Surface-modified and internally cationic polyamidoamine dendrimers for efficient siRNA delivery

Area of Science:

• Biomaterials Science
• Nanotechnology
• Gene Delivery

Background:

• Poly(amidoamine) (PAMAM) dendrimers are widely explored for gene delivery.
• Surface modifications are crucial for optimizing dendrimer performance and reducing toxicity.
• Developing dendrimers with controlled charge distribution is key for efficient and safe nucleic acid delivery.

Purpose of the Study:

• To synthesize and characterize a novel internally quaternized and surface-acetylated poly(amidoamine) dendrimer (QPAMAM-NHAc).
• To evaluate QPAMAM-NHAc as a nanocarrier for intracellular siRNA delivery.
• To compare the properties and performance of QPAMAM-NHAc with other PAMAM dendrimers.

Main Methods:

• Synthesis and characterization of QPAMAM-NHAc dendrimer.
• Preparation and characterization of dendrimer/siRNA polyplexes using atomic force microscopy (AFM).
• Assessment of cytotoxicity and cellular uptake via confocal microscopy.

Main Results:

• QPAMAM-NHAc formed well-condensed, spherical siRNA polyplexes, unlike PAMAM-NH2 which formed nanofibers.
• Surface acetylation significantly reduced dendrimer cytotoxicity, with QPAMAM-NHAc exhibiting the lowest toxicity.
• QPAMAM-NHAc demonstrated enhanced cellular uptake and homogeneous intracellular siRNA distribution.

Conclusions:

• QPAMAM-NHAc is a promising nanocarrier for siRNA delivery due to its low cytotoxicity and efficient cellular internalization.
• The internal quaternization and neutral surface acetylation provide advantages over surface-charged dendrimers.
• Developed QPAMAM-NHAc/siRNA polyplexes show distinct benefits compared to existing dendrimeric nucleic acid carriers.