Detection Of Platelet-derived Growth Factor BB Research Articles

Label-free detection of platelet-derived growth factor-BB via liquid crystal/aqueous interface functionalized using a double-stranded DNA probe

A liquid crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with cationic surfactant octyltrimethylammonium bromide (OTAB) and adsorbed with a double-stranded deoxyribonucleic acid (dsDNA) probe at the LC/aqueous interface (TEMOTAB/DNA) was utilized for the highly specific detection of platelet-derived growth factor (PDGF-BB). Upon adsorption of the OTAB-coated 4-cyano-4′-pentylbiphenyl (5CB) on the TEM grid (TEMOTAB) and subsequent adsorption of the dsDNA probe, a homeotropic orientation was observed. Subsequently, the TEMOTAB/DNA biosensor was exposed to PDGF-BB, which induced a homeotropic-to-planar configurational change in 5CB, as observed using polarized optical microscopy with crossed polarizers. The optimized adsorption density of the dsDNA probe facilitated the detection of 2.63 pg mL−1 PDGF-BB in the detection range of 5–200 pg mL−1. Remarkably, this LC-based biosensor discriminated PDGF-BB from bovine serum albumin, immunoglobulin G, hemoglobin, carcinoembryonic antigen, epidermal growth factor, PDGF-AA, and PDGF-AB. The application potential of this sensor was further demonstrated by its effective performance in detecting PDGF-BB in both human serum and synthetic urine samples. Because of its high specificity, sensitivity, and label-free detection capabilities, this biosensor has potential applications in cancer detection.

Self-Powered Biosensing System with Multivariate Signal Amplification for Real-Time Amplified Detection of PDGF-BB.

A self-powered biosensing system with multivariate signal amplification is designed for the ultrasensitive, highly efficient, rapid-response, and real-time detection of platelet-derived growth factor-BB (PDGF-BB). The biosensing system is composed of enzymatic biofuel cells (EBFCs), a capacitor, a digital multimeter (DMM), and a computer. Using the hybridization chain reaction (HCR), a few single DNA chains are transformed into abundant double-helix chains, which stimulates the reduction of [Ru(NH3)6]3+ to [Ru(NH3)6]2+ by electrostatic interaction, corresponding to the "on" state for HCR. As a result, the open-circuit voltage (EOCV) is significantly increased in this self-powered biosensing system. When PDGF-BB is present, a binding interaction between the target and the aptamer, i.e., PDGF-BB/Apt, corresponding to the "off" state for HCR, results in a decrease of EOCV. The PDGF-BB concentration is inversely proportional to EOCV, allowing readable, effective, and precise real-time detection of PDGF-BB. The detection limit of the biosensing system is 0.031 pg/mL (S/N = 3). This strategy provides a promising and powerful tool for the early clinical diagnosis of related colorectal cancer markers.

CRISPR Cas12a-Powered Silicon Surface-Enhanced Raman Spectroscopy Ratiometric Chip for Sensitive and Reliable Quantification

Sensitive and reliable clustered regularly interspaced short palindromic repeats (CRISPR) quantification without preamplification of the sample remains a challenge. Herein, we report a CRISPR Cas12a-powered silicon surface-enhanced Raman spectroscopy (SERS) ratiometric chip for sensitive and reliable quantification. As a proof-of-concept application, we select the platelet-derived growth factor-BB (PDGF-BB) as the target. We first develop a microfluidic synthetic strategy to prepare homogeneous silicon SERS substrates, in which uniform silver nanoparticles (AgNPs) are in situ grown on a silicon wafer (AgNPs@Si) by microfluidic galvanic deposition reactions. Next, one 5'-SH-3'-ROX-labeled single-stranded DNA (ssDNA) is modified on AgNPs via Ag-S bonds. In our design, such ssDNA has two fragments: one fragment hybridizes to its complementary DNA (5'-Cy3-labeled ssDNA) to form double-stranded DNA (dsDNA) and the other fragment labeled with 6'-carboxy-X-rhodmine (ROX) extends out as a substrate for Cas12a. The cleavage of the ROX-tagged fragment by Cas12a is controlled by the presence or not of PDGF-BB. Meanwhile, Cy3 molecules serving as internal standard molecules still stay at the end of the rigid dsDNA, and their signals remain constant. Thereby, the ratio of ROX signal intensity to Cy3 intensity can be employed for the reliable quantification of PDGF-BB concentration. The developed chip features an ultrahigh sensitivity (e.g., the limit of detection is as low as 3.2 pM, approximately 50 times more sensitive than the fluorescence counterpart) and good reproducibility (e.g., the relative standard deviation is less than 5%) in the detection of PDGF-BB.

