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Y. Dong et al.
lysates, or patient serums, could be spotted or immobilized successfully as a highdensity or low-density protein microarray for subsequent protein–protein interaction and relevant characterization researches. Nevertheless, because of the poor
cost-effectiveness of chip manufacturing and instability of product quality, DNA
microarray still prevailed protein microarray in various medical applications.
Using aptamers as DNAs or antibodies spotted on the glass slides of DNA or
protein microarray, one can easily fabricate an aptamer microarray biochip for
customized medical research. Compared with antibodies, the aptamers will offer
great advantages and applicability of long-term stability, ease of in vitro synthesis
and post modification, facile immobilization, highly specific characterization, sensitively precise detection, etc. In addition, antibodies against toxic compounds or low
immunogenic molecules cannot be easily acquired because of the intolerance of
experimental animals or the difficulty of hapten conjugation to an antigen. On the
contrary, aptamers can be generated and synthesized with ease and batch-to-batch
stability. Hence, aptamer microarray biochip with the merits of aptamer will furnish
more applicative flexibilities inherently.
Different chemistry strategies can be utilized to immobilize modified aptamers
onto various functionalized surfaces of the aptamer microarray biochips, among
which hydroxyl-, amine-, carboxyl-, aldehyde-, or epoxy- are most frequently used
surface chemical groups for covalent aptamer immobilization. For instance, an
amine-modified aptamer can be attached to a carboxyl- functionalized biochip with
1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated coupling chemistry in the presence of N-hydroxysuccinimide (NHS) or N-hydroxysulfosuccinimide
(sulfo-NHS). Alternatively, an amine-modified aptamer can be coupled to an
aldehyde-functionalized biochip by conventional aldimine condensation reaction
with the production of Schiff bases. Sometimes, non-covalent strategies with
great affinities, such as hybridization, biotinylated aptamers with avidin or streptavidin functionalized biochip surface, or vice versa, can be applied for aptamer
immobilization as well.
In addition, to ensure real-world functionality of a fabricated aptamer microarray
biochip, different steric parameters, e.g., surface charge, immobilization loading
capacity or density, and the incorporation of spacers into aptamers for chip proximity tuning, which might exert influence on adaptive folding recognition behaviors
of the immobilized aptamers, need to be thoroughly optimized. Because of inherent
difficulties, there is at present time no well-generalized rule for the said optimization, all aptamer microarray biochip experiments are performed case by case. Probably, computer-aided simulation and molecular docking will be a good fit for the
purpose. To step into a further understanding of aforementioned parameters, the
readers are suggested to Martin Witt’s review article entitled “Aptamer microarrayscurrent status and future prospects” published in an open access journal Microarrays
(ISSN 2076-3905) herein [12].
For proteomic or biomarker discovery researches, high affinity and slow offrate modified aptamer (SOMAmer
TM ), the protein-specific binding reagent used in
SomaScan
TM Assay developed by SomaLogic, is probably the most efficient recognition element commercially available for aptamer microarray biochip investigations.
Y. Dong et al.
lysates, or patient serums, could be spotted or immobilized successfully as a highdensity or low-density protein microarray for subsequent protein–protein interaction and relevant characterization researches. Nevertheless, because of the poor
cost-effectiveness of chip manufacturing and instability of product quality, DNA
microarray still prevailed protein microarray in various medical applications.
Using aptamers as DNAs or antibodies spotted on the glass slides of DNA or
protein microarray, one can easily fabricate an aptamer microarray biochip for
customized medical research. Compared with antibodies, the aptamers will offer
great advantages and applicability of long-term stability, ease of in vitro synthesis
and post modification, facile immobilization, highly specific characterization, sensitively precise detection, etc. In addition, antibodies against toxic compounds or low
immunogenic molecules cannot be easily acquired because of the intolerance of
experimental animals or the difficulty of hapten conjugation to an antigen. On the
contrary, aptamers can be generated and synthesized with ease and batch-to-batch
stability. Hence, aptamer microarray biochip with the merits of aptamer will furnish
more applicative flexibilities inherently.
Different chemistry strategies can be utilized to immobilize modified aptamers
onto various functionalized surfaces of the aptamer microarray biochips, among
which hydroxyl-, amine-, carboxyl-, aldehyde-, or epoxy- are most frequently used
surface chemical groups for covalent aptamer immobilization. For instance, an
amine-modified aptamer can be attached to a carboxyl- functionalized biochip with
1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated coupling chemistry in the presence of N-hydroxysuccinimide (NHS) or N-hydroxysulfosuccinimide
(sulfo-NHS). Alternatively, an amine-modified aptamer can be coupled to an
aldehyde-functionalized biochip by conventional aldimine condensation reaction
with the production of Schiff bases. Sometimes, non-covalent strategies with
great affinities, such as hybridization, biotinylated aptamers with avidin or streptavidin functionalized biochip surface, or vice versa, can be applied for aptamer
immobilization as well.
In addition, to ensure real-world functionality of a fabricated aptamer microarray
biochip, different steric parameters, e.g., surface charge, immobilization loading
capacity or density, and the incorporation of spacers into aptamers for chip proximity tuning, which might exert influence on adaptive folding recognition behaviors
of the immobilized aptamers, need to be thoroughly optimized. Because of inherent
difficulties, there is at present time no well-generalized rule for the said optimization, all aptamer microarray biochip experiments are performed case by case. Probably, computer-aided simulation and molecular docking will be a good fit for the
purpose. To step into a further understanding of aforementioned parameters, the
readers are suggested to Martin Witt’s review article entitled “Aptamer microarrayscurrent status and future prospects” published in an open access journal Microarrays
(ISSN 2076-3905) herein [12].
For proteomic or biomarker discovery researches, high affinity and slow offrate modified aptamer (SOMAmer
TM ), the protein-specific binding reagent used in
SomaScan
TM Assay developed by SomaLogic, is probably the most efficient recognition element commercially available for aptamer microarray biochip investigations.