Summary: Nanostructures are promising candidates for use as active materials for the detection of chemical and biological species, mainly due to the high surface-to-volume ratio and the unique physical properties arising at the nanoscale. Among the various nanostructures, materials comprised of sp2-carbon enjoy a unique position due to the possibility to readily prepare them in various dimensions ranging from 0D, through 1D to 2D. This review focuses on the use of 1D (carbon nanotubes) and 2D (graphene) carbon nanostructures for the detection of biologically relevant molecules. A key advantage is the possibility to perform the sensing operation without the use of any labels or complex reaction schemes. Along this spirit, various strategies reported for the label-free electrical detection of biomolecules using carbon nanostructures are discussed. With their promise for ultimate sensitivity and the capability to attain high selectivity through controlled chemical functionalization, carbon-based nanobiosensors are expected to open avenues to novel diagnostic tools as well as to obtain new fundamental insight into biomolecular interactions down to the single molecule level.
Over 800 publications using NanoIntegris materials!
Citation: Antonio Radoi, Alexandru Cosmin Obreja, Sandra A. V. Eremia, Adina Bragaru, Adrian Dinescu, Gabriel-Lucian Radu,Journal of Applied Electrochemistry October 2013, Volume 43, Issue 10, pp 985-994.
Summary: Pristine graphene platelets and graphene oxide were used as electrode modifiers, aiming the investigation of their electrochemical efficacy towards β-nicotinamide adenine dinucleotide (NADH). The electrochemical detection of NADH is one of the most studied areas of bioelectroanalysis because of the ubiquity of NAD(P)H-based enzymatic reactions in nature. Commercially available graphene and laboratory prepared graphene oxide were used to modify glassy carbon electrodes and the behaviour of such modified electrodes against potassium ferricyanide (III) and NADH was reported. Relying on the graphene-modified transducer, l-lactic dehydrogenase (l-LDH) was successfully immobilised in a 1 % Nafion® membrane. The developed biosensor, working at +250 mV versus Ag/AgCl reference electrode, was used to assess l-lactic acid in four different types of yogurts, revealing an l-lactic acid concentration ranging between 0.3 and 0.6 %.p>
Citation: Hyun Young Jung, Young Lae Kim, Sora Park, Aniket Datara, Hyung–June Lee, Jun Huanga, Sivasubramanian Somua, Ahmed Busnainaa, Yung Joon Junga, and Young–Kyun KwonRoyal Society of Chemistry, Analyst 2013, 138, 7206-7211.
Summary: Here we report the highly effective detection of hydrogen sulfide (H2S) gas by redox reactions based on single-walled carbon nanotubes (SWCNTs) functionalized with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as a catalyst and we also discuss the important role of water vapor in the electrical conductivity of SWCNTs during the sensing of H2S molecules. To explore the H2S sensing mechanism, we investigate the adsorption properties of H2S on carbon nanotubes (CNTs) and the effects of the TEMPO functionalization using first-principles density functional theory (DFT) and we summarize current changes of devices resulting from the redox reactions in the presence of H2S. The semiconducting-SWCNT (s-SWCNT) device functionalized with TEMPO shows a very high sensitivity of 420% at 60% humidity, which is 17 times higher than a bare s-SWCNT device under dry conditions. Our results offer promising prospects for personal safety and real-time monitoring of H2S gases with the highest sensitivity and low power consumption and potentially at a low cost.
Summary: We developed a scalable, label-free all-electronic sensor for D-glucose based on a carbon nanotube transistor functionalized with pyrene-1-boronic acid. This sensor responds to glucose in the range 1 μM–100 mM, which includes typical glucose concentrations in human blood and saliva. Control experiments establish that functionalization with the boronic acid provides high sensitivity and selectivity for glucose. The devices show better sensitivity than commercial blood glucose meters and could represent a general strategy to bloodless glucose monitoring by detecting low concentrations of glucose in saliva.
Summary: We demonstrate a practical sensing platform, consisting of SnO2 nanoparticle-decorated semiconducting single-walled carbon nanotubes assembled on gold electrodes via a dielectrophoretic process, for highly sensitive CO detection with fast response at room temperature. The highest sensitivity obtained was 0.27 and the response time was ~2 s for 100 ppm CO detection. The lower detection limit was ~1 ppm. These results indicate that the sensing performance of our device is among the best of CO sensors implemented with SWNTs. Further, we observed a significant increase in sensitivity to 0.67 after subjecting the device to an electrical breakdown at 8 V. We also proposed a theoretical model to reveal the relationship between the sensitivity and the gas concentration. The new model not only resulted in a nice fit to our data, but also allowed us to estimate the contact resistance between an individual SWNT and the gold electrodes.
Summary: Horseradish peroxidase (HRP) multimer on a graphene modified glassy carbon electrode (GCE) has been fabricated by carbodiimide coupling reaction. The possible adsorption sites of HRP on graphene were predicted by Lamarckian genetic algorithm. It has been observed that HRP has five possible sites for its adsorption to graphene. Scanning electron microscopy and atomic force microscopy measurements support the evidence of formation of HRP multimer graphene. The graphene–HRP multimer film showed good electrocatalytic activity for the reduction of hydrogen peroxide. The electrochemical studies showed that graphene on the GCE increased the effective surface area, reduced the charge transfer resistance of the electrode and enhanced the electrochemical signal. The detection limit of H2O2 (9 nM) at graphene–HRP multimer was also lower than that of other electrodes studied in this work. The sensitivity of the graphene–HRP multimer film towards H2O2 determination was 7.8 μA μM−1 cm−2. Differential pulse voltammetry and selectivity studies revealed that GCE modified by graphene–HRP multimer film can be efficiently used for H2O2 determination in real samples.
Summary: The conduction responses of semiconducting single-walled carbon nanotube (SWCNT) films irradiated by 6 and 15 MV X-rays were evaluated. Results indicate that the average resistance–dose rate relations of the SWCNT network are quasi-linear and can be used for dosimetry measurements in medical radiation applications. The dynamic responses exhibit fluctuations which reveal an intrinsic feature of SWCNT networks due to the large number of interconnections between individual SWCNTs.
Summary: The electrochemical sensing of hydrogen peroxide is of substantial interest to the operation of oxidase-based amperometric biosensors. We explore the fabrication of a novel and highly sensitive electro-analytical biosensor using well characterised commercially available graphene and compare and contrast responses using Nafion -graphene and -graphite modified electrodes. Interestingly we observe that graphite exhibits a superior electrochemical response due to its enhanced percentage of edge plane sites when compared to graphene. However, when Nafion, routinely used in amperometric biosensors, is introduced onto graphene and graphite modified electrodes, re-orientation occurs in both cases which is beneficial in the former and detrimental in the latter; insights into this contrasting behaviour are consequently presented providing acuity into sensor design and development where graphene is utilised in biosensors.
Summary: The flexible cancer sensor based on layer-by-layer self-assembled graphene reported in this letter demonstrates features including ultrahigh sensitivity and low cost due to graphene material properties in nature, self-assembly technique, and polyethylene terephthalate substrate. According to the conductance change of self-assembled graphene, the label free and labeled graphene sensors are capable of detecting very low concentrations of prostate specific antigen down to 4 fg/ml (0.11 fM) and 0.4 pg/ml (11 fM), respectively, which are three orders of magnitude lower than carbon nanotube sensors under the same conditions of design, manufacture, and measurement.
Summary: Semiconducting networks were found to be extremely sensitive to charges, which promises the electrical detection of ultralow concentrations of DNA (down to 0.1 fM, ∼100 DNA molecules).