Target-triggered tertiary amplifications for sensitive and label-free protein detection based on lighting-up RNA aptamer transcriptions

Proteins play vital roles in regulating a series of living activities and can be potentially considered to be useful indicators for diagnosing various diseases. Here, a target-triggered transcription cascade amplification strategy with the use of the fluorescence switch-on RNA aptamer is constructed for label-free and sensitive platelet-derived growth factor-BB (PDGF-BB) protein biomarker detection. The target molecule of PDGF-BB binds a rationally designed multifunctional hairpin probe to switch its structure and to expose a primer binding region. The primer sequence further binds such a region to initiate the target recycling and lighting-up RNA aptamer transcription cascade cycles to yield tremendous RNA aptamers. And, the fluorescence of the organic dye is substantially enhanced upon binding to these RNA aptamers for realizing highly sensitive and label-free PDGF-BB detection with the detection limit being lowered to 0.8 pM. Moreover, the developed strategy has superior selectivity and exhibits a promising potential to detect PDGF-BB spiked into serums with buffer dilution, which makes this method an attractive sensing system for detecting other biomarkers at trace levels.

Chemiluminescent detection of platelet derived growth factor-BB based on sandwich label-free aptasensor and biotin–streptavidin strategy

We reported an aptamer-based sandwich-type biosensor to detect the platelet derived growth factor-BB (PDGF-BB) by chemiluminescence (CL). Employing magnetic beads as a peculiar immobilizing carriers, a sandwich-type biosensor for detection of PDGF-BB had developed. Firstly, Anti-PDGF-BB was immobilized on the surface of magnetic beads to serve as capture antibody. Then we added PDGF-BB and PDGF-BB-binding aptamer to make sandwich-type complex eventually. CL signal was generated by reaction of 3,4,5-trimethoxyl-phenylglyoxal (TMPG) and guanine nucleobases (G) of PDGF-BB aptamer strands. Moreover, this strategy further improved the sensitivity of detection via biotin-streptavidin reaction that one streptavidin molecule combined with four G-rich sequences which included aptamer. The experimental results showed that the CL intensity was linear to the concentration of PDGF-BB in the range from 1 × 10−8 to 2 × 10−7 M. With magnified protocol, the CL intensity had a good linear relation on the concentration of PDGF-BB in the range from 4 × 10−10 to 2 × 10−8 M. The limit of detection was 0.15 nM at a signal-to-noise ratio of 3. The proposed method was simple, label-free and had high sensitivity which to be expected to provide new way for clinical detection of PDGF-BB.

Novel Integration of Bipolar Exfoliated Graphene with 3D C-MEMS Microelectrodes for Label-Free Electrochemical Cancer Biomarkers Aptasensors

