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Purwidyantri, Agnes, et al. Sensors and Actuators B: Chemical 367 (2022): 132044.
Graphene field-effect transistor (FET) chips have been effectively utilized in constructing a highly sensitive and fully automated lab-on-a-chip (LoC) system for real-time DNA detection. This integrated platform combines a multi-sensor graphene FET chip with a programmable microfluidic flow system and a portable graphene curve reader to monitor biochemical events through shifts in Dirac voltage.
The graphene FET surface was functionalized using a layered approach: dodecanethiol (DDT) was used to passivate the gold contacts, followed by non-covalent immobilization of pyrene-based PBSE linkers on the graphene surface via π-π stacking. Amine-tagged probe DNA was then introduced into the PDMS flow cell mounted on the FET chip for hybridization detection.
The device exhibited exceptional sensitivity (\~44 mV/decade) and an ultra-low limit of detection (\~0.642 aM) for target DNA, surpassing most conventional biosensors. Fluid delivery was precisely controlled via a programmable multi-position valve system, enabling sequential operations including probe immobilization, blocking, hybridization, and washing-critical for robust, unattended performance.
The use of a nine-graphene-sensor array on a single chip significantly enhanced reliability and throughput. The integration of microfluidics with FET sensing enables high-precision, low-cost, and portable biosensing-ideal for point-of-care diagnostics and molecular biology research. This study demonstrates the promising future of graphene FET chips in scalable, label-free biomolecular detection platforms.
Hajian, Reza, et al. Nature biomedical engineering 3.6 (2019): 427-437.
Graphene-based field-effect transistors (gFETs) have been successfully employed in the design of CRISPR-Chip, a next-generation biosensing platform enabling direct, amplification-free detection of target DNA sequences within intact genomic material. This system leverages the high charge sensitivity of graphene with the sequence-specific recognition capability of the catalytically deactivated CRISPR-Cas9 complex (dRNP).
The CRISPR-Chip integrates a functionalized graphene channel with immobilized dCas9-sgRNA complexes, forming a biosensing surface capable of selectively binding to complementary DNA sequences. Upon hybridization with the target, local charge redistribution at the graphene interface modulates the gFET's electrical properties, generating a measurable output signal using a portable reader.
Notably, the device demonstrated rapid detection within 15 minutes, achieving a remarkable sensitivity of 1.7 fM without nucleic acid amplification or labeling. It was validated using genomic DNA from HEK293T cell lines and clinical samples with Duchenne muscular dystrophy mutations, showing clear signal enhancement upon target binding.
This work highlights the transformative potential of graphene-based field-effect transistors in precision molecular diagnostics. CRISPR-Chip exemplifies a compact, reagent-free, and cost-effective genomic detection tool, expanding CRISPR's application from gene editing to real-time, on-chip biosensing. The seamless integration of gFETs with CRISPR recognition chemistry opens new avenues in point-of-care diagnostics, genetic screening, and personalized medicine.
Nekrasov, Nikita, et al. Toxins 11.10 (2019): 550.
Graphene field-effect transistors (GFETs) have been effectively utilized in developing a highly sensitive and rapid aptasensor for the detection of ochratoxin A (OTA), a hazardous mycotoxin found in food and beverages. This on-chip GFET-based platform combines the exceptional electrical properties of graphene with the molecular recognition capability of aptamers, enabling selective and label-free detection of OTA at ultra-low concentrations.
The sensor was fabricated using scalable large-area graphene deposition techniques, ensuring cost-efficiency and mass production potential. Functionalization of the GFET surface was achieved via covalent bonding of an OTA-specific aptamer, facilitated by ester linkages and π-π interactions. Upon binding with OTA, the aptamer induces a significant shift in the GFET's transfer I-V characteristics, forming the basis of detection.
The device demonstrated a rapid response time of under 5 minutes and an impressive detection limit of 4 pg/mL, with a wide linear detection range (10 pg/mL-4 ng/mL). High reproducibility and excellent regeneration (time constant \~5.6 s) were observed across multiple GFETs and reusability cycles. The sensor's performance was validated in real matrices such as spiked red wine, achieving \~105% recovery, and demonstrated strong selectivity over interfering toxins like zearalenone.
This study underscores the potential of GFET-based aptasensors for in-field, multiplexed detection of foodborne contaminants, combining sensitivity, portability, and rapid operation in a compact on-chip format.
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