Synthetic biological alternative to natural lipids for conjugation with nitrilotriacetic acid (NTA) for enhanced His-tagged protein interaction and long-term stability.

Biomimetic lipid vesicles, such as liposomes, have multiple biotechnology and drug delivery applications as their lipid bilayer innately interacts with natural cell membranes. To enhance cellular interactions, the surfaces of liposomes are arrayed with proteins using nitrilotriacetic acid (NTA)-conjugated lipids. However, limited commercially available NTA-conjugated lipids exist. Further, the activity and stability of NTA-conjugated lipids decreases rapidly following exposure to air and within weeks to months following storage at -20°C.

Janus dendrimers (JDs) are synthetic alternatives to natural lipids that effectively self-assemble, encapsulate high concentrations of organic compounds, and exhibit ideal mechanical properties allowing interactions with natural lipid bilayers. NTA-conjugated JDs exhibit increased stability and protein affinity when compared to NTA-conjugated lipids.

Qi Xiao and the Percec group have developed JDs conjugated to both monovalent NTA and TrisNTA as biological membrane mimetics. Although TrisNTA provides greater protein affinity than monovalent NTA, TrisNTA is complex and expensive to synthesize. A modular, synthetic approach allowed for the development of a library of both JD-NTA and JD-TrisNTA compounds. Both types of compounds do not decompose when exposed to air, remain highly stable at room temperature, and provide higher affinities to His-tagged proteins when compared to NTA-conjugated lipid-based approaches.

• Provides infinitely higher stability at room temperature, which is key for conjugation conditions and long-term storage
• Displays ~30-fold enhanced protein affinity with JD-NTA compared to lipid-NTA, which is key for maximizing protein interactions in biological approaches
• Provides ~1000-fold enhanced protein affinity with TrisNTA compared to monovalent NTA, which is key for conserving expensive reagents without compromising sensitivity