Early detection of cancer can noticeably increase the survival chance of many cancer patients. Quantifying cancer biomarkers detectable from blood is an efficient way for the early detection of cancer diseases. Among various discovered cancer biomarkers, platelet-derived growth factor-BB (PDGF-BB) is an essential biomarker for early detection of cancer and monitoring cancer patients. This biomarker plays a vital role in developing and lymphatic metastasis of solid malignant tumors such as brain, lung, breast, and liver, which enlightens the importance of developing point-of-care (POC) biosensors for the detection of PDGF-BB. In recent years, the application of synthetic DNA or RNA-based bio-recognizers (i.e., aptamers) in cancer biomarker sensor development has been vastly investigated. Electrochemical label-free aptamer-based biosensors (also known as aptasensors) are highly suitable for POC. The well-established C-MEMS (carbon microelectromechanical systems) platforms have distinguishing features which are highly suitable for biosensing applications such as low background noise, high capacitance, high stability when exposed to different physical/chemical treatments, biocompatibility, and good electrical conductivity. Furthermore, the surface of C-MEMS can be modified effectively via depositing nanomaterials which can enhance the electrochemical and sensing performances of the C-MEMS based biosensors. In this study, the integration of bipolar exfoliated (BPE) reduced graphene oxide (rGO) with 3D C-MEMS microelectrodes for developing PDGF-BB label-free aptasensors is investigated. A single setup has been used for exfoliation, reduction, and deposition of rGO on the 3D C-MEMS microelectrodes based on the principle of bipolar electrochemistry of graphite in deionized water. The electrochemical bipolar exfoliation of rGO resolves the drawbacks of commonly applied methods for synthesis and deposition of rGO such as requiring complicated and costly processes, excessive use of harsh chemicals, and complex subsequent deposition procedures. The PDGF-BB affinity aptamers were covalently immobilized by binding amino-tag terminated aptamers and rGO surfaces. The scanning electron microscopy (SEM) analysis confirms that the rGO deposited on 3D C-MEMS microelectrodes has a porous vertically aligned structure with pore sizes of around 100 nm. Cyclic voltammetry (CV) was used for characterizing the aptasensors in different stages of development and their sensing performances. The CV analysis confirms that deposition of BPE-rGO noticeably increases the capacitance of 3D C-MEMS electrodes. The turn-off sensing strategy was implemented by measuring the areal capacitance from CV plots. The aptasensor showed a wide linear range of 1 pM-10 nM, high sensitivity of 3.09 mF cm-2 Logc-1 (unit of c, pM), and a low detection limit of 0.75 pM. This study demonstrated the successful deposition of BPE-rGO on 3D CMEMS microelectrodes. Considering the high potential of C-MEMS technology and BPE technique's simplicity and efficiency, this novel technique is highly promising for developing feasible and mass-producible lab-on-chip and point-of-care cancer diagnosis technologies.

Novel Electrochemical Aptasensors Based on Bipolar Exfoliated Graphene for Label-Free Detection of Cancer Biomarkers

Early detection of cancer can noticeably increase the survival chance of many cancer patients. Quantifying cancer biomarkers detectable from blood is an efficient way for early detection of cancer diseases. Among various discovered cancer biomarkers, platelet-derived growth factor-BB (PDGF-BB) is an essential biomarker for early detection of cancer and monitoring cancer patients. This biomarker plays a vital role in developing and lymphatic metastasis of solid malignant tumors such as brain, lung, breast, and liver; which enlightens the importance of developing point-of-care (POC) biosensors for the detection of PDGF-BB. In recent years, the application of synthetic DNA or RNA-based bio-recognizers (i.e., aptamers) in cancer biomarker sensor development has been vastly investigated. Electrochemical label-free aptamer-based biosensors (also known as aptasensors) are highly suitable for POC. In this study, the application of bipolar exfoliated (BPE) graphene for developing PDGF-BB label-free aptasensors is investigated. Graphene as a single, two-dimensional layer of carbon atoms has very interesting features suitable for biosensor applications. The common graphene synthesis methods require complicated and costly processes and excessive use of harsh chemicals, as well as complex subsequent deposition procedures. In this study, a single setup has been used for exfoliation, reduction, and deposition of graphene nanosheets on a conductive electrode based on the principle of bipolar electrochemistry of graphite in deionized water. We investigated the properties of aptasensors based on graphene oxide (GO) deposited on a positive electrode feeding electrode and reduced-GO (rGO) deposited on a negative electrode feeding electrode. The PDGF-BB affinity aptamers were covalently immobilized by binding amino-tag terminated aptamers and carboxyl groups of GO and rGO surfaces. In this study, Fourier-transform infrared spectroscopy (FTIR) was used to study the surface characteristics of synthesized graphene and developed aptasensors. The scanning electron microscopy (SEM) was used to study the morphology of the bipolar exfoliated GO and rGO. The SEM study demonstrated that the rGO has a porous vertically aligned structure with pore sizes of around 100 nm, while GO has bulky flattened plates with random cracks. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used for characterizing the BPE graphene-based aptasensors in different stages of development and their sensing performances. The turn-off sensing strategy was implemented by measuring the peak-currents from DPV plots. The optimized aptasensor based on rGO showed a wide linear range of 0.75 pM-10 nM, high sensitivity of 7.83 A Logc-1 (unit of c, pM), and a low detection limit of 0.53 pM. However, the optimized aptasensor based on GO reached to its saturation point around 150 pM. This study demonstrated that bipolar electrochemistry is a simple yet efficient technique that could provide high-quality graphene for biosensing applications. Considering the BPE technique's simplicity and efficiency, this technique is highly promising for developing feasible and affordable lab-on-chip and point-of-care cancer diagnosis technologies.

