4 Aptamer-Based Drug Delivery Systems
105
4.5 Challenges
Currently, aptamers, aptamer-drug conjugates and aptamer functionalized nanoparticles have shown attraction in drug delivery, while most applications are still in the
experimental stage, with many challenges ahead. Although aptamers exhibit excellent performance in vitro, there are still many bottlenecks in transforming scientific
achievements into clinical applications. For example, aptamers can be easily affected
by external substances, such as nonspecific serum binding protein in the complex
environment of human body, easy DNA degradation in the presence of nucleases
in blood which will affect in vivo performance of aptamers. It is worth noting that
some screened aptamers, although having a low dissociation constant in vitro, exhibited unsatisfied targeting affinity in vivo. In addition, it is necessary to screen more
ideal aptamers towards clinically relevant targets. The FDA approved aptamers for
clinical usage are very limited to date. Moreover, the toxicity and long-term health
effects of nanomaterials in vitro and in vivo need more studies, including inflammation and immune response. In short, the road ahead is still long, while we expect
that aptamer-based drug delivery will eventually become a practical way able to
overcome the biomedical challenges.
4.6 Future Perspectives
Due to their unique properties, aptamers have attracted increasing attention of scientists in the field of targeted therapy. In recent years, as aptamer screening technology
has been increasingly developed, more and more aptamers have been screened for
different targets. The application of aptamer is not only limited in targeted therapy
of cancer but also other diseases. How to make use of the advantages of aptamers
and other materials, and designing more innovative, effective and rational delivery
systems are the research focus and frontier. How to further improve its performance
and application for in vivo administration is essential for future research. In addition,
the specific mechanisms of therapeutic aptamers also need further study. Aptamers
with higher affinity to target receptors require to be screened for benefited cellular
uptake. Although it will be a long way to go for the clinical application of aptamer
based-targeted drug preparations, with the deepening of research and the continuous
improvement of the properties of aptamers, we believe that aptamers will have broad
prospects with the use of interdisciplinary knowledge.
4.7 Conclusion
Aptamers have presented versatile applicability as target agents to construct targeted
drug delivery systems, and possess great potential to be used in therapeutic agents
and diagnostics. A growing number of aptamers have been applied as therapeutic
105
4.5 Challenges
Currently, aptamers, aptamer-drug conjugates and aptamer functionalized nanoparticles have shown attraction in drug delivery, while most applications are still in the
experimental stage, with many challenges ahead. Although aptamers exhibit excellent performance in vitro, there are still many bottlenecks in transforming scientific
achievements into clinical applications. For example, aptamers can be easily affected
by external substances, such as nonspecific serum binding protein in the complex
environment of human body, easy DNA degradation in the presence of nucleases
in blood which will affect in vivo performance of aptamers. It is worth noting that
some screened aptamers, although having a low dissociation constant in vitro, exhibited unsatisfied targeting affinity in vivo. In addition, it is necessary to screen more
ideal aptamers towards clinically relevant targets. The FDA approved aptamers for
clinical usage are very limited to date. Moreover, the toxicity and long-term health
effects of nanomaterials in vitro and in vivo need more studies, including inflammation and immune response. In short, the road ahead is still long, while we expect
that aptamer-based drug delivery will eventually become a practical way able to
overcome the biomedical challenges.
4.6 Future Perspectives
Due to their unique properties, aptamers have attracted increasing attention of scientists in the field of targeted therapy. In recent years, as aptamer screening technology
has been increasingly developed, more and more aptamers have been screened for
different targets. The application of aptamer is not only limited in targeted therapy
of cancer but also other diseases. How to make use of the advantages of aptamers
and other materials, and designing more innovative, effective and rational delivery
systems are the research focus and frontier. How to further improve its performance
and application for in vivo administration is essential for future research. In addition,
the specific mechanisms of therapeutic aptamers also need further study. Aptamers
with higher affinity to target receptors require to be screened for benefited cellular
uptake. Although it will be a long way to go for the clinical application of aptamer
based-targeted drug preparations, with the deepening of research and the continuous
improvement of the properties of aptamers, we believe that aptamers will have broad
prospects with the use of interdisciplinary knowledge.
4.7 Conclusion
Aptamers have presented versatile applicability as target agents to construct targeted
drug delivery systems, and possess great potential to be used in therapeutic agents
and diagnostics. A growing number of aptamers have been applied as therapeutic