The vascular endothelial growth factor, VEGF, is an important biomarker for different diseases and clinical disorders. We present a series of optical aptasensor-based sensing platforms for VEGF that include the following: (i) A FRET-based sensor that involves the VEGF-induced separation of aptamer-functionalized quantum dots blocked by a quencher nucleic acid (detection limit 1 nM). (ii) A FRET-based sensor based on the VEGF-induced assembly of the aptamer subunits functionalized with QDs and a dye acceptor (Cy5), respectively (detection limit 12 nM). (iii) A chemiluminescence aptasensor based on VEGF-induced assembly of a hemin/G-quadruplex catalyst (detection limit 18 nM). (iv) A chemiluminescence aptasensor based on the VEGF-stimulated assembly of two aptamer subunits into the hemin/G-quadruplex catalyst (detection limit 2.6 nM). (v) A chemiluminescence resonance energy transfer (CRET) aptasensor based on the VEGF-induced assembly of a semiconductor QDs-hemin/G-quadruplex supramolecular structure (detection limit 875 pM). Furthermore, an amplified optical aptasensor system based on the Exonuclease III (Exo III) recycling of the VEGF analyte was developed. In this system, one aptamer subunit is modified at its 5' and 3' ends with QDs and a black hole quencher, respectively. The VEGF-induced self-assembly of the aptamer subunits result in the digestion of the quencher units and the autonomous recycling of the analyte, while triggering-on the luminescence of the QDs (detection limit 5 pM). The system was implemented to analyze VEGF in human sera samples.

Well‐graphitized core/shell iron/carbon nanoparticles (Fe@CNPs) were formed in toluene solutions containing Fe(CO)5‐C60/70 via an novel microwave arcing process. High temperature γ‐Fe phase was found to be stable at room temperature when encapsulated inside graphene shells. In the absence of C60/70, the structures of graphene shells are poor. Pre‐synthesized Co nanoparticles were used as templates for the growth of graphene shells in toluene‐C60/70 solutions. Via acid etching and removal of the central core Co nanoparticles, hollow carbon nanoparticles could be obtained. Further thermal annealing by focused microwave irradiation leads to merging of small core/shell metal/carbon nanoparticles into large ones, as well as conversion of body centered cubic (bcc) α‐Fe to face centered cubic (fcc) γ‐Fe. The possible growth mechanisms of core/shell metal/carbon nanoparticles were discussed.

We have developed a sensitive electrochemical immunoassay system for the detection of a protein tumor marker, carcinoembryonic antigen (CEA), that is based on a carbon nanoparticle (CNP)/poly(ethylene imine) (PEI)-modified screen-printed graphite electrode (CNP-PEI/SPGE) covered with anti-CEA antibodies. The signal amplification strategy--using CdS nanocrystals as biotracers and CNPs to enhance electron transfer--improves the sensitivity and detection limit for CEA, suggesting that this system holds promise for development into a point-of-care or disposable home-care self-diagnostic tool. This biosensor is based on a sandwich complex immunoassay, which we assembled from sequential layers of the anti-CEA antibody (alphaCEA) on CNP-PEI/SPGE, the CEA sample, and the CdS nanocrystal quantum dots (QDs) sensitized with alphaCEA (alphaCEA-CdS QD). We used square wave anodic stripping voltammetry (SWASV) to amplify the signal current response obtained from the dissolved alphaCEA-CdS QDs. The calibration curve for CEA concentration was linear in the range of 0.032-10 ng/mL; the detection limit (estimated as the mean of the blank sample plus three times the standard deviation obtained on the blank sample) was 32 pg/mL (equivalent to 160 fg in a 5 microL sample). This method is suitably precise and sensitive to function as a means of determining urinary CEA, which is a better marker than serum CEA for the early detection of urothelial carcinoma.

Lichtkontrolliert: Ein Wirkstoff gegen Krebs (rote Punkte im Bild) wurde in bioabbaubaren Nanopartikeln eingeschlossen, die photoaktivierbare Folsäuregruppen auf der Oberfläche tragen. Nach Bestrahlung wird die Photoschutzgruppe (grün) abgespalten, und die freie Folsäuregruppe, ein tumorbindendes Agens, bindet an Folsäurerezeptoren auf Zelloberflächen und führt so zu spezifischer Aufnahme durch die Zielzellen.