Abstract:This study reports biosensing using graphene field-effect transistors with the aid of pyrene-tagged DNA aptamers, which exhibit excellent selectivity, affinity, and stability for Escherichia coli (E. coli) detection. The aptamer is employed as the sensing probe due to its advantages such as high stability and high affinity toward small molecules and even whole cells. The change of the carrier density in the probe-modified graphene due to the attachment of E. coli is discussed theoretically for the first time a… Show more
“…Value of CLG was taken to be 1.65 µF/cm 2 based on the sum of the quantum capacitance (CQ) of graphene and electric double layer capacitance (CDL) consistent with 0.01x PBS. 18 Results from a high mobility device are shown in Figure 1b, while the average hole and electron mobility values obtained from different devices are ~670 ± 125 and ~690 ± 83 cm 2 /V·s, respectively. These mobilities are consistent with reported values for CVD graphene on SiO2 substrates.…”
Section: G-fet Devices Consist Of a Low Pressure Chemical Vapor Deposmentioning
confidence: 97%
“…12-15 However, the use of G-FET sensors for bacterial detection is still in its infancy with only a small number of papers describing the detection of a lab strain of Escherichia coli, but no reports on the sensing of clinically relevant pathogenic bacteria, nor on antibiotic resistant strains. [16][17][18]…”
mentioning
confidence: 99%
“…This results from the fixed amount of charge per cell, whereas the shift is dependent on the induced charge density. 18 As such the effect of the bacteria on a single G-FET could be enhanced with smaller active areas, however this also requires a far higher cell density, potentially at a level that is much above what is considered to be clinically relevant.…”
Time-consuming, expensive and low sensitivity diagnostic methods used for monitoring bacterial infections lead to unnecessary or delays in prescription of the right antibiotic treatment.Determining an optimal clinical treatment requires rapid detection and identification of pathogenic bacteria and their sensitivity to specific antimicrobials. However, diagnostic devices that meet all of these criteria have proven elusive thus far. Graphene field effect transistors (G-FET) are a promising solution, since they are highly sensitive to chemical/biological modification, can have fast detection times and can be placed on different substrates. Here, by integrating specific peptide probes over G-FETs, we present a proof-of-concept study for species and strain specific label-free detection of clinical strains of pathogenic bacteria with high specificity and sensitivity. We found that pyrene-conjugated peptides immobilized on G-FETs were capable of detecting pathogenic Staphylococcus aureus at the single-cell level and discriminate against other gram-positive and gram-negative bacterial pathogens. A similar device was able to discriminate between antibiotic resistant and sensitive strains of Acinetobacter baumannii, suggesting that these devices can also be used for detecting antibiotic resistive pathogens. Furthermore, a new means of enhancing attachment, electric-field assisted binding, reduced the detection limit to 10 4 cells/ml and the detection time to below 5 minutes. The combination of single step attachment, inexpensive production, rapid, selective and sensitive detection suggest G-FETs plus pyrene-conjugated peptides are a new platform for solving major challenges faced in point of care diagnostics to fight infectious diseases and antimicrobial resistance.Bacterial infections cause a wide range of diseases and significant mortality 1 . While antibiotics are key in controlling disease severity and reducing mortality, their over prescription and misuse are some of the most important factors in the surge of antibiotic resistant cases around the world. [2][3][4] In order to solve this crisis, diagnostic methods are needed that can rapidly and accurately identify the bacterium causing the infection and determine its associated antibiotic resistance profile. Antibiotic susceptibility testing (AST) is mostly carried out by phenotypic methods that require prior identification of bacterial pathogens from patients (at the species and/or strain level) and incubation under antibiotic conditions, 5, 6 a lengthy process that can take up to 24 hours to a month depending on the species. 7 Moreover, both species/strain identification and AST require trained specialists, specific laboratory environments and often expensive instrumentation. 5, 6, 8 Since these conditions limit widespread application and implementation into actual treatment strategies at most points of care, there is much room for improvement to develop new diagnostic devices that have the potential for adoption across a large variety of use cases. Ideally these dev...
