الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 68 |  |  |
| | | from | 68 | | |
Abstract
Aptamers are short DNA or RNA oligonucleotides specialized in the specific and efficient binding to a target molecule. They are obtained by in vitro selection or evolution processes. It was in 1990 that two independent research groups described the bases of a new in vitro technology for the identification of RNA molecules able to specifically bind to a target .Tuerk and Gold established the principals of the in vitro selection process that was named SELEX (Systematic Evolution of Ligands by Exponential enrichment), which is based on iterative cycles of binding, partitioning, and amplification of oligonucleotides from a pool of variant sequences . Ellington and Szostak coined the term aptamer to define the selected molecules by the application of this method
Modifications and optimization of the SELEX procedure aimed to get newly modified aptamers has also attracted much interest and theses advances along with the parallel progresses in the nucleic acids chemistry and cellular delivery fields have allowed for the rise of a new hope in developing aptamers as efficient molecular tools for diagnostics and therapeutics.
Aptamers have several advantages over protein antibodies: lower immunogenicity, easier production, and smaller size. Both aptamers and antibodies can potentially serve as diagnostic and therapeutic tools. Since the first monoclonal antibody was produced in the 1970s, more widespread distribution and adoption of antibodies as well as a well-developed infrastructure have led to widespread application of antibodies to disease diagnosis. However, aptamers are more stable and easier to label and modify, and have a much lower cost of manufacture as compared with antibodies. Therapeutic aptamers have the advantages over antibodies in the treatment of antitoxin, antivenom and anti-multiple drug resistant bacterial and viral infections, but the therapeutic effects and safety of aptamers should be carefully studied.
Aptamers hold an advantage in providing more complex and diverse 3D structures, which is helpful for selecting aptamers with high affinity for complex targets needed for disease therapy.
Due to their unique physical, chemical, and biological properties.aptamer technology has been widely used in diagnosis and treatment of hematological and immunological diseases, including leukemia, lymphoma, and multiple myeloma ,SLE and others .
Aptamer-mediated treatments provide an advantageous approach compared to conventional therapies, and they present a promising perspective in clinical applications given their aforementioned unique properties and development potential. However, several challenges remain to be addressed. Unmodified RNA aptamers are vulnerable to nuclease-mediated degradation in the bloodstream, and thus methods to improve the in vivo biostability of aptamers are urgently needed.
Aptamer-based products initially had limited commercial success in the markets because aptamer technology was new, and relevant systematic academic studies on pharmacokinetics and pharmacodynamics were not available. The aforementioned issues should be addressed prior to the future application of aptamers as dominant therapeutics in the clinic.
The aptamer field has probably touched only the tip of the iceberg. Researchers are focus on optimization of the SELEX methods, aptamer modifications, combinations of aptamers and targeted drug delivery. The aptamer technology continues to reveal its promising feature and the vast diagnostic and therapeutic potential for Hematological and immunological diseases in the present and the future.