image: The previously reported CBApt construction technology faces several challenges, including the use of T4 ligase, and the need for 13 additional complementary nucleosides at the end of each aptamer. The newly developed strain-promoted alkyne-azide cycloaddition (SPAAC) strategy is a practical method to access CBApts because of its mild reaction conditions, ease of operation, and high compatibility with respect to aptamer conformations. view more
Credit: ©Science China Press
This study was performed by Professor Xue-Qiang Wang’s research group at Hunan University. Aptamers, known as ̒chemical antibodies̕, can specifically recognize various targets. Therefore, they are widely used in various fields such as bioanalysis, diagnosis and therapeutics. However, further application of aptamers in new research areas and clinical translations has been greatly hampered by their inherent limitations. To overcome these limitations, researchers developed a strain-promoted alkyne-azide cycloaddition (SPAAC) strategy to engineer circular bivalent aptamers (CBApts) to improve the biomedical properties of aptamers, thus paving the way for their further applications in biomedicine field.
After detailed reaction conditions optimization, the optimal reaction conditions were established, the versatility of the newly developed method was then investigated. Notably, this method showed excellent compatibility, it could be applied to different aptamers and single-stranded nucleic acids with different lengths, and the target cyclized FNAs were engineered in moderate to excellent yields.
The team then compared the biological properties of CBApts with monovalent aptamers. It was found that the stability of bivalent aptamers in 10% FBS and 0.25 U/μL Exo I was much higher than that of monovalent aptamers. In addition, CBApts exhibited significantly enhanced specific recognition and binding abilities against target cancer cells. These distinguished properties might be beneficial for designing new aptamer-based targeted drug delivery strategies.
To further examine the potential of applying CBApts in the field of biomedicine, researchers designed a “recognition-then-interaction” strategy to regulate cell interactions. Benefiting from the enhanced recognition and binding functions of the aptamers, two kinds of cells that originally can not interact with each other were dragged closely to each other in the presence of a CBApt, which provides a new technique for cell behavior regulation.
The team further explore the possibility of applying CBApt in vivo. CBApt is much better than simply using a mixture of two aptamers to selectively accumulate in tumor tissues, and the retention time is also greatly extended. They also compared CBApt obtained using the methodology described herein with the CBApt obtained using the T4 ligase method and found that SXCBApt exhibited a superior ability to recognize, accumulate and retain in tumor tissues than T4-SXCBApt, indicating that the construction methods indeed have effects on biological properties of CBApts.
###
See the article:
A Versatile Strategy for Convenient Circular Bivalent Functional Nucleic Acids Construction
https://doi.org/10.1093/nsr/nwac107
Journal
National Science Review