Highly sensitive detection of platelet-derived growth factor on a functionalized diamond surface using aptamer sandwich design.

Aptamer-based fluorescence detection of platelet-derived growth factor (PDGF) on a functionalized diamond surface was demonstrated. In this work, a sandwich design based on the ability of PDGF to bind with aptamers at its two available binding sites was employed. It was found that this sandwich design approach significantly increases the fluorescence signal intensity, and thereby a very low detection limit of 4 pM was achieved. The effect of the ionic strength of MgCl(2) buffer solution was also investigated, and the most favourable binding for PDGF-BB occurred at a Mg(2+) concentration of 5.5 mM. Since the aptamers bind to the target PDGF with high affinity, fluorescence detection exhibited high selectivity towards different biomolecules. The high reproducibility of detection was confirmed by performing three cycles of measurements over a period of three days.

Platelet-derived growth factor oncoprotein detection using three-dimensional carbon microarrays.

The potential of aptamers as ligand binding molecule has opened new avenues in the development of biosensors for cancer oncoproteins. In this paper, a label-free detection strategy using signaling aptamer/protein binding complex for platelet-derived growth factor (PDGF-BB) oncoprotein detection is reported. The detection mechanism is based on the release of fluorophore (TOTO intercalating dye) from the target binding aptamer's stem structure when it captures PDGF. Amino-terminated three-dimensional carbon microarrays fabricated by pyrolyzing patterned photoresist were used as a detection platform. The sensor showed near linear relationship between the relative fluorescence difference and protein concentration even in the sub-nanomolar range with an excellent detection limit of 5pmol. This detection strategy is promising in a wide range of applications in the detection of cancer biomarkers and other proteins.

Three-dimensional graphene nanosheet encrusted carbon micropillar arrays for electrochemical sensing.

Integrating graphene onto three-dimensional (3D) microelectrodes is a plausible technique to significantly improve the sensitivity of electrochemical devices. However, the construction of graphene coated 3D microstructures has been a considerable challenge. In this paper, we present a simple methodology using electrostatic spray deposition (ESD) to conformally coat graphene onto 3D carbon micropillars that are fabricated by pyrolyzing finely patterned photoresist. During the ESD, changes in the critical parameters such as substrate temperature, deposition time, and nozzle to substrate distance have shown a significant effect on the morphology of the deposited graphene film. The amperometric response of graphene/carbon micropillar electrode arrays exhibited higher electrochemical activity, improved charge transfer and a linear response towards H(2)O(2) detection between 250 µM and 5.5 mM. The ESD technique, with the flexibility of integrating a wide variety of functional nanomaterials onto complex 3D microstructures, is attractive in the field of electrochemistry and biotechnology.