Photochemical Stabilization of Self-Assembled Spherical Nucleic Acids

Area of Science:

• Biotechnology
• Nanomedicine
• Molecular Biology

Background:

• Oligonucleotide therapeutics face challenges like degradation and poor cellular uptake.
• Spherical nucleic acids (SNAs) are promising for nucleic acid delivery but can be unstable in biological conditions.
• Non-covalent self-assembly of DNA amphiphiles can lead to fragility upon interaction with serum proteins.

Purpose of the Study:

• To develop methods for covalently crosslinking self-assembled SNAs to enhance their stability.
• To investigate the impact of crosslinking on SNA resistance to serum proteins and cellular uptake.
• To evaluate the effect of crosslinking on the therapeutic release and gene silencing activity of SNAs.

Main Methods:

• Sequence-defined DNA amphiphiles were synthesized and self-assembled into SNAs.
• Two UV-induced covalent crosslinking strategies were employed: thymine photodimerization and disulfide crosslinking.
• SNA stability was assessed against human serum albumin (HSA) binding.
• Cellular uptake and gene silencing efficacy were evaluated in vitro.

Main Results:

• UV crosslinking significantly enhanced SNA stability against HSA.
• Disulfide crosslinked SNAs showed improved cellular uptake compared to non-crosslinked counterparts.
• Crosslinking maintained therapeutic nucleic acid accessibility and sustained activity.
• Enhanced stability led to improved unaided gene silencing efficiency.

Conclusions:

• UV-induced covalent crosslinking is an effective strategy to stabilize SNAs.
• Stabilized SNAs exhibit improved cellular delivery and enhanced gene silencing.
• These findings support the potential of crosslinked SNAs for preclinical and in vivo therapeutic applications.