Development of microdevices for applications to bioanalysis

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Title: Development of microdevices for applications to bioanalysis
Author: Kim, Joohoon, 1976-
Abstract: The development of microdevices for applications related to bioanalysis is described . There are two types of microdevices involved in this study : DNA (or RNA ) microarrays and bead -based microfluidic devices . First , a new method to fabricate DNA microarrays is developed : replication of DNA microarrays . It was shown that oligonucleotides immobilized on a glass master can hybridize with their biotin -modified complements , and then the complements can be transferred to a streptavidinfunctionalized replica surface . This results in replication of the master DNA array . Several innovative aspects of replication are discussed . First , the zip code approach allows fabrication of replica DNA arrays having any configuration using a single , universal master array . It is demonstrated that this approach can be used to replicate master arrays having three different sequences (spot feature sizes as small as 100 [mu]m ) and that master arrays can be used to prepare multiple replicas . Second , it is shown that a surface T4 DNA polymerase reaction improves the DNA microarray replication method by removing the requirement for using presynthesizd oligonucleotides . This in -situ , enzymatic synthesis approach is used to replicate DNA master arrays consisting of 2304 spots and arrays consisting of different oligonucleotide sequences . Importantly , multiple replica arrays prepared from a single master show consistent functionality to hybridization -based application . It is also shown that RNA microarrays can be fabricated utilizing a surface T4 DNA ligase reaction , which eliminates the requirement of modified RNA in conventional fabrication schemes . This aspect of the work shows that the replication approach may be broadly applicable to bioarray technologies . A different but related aspect of this project focuses on biosensors consisting of microfluidic devices packed with microbeads conjugated to DNA capture probes . The focus here is on understanding the parameters affecting the hybridization of DNA onto the probeconjugated microbeads under microfluidic flow conditions . These parameters include the surface concentration of the probe , the flow rate of the solution , and the concentration of the target . The simple microfluidic device packed with probe -conjugated microbeads exhibits efficient target capture resulting from the inherently high surface -area -to -volume ratio of the beads , optimized capture -probe surface density , and good mass -transfer characteristics . Furthermore , the bead -based microchip is integrated with a hydrogel preconcentrator enhancing the local concentration of DNA in a icrochannel . The integration of the preconcentrator into the bead -based capture chip allows significantly lower limit of detection level ( ~10 -fold enhancement in the sensitivity of the microbeadbased DNA detection ) .
URI: http : / /hdl .handle .net /2152 /3286
Date: 2008-08-28


Development of microdevices for applications to bioanalysis. Doctoral dissertation, The University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /3286 .

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