Label-Free Electrochemical Aptasensors Based on Photoresist Derived Carbon for Cancer Biomarker Detection

Cancer biomarkers are substances found in the human fluid, tissue, and bone marrow that can indicate the presence of cancer diseases in the human body. In the past decades, various cancer biomarkers have been discovered for early detection of cancers and risk assessment of reoccurring cancers. Among the discovered cancer biomarkers, platelet-derived growth factor-BB (PDGF-BB) is an essential biomarker for early detection of cancer diseases. This biomarker plays a significant role in the development of multiple solid malignant tumors (e.g., breast, brain, pancreatic, prostate, and ovarian) and lymphatic metastasis. A feasible means for early detection of cancers is developing point-of-care biosensors based on synthetic DNA or RNA bio-recognizers (i.e., aptamers), which are referred to as aptasensors. Various advanced technologies have been investigated for developing cancer biomarker aptasensors, including optical, piezoelectric, and electrochemical based techniques. Among the developed technologies, label-free electrochemical aptasensors are highly potent means for this purpose since they can reduce the cost and complications of sample preparation, and the electrochemical cells can be efficiently miniaturized and integrated with available lab-on-chips and MEMS technologies. However, the sensing performance of the label-free electrochemical cancer aptasensors, including the limit of detection, selectivity, and dynamic range requires further enhancements to be at similar levels to benchtop testing. In the light of the importance of PDGF-BB detection and demanded enhancements for label-free electrochemical aptasensors, we have developed label-free electrochemical aptasensors based on photoresist derived carbon microelectrodes. The active electrode of this aptasensor was synthesized via well-established C-MEMS (carbon microelectromechanical systems) fabrication technology. C-MEMS platforms have distinguishing features such as low background capacitance, high stability when they exposed to different physical/chemical treatments, biocompatibility, and good electrical conductivity. Furthermore, the surface of C-MEMS can be modified effectively via electrochemical processes as well as depositing nanomaterials. The applied C-MEMS fabrication in this study includes photopatterning of SU-8 25 negative photoresist-based microelectrodes and carbonization of the developed microelectrodes at high temperatures and oxygen-free tube furnaces. The carbonized microelectrodes were functionalized utilizing oxygen plasma oxidation pretreatment to introduce carboxyl groups to the surfaces of the carbon microelectrodes. The PDGF-BB affinity aptamers were covalently immobilized via amid binding of amino-tag terminated aptamers and carboxyl groups covered carbon surfaces. The Fourier-transform infrared spectroscopy (FTIR) confirmed the successful carboxyl group functionalization of the C-MEMS microelectrodes and covalent immobilization of affinity aptamers via amide biding. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for characterizing the C-MEMS based aptasensors in different stages of development and sensing performances. The turn-on sensing strategy was deployed via measuring the charge transfer resistance (RCT) from EIS Nyquist plots, which yielded to wide sensing linear range of 0.005 – 50 nM with a high sensitivity of 14.82 × 103 Ω.(Log (M))-1 and low limit of detection of 1.9 pM (S/N=3). The turn-off sensing strategy was applied via measuring capacitance from CV curves, which conceded to wide linear response range of 0.01 – 50 nM with a high sensitivity of 29.97 mF.cm-2.(Log (M))-1 and low limit of detection of 7 pM (S/N=3) toward the PDGF-BB. The developed label-free electrochemical aptasensor exhibited good selectivity, stability, and repeatability, which is highly promising for future lab-on-chip and point-of-care cancer diagnosis technologies.

