The Synthesis of GoldMag Nano-Particles and their Application for Antibody Immobilization

Biomedical Microdevices 7:2, 153156, 2005C 2005 Springer Science + Business Media, Inc. Manufactured in The Netherlands.The Synthesis of GoldMag Nano-Particles and their Application

for Antibody ImmobilizationYali Cui,1, Yani Wang,1 Wenli Hui,3 Zhifeng Zhang,2

Xiaofang Xin,3 and Chao Chen2,1Biochip Research and Development Center, Northwest University,

Xian, 710069, P.R. China2National Engineering Research Center for Miniaturized Detection

Systems, Xian, 710069, P.R. China3Shaanxi Lifegen Ltd. Xian, Shaanxi, 710002, P.R. China

E-mail: yali cui@ mail.comE-mail: chaochen@ nwu.edu.cnAbstract. Fe3O4/Au (GoldMag) particles with core/shell structure

were synthesized by reduction of Au3+ with hydroxylamine in the

presence of Fe3O4. The synthesized particles have an average size

smaller than 100 nm in diameter with of superparemagnetic properties due to their Fe oxide cores. The particles show optical features

with a plasmon resonance peak from 550, 570 to 590 nm correlating

with increasing diameters from 50 nm, 70 nm to 100 nm.The Gold-

Mag particles need only a single step for antibody immobilization

and have high binding capacity for antibodies. These advantages

permit improved methods of isolating and detecting biomolecules.Key Words. Fe3O4/Au, nanopaticle, antibody, immobilization1. IntroductionSince the technique of colloid gold conjugated antibody

was introduced in the 1970s (Faulk et al., 1971), it has

shown a wide range of applications in immunochemistry,

immunohistochemistry and immunoblotting for electron

microscopy (EM) because of high electron densities of

colloid gold. On the other hand, colloid gold also exhibits

UV-Vis spectrum of surface plasmon resonance (Kreibig,

1985), which depends on the size of colloid gold particles

and nature of the biological reaction that is carried out on

the surface of the particulars. Based on the properties of the

colloid gold, several technologies have been developed for

the detection of biomolecules, such as the method for DNA

detection by using cross-linked assembling phenomenon

of DNA and oligonucleotide on the nano-gold surface

(Storhoff et al., 2000; Jin et al., 2003; Mirkin et al., 1996;

Taton et al., 2000). Magnetic particles with micro- and

nano-scale modified with various chemical groups have

been studied extensively. These particles exhibit magnetic responsiveness to an external magnetic field. Nanomagnetic particles have the typical superparamegnetic nature, which provides convenient means for the separation,

isolation and purification of biological samples when the

functional reagents are attached on the surface of the particles (Gruttner, 1999; Martin et al., 1998;...