higher in monolayer and suspension cultures, respectively. Pluronic F-68 increases the specific growth rate and the growth yield of the cell as well as protects the cell from the shear damage.

A cell recycle system is studied for two-stage continuous fermentation. Cell recycle around the second stage provides higher cell concentrations than processes without recycle and a longer residence time of the cell, which is necessary for inducible products, especially in recombinant cell fermentation. Residence time distribution of the cell in the fermentor is important for the optimization of inducible products. The residence time distributions are studied for the cases with and without significant cell growth in the second stage. With cell growth in the second stage, three cases are considered. These are the cases of (1) zero residence time for two daughter cells after the cell division, (2) zero residence time of one daughter cell after the cell division and inherited residence time for the other daughter cell from the mother cell after the cell division, and (3) two daughter cells having the residence time of the mother cell after the cell division.

Fabrication and characterization of nano electro-magnets are reported. The nano-transformer consisting of two concentric loops has been made and Faraday's induction experiment has been successfully performed. The mutual inductance value extracted from the measured induced current is consistent with the simulated results of mutual inductance between two macroscopic loops with nano-meter spacing. It is also demonstrated that only a small number of magnetic particles can be captured by controlling the design and current level of the electro-magnet.

A method of estimating effectiveness factor for immobilized whole cells is developed by considering microbial cells as microspheres containing enzyme activity dispersed in the gel phase of the support matrix. The proper model equations describing the system are solved and the corresponding effectiveness factors calculated for various bead sizes, and numbers and activities of cells. The cell wall resistance (permeability) is found to be one of most important variables in the system. The model is applied in predicting the experimental data of other investigators.

The effects of a derepressor, IAA (3β-indoleacrylic acid) ontrp promoter inE. coli are studied. Kinetic parameters for the effect are estimated through the model equations and experiments. IAA concentration of 40 μg/ml is high enough to give the maximum transcriptional efficiency in M9 media supplemented with glucose and casamino acid.

International audience; Sweet taste is an important factor that regulates calorie intake and contributes to food preferences in humans and animals. Therefore, the evaluation of sweet substances is essential for various fields such as healthcare, food, and pharmaceutical industries. Sweet tastants are detected by sweet taste receptors which are class C G-protein-coupled receptors (GPCRs). T1R2 venus flytrap (VFT) of sweet taste receptor is known as a primary ligand-binding domain for sweet tastants. In this study, we developed an ultrasensitive artificial sweet taste bioelectronic tongue based on the T1R2 VFT of a human sweet taste receptor. Here, the T1R2 VFT of a human sweet taste receptor was successfully overexpressed in a bacterial expression system. A T1R2 VFTimmobilized carbon nanotube field-effect transistor with floating electrodes was exploited as an artificial sweet taste sensory system. Significantly, our T1R2 VFT-functionalized bioelectronic tongue could be used to detect solutions of sweet tastants down to 0.1 fM and selectively discriminate sweet substances from other taste substances. Furthermore, our device could be used to monitor the response of T1R2 VFT domain of a sweet taste receptor to sweet substances in real food environments such as apple juice and chamomile herb tea. Moreover, our device was used to evaluate the inhibition and enhancement effects on sweet taste receptors by zinc ions and chamomile tea, respectively. In addition, our device demonstrated a long-term storability and reusability. In this respect, our sweet taste bioelectronic tongue could be a promising tool for various basic research and industrial applications.

Silicone tube was used to facilitate gas transport in mammalian cell culture. A bundle of silicone tubes provides anchorage dependent ceils (BHK 21 cells) with surface. It was found that the surface characteristic of silicone tube for the cell attachment was the same as that of commercial tissue culture dish. Also high O2 permeability of silicone membrane gives rise to a faster metabolism of cells.

Optimal operating conditions have been determined for recombinant Escherichia coli cells in a fed-batch and two-stage continuous fermentors. The model expression system used in this article was the E. coli trp promoter cloned on plasmids. Model equations for cell growth and cloned-gene expression have been formulated and used to evaluate process performances under different operating modes. The operating variables manipulated for maximum performance include the timing of IAA addition to derepress transcription from the trp promoter. The total operating period and the nutrient concentration profile during fermentations. For a fed-batch mode, the performance was significantly improved by adjusting the IAA addition (environmental switch) time relative to the total operation period. It was found that the optimal switching time exists for a given total operation period. For a two-stage continuous fermentation system, the productivity is more sensitive to the combination of the dilution rates than to the volume ratio of two reactors. In general, as long as the down time is less than the total operation time in the fed-batch mode, the fed-batch mode gives higher productivity than the two-stage continuous system.

A novel bioreactor with hollow fibres was developed to facilitate substrate transfer across membrane walls as well as to retain a continuous cell growth in the shell side. Ultrafiltration was induced through membrane by pressurizing feed solution to the inside of a hollow fibre with inlet and outlet pumps. The ultrafiltrate accumulated outside the hollow fibres was recirculated through a reservoir where a part of solution containing cells and substrate was removed to keep the level of reservoir solution constant. Ethanol production by Saccharomyces cerevisiae was carried out to test the feasibility of this reactor. The productivity of this reactor was compared with that of a continuous stirred tank reactor (CSTR).

The hollow fiber enzyme reactor with pulsation developed by Kim and Chang (1983) was operated in a differential mode by recycling a substrate solution, in order to assess the efficiency of ultrafiltration swing. The rates of lactose conversion by beta-galactosidase contained in the shell side of the reactor were measured to determine the effects of recirculation rate, pulsation period, and amplitude. The conversion increased with the increase of recirculation flow rate and the amplitude while variation in period affected the conversion relatively little. The maximum increase of 113% in the activity was observed in the reactor with pulsation as compared to that without pulsation. The two-compartment model well described the experimental data obtained in this study. Square-wave pulsation was theoretically more effective in increasing conversion than sine wave pulsation. However, in experimental operation the damping effect of the hollow fiber wall narrowed the difference between these two wave forms.

International audience; Dimetyl metylphosphonate (DMMP) is a simulant of sarin, which is a representative of nerve agents. Sarin is an organophosphorus toxic compound that is an inhibitor of acetylcholinesterase, paralyzing human neurotransmission and the autonomic nervous system. Detection of these nerve agents has been considered important for safety issues to prevent terrorism and to counter military threats. Although there have been various studies on sensors for detecting DMMP as a simulant of sarin, limitations still exist in specificity, sensitivity, and reliability. To overcome these limitations, we utilized a human olfactory receptor (hOR)-based single-walled carbon nanotube-field effect transistor (swCNT-FET) as a platform for the detection of DMMP. The hORs have high specificity for their certain target molecules. swCNT-FET can also convert biological signals of hORs to electrical signals with high sensitivity. By screening of hORs, hOR2T7 with high selectivity for DMMP was selected, and it was produced for development of the hOR2T7-conjugated bioelectronic nose (hOR2T7 B-nose). A hOR2T7 B-nose was able to selectively detect DMMP at a concentration of 10 fM. This shows ultrasensitive and selective performance for the detection of DMMP as a tool for sensing chemical warfare agents (CWAs), which could be used for practical applications in the field of safety.