Highly sensitive label-free electrochemical aptasensors based on photoresist derived carbon for cancer biomarker detection

-Label-free electrochemical aptasensors for cancer biomarker detection can be a promising means for early detection of cancer due to their high sensitivity, selectivity, and stability, and low cost. In this study, a highly sensitive and selective label-free electrochemical aptasensor based on carbon microelectromechanical systems (C-MEMS) was developed for the detection of platelet-derived growth factor-BB (PDGF-BB). The active electrodes of the aptasensors were synthesized via carbonization of SU-8 derived electrodes at high temperatures in an oxygen-free furnace. An oxygen-plasma oxidation treatment was used to functionalize the C-MEMS electrodes, which provided efficient covalent immobilization of amino terminated affinity aptamers. The turn-off and turn-on detection strategies–based on capacitance and resistance measurement, respectively—were employed. The capacitance detection strategies exhibited a wide linear response range of 0.01–50 nM, with a high sensitivity of 3.33 mF cm-2 Logc-1 (unit of c, nM) and a low limit of detection of 7 pM (S/N = 3). The resistance detection strategies exhibited an even wider linear response range of 0.005–50 nM, and a lower limit of detection of 1.9 pM (S/N = 3), with a high sensitivity of 1.65 × 103 Ω Logc-1 (unit of c, nM). Both detection strategies provided high selectivity for PDGF-BB and high stability of 90.34% after 10 days. This research demonstrates that the developed label-free electrochemical C-MEMS based PDGF-BB aptasensor is highly sensitive, selective, and robust. This aptasensor is a promising prospect for the highly demanding task of early detection of cancer biomarkers.

A light-induced self-powered competitive immunosensor for the detection of platelet derived growth factor-BB via an elaborately assembled bioconjugate

A photocatalytic fuel cell (PFC) coupling with competitive immunoassay was designed for self-powered sensing of platelet derived growth factor-BB (PDGF-BB). In the PFC, the effective oxidation of ascorbic acid (AA) on a photoanode under visible light illumination and catalytic reduction of [Fe(CN)6]3− on a cathode generated electrical output. In order to realize the specific detection of PDGF-BB, the antibody of PDGF-BB (Ab) was immobilized on photoanode to act as the recognition element. Meanwhile, a bioconjugate, PDGF-BB@AuNPs@dopamine–melanin nanosphere, was used as the competitive element of target which could dramatically reduce the output of PFC by blocking the transfer of AA to the photoanode. When the target PDGF-BB coexisted with the bioconjugate, the competitive binding of smaller target molecule with Ab immobilized on photoanode could reduce the binding amount of bioconjugate and induce an elevated output of PFC. Under the optimum condition, the output of PFC was linearly proportional to the logarithm of PDGF-BB concentration from 20 pg mL-1 to 200 ng mL-1, with a detection limit (3S/N) of 6.2 pg mL-1. Moreover, the developed self-powered competitive immunosensor was successfully applied to the detection of PDGF-BB in human serum.

A signal-enhanced and sensitive lateral flow aptasensor for the rapid detection of PDGF-BB.

Platelet-derived growth factor BB (PDGF-BB) is a potential biomarker of tumor angiogenesis. For the first time, we developed a highly sensitive aptasensor for PDGF-BB with an enhanced test line signal by using two different gold nanoparticles (AuNPs). Herein, we describe a highly sensitive biosensor for PDGF-BB detection that combines biotinylated aptamer on a sample pad and poly thymine-Cy3-AuNP-monoclonal antibody complexes against PDGF-BB immobilized on conjugate pad A. Streptavidin (SA) and rabbit anti-mouse polyclonal antibody were also immobilized in the nitrocellulose membrane at the test and control zones, respectively. When the target PDGF-BB protein was added, it first bound the aptamer, and later the monoclonal antibody to form a biotinylated complex that was captured by SA, resulting in a visual red line on the test zone. In addition, to enhance the sensitivity, another monoclonal antibody against Cy3 was conjugated on AuNP B and immobilized on conjugate pad B to form a AuNPs (A&B)-antibody-(PDGF-BB-Cy3)-aptamer-biotin-SA complex on the test line when a loading buffer was subsequently added. This approach showed a linear response to PDGF-BB from 3 ng mL−1 to 300 ng mL−1 with a limit of detection as low as 1 ng mL−1 obtained in 10 minutes. Our biosensor displayed results through red lines readable by the naked eye. Interestingly, our approach has been successfully applied for real sample verification, proving its applicability for cancer monitoring and diagnosis.

