field-effect transistor
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The potential of organic semiconductor based devices for light generation is demonstrated by the commercialisation of display technologies using organic light emitting diode (OLED). In OLED, organic materials plays an important role of emitting light once the current is passed through. However OLED have drawbacks whereby it suffers from photon loss and exciton quenching. Organic light emitting transistor (OLET) emerged as a new technology to compensate the efficiency and brightness loss encountered in OLED. The structure has combinational capability to switch the electronic signal such as the field effect transistor (FET) as well as to generate light. Different colours of light could be generated by using different types of organic material. The light emission could also be tuned and scanned in OLET. The studies carried out in this paper focuses on investigation of fabricated MEH-PPV based OLED and also OLET via current voltage characteristics. These studies will continue with a view to develop an optimised MEH-PPV based OLET.
- MeSH
- analýza selhání vybavení MeSH
- design vybavení MeSH
- elektrická vodivost MeSH
- elektronické tranzistory * MeSH
- organické látky chemie MeSH
- osvětlení přístrojové vybavení MeSH
- polovodiče * MeSH
- transport elektronů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
We show the influence of osteoblastic SAOS-2 cells on the transfer characteristics of nanocrystalline diamond solution-gated field-effect transistors (SGFET) prepared on glass substrates. Channels of these fully transparent SGFETs are realized by hydrogen termination of undoped diamond film. After cell cultivation, the transistors exhibit about 100× increased leakage currents (up to 10nA). During and after the cell delamination, the transistors return to original gate currents. We propose a mechanism where this triggering effect is attributed to ions released from adhered cells, which depends on the cell adhesion morphology, and could be used for cell culture monitoring.
- MeSH
- akční potenciály * MeSH
- biosenzitivní techniky přístrojové vybavení MeSH
- buněčná adheze * MeSH
- diamant chemie MeSH
- elektronické tranzistory * MeSH
- ionty MeSH
- lidé MeSH
- nádorové buňky kultivované MeSH
- nádory kostí * MeSH
- osteosarkom * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Due to high biocompatibility, miniaturization, optical transparency and low production cost together with high radiation hardness the diamond-based sensors are considered promising for radiation medicine and biomedicine in general. Here we present detection of fibroblast cell culture properties by nanocrystalline diamond solution-gated field-effect transistors (SG-FET), including effects of gamma irradiation. We show that blank nanocrystalline diamond field-effect biosensors are stable at least up to 300 Gy of γ irradiation. On the other hand, gate current of the diamond SG-FET biosensors with fibroblastic cells increases exponentially over an order of magnitude with increasing radiation dose. Extracellular matrix (ECM) formation is also detected and analyzed by correlation of electronic sensor data with optical, atomic force, fluorescence, and scanning electron microscopies.
Biosensors based on graphene field-effect transistors have become a promising tool for detecting a broad range of analytes. However, their performance is substantially affected by the functionalization protocol. In this work, we use a controlled in-vacuum physical method for the covalent functionalization of graphene to construct ultrasensitive aptamer-based biosensors (aptasensors) able to detect hepatitis C virus core protein. These devices are highly specific and robust, achieving attomolar detection of the viral protein in human blood plasma. Such an improved sensitivity is rationalized by theoretical calculations showing that induced polarization at the graphene interface, caused by the proximity of covalently bound molecular probe, modulates the charge balance at the graphene/aptamer interface. This charge balance causes a net shift of the Dirac cone providing enhanced sensitivity for the attomolar detection of the target proteins. Such an unexpected effect paves the way for using this kind of graphene-based functionalized platforms for ultrasensitive and real-time diagnostics of different diseases.
- MeSH
- aptamery nukleotidové * MeSH
- biosenzitivní techniky * MeSH
- grafit * MeSH
- hepatitida C * diagnóza MeSH
- lidé MeSH
- proteiny virového jádra MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Diamond is recognized as an attractive material for merging solid-state and biological systems. The advantage of diamond field-effect transistors (FET) is that they are chemically resistant, bio-compatible, and can operate without gate oxides. Solution-gated FETs based on H-terminated nanocrystalline diamond films exhibiting surface conductivity are employed here for studying effects of fetal bovine serum (FBS) proteins and osteoblastic SAOS-2 cells on diamond electronic properties. FBS proteins adsorbed on the diamond FETs permanently decrease diamond conductivity as reflected by the -45 mV shift of the FET transfer characteristics. Cell cultivation for 2 days results in a further shift by another -78 mV. We attribute it to a change of diamond material properties rather than purely to the field-effect. Increase in gate leakage currents (by a factor of 4) indicates that the FBS proteins also decrease the diamond-electrolyte electronic barrier induced by C-H surface dipoles. We propose a model where the proteins replace ions in the very vicinity of the H-terminated diamond surface.
