Immobilized rolling circle amplification on extended-gate field-effect transistors with integrated readout circuits for early detection of platelet-derived growth factor

Abstract

Detection of tumor-related proteins with high specificity and sensitivity is important for early diagnosis and prognosis of cancers. While protein sensors based on antibodies are not easy to keep for a long time, aptamers (single-stranded DNA) are found to be a good alternative for recognizing tumor-related protein specifically. This study investigates the feasibility of employing aptamers to recognize the platelet-derived growth factor (PDGF) specifically and subsequently triggering rolling circle amplification (RCA) of DNAs on extended-gate field-effect transistors (EGFETs) to enhance the sensitivity. The EGFETs are fabricated by the standard CMOS technology and integrated with readout circuits monolithically. The monolithic integration not only avoids the wiring complexity for a large sensor array but also enhances the sensor reliability and facilitates massive production for commercialization. With the RCA primers immobilized on the sensory surface, the protein signal is amplified as the elongation of DNA, allowing the EGFET to achieve a sensitivity of 8.8 pM, more than three orders better than that achieved by conventional EGFETs. Moreover, the responses of EGFETs are able to indicate quantitatively the reaction rates of RCA, facilitating the estimation on the protein concentration. Our experimental results demonstrate that immobilized RCA on EGFETs is a useful, label-free method for early diagnosis of diseases related to low-concentrated tumor makers (e.g., PDGF) for serum sample, as well as for monitoring the synthesis of various DNA nanostructures in real time. Graphical Abstract The tumor-related protein, PDGF, is detected by immobilizing rolling circle amplification on an EGFET with integrated readout circuit.

Predicting Future Prospects of Aptamers in Field-Effect Transistor Biosensors

“…Abundant negative charges from elongated oligonucleotides on the nanowire surface significantly improved the signal-to-noise ratio of their fabricated FET biosensors by more than 20× to detect HBV DNA at a decreased concentration of 1 fM [144]. RCA was also used by Chen et al to enhance sensitivity of aptameric extended-gate field-effect transistors (EGFETs) sensing platelet-derived growth factor (PDGF) [145]. A more complicated strategy, also based on the mechanism of negative charged DNA, was published by a group of scientists from the United States, China, Hong Kong and Ecuador.…”

Field-Effect Transistor Biosensors for Biomedical Applications: Recent Advances and Future Prospects

“…However, in spite of continuous advancement in large-scale assembly techniques (fluid flow directed assembly [15], bubble-blown assembly [16], contact assembly [17], electric-field-assisted assembly [18], Langmuir-Blodgett assembly [19], field-assisted electrospinning [20], the “place then grow” method [21] and superlattice nanowire pattern transfer [22]) with a well-controlled dimension, orientation and density of synthesized nanowires [23], high device-to-device variation and low carrier mobility are primary issues crucially overcome on the way to commercialize SiNWFETs [24]. Since SiNWFET-based sensors have been successfully employed to detect a variety of biological and chemical molecules (proteins [9,10,11,12,13,25], nucleic acids [14,25,26,27,28], viruses [29,30] and different targeted substances [9,31,32,33,34]), there have been plentiful strategies to improve their sensing capability by operating detection in subthreshold regime [35], using frequency domain measurement [36], optimizing surface modification with electrical field alignment [37], integrating with nanopore morphology [38] or electrokinetic devices [39], and fabricating branched nanowires [40] for clinical diagnosis, the ultimate goal of profuse biomedical applications [41]. CNTs, whereas, possess superior physical and chemical properties for biosensor applications such as: High mechanical strength, surface area and aspect ratio, excellent chemical and thermal stability [42]; outstanding conductivity for nanoscale transducers [43,44,45] and ideal semiconducting behavior as nanoscale FETs [46]; especially advantageous to immobilize bio-probes (antibodies, enzymes, oligonucleotides, etc.)…”

Deep Submicron EGFET Based on Transistor Association Technique for Chemical Sensing

“…However, most of the applications found in the literature use commercially available n–channel metal–oxide semiconductor field-effect transistors (MOSFETs) to implement EGFET biosensors [19,20,21,22]. Custom design of monolithic FET results in arduous sensor development in terms of effort, time, and cost with significant variability, also requiring biological modification directly on the channel region for improved performance [23]. CMOS technology is actually a consolidated technology with an easier single-chip and array integration, characterized by reduced variability, noise, and wiring complexity [23,24].…”

“…Custom design of monolithic FET results in arduous sensor development in terms of effort, time, and cost with significant variability, also requiring biological modification directly on the channel region for improved performance [23]. CMOS technology is actually a consolidated technology with an easier single-chip and array integration, characterized by reduced variability, noise, and wiring complexity [23,24]. Moreover, since it does not require post-processing, multi-purpose CMOS technologies have been used to fabricate EGFETs [25,26].…”