Proximity Binding-Triggered Assembly of Two MNAzymes for Catalyzed Release of G-Quadruplex DNAzymes and an Ultrasensitive Homogeneous Bioassay of Platelet-Derived Growth Factor.

When the target biorecognition-triggered assembly of two Mg2+-dependent DNAzymes (MNAzymes) is employed for dually catalytic release of peroxidase-mimicking G-quadruplex DNAzymes (G-DNAzymes), this work develops a novel homogeneous colorimetric method for an ultrasensitive bioassay of platelet-derived growth factor-BB (PDGF-BB). The first MNAzyme assembly is realized through a highly specific aptamer biorecognition-driven proximity ligation reaction. Its catalytic cleavage toward the two designed hairpin substrates not only releases a large amount of G-DNAzymes for colorimetric signal transduction but also enables the spontaneous assembly of another MNAzyme for signal amplification. This leads to the successful detection of PDGF-BB in a wide linear range from 2.0 pg mL-1 to 20 ng mL-1 with a very low detection down to 0.088 pg mL-1. As the whole reactions including aptamer biorecognitions, DNA hybridizations, and catalytic cleavages of MNAzymes are conducted in a homogeneous solution, this method has very simple manipulations and also has high repeatability. In addition, the high specificity of the aptamer biorecognition-triggered signal transduction decides the excellent selectivity of the method. This bioassay does not require an expensive instrument and nucleic acid labeling for signal readout or any nanomaterial, enzyme, or nuclease for signal amplification. Thus, it displays an extensive potential for clinical diagnostic applications.

Aptamer recognition and proximity-induced entropy-driven circuit for enzyme-free and rapid amplified detection of platelet-derived growth factor-BB

Platelet-derived growth factor-BB (PDGF-BB) is currently used as a biomarker protein for cancer early diagnosis and clinical treatment. Herein, we reported a robust and enzyme-free strategy based on aptamer recognition and proximity-induced entropy-driven circuits (AR-PEDC) for homogeneous and rapid detection of platelet-derived growth factor BB (PDGF-BB) without any washing steps or thermocycling. The proximity probes specifically recognize target protein to form the completed trigger (CT). Then, the CT reacts with three-strand complex to form intermediate, which subsequently binds to fuel strand to release reporter strand, assistant strand and the CT. The revised proximity probes exhibit significantly improved signal-to-background ratio and faster association rate. Moreover, target protein/proximity probes interaction can specifically initiate entropy-driven circuits, thus providing immense signal amplification for ultrasensitive detection of PDGF-BB with low detection limit of 9.6 pM. The practical ability of the developed strategy is demonstrated by detection of PDGF-BB in human serum with satisfactory results. In addition, this method is flexible and can be conveniently extended to a variety of targets by simply substituting the target specific sequence. Thus, this strategy presents a rapid, low background and versatile amplification mechanism for the detection of protein biomarkers and offers a promising alternative platform for clinical diagnosis.

Lateral Flow Aptasensor for Simultaneous Detection of Platelet-Derived Growth Factor-BB (PDGF-BB) and Thrombin.

Here we report a lateral flow aptasensor (LFA) for the simultaneous detection of platelet-derived growth factor-BB (PDGF-BB) and thrombin. Two pairs of aptamers, which are specific against PDGF-BB and thrombin, respectively, were used to prepare the LFA. Thiolated aptamers were immobilized on a gold nanoparticle (AuNP) surface and biotinylated aptamers were immobilized on the test zones of an LFA nitrocellulose membrane. The assay involved the capture of PDGF-BB and thrombin simultaneously in sandwich-type formats between the capture aptamers on the test zones of LFA and AuNP-labeled detection aptamers. AuNPs were thus captured on the test zones of the LFA and gave red bands to enable the visual detection of target proteins. Quantitative results were obtained by reading the test band intensities with a portable strip reader. By combining the highly specific molecular recognition properties of aptamers with the unique properties of lateral flow assay (low-cost, short assay time and a user-friendly format), the optimized aptasensor was capable of simultaneously detecting 1.0 nM of PDGF-BB and 1.5 nM of thrombin in association with a 10-min assay time. The biosensor was also successfully applied to detect PDGF-BB and thrombin in spiked human serum samples. The LFA shows great promise for the development of aptamer-based lateral flow strip biosensors for point-of-care or for the in-field detection of disease-related protein biomarkers.

A novel fluorescent aptasensor for sensitive detection of PDGF-BB protein based on a split complementary strand of aptamer and magnetic beads

In this work, a simple and sensitive aptamer-based fluorescent biosensor was fabricated for ultrasensitive detection of platelet-derived growth factor-BB (PDGF-BB) protein, which is known as a potential biomarker for diagnosis of different cancers. The developed aptasensor was based on PDGF-BB aptamer (Apt), a split complementary strand of aptamer (CS), magnetic beads and picogreen (PG) as a sensitive double-stranded DNA (dsDNA) fluorescent dye. Presence of magnetic beads with the capability of sample condensation and split CS in the fabricated biosensor improved the analytical performance of the aptasensor. In the absence of PDGF-BB protein, dsDNA (CS1-CS2/Apt) is formed on the surfaces of magnetic beads. Therefore, after addition of PG to the sample, a strong fluorescence signal is recorded. On the contrary, in the presence of PDGF-BB protein only CS2 as a very short single-stranded DNA (ssDNA) remains on the surfaces of magnetic beads, leading to a weak fluorescence response following the addition of PG. Under optimized condition, the designed biosensor showed a linear response to concentrations of protein from 0.2 to 100 nM with detection limit as low as 0.13 nM. The biosensor was further employed to detect PDGF-BB protein in serum samples and demonstrated satisfied recovery, ranging from 103.6 to 105.2%.

Electrochemical biosensor based on Se-doped MWCNTs-graphene and Y-shaped DNA-aided target-triggered amplification strategy.

A highly sensitive electrochemical biosensor for detection of platelet-derived growth factor-BB (PDGF-BB) is developed by using Se-doped multi-walled carbon nanotubes (MWCNTs)-graphene hybrids as electrode supporting substrate, hemin/G-quadruplex as trace labels and Y-shaped DNA-aided target recycling as signal magnifier. The aptamer-containing hairpin probes were first immobilized on the electrode. When target PDGF-BB was added, the aptamer binded PDGF-BB to trigger catalytic assembly of two other hairpins to form many G-quadruplex Y-junction DNA structures, which released PDGF-BB to again bind the intact aptamer to initiate another assembly cycle. G-quadruplex/hemin complexes were produced when hemin was added to generate substantially amplified current output. The developed assay showed a linear range toward PDGF-BB from 0.1 pM to 10 nM with a detection limit of 27 fM (S/N = 3). The method showed excellent specificity and repeatability, and could be expediently applied for sensitive detection of other molecules by simply changing the aptamers.

Detecting Novel Urine Biomarkers for the Early Diagnosis of Prostate Cancer: Platelet Derived Growth Factor-BB as a Possible New Target

Introduction: Although the prostate specific antigen revolutionized the diagnosis of prostate cancer (PCa), it has its limitations. We prospectively examined the potential use of the platelet-derived growth factor-BB (PDGF-BB) as a urine biomarker for the early diagnosis of PCa. Materials and Methods: The urine samples of 118 patients were collected after a prostatic massage and all the patients subsequently underwent ultrasound-guided transrectal biopsy. PDGF-BB was detected in the urine by enzyme-linked immunosorbent assay. Results: Patients with PCa had greater levels of prostate specific antigen and PDGF-BB. Receiver operating characteristic curve analysis showed that the optimal cut-of of PDGF-BB for the prediction of PCa was 1,504.9 with a sensitivity of 60% and a specificity of 51.3%. For a 100 unit increase in PDGF-BB, the likelihood for PCa increased about 4%. Conclusion: PDGF-BB showed a significant predictive ability for PCa. Detection of PDGF-BB in urine with Elisa was easy and improved our diagnostic accuracy in the diagnosis of PCa.

