Sandwich-format electrochemiluminescence assay for PDGF-BB using quantum dots–dendrimer nanocomposites as probe

Carbon Based Nanodots in Early Diagnosis of Cancer

Detection of cancer at an early stage is one of the principal factors associated with successful treatment outcome. However, current diagnostic methods are not capable of making sensitive and robust cancer diagnosis. Nanotechnology based products exhibit unique physical, optical and electrical properties that can be useful in diagnosis. These nanotech-enabled diagnostic representatives have proved to be generally more capable and consistent; as they selectively accumulated in the tumor site due to their miniscule size. This article rotates around the conventional imaging techniques, the use of carbon based nanodots viz Carbon Quantum Dots (CQDs), Graphene Quantum Dots (GQDs), Nanodiamonds, Fullerene, and Carbon Nanotubes that have been synthesized in recent years, along with the discovery of a wide range of biomarkers to identify cancer at early stage. Early detection of cancer using nanoconstructs is anticipated to be a distinct reality in the coming years.

Recent advances on aptamer-based biosensors to detection of platelet-derived growth factor

Platelet-derived growth factor (PDGF-BB), a significant serum cytokine, is an important protein biomarker in diagnosis and recognition of cancer, which straightly rolled in proceeding of various cell transformations, including tumor growth and its development. Fibrosis, atherosclerosis are certain appalling diseases, which PDGF-BB is near to them. Generally, the expression amount of PDGF-BB increases in human life-threatening tumors serving as an indicator for tumor angiogenesis. Thus, identification and quantification of PDGF-BB in biomedical fields are particularly important. Affinity chromatography, immunohistochemical methods and enzyme-linked immunosorbent assay (ELISA), conventional methods for PDGF-BB detection, requiring high-cost and complicated instrumentation, take too much time and offer deficient sensitivity and selectivity, which restrict their usage in real applications. Hence, it is essential to design and build enhanced systems and platforms for the recognition and quantification of protein biomarkers. In the past few years, biosensors especially aptasensors have been received noticeable attention for the detection of PDGF-BB owing to their high sensitivity, selectivity, accuracy, fast response, and low cost. Since the role and importance of developing aptasensors in cancer diagnosis is undeniable. In this review, optical and electrochemical aptasensors, which have been applied by many researchers for PDGF-BB cancer biomarker detection, have been mentioned and merits and demerits of them have been explained and compared. Efforts related to design and development of aptamer-based biosensors using nanoparticles for sensitive and selective detection of PDGF-BB have been reviewed considering: Aptamer importance as recognition elements, principal, application and the recent improvements and developments of aptamer based optical and electrochemical methods. In addition, commercial biosensors and future perspectives for rapid and on-site detection of PDGF-BB have been summarized.

Progress and challenges in electrochemiluminescent aptasensors

The importance of developing new diagnostic and detection technologies for the growing number of sensing challenges is rising each year. Here, we present a comprehensive and concise review on electrochemiluminescent (ECL) aptasensors by putting special emphasis on its characteristic features, advances, challenges, and applications of ECL based aptasensors. ECL is an ideal tool for constructing such sensors because of its inherent characteristics and can be easily integrated into aptamer based sensing platforms. This review summarizes the "synergistic benefits" of ECL aptamer-based sensors; classifications of ECL aptamer-based assay designs, and signal amplification strategies. This critical review highlights the effects of integration of nanomaterials, immobilization techniques, and amplification/detection strategies on the analytical performance of ECL based aptasensors. Moreover, several proof-of-concepts with appropriate figures and explanations have been shown to provide a general guide for the design of ECL aptasensors, and to stimulate further application of these ECL aptasensors. Finally, we conclude with the remaining challenges and opportunities to inspire further developments in ECL aptasensors.

Enhanced electrogenerated chemiluminescence behavior of C3N4 QDs@ C3N4 nanosheet and its signal-on aptasensing for platelet derived growth factor

A novel g-C₃N₄ nanosheets embedded with C₃N₄ QDs nanocomposites (QD@CNNS) was prepared by simple oxidation using hydrogen peroxide and UV light irradiation. This nanocomposite exhibits more stable and stronger electrochemiluminescent (ECL) behavior compared with CNNS. Coupling this nanocomposite with Fc-labeled aptamer, a signal-on aptasensor for platelet derived growth factor BB (PDGF-BB) is fabricated. Initially, the Fc-labeled aptamer binds onto QD@CNNS via π-π conjugation and electrostatic interaction, quenching ECL emission from QD@CNNS. The introduction of target efficiently recovers the ECL signal by the formation of PDGF-BB/aptamer complex. The ECL intensity is proportion to the concentration of PDGF-BB in the range of 0.02-80nM with a detection limit of 0.013nM. This work demonstrates a simple synthesis method to obtain QD@CNNS with excellent ECL behavior, and opens up the application of g-C₃N₄ nanocomposite in signal-on aptasensing.

Efficient electrochemiluminescence quenching of carbon-coated petalous CdS nanoparticles for an ultrasensitive tumor marker assay through coreactant consumption by G-quadruplex-hemin decorated Au nanorods

A novel competitive electrochemiluminescence aptasensor was designed for the detection of carcinoembryonic antigen using carbon-coated petalous CdS nanopaticles as an ECL emitter and DNAzyme/Au nanorods–complementary DNA as a quenching probe.

Protein-templated cobaltous phosphate nanocomposites for the highly sensitive and selective detection of platelet-derived growth factor-BB

We synthesized novel Co3(PO4)2-based nanocomposites with 3D porous architectures via self-assembly; here, bovine serum albumin (BSA) and aptamer were used as organic phases to produce Co3(PO4)2@BSA and Co3(PO4)2@Apt nanocomposites, respectively. The formation mechanism of Co3(PO4)2-based nanocomposites was described based on characterizations of their physio-chemical performance, and the developed nanocomposites were applied as scaffold materials to construct a novel electrochemical aptasensor and detect platelet-derived growth factor-BB (PDGF-BB). The PDGF-BB targeting aptamer must be immobilized onto the Co3(PO4)2@BSA-modified electrode to detect PDGF-BB, whereas Co3(PO4)2@Apt-based aptasensor may be directly used to determine the target protein. Electrochemical impedance spectroscopy results showed that the developed Co3(PO4)2@BSA- and Co3(PO4)2@Apt-based aptasensors present highly sensitive detection ability toward PDGF-BB. Due to the special nanoflower structure, the Co3(PO4)2@BSA-based aptasensor features a detection limit of 3.7 pg mL(-1); while the limit of detection of the Co3(PO4)2@Apt-based aptasensor is 61.5 pg mL(-1), which is the possible bioactivity loss of the aptamer in Co3(PO4)2@Apt nanocomposite. The two detection limits obtained are still much lower than or comparable with those of previously reported aptasensors. The Co3(PO4)2@BSA- and Co3(PO4)2@Apt-based aptasensors showed high selectivity, stability, and applicability for detecting the desired protein. This finding indicates that the Co3(PO4)2-based nanocomposites could be used as an electrochemical biosensor for various detection procedures in the biomedical field.