Development and evaluation of realistic microbioassays in freely suspended droplets on a chip.
A novel technique for biomolecular detection in microliter droplets floating on the surface of high density oil is presented. Each droplet was captured and manipulated dielectrophoretically and was used as a site for a microscopic bioassay based on agglutination of antibody-conjugated particles. The results were read out by the pattern of unagglomerated gold nanoparticles collected on the droplet surface. Two formats of bioassays, namely gold only agglutination and gold and latex agglutination, were investigated experimentally by varying analyte concentration, particle size and concentration, number of antigen binding sites per particle, time for incubation, and rate of particle collection on the droplet surface. The microbioassays performance was also evaluated with ricin antibodies and compared to the ricin assays in field use. It is estimated that the droplet based assays require 100x smaller sample volume and are ten times more sensitive, though they require longer times to complete. The experiments were interpreted by modeling the kinetics of particle agglutination and mass transfer processes inside the droplets. The incubation time and antigen concentration values calculated by the model correlate well with the experimental results. The results could allow for development of efficient immunoassays on a chip requiring even smaller sample volumes.
Rastogi
Vinayak
V
Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905.
Velev
Orlin D
OD
J Chromatogr. 1976 Apr 21;127(11):1-28
6485
Anal Biochem. 1978 Jun 1;86(2):620-47
26290
Am Clin Lab. 1990 May;9(4):16-7
10148248
Anal Biochem. 2006 Aug 1;355(1):102-9
16762307
Lab Chip. 2004 Aug;4(4):310-5
15269796
J Chromatogr. 1990 Jun 27;510:347-54
2205619
Toxicon. 2002 Mar;40(3):255-8
11711121
Hybrid Hybridomics. 2002 Feb;21(1):69-73
11991819
Langmuir. 2006 Aug 1;22(16):6723-6
16863209
J Immunol Methods. 1988 Oct 4;113(1):3-15
3049824
Langmuir. 2006 Feb 14;22(4):1459-68
16460062
Biotechniques. 2003 Oct;35(4):850-9
14579751
Proteins. 1991;10(3):240-50
1881880
Annu Rev Biophys Biophys Chem. 1985;14:131-60
3890878
Environ Sci Technol. 1995 Mar 1;29(3):553-61
22200262
Nat Mater. 2005 Jan;4(1):98-102
15608646
Int J Food Microbiol. 2005 Mar 15;99(2):185-94
15734566
J Immunol Methods. 2003 Sep;280(1-2):183-202
12972199
Nature. 2003 Dec 4;426(6966):515-6
14654830