Electrochemiluminescent aptasensor based on β-cyclodextrin/graphitic carbon nitride composite for highly selective and ultrasensitive assay of platelet derived growth factor BB

Here, an electrochemiluminescent aptasensor based on β-cyclodextrin/graphitic carbon nitride (β-CD/g-C3N4) composite for selective and highly ultrasensitive assay of platelet derived growth factor BB (PDGF-BB) is fabricated. To achieve the sensitive and specific detection of PDGF-BB, it is an available strategy to explore excellent electrochemiluminescent (ECL) luminophores with the advantages of high electrochemical-driven luminescent activity and a specific recognition function. In this work, for the first time a novel β-CD non-covalently functionalized g-C3N4 composite β-CD/g-C3N4 was employed to construct the ECL detection platform for PDGF-BB based on its aptamer. The limit of detection was determined to be as low as 2.6 × 10−13 g/mL. It was observed that β-CD was playing a key role in improving the adamantane-labeled DNA amount modified on the electrode surface. It can further help to amplify the ECL quenching effect by both energy transfer and photo-excited electron transfer processes between g-C3N4 emitter and ferrocene quencher. It is anticipated that β-CD/g-C3N4 may be a class of promising material for constructing ECL sensors.

A biolayer interferometry-based enzyme-linked aptamer sorbent assay for real-time and highly sensitive detection of PDGF-BB

Accurate, fast and sensitive detection of disease-specific protein biomarkers, especially in blood, urine, or other bodily fluids, is an important approach to achieve early disease diagnosis. Platelet-derived growth factor-BB (PDGF-BB), a widely used biomarker, is involved in a substantial number of serious diseases, such as hepatic fibrosis, atherosclerosis, age-related macular degeneration and diabetic eye disease and is often over-expressed in human malignant tumors. Therefore, the development of sensitive and specific detection methods for PDGF-BB is of great importance for the early diagnosis of disease and assessments of patient recovery. In the current study, a biolayer interferometry-based enzyme-linked aptamer sorbent assay (BLI-ELASA) was successfully established for rapid (20–25min), high-throughput (8 or 16 samples) and real-time monitoring of PDGF-BB in clinical samples. The method exhibited a broad detection range from 0.5 to 1000ng/mL of PDGF-BB (good linear range from 0.5 to 10ng/mL), with a low detection limit of 0.08ng/mL. Moreover, BLI-ELASA was applied to the detection of PDGF-BB in spiked serum and urine samples and showed a high degree of selectivity for PDGF-BB, good reproducibility, and stability. We believe that the methodology in this work can be easily adapted to detect other biomolecules in clinical samples, including viruses, pathogens and toxins, in a rapid, sensitive, high-throughput and real-time manner.

Carbon-based nanocomposites with aptamer-templated silver nanoclusters for the highly sensitive and selective detection of platelet-derived growth factor

We synthesized two kinds of carbon-based nanocomposites of silver nanoclusters (AgNCs). An aptamer for targeted platelet-derived growth factor-BB (PDGF-BB) detection was used as the organic phase to produce AgNCs@Apt, three dimensional reduced graphene oxide@AgNCs@Aptamer (3D-rGO@AgNCs@Apt), and graphene quantum dots@AgNCs@Aptamer (GQD@AgNCs@Apt) nanocomposites. The formation mechanism of the developed nanocomposites was described by detailed characterizations of their chemical and crystal structures. Subsequently, the as-synthesized nanoclusters containing aptamer strands were applied as the sensitive layers to fabricate a novel electrochemical aptasensor for the detection of PDGF-BB, which may be directly used to determine the target protein. Electrochemical impedance spectra showed that the developed 3D-rGO@AgNCs@Apt-based biosensor exhibited the highest sensitivity for PDGF-BB detection among three kinds of fabricated aptasensors, with an extremely low detection limit of 0.82pgmL−1. In addition, the 3D-rGO@AgNCs@Apt-based biosensor showed high selectivity, stability, and applicability for the detection of PDGF-BB. This finding indicated that the AgNC-based nanocomposites prepared by a one-step method could be used as an electrochemical biosensor for various detection procedures in the biomedical field.