“…Value of CLG was taken to be 1.65 µF/cm 2 based on the sum of the quantum capacitance (CQ) of graphene and electric double layer capacitance (CDL) consistent with 0.01x PBS. 18 Results from a high mobility device are shown in Figure 1b, while the average hole and electron mobility values obtained from different devices are ~670 ± 125 and ~690 ± 83 cm 2 /V·s, respectively. These mobilities are consistent with reported values for CVD graphene on SiO2 substrates.…”
Section: G-fet Devices Consist Of a Low Pressure Chemical Vapor Deposmentioning
confidence: 97%
“…12-15 However, the use of G-FET sensors for bacterial detection is still in its infancy with only a small number of papers describing the detection of a lab strain of Escherichia coli, but no reports on the sensing of clinically relevant pathogenic bacteria, nor on antibiotic resistant strains. [16][17][18]…”
mentioning
confidence: 99%
“…This results from the fixed amount of charge per cell, whereas the shift is dependent on the induced charge density. 18 As such the effect of the bacteria on a single G-FET could be enhanced with smaller active areas, however this also requires a far higher cell density, potentially at a level that is much above what is considered to be clinically relevant.…”
Time-consuming, expensive and low sensitivity diagnostic methods used for monitoring bacterial infections lead to unnecessary or delays in prescription of the right antibiotic treatment.Determining an optimal clinical treatment requires rapid detection and identification of pathogenic bacteria and their sensitivity to specific antimicrobials. However, diagnostic devices that meet all of these criteria have proven elusive thus far. Graphene field effect transistors (G-FET) are a promising solution, since they are highly sensitive to chemical/biological modification, can have fast detection times and can be placed on different substrates. Here, by integrating specific peptide probes over G-FETs, we present a proof-of-concept study for species and strain specific label-free detection of clinical strains of pathogenic bacteria with high specificity and sensitivity. We found that pyrene-conjugated peptides immobilized on G-FETs were capable of detecting pathogenic Staphylococcus aureus at the single-cell level and discriminate against other gram-positive and gram-negative bacterial pathogens. A similar device was able to discriminate between antibiotic resistant and sensitive strains of Acinetobacter baumannii, suggesting that these devices can also be used for detecting antibiotic resistive pathogens. Furthermore, a new means of enhancing attachment, electric-field assisted binding, reduced the detection limit to 10 4 cells/ml and the detection time to below 5 minutes. The combination of single step attachment, inexpensive production, rapid, selective and sensitive detection suggest G-FETs plus pyrene-conjugated peptides are a new platform for solving major challenges faced in point of care diagnostics to fight infectious diseases and antimicrobial resistance.Bacterial infections cause a wide range of diseases and significant mortality 1 . While antibiotics are key in controlling disease severity and reducing mortality, their over prescription and misuse are some of the most important factors in the surge of antibiotic resistant cases around the world. [2][3][4] In order to solve this crisis, diagnostic methods are needed that can rapidly and accurately identify the bacterium causing the infection and determine its associated antibiotic resistance profile. Antibiotic susceptibility testing (AST) is mostly carried out by phenotypic methods that require prior identification of bacterial pathogens from patients (at the species and/or strain level) and incubation under antibiotic conditions, 5, 6 a lengthy process that can take up to 24 hours to a month depending on the species. 7 Moreover, both species/strain identification and AST require trained specialists, specific laboratory environments and often expensive instrumentation. 5, 6, 8 Since these conditions limit widespread application and implementation into actual treatment strategies at most points of care, there is much room for improvement to develop new diagnostic devices that have the potential for adoption across a large variety of use cases. Ideally these dev...
“…More importantly, the devices showed no obvious change of output performance when bent at two totally different directions, as seen in Figure c, further demonstrating its potential in flexible and disposable bioelectronics. Recently, Escherichia coli ( E. coli ) was successfully detected using an inorganic graphene‐based FET functionalized with pyrene‐tagged DNA aptamers . The excellent bacterial sensing performance in terms of high sensitivity, selectivity, and stability and low LOD can be ascribed to the effective E. coli ‐induced electrostatic gating via probe–target interaction.…”
Section: Integration Of Biomacromolecules Into Otft‐based Sensorsmentioning
Sensors based on organic thin-film transistors (OTFTs) present various advantages, including high sensitivity and mechanical flexibility, thus possessing potential applications such as wearable devices and biomedical electronics for health monitoring, etc. However, such applications are partially limited by the biocompatibility, biodegradability, and sensitivity to target analytes of OTFT-based sensors, which can be improved by the incorporation of diverse biomaterials. This article presents a brief review from the viewpoint of the type of the integrated biomaterials, including naturally occurring biomacromolecules such as proteins, enzymes, and deoxyribonucleic acid, as well as biocompatible polymers such as polylactide, poly(lactide-co-glycolide), poly(ethylene glycol), cellulose, polydimethylsiloxane, parylene, etc. It is believed that future work in this field should be devoted to the selectivity, sensitivity, and stability improvement as well as the high-level integration and sophistication on the basis of the OTFT-based sensors for physical, chemical, and biological sensing applications.
“…One potential application of the self‐assembled DNAµPs was to capture/sequester biologically interesting molecules, for example, microRNAs by hybridization and small molecules by aptamers . To demonstrate the feasibility of such capturing/sequestering, we used the DNAµPs assembled from 4Pt, 5Pt, 6Pt, or 7Pt to sequester a target DNA strand T, which is complementary to the tail of the polymerizable DNAs ( Figure ).…”
DNA is a superb molecule for self‐assembly of nanostructures. Often many DNA strands are required for the assembly of one DNA nanostructure. For lowering the cost of synthesizing DNA strands and facilitating the assembly process, it is highly desirable to use a minimal number of unique strands for potential technological applications. Herein, a strategy is reported to assemble a series of DNA microparticles (DNAµPs) from one component DNA strand. As a demonstration of the application of the resulting DNAµPs, the design and assembled DNAµPs are modified to carry additional single‐stranded tails on their surfaces. The modified DNAµPs can either capture other nucleic acids or display CpG motifs to stimulate immune responses.
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