Integrated microfluidic devices for the purification, amplification, and detection of nucleic acids are a prevalent area of research due to their potential for miniaturization, assay integration, and increased efficiency over benchtop assays. These devices frequently contain micrometer-sized magnetic beads with a large surface area for the capture and manipulation of biological molecules such as DNA and RNA. Although magnetic beads are a standard tool for many biological assays, beads functionalized with biological molecules can adhere to microchannel walls and prevent further manipulation of the beads within the channel. Here, we analyze the effects of solution composition, microchannel hydrophobicity, and bead surface hydrophobicity on DNA-functionalized bead adhesion in a borosilicate glass microfluidic device. Bead adhesion is primarily a result of adsorption of the bead-linked DNA molecule to the microchannel wall; >81% of beads are consistently removed when not functionalized with DNA. Hydrophobicities of both the microchannel walls and the microbead surface are the primary determinants of bead adhesion, rather than electrostatic interactions and ion bridging. Surprisingly, DNA-functionalized bead adhesion in a standard RNA amplification solution was virtually eliminated by using hydrophobic microbeads with hydrophobic microchannel walls; under such conditions, 96.6 ± 1.6% of the beads were removed in one 43 nl/s, 10-min wash. The efficiency of a downstream RNA amplification reaction using DNA-functionalized beads did not appear to be affected by the hydrophobicity of the microbead surface. These findings can be applied to assays that require the efficient use of magnetic beads in DNA-based microfluidic assays.

1.
S. E.
McCalla
and
A.
Tripathi
, “
Microfluidic reactors for diagnostics applications
,”
Annu. Rev. Biomed. Eng.
13
,
321
343
(
2011
).
2.
E.
Verpoorte
, “
Beads and chips: New recipes for analysis
,”
Lab Chip
3
(
4
),
60N
68N
(
2003
).
3.
J.
Wen
,
L. A.
Legendre
,
J. M.
Bienvenue
, and
J. P.
Landers
, “
Purification of nucleic acids in microfluidic devices
,”
Anal. Chem.
80
(
17
),
6472
6479
(
2008
).
4.
I.
Nikcevic
,
A.
Bange
,
E. T. K.
Peterson
,
I.
Papautsky
,
W. R.
Heineman
,
H. B.
Halsall
, and
C. J
.
Seliskar
, “
Adsorption of fluorescently labeled microbeads on PDMS surfaces
,”
Proc. SPIE
5718
,
159
168
(
2005
).
5.
R.
Boom
,
C. J. A.
Sol
,
M. M. M.
Salimans
,
C. L.
Jansen
,
P. M. E.
Wertheim-van Dillen
, and
J.
van der Noordaa
, “
Rapid and simple method for purification of nucleic acids
,”
J. Clin. Microbiol.
28
(
3
),
495
503
(
1990
).
6.
M. C.
Breadmore
,
K. A.
Wolfe
,
I. G.
Arcibal
,
W. K.
Leung
,
D.
Dickson
,
B. C.
Giordano
,
M. E.
Power
,
J. P.
Ferrance
,
S. H.
Feldman
,
P. M.
Norris
, and
J. P.
Landers
, “
Microchip-based purification of DNA from biological samples
,”
Anal. Chem.
75
(
8
),
1880
1886
(
2003
).
7.
K. A.
Hagan
,
J. M.
Bienvenue
,
C. A.
Moskaluk
, and
J. P.
Landers
, “
Microchip-based solid-phase purification of RNA from biological samples
,”
Anal. Chem.
80
(
22
),
8453
8460
(
2008
).
8.
K. A.
Melzak
,
C. S.
Sherwood
,
R. F. B.
Turner
, and
C. A.
Haynes
, “
Driving forces for DNA adsorption to silica in perchlorate solutions
,”
J. Colloid Interface Sci.
181
(
2
),
635
644
(
1996
).
9.
S. K.
Parida
,
S.
Dash
,
S.
Patel
, and
B. K.
Mishra
, “
Adsorption of organic molecules on silica surface
,”
Adv. Colloid Interface Sci.
121
(
1-3
),
77
110
(
2006
).
10.
K. A.
Wolfe
,
M. C.
Breadmore
,
J. P.
Ferrance
,
M. E.
Power
,
J. F.
Conroy
,
P. M.
Norris
, and
J. P.
Landers
, “
Toward a microchip-based solid-phase extraction method for isolation of nucleic acids
,”
Electrophoresis
23
(
5
),
727
733
(
2002
).
