Cell penetrating peptide mimics (CPPMs) and protein transduction domain mimics (PTDMs) have a well-established ability to enable cellular uptake of macromolecular cargos such as proteins and siRNA which has significant implications in the field of drug and biologics delivery. Synthetic PTDMs that feature both a hydrophobic and cationic block in their polymer architecture perform superiorly in terms of facilitating cellular uptake when compared to their cationic homopolymer counterparts. Modulating PTDM hydrophobicity has been shown to affect the ability to enhance cargo uptake, but the role of hydrophobicity in PTDM-binding of the desired cargo is not fully understood. Herein, block copolymer PTDMs synthesized from a palette of hydrophobic monomers were synthesized via ring-opening metathesis polymerization to probe the effect of varying hydrophobicity on the ability of the PTDM to bind enhanced green fluorescent protein (EGFP). The correlation between hydrophobicity and binding was extended further to clarify how both aspects affect cellular uptake of EGFP in Jurkat T cells. High performance liquid chromatography was used to quantify the relative hydrophