Nanoparticle-based biosensors and bioassays - Electrochemical Sensors, Biosensors and Their Biomedical Applications - page 457

Step 1.
Target Protein
Capture with
MMP Probes

A B

Step 2.
Sandwich Captured Target
Proteins with NP Probes

1.

SH
Bevine Serum Albumin 2.

3.

Nanoparticle (NP) Probe

Target Protein
(PSA)

13 nm NPs for Bio-Bar-Code PCR
30 nm NPs for PCR-less Method

1.

Step 5.
Chip-Based Detection
of Bar-Code DNA for
Protein Identification

2. Bevine Serum Albumin Step 4.

Polymerase
Chain Reaction

Step 3.
MMP Probe Separation
and Bar-Code DNA
Dehybridization

Magnetic Microparticle
(MMP) Probe

Bar-Code DNA

Ag
Au

Gold Nanoparticle SH Capture DNA Bar-Code DNA

Amine-Functionalized
Magnetic Particle

Monoclonal Anti-PSA Polyclonal Anti-PSA

M

Step 4.
PCR-less Detection
of Bar-Code DNA from
30 nm NP Probes

Magnetic
Field

Plate 14 The bio-bar-code assay method. (a) Probe design and preparation. (b) PSA detection and bar-code DNA amplifi cation
and identifi cation (Reproduced from [17] with permission.) (see Figure 14.2).

MB

Biotinylated
Capture Probe

Biotinylated
Target

CdS labeled
probe

Cd
Amplification

HBr
Au(III)

Silver Enhancement

HNO 3

HNO 3

Ag(I)

Zn Cd Pb

Au(III)

MD

Me

Au(III)

Me 2
Mercury Coated Glassy
Carbon Electrode

Me 2

M

Au(I)

Disposable Screen-
Printed Electrode

MD

Au(I)

Disposable Screen-
Printed Electrode

(a) (b) (c) (d) (e)

Plate 15 Nanoparticle-based electrochemical detection of DNA. These assays involve the introduction of the probe coated
magnetic beads, the addition of the target/hybridization event, magnetic removal of unwanted materials, binding of the metal, and
amplifi ed electrochemical detection of the dissolved gold (a), silver (b), and cadmium sulfi de (d) nanoparticles. Me: metal tag. Also
shown are solid-state stripping (c) and multi-target (e) detection protocols. See text for details (see Figure 14.3).