11.
M.
Karwa
,
D.
Hahn
, and
S.
Mitra
, “
A sol-gel immobilization of nano and micron size sorbents in poly(dimethylsiloxane) (PDMS) microchannels for microscale solid phase extraction (SPE)
,”
Anal. Chim. Acta
546
(
1
),
22
29
(
2005
).
12.
H. J.
Tian
,
A. F. R.
Huhmer
, and
J. P.
Landers
, “
Evaluation of silica resins for direct and efficient extraction of DNA from complex biological matrices in a miniaturized format
,”
Anal. Biochem.
283
(
2
),
175
191
(
2000
).
13.
N.
Singh
and
R. C.
Willson
, “
Boronate affinity adsorption of RNA: Possible role of conformational changes
,”
J. Chromatogr. A
840
(
2
),
205
213
(
1999
).
14.
A.
Elaissari
,
M.
Rodrigue
,
F.
Meunier
, and
C.
Herve
, “
Hydrophilic magnetic latex for nucleic acid extraction, purification and concentration
,”
J. Magn. Magn. Mater.
225
(
1-2
),
127
133
(
2001
).
15.
P. E.
Vandeventer
,
J. S.
Lin
,
T. J.
Zwang
,
A.
Nadim
,
M. S.
Johal
, and
A.
Niemz
, “
Multiphasic DNA adsorption to silica surfaces under varying buffer, pH, and ionic strength conditions
,”
J. Phys. Chem. B
116
(
19
),
5661
5670
(
2012
).
16.
P. E.
Vandeventer
,
J.
Mejia
,
A.
Nadim
,
M. S.
Johal
, and
A.
Niemz
, “
DNA adsorption to and elution from silica surfaces: Influence of amino acid buffers
,”
J. Phys. Chem. B
117
(
37
),
10742
10749
(
2013
).
17.
C. W.
Hollars
,
J.
Puls
,
O.
Bakajin
,
B.
Olsan
,
C. E.
Talley
,
S. M.
Lane
, and
T.
Huser
, “
Bio-assay based on single molecule fluorescence detection in microfluidic channels
,”
Anal. Bioanal. Chem.
385
(
8
),
1384
1388
(
2006
).
18.
G. L.
Kenausis
,
J.
Voros
,
D. L.
Elbert
,
N. P.
Huang
,
R.
Hofer
,
L.
Ruiz-Taylor
,
M.
Textor
,
J. A.
Hubbell
, and
N. D.
Spencer
, “
Poly(L-lysine)-g-poly(ethylene glycol) layers on metal oxide surfaces: Attachment mechanism and effects of polymer architecture on resistance to protein adsorption
,”
J. Phys. Chem. B
104
(
14
),
3298
3309
(
2000
).
19.
X. Z.
Liu
,
D.
Erickson
,
D. Q.
Li
, and
U. J.
Krull
, “
Cationic polymer coatings for design of electroosmotic flow and control of DNA adsorption
,”
Anal. Chim. Acta
507
(
1
),
55
62
(
2004
).
20.
P.
Zhang
and
J. C.
Ren
, “
Study of polydimethylacrylamide- and polydiethylacrylamide-adsorbed coatings on fused silica capillaries and their application in genetic analysis
,”
Anal. Chim. Acta
507
(
2
),
179
184
(
2004
).
21.
P.
Cai
,
Q.
Huang
, and
X.
Zhang
, “
Microcalorimetric studies of the effects of MgCl2 concentrations and pH on the adsorption of DNA on montmorillonite, kaolinite and goethite
,”
Appl. Clay Sci.
32
(
1-2
),
147
152
(
2006
).
22.
T.
Poeckh
,
S.
Lopez
,
A. O.
Fuller
,
M. J.
Solomon
, and
R. G.
Larson
, “
Adsorption and elution characteristics of nucleic acids on silica surfaces and their use in designing a miniaturized purification unit
,”
Anal. Biochem.
373
(
2
),
253
262
(
2008
).
23.
S. A.
Gani
,
D. C.
Mukherjee
, and
D. K.
Chattoraj
, “
Adsorption of biopolymer at solid–liquid interfaces. 1. Affinities of DNA to hydrophobic and hydrophilic solid surfaces
,”
Langmuir
15
(
21
),
7130
7138
(
1999
).