- MeSH
- adsorpce MeSH
- biosenzitivní techniky přístrojové vybavení metody MeSH
- buněčné linie MeSH
- diamant chemie MeSH
- elektrochemie metody MeSH
- elektronické tranzistory MeSH
- ionty MeSH
- krevní proteiny chemie MeSH
- lidé MeSH
- mikroskopie elektronová rastrovací MeSH
- nanočástice chemie ultrastruktura MeSH
- povrchové vlastnosti MeSH
- roztoky MeSH
- skot MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This study presents a graphene field-effect transistor (gFET) biosensor with dual detection capabilities for SARS-CoV-2: one RNA detection assay to confirm viral positivity and the other for nucleocapsid (N-)protein detection as a proxy for infectiousness of the patient. This technology can be rapidly adapted to emerging infectious diseases, making an essential tool to contain future pandemics. To detect viral RNA, the highly conserved E-gene of the virus was targeted, allowing for the determination of SARS-CoV-2 presence or absence using nasopharyngeal swab samples. For N-protein detection, specific antibodies were used. Tested on 213 clinical nasopharyngeal samples, the gFET biosensor showed good correlation with RT-PCR cycle threshold values, proving its high sensitivity in detecting SARS-CoV-2 RNA. Specificity was confirmed using 21 pre-pandemic samples positive for other respiratory viruses. The gFET biosensor had a limit of detection (LOD) for N-protein of 0.9 pM, establishing a foundation for the development of a sensitive tool for monitoring active viral infection. Results of gFET based N-protein detection corresponded to the results of virus culture in all 16 available clinical samples and thus it also proved its capability to serve as a proxy for infectivity. Overall, these findings support the potential of the gFET biosensor as a point-of-care device for rapid diagnosis of SARS-CoV-2 infection and indirect assessment of infectiousness in patients, providing additional information for clinical and public health decision-making.
- MeSH
- biosenzitivní techniky * přístrojové vybavení metody MeSH
- COVID-19 * diagnóza virologie MeSH
- design vybavení MeSH
- elektronické tranzistory MeSH
- fosfoproteiny MeSH
- grafit * chemie MeSH
- koronavirové nukleokapsidové proteiny izolace a purifikace MeSH
- lidé MeSH
- limita detekce MeSH
- nazofarynx virologie MeSH
- RNA virová * izolace a purifikace analýza MeSH
- SARS-CoV-2 * izolace a purifikace genetika MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Edukační publikace se zabývá některými postupy, které rozšířily aplikaci imunochemie v posledním desetiletí. Fluorescenční imunochromatografie spojuje výhody chromatografických a imunochemických metod značených fluoroforem. Nejvíce se používá průtoková horizontální analýza s fluoroforem Alexa 647 nebo sulforhodaminem B (může být i v liposomech). Dal- šími fluorofory jsou nanočástice s ionty europia, křemenem potažené či polovodičové nanokrystaly. Imunochromatografie ve spojení s tandemovou hmotnostní spektrometrií má zatím větší uplatnění ve výzkumu než v klinické laboratorní praxi. K obohacení stanovovaného analytu se využívá imunoafinitní chromatografie. Ke standardizaci slouží inkorporace stabilních izotopů do cílových peptidů. V poloprovozní fázi je zavádění ultracitlivých metod: aplikace senzoru obřího elektrického odporu magnetického pole a technologie tranzistoru řízeného polem. Klíčová slova: fluorescenční imunochromatografie, hmotnostní spektrometrie, senzor obřího elektrického odporu magnetického pole, tranzistor řízený polem.
The educational article deals with some procedures that extended applications of immunochemistry in the last decade. Fluorescence immunochromatography combines advantages of chromatographic methods and immunoassays with fluorophor labels. Flow horizontal detection using a fluorophor such as Alexa 647 or sulfo-rhodamine B (also incorporated in liposomes) is most widely used. Nanoparticles combined with europium ions, silica coated or semiconductor nanocrystals are also used as fluorophors. Immunochromatography in connection with tandem mass spectrometry has been used in research rather than in clinical laboratory practice. For enrichment of determined analyte immunoaffinity chromatography is used. For standardization incorporating stable-isotopes into the specific peptides of interest is applied. Implementing of ultrasensitive methods, such as application of giant electrical magnetoresistive sensor or field-effect transistor technology, is in a pilot stage. Keywords: fluorescence immunochromatography, mass spectrometry, giant electrical magnetoresistive sensor, field-effect transistor.
