13 Some Frontier Technologies for Aptamers in Medical Applications
387
13.3.1 Aptamer Microarray Biochip
Invented by Patrick O. Brown in 1983, DNA microarray as schematically shown
in Fig. 13.7 was once the most intriguing and promising technology in 1990s for
its high-throughput characterizing capability of DNA–RNA, DNA–DNA, protein–
protein, or protein–DNA interactions. In a typical microarray biochip gene expression
assay, several hundreds to tens of thousands of various DNA probes were spotted
or printed in parallel via in situ synthesis with photolithography or phosphoramidite
chemistry onto the surface of a functionalized glass slide firstly, then fluorescence
labeled cDNAs from transcripted mRNAs of target samples (reference vs. tumor,
etc.) were placed onto the DNA microarray where they would hybridize to the probes
attached on the microarray, and non-bound sequences were washed and fluorescently
labeled target sequences that bounded to probes would generate optical signals when
excited by a laser, the total strength of the fluorescence signal would correlate to the
expression level of various genes expressed in the samples, and a digital image of
the microarray was created for qualitative or quantitative assessment thereafter.
Up to now, DNA microarray had achieved great success in fields of mRNA
transcriptome, gene expression profiling, genotyping, and chip-based sequencing;
however, the technique was not clinically applicable for protein researches of expression profiling, post-translational modifications, and low abundance characterization,
hence, protein microarray in lieu of DNA microarray, which could be analytical or
capture antibody microarray, functional or target protein microarray, and reversephase protein microarray, was developed for the purpose, accordingly. Various antibodies, allergens, full length proteins or their structural domains, living cells, cell
Fig. 13.7 A typical microarray test scheme. Reprinted from Ref. [11], with kind permission from
Springer Science + Business Media 2008
387
13.3.1 Aptamer Microarray Biochip
Invented by Patrick O. Brown in 1983, DNA microarray as schematically shown
in Fig. 13.7 was once the most intriguing and promising technology in 1990s for
its high-throughput characterizing capability of DNA–RNA, DNA–DNA, protein–
protein, or protein–DNA interactions. In a typical microarray biochip gene expression
assay, several hundreds to tens of thousands of various DNA probes were spotted
or printed in parallel via in situ synthesis with photolithography or phosphoramidite
chemistry onto the surface of a functionalized glass slide firstly, then fluorescence
labeled cDNAs from transcripted mRNAs of target samples (reference vs. tumor,
etc.) were placed onto the DNA microarray where they would hybridize to the probes
attached on the microarray, and non-bound sequences were washed and fluorescently
labeled target sequences that bounded to probes would generate optical signals when
excited by a laser, the total strength of the fluorescence signal would correlate to the
expression level of various genes expressed in the samples, and a digital image of
the microarray was created for qualitative or quantitative assessment thereafter.
Up to now, DNA microarray had achieved great success in fields of mRNA
transcriptome, gene expression profiling, genotyping, and chip-based sequencing;
however, the technique was not clinically applicable for protein researches of expression profiling, post-translational modifications, and low abundance characterization,
hence, protein microarray in lieu of DNA microarray, which could be analytical or
capture antibody microarray, functional or target protein microarray, and reversephase protein microarray, was developed for the purpose, accordingly. Various antibodies, allergens, full length proteins or their structural domains, living cells, cell
Fig. 13.7 A typical microarray test scheme. Reprinted from Ref. [11], with kind permission from
Springer Science + Business Media 2008