24.
S. H.
Behrens
and
D. G.
Grier
, “
The charge of glass and silica surfaces
,”
J. Chem. Phys.
115
(
14
),
6716
6721
(
2001
).
25.
E.
Lázaro
,
M.
Arribas
,
F.
Moran
, and
E.
Domingo
, “
Effect of metal ions on the efficiency of DNA amplification: Implications for nucleic acid replication during early stages of life
,” in
Proceedings of the Third European Workshop on Exo-Astrobiology
(
ESA Publications Division
,
2003
), pp.
137
140
.
26.
J.
Křížová
,
A.
Španová
,
B.
Rittich
, and
D.
Horák
, “
Magnetic hydrophilic methacrylate-based polymer microspheres for genomic DNA isolation
,”
J. Chromatogr. A
1064
(
2
),
247
253
(
2005
).
27.
M.
Cárdenas
,
K.
Schillén
,
D.
Pebalk
,
T.
Nylander
, and
B.
Lindman
, “
Interaction between DNA and charged colloids could be hydrophobically driven
,”
Biomacromolecules
6
(
2
),
832
837
(
2005
).
28.
S. E.
McCalla
,
A. L.
Luryi
, and
A.
Tripathi
, “
Steric effects and mass-transfer limitations surrounding amplification reactions on immobilized long and clinically relevant DNA templates
,”
Langmuir
25
(
11
),
6168
6175
(
2009
).
29.
S. E.
McCalla
and
A.
Tripathi
, “
Quantifying transcription of clinically relevant immobilized DNA within a continuous flow microfluidic reactor
,”
Langmuir
26
(
17
),
14372
14379
(
2010
).
30.
K. E.
Sung
and
M. A.
Burns
, “
Optimization of dielectrophoretic DNA stretching in microfabricated devices
,”
Anal. Chem.
78
(
9
),
2939
2947
(
2006
).
31.
A.
Gulliksen
,
L.
Solli
,
F.
Karlsen
,
H.
Rogne
,
E.
Hovig
,
T.
Nordstrøm
, and
R.
Sirevåg
, “
Real-time nucleic acid sequence-based amplification in nanoliter volumes
,”
Anal. Chem.
76
(
1
),
9
14
(
2004
).
32.
E.
Delamarche
and
G. V.
Kaigala
,
Open-space Microfluidics Concepts, Implementations, Applications
(
Wiley
,
2018
).
33.
C.
Tanford
,
The Hydrophobic Effect: Formation of Micelles and Biological Membranes,
2nd ed. (
Wiley
,
1980
).
34.
H. F.
Gilbert
,
Basic Concepts in Biochemistry: A Students Survival Guide
(
McGraw-Hill Health Professions Division
,
2000
).
35.
P.
de Gennes
, “
Conformations of polymers attached to an interface
,”
Macromolecules
13
(
5
),
1069
1075
(
1980
).
36.
H.
Bordelon
,
P. K.
Russ
,
D. W.
Wright
, and
F. R.
Haselton
, “
A magnetic bead-based method for concentrating DNA from human urine for downstream detection
,”
PloS one
8
(
7
),
e68369
(
2013
).
37.
B.
Bruijns
,
A.
Van Asten
,
R.
Tiggelaar
, and
H.
Gardeniers
, “
Microfluidic devices for forensic DNA analysis: A review
,”
Biosensors
6
(
3
),
41
(
2016
).
38.
N. V.
Zaytseva
,
V. N.
Goral
,
R. A.
Montagna
, and
A. J.
Baeumner
, “
Development of a microfluidic biosensor module for pathogen detection
,”
Lab Chip
5
(
8
),
805
811
(
2005
).
39.
B. E.
Root
,
A. K.
Agarwal
,
D. M.
Kelso
, and
A. E.
Barron
, “
Purification of HIV RNA from serum using a polymer capture matrix in a microfluidic device
,”
Anal. Chem.
83
(
3
),
982
988
(
2011
).
40.
T.
Geng
,
N.
Bao
,
O. Z.
Gall
, and
C.
Lu
, “
Modulating DNA adsorption on silica beads using an electrical switch
,”
Chem. Commun.
7
,
800
802
(
2009
).
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