Single chip dynamic nuclear polarization microsystem

The integration on a single chip of the sensitivity-relevant electronics of nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectrometers is a promising approach to improve the limit of detection, especially for samples in the nanoliter and subnanoliter range. Here we demonstrate the co-integration on a single silicon chip of the front-end electronics of an NMR and an ESR detector. The excitation/detection planar spiral microcoils of the NMR and ESR detectors are concentric and interrogate the same sample volume. This combination of sensors allows to perform dynamic nuclear polarization (DNP) experiments using a single-chip integrated microsystem having an area of about 2 mm$^2$. In particular, we report $^1$H DNP-enhanced NMR experiments on liquid samples having a volume of about 1 nL performed at 10.7 GHz(ESR)/16 MHz(NMR). NMR enhancements as large as 50 are achieved on TEMPOL/H$_{2}$O solutions at room temperature. The use of state-of-the-art submicrometer integrated circuit technologies should allow the future extension of the single-chip DNP microsystem approach proposed here up the THz(ESR)/GHz(NMR) region, corresponding the strongest static magnetic fields currently available. Particularly interesting is the possibility to create arrays of such sensors for parallel DNP-enhanced NMR spectroscopy of nanoliter and subnanoliter samples

An easier and safe affair, pleural drainage with ultrasound in critical patient: a technical note

Abstract Thoracic ultrasound is a powerful diagnostic imaging technique for pleural space disorders. In addition to visualising pleural effusion, thoracic ultrasound also helps clinicians to identify the best puncture site and to guide the drainage insertion procedure. Thoracic ultrasound is essential during these invasive manoeuvres to increase safety and decrease potential life-threatening complications. This paper provides a technical description of pigtail-type drainage insertion using thoracic ultrasound, paying particular attention to indications, contraindications, ultrasound guidance, preparation/equipment, procedure and complications

Implantable devices: the future of blood monitoring? (Editorial)

Implantable devices can be developed for the simultaneous monitoring of a specific group of key metabolites, identified by more complex techniques, such as mass spectroscopy- or nuclear magnetic -based analysis.. Since there is a strong correlation between metabolite concentration in the blood and in the extracellular space, often it is more convenient to locate the implant into the subcutaneous tissues, to avoid coagulation problems and long-term pharmacological therapies

Carbon Nanotubes-Based Biosensors for Metabolite Monitoring in Cell Culture Medium

Cell analysis requires increasingly more complex equipment to investigate cellular and molecular mechanisms. The goal of the present research is to develop a platform of integrated amperometric biosensors to better understand biological processes by real-time monitoring of different metabolites over the duration of a cell culture. The simultaneous use of carbon nanotubes (CNTs) to enhance the signal and oxidases to confer specificity can really lead to an innovative tool for several research activities. We propose an integrated electrochemical cell fabricated with CMOS compatible technology. The platform consists of five working electrodes, which are nanostructurated with CNTs, previously dispersed in Nafion, and functionalized with different oxidases. A microfluidic system on the top of the biosensor guarantees continuously fresh solution at the electrode surface. For measurements in culture medium, a microdialysis probe helps to limit interference from other electroactive species and to provide a broader linear range. Initially, CNTs-based biosensors are characterized in phosphate buffer saline (PBS) solution in terms of sensitivity and detection limit. Chronoamperometries are then performed in cell culture medium in a wider range of concentrations. Continuous measurements are also performed over 7 hours to validate operational stability. Considering calibration in PBS, our system shows 10x higher sensitivity compared to other works with similar nanostructuration. In fact, CNTs and Nafion form an optimal immobilization surface for enzymes. The detection of multiple metabolites is achieved in pure medium, while previous art requires dilution steps. Moreover, the biosensor covers the entire range of interest thanks to the microdialysis probe, a significant improvement as compared to our previous work. The operational stability exhibited during longer measurements leads us to conclude that the developed biosensor is highly suitable for cell line monitoring

Amperometric biosensor with nanostructured electrodes by using multi-alled carbon nanotubes for glucose detection in cell culture medium

The monitoring of metabolic compounds such as glucose is largely reported in literature. The applications of this type of analysis are mainly related to clinical purposes, e.g. in diabetes pathology, where a lot of studies are presented in literature. Recently, some authors presented studies about glucose and lactate detection in cell culture monitoring [1], [2]. A clear identification of medium compounds could be interesting for biologists and biotechnologists, since they may be identified as markers of different cell states. It can also pave the way to automated systems, as a feedback of the medium state. In the field of amperometric biosensors, a lot of techniques related to the structuration of the electrodes have been presented in the last twenty years. Especially for glucose biosensors, a lot of mediators have been employed to carry the electrons released from the redox reaction to the surface of the electrode [3], [4]. Recently, some authors presented great results in terms of sensitivity and limit detection by using nanostructured electrodes. The employment of carbon nanotubes has shown promising results, due to their ability to promote the electron transfer from the active site of the enzyme onto the surface of the electrode, because of their electrocatalytic properties. Since we observed an improvement in terms of sensitivity and detection limit by using Multi-walled Carbon Nanotubes (MWCNT) for hydrogen peroxide (H2O2) detection, we decided to modify the nanostructured electrodes with glucose oxidase (GOD), since glucose is the most interesting compound in cell culture. We dropped 40 µl (1 mg ml-1) MWCNT onto Screen Printed Electrodes (SPE) purchased from Dropsens (Spain), and after, we deposited a certain quantity of GOD (3.5 U mm-2) and we stored the electrode overnight at +4°C. The result of the detection from chronoamperometry in stirring conditions with PBS as support electrolyte is shown in Figure 1

Sensitivity Enhancement by Carbon Nanotubes: Applications to Stem Cell Cultures Monitoring

Nano-biosensing provides new tools to investigate cellular differentiation and proliferation. Upon the various metabolic compounds secreted by cells during life cycles, glucose, lactate and hydrogen peroxide (H2O2) are of first interest. Nanostructured electrodes may enhance the compounds sensitivity in order to precisely detect cell cycle variation. In the present paper, the detection with electrodes nanostructured by using Multi-Walled Carbon Nanotubes (MWCNT) was investigated in order to develop an amperometric biosensor. Good improvement in sensitivity was obtained, suggesting that carbon nanotubes can be the right candidates to improve biosensing. The final aim of the study is the development of a bio-chip, which can be integrated in Petri dishes for automatic stem cell culture monitoring

NMR spectroscopy of single sub-nL ova with inductive ultra-compact single-chip probes

Nuclear magnetic resonance (NMR) spectroscopy enables non-invasive chemical studies of intact living matter. However, the use of NMR at the volume scale typical of microorganisms is hindered by sensitivity limitations, and experiments on single intact organisms have so far been limited to entities having volumes larger than 5 nL. Here we show NMR spectroscopy experiments conducted on single intact ova of 0.1 and 0.5 nL (i.e. 10 to 50 times smaller than previously achieved), thereby reaching the relevant volume scale where life development begins for a broad variety of organisms, humans included. Performing experiments with inductive ultra-compact (1 mm2) single-chip NMR probes, consisting of a low noise transceiver and a multilayer 150 μm planar microcoil, we demonstrate that the achieved limit of detection (about 5 pmol of 1H nuclei) is sufficient to detect endogenous compounds. Our findings suggest that single-chip probes are promising candidates to enable NMR-based study and selection of microscopic entities at biologically relevant volume scales