Investigating polymer thiolation in gene delivery

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Gene Delivery Systems

Background:

• Thiolated polymers with disulfide bonds are explored for gene delivery.
• The formation of disulfide bonds and the role of free thiols in these polymers are not fully understood.
• Understanding polymer behavior is crucial for optimizing delivery systems.

Purpose of the Study:

• To investigate disulfide linking in a thiol-containing polymer.
• To determine the impact of free thiols on the polymer's gene delivery potential.
• To evaluate the cellular interaction and fate of these thiolated polymers.

Main Methods:

• Synthesis of a fluorescent cationic polymer using poly(allylamine) and 2-iminothiolate (Traut's reagent).
• Assessment of polymer fluorescence via UV plate readings and fluorescent microscopy.
• Evaluation of transfection efficiency and cytotoxicity in MCF-7 breast cancer cells.
• Analysis using DNA electrophoresis to study polymer-DNA interactions.

Main Results:

• Thiolated polymers exhibited fluorescence at excitation/emission wavelengths of approximately 595/620 nm.
• Fluorescent measurements and microscopy revealed that the polymers are not internalized by cells.
• DNA electrophoresis confirmed polymer-cell surface binding, not internalization.
• No significant transfection efficiency or cytotoxicity was observed in MCF-7 cells.

Conclusions:

• The studied thiolated polymers do not appear to form significant disulfide bonds for intracellular delivery.
• These polymers do not get internalized by cells, limiting their use in traditional gene delivery.
• The observed cell surface binding suggests potential applications in areas requiring cell adhesion.