Microchip and Method for Detecting Molecules and Molecular Interactions

• US 20080108095A1
• Filed: 04/01/2005
• Published: 05/08/2008
• Est. Priority Date: 04/01/2004
• Status: Active Grant

• Current Assignee: Nanyang Technology University
• Original Assignee: Nanyang Technology University
• Inventors: Li, Changming
• Granted Patent: US 9,863,941 B2
• Time in Patent Office: Days
• US Class Current: 435/7.93
• CPC Class Codes: B01L 2200/027 for microfluidic devices
• CPC Class Codes: B01L 2200/141 Preventing contamination, tampering
• CPC Class Codes: B01L 2300/0636 Integrated biosensor, microarrays
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0851 Bottom walls
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2300/0867 Multiple inlets and one sample wells, e.g. mixing, dilution
• CPC Class Codes: B01L 2300/0874 Three dimensional network
• CPC Class Codes: B01L 2400/0457 passive flow or gravitation
• CPC Class Codes: B01L 2400/0487 fluid pressure, pneumatics
• CPC Class Codes: B01L 3/502746 characterised by the means for controlling flow resistance, e.g. flow controllers, baffles B01L3/502738 takes precedence
• CPC Class Codes: G01N 33/54366 Apparatus specially adapted for solid-phase testing
• CPC Class Codes: G01N 33/5438 Electrodes

Abstract

A microchip with flow-through inlet (104) and outlet (106) channels and test channels (108). The test channels (108) are in fluid communication with the inlet (104) and outlet (106) channels, through inlets (114) and outlets (116) respectively. Each test channel (108) has one test site therein for detection of specific molecules or molecular interactions. The inlet (114) in a test channel (108) is elevated from the outlet (116) of the test channel (108) and the outlet (116) is elevated from a fluid level (124) in the outlet channel (106). Back diffusion from outlet channel (106) to the test channels (108) and from the test channels (108) to the inlet channel (104) can thus be inhibited to reduce or eliminate cross-interference between different test sites. The microchip can be useful as a flow-through high density enzyme immunoassay array device with high-throughput.

Claims

1. A microchip comprising:

a substrate;

an inlet channel in said substrate;

an outlet channel in said substrate for guiding fluid below a fluid level;

a plurality of test channels in said substrate for guiding fluid flow from said inlet channel to said outlet channel, each one of said test channels having an inlet for fluid communication with said inlet channel and an outlet for fluid communication with said outlet channel, said inlet elevated from said outlet for inhibiting back flow through said inlet, said outlet elevated from said fluid level for inhibiting back flow through said outlet; and

one test site in each one of said test channels, for detection of at least one of a specific molecule and a molecular interaction at said test site.

2. The microchip of claim 1, wherein each one of said channels has a substantially flat bottom, said bottom of said inlet channel elevated from bottoms of said test channels, said bottoms of said test channels elevated from said bottom of said outlet channel.

3. The microchip of claim 1, wherein at least one of said test channels comprises a well for holding fluid therein.

4. The microchip of any one of claim 1, wherein said inlet and outlet channels are adapted to allow a liquid to flow at a greater rate in said outlet channel than in said inlet channel.

5. The microchip of any one of claim 1, wherein each one of said test sites comprises a surface suitable for immobilizing specific molecules thereon.

6. The microchip of any one claim 1, further comprising probe molecules immobilized at each one of said test sites, said probe molecules having specific affinity to selected target molecules.

7. The microchip of claim 6, wherein different probe molecules are immobilized at different ones of said test sites for detecting different target molecules.

8. The microchip of any one of claim 1, further comprising a plurality of electrodes, one of said electrodes at each one of said test sites.

9. The microchip of claim 8, wherein at least one of said test channels comprises a narrowed section proximate said test site in said at least one test channel for guiding fluid towards said test site.

10. The microchip of claim 8, wherein said plurality of electrodes are first electrodes, said microchip further comprising a plurality of second electrodes, one of said second electrodes in each one of said test channels.

11. The microchip of claim 10, wherein said first electrodes are interconnected and said second electrodes are interconnected, such that each pair of said electrodes in each one of said test channels is uniquely addressable.

12. The microchip of claim 10, further comprising probe molecules immobilized proximate said first electrodes.

13. The microchip of any one of claim 1, wherein said test channels extend substantially in parallel.

14. The microchip of any one of claim 1, further comprising a dilution channel formed in said substrate, said dilution channel in fluid communication with said inlet channel and having a first inlet for reception of a first fluid and at least one second inlet for reception of a second fluid to dilute said first fluid.

15. The microchip of claim 14, wherein said at least one second inlet comprises a plurality of second inlets.

16. The microchip of any one of claim 1, wherein said substrate comprises polydimethylsiloxane (PDMS).

17. The microchip of claim 16, wherein a PDMS surface in each one of at least one of said plurality of test sites is coated with aminopropyltriethoxysilane (APTES), thus forming a PDMS-APTES surface.

18. The microchip of claim 17, wherein probe molecules are covalently immobilized on said PDMS-APTES surface through cross-linkers.

19. The microchip of claim 18, wherein said cross-linkers comprise at least one of glutaraldehyde and 1-ethyl-3-(3-dimethylaminopropyl)carbodi-imide.

20. The microchip of any one of claim 1, wherein at least one of said channels is adapted for connection to at least one of a pump and a valve for regulating fluid flow.

21. A method of detecting molecules or molecular interaction, comprising:

providing a microchip having a substrate, an inlet channel in said substrate, an outlet channel in said substrate, a plurality of test channels in said substrate each having an inlet for fluid communication with said inlet channel and an outlet for fluid communication with said outlet channel, said inlet elevated from said outlet, and one test site in each one of said plurality of test channels;

introducing a fluid to said test channels through said inlet channel;

inhibiting back flow of said fluid through said inlets and outlets by allowing overflow of said fluid from said test channels to said outlet channel through said outlets and maintaining the fluid level in said outlet channel below said outlets, thus inhibiting diffusion of molecules in said fluid from one of said test sites to another one of said test sites; and

after said fluid has been introduced to said test channels, detecting at least one of a molecule and a molecular interaction at a test site within said plurality of test sites.

22. The method of claim 21, wherein said detecting comprises detecting a signal indicative of at least one of the presence of said molecule and the occurrence of said molecular interaction, said signal comprising at least one of optical, electrical, magnetic, radiation, and electromagnetic signals.

23. The method of claim 21, wherein probe molecules are immobilized at said test site for selectively capturing at least one of target molecules and reporter molecules.

24. The method of any one of claim 21, wherein said at least one of said molecule and molecular interaction is detected at said test site by enzyme immunoassaying (EIA).

25. The method of claim 24, wherein said EIA comprises enzyme-linked immunosorbent assaying (ELISA).

26. The method of claim 24, wherein said EIA comprises electrochemical EIA (EIA-EC).

27. The method of any one of claim 26, wherein said EIA comprises one of direct EIA, competitive EIA, competitive inhibition EIA, and sandwich EIA:

28. The method of claim 27, wherein said detecting comprises detecting an electrical signal and said microchip comprises a plurality of electrodes, at least one of said electrodes at each one of said test sites for detecting said electric signal.

29. The method of claim 28, wherein said electric signal comprises at least one of a current, a voltage, and impedance.

30. The method of any one of claim 29, wherein said microchip further comprises a dilution channel in fluid communication with said inlet channel and having a first inlet and at least one second inlet, said introducing a fluid comprising feeding said fluid into said dilution channel through said first inlet and feeding a dilution fluid into said dilution channel through said at least one second inlet so that a diluted fluid is received in said inlet channel and thus said test channels.