Immunoassay utilizing magnetic beads for rapidvirus detection in the microfluidic flow cytometer system

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Immunoassay utilizing magnetic beads for
rapidvirus detection in the microfluidic flow
cytometer system

• Sung-Yi Yang, Kang-Yi Lien, Kao-Jean Huang,
  Huan-Yao Lei, Gwo-Bin Lee
• National Cheng Kung University, Tainan Taiwan
• uTAS2007

Professor Liu, Cheng-Hsien    Student Olof
Sterner
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Agenda

1. Introduction
2. Design and Fabrication
3. Results
4. Conclusion
5. Discussion

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Introduction

• In this article
• Integrated fluid chip for rapid virus
  identification.
• Fluid movement is performed by micro circulatory
  pump driven by airpressure.
• Magnetic beads covered with specific antibodies.
• Detection of virus is made through fluorescence
  by a PMT module.

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Introduction

• Current viruses threatening mankind
• Influenza
• Hepatitis
• HIV
• Dengue fever
• Ebola
• Yellow Fever
• Etc
• Treatment for viral infections are far behind
  those of bacterial infections
• Quick diagnosis crucial

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Design and Fabrication

• Magnetic beads
• Covered in specific antibodies toward a certain
  virus
• Virus particle functions as antigen and binds
  specifically to the primary antibody on the
  magnetic bead.
• Secondary antibody towards the same virus but
  targeting a different epitope binds to the virus
  and carries a fluorescent compound.

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Design and Fabrication

• Main detection principle

1. Magnetic beads with primary target antibody
2. Target antigen is added (Virus)
3. Secondary fluorescent antibodies is added
4. Fluidic focusing
5. Detection by means of fluorescense

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Design and Fabrication

• The integrated flow cytometer system

A
B
C
Dimensions 46 mm 66 mm 5 mm
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Design and Fabrication

• A Virus attachement to magnetic beads.

1. Injection of bio sample and magnetic beads
2. Introduction of sec fluorescent antibodies
3. Mixing with rotary microfluidic pump

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Design and Fabrication

• Airpressure driven rotary microfluidic pump

Biomed Microdevices (2007) 9545554 DOI
10.1007/s10544-007-9062-6
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Design and Fabrication

• B Washing and Pretreatment

Purification and enrichment of virus samples
utilizing magnetic beads on a microfluidic
system, Lab Chip, DOI 10.1039/b700516d, (2007)

• Cu microcoils induced magnetic field attracts
  magnetic beads
• Washing with buffer
• Release of magnetic beads
• (Flow generated by rotary microfluidic pump)

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Design and Fabrication

• C Fluid focusing, detection and sorting

• Sheath flow injection
• Flow from rotary microfluidic pump for fluid
  focusing
• Detection by PMT module
• Sorting of magnetic beads using feedback signals
  from PMT
• Collection of magnetic beads
• (Flow generated by rotary microfluidic pump

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Results

• Evaluation of
• Pumping rate vs driving frequency of circulatory
  pump
• Magnetic field and Temperatur vs Applied current
• Fluorescence signal amplitude vs time
• Virus detection limit

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Results
Magnetic field and Temperature in focusing vs
Applied current

• Pumping rate vs driving frequence of circulatory
  pump

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Results

• Signal amplitude from fluorescence measurement vs
  time

Singal to Noise ratio of 30
Minimum concentration of 104 pfu/ml of Dengue
virus could be detected. RT-PCR has detection
limit of 1 pfu/ml
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Conclusion

• Design for rapid virus diagnosis has been
  proposed

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Discussion

• Easy principle, sandwich immunoassay is well
  documented
• Gate design is not included in article
• Sensitivity needs to be enchanced

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References

• Lab Chip, 2007, 7, 868875, DOI 10.1039/b700516d
• Biomed Microdevices (2007) 9545554 DOI
  10.1007/s10544-007-9062-6

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• TACK!