Cancer biomarkers detection using nanochannels
A rapid nanochannel-based immunoassay capable of the filtering and subsequent detection of proteins in whole blood without any sample preparation is described. This is accomplished by using a nanoporous/nanochannel membrane modifi ed with antibodies, the conductivity of which toward a redox indicator is tuned by primary and secondary immunoreactions with proteins and gold nanoparticles. This interesting nanopore blockage by gold nanoparticles is enhanced by silver deposition that further decreases the diffusion of the signaling indicator through the nanochannel. The effi ciency of the nanochannels to act as immunoreaction platforms including the use of nanoparticles is also monitored by microscopic techniques. Successful detection of immunoglobulins including a cancer biomarker is achieved in buffer as well as in whole blood. This system constitutes an effi cient immunoassay capable of detecting up to 52 U mL-1 of CA15-3. The developed nanochannel/nanoparticle-based device can be used for several other proteins and extended also to DNA detection with interest not only for diagnostics but also environmental monitoring, food analysis, safety, and security applications. In this work we combine for the first time the capability of current tuning of a nanopore/nanochannel-based platform upon immunoblocking through nanoparticles for the detection of proteins, by taking advantage of an electrotransducer fabricated by screen-printing technology and a simple voltammetric detection mode. In addition, we show that the use of AuNP tags as blocking agents improves the detection limits of the label-free immunosensor. The catalytic properties of AuNPs upon silver deposition, applied also for protein detection, are examined for the in-nanochannel enhancement of AuNPs, which increases to a very high extent the pore-blocking efficiency and consequently the sensitivity of the assays. We also demonstrate for the
first time the efficiency of the developed nanochannel/nanoparticle device for future applications in the direct detection of cancer biomarkers in whole blood, where the membranes act as both "filtering" and sensing platforms and thus avoid matrix effects.
This work is highlighted by By Michael Berger. Copyright 2011 Nanowerk: