Sensing and Actuation in Miniaturized Systems PRESENTATION

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Sensing and Actuation in Miniaturized Systems
PRESENTATION

• DNA Transformation by
• Local Heat Shock

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Outline

• Abstract
• Introduction
• Design And Fabrication
• Experimental Procedure
• Results
• Conclusions

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Abstract

• DNA transformation by local heat shock using a
  MEMS device has been successfully demonstrated
  using an on-chip micro heater and corresponding
  microfluidic system
• The transformation experiments have been
  conducted and 200 improvement in transformation
  efficiency was showed as compared with control
  tests using conventional methodology

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Introduction

• Widely used in genetic engineering and molecular
  biology as an indispensable and key process in
  gene cloning, gene therapy and protein expression
• Among all the DNA transformation methods,
  electroporation and heat shock are two commonly
  used procedures. Heat shock devices are easy to
  make and biocompatible.
• Some researchers believe that the abrupt heat
  pulse makes cell membranes more fluid and
  permeable for the foreign DNA to transport into
  cells

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1. Bacterial cells, which were treated by chemicals
   such as CaCl2 to make the cell membrane
   permeable
2. Plasmid DNA, a circular DNA that can replicate
   itself after DNA transformation process

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Design and Fabrication

• The competent cells and the recombinant plasmids
  are mixed
• The mixture is then treated by a brief heat pulse
  at 42? for 90seconds for the transformation
  process
• A fluidic cap using molded PDMS to construct
  micro chamber and channels and a heating
  substrate with microheaters constructed by
  resistive heaters with electrical insulation
  layer on the top

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Experimental Procedure

• A fine thermocouple (CHAL-0005), was good
  linearity between 0 to 65?, TCR of the heater
  0.0015/? and the coefficient of determination of
  the linear fit is 0.9999

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• E. coli stored was thawed on ice and mixed with
  plasmid DNA, which contains both Venus and
  ampicillin resistance gene
• Compare local heat shock, conventional heat
  shock, and without heat shock

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Results

• The micro device achieves 2.62106colonies/µg,
  which is about over 200 better than the
  conventional heat shock result at
  1.13106colonies/µg
• No transformed cell can be observed without heat
  shock procedure

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Conclusions

• A MEMS local heat shock device has been
  successfully designed, fabricated and tested to
  demonstrate effective DNA transformation using
  competent E. coli cells and plasmid DNA with
  embedded Venus gene.
• The improvement in efficiency is likely coming
  from the effective heating process in the micro
  scale . As such, this MEMS device has potentials
  to be part of lab-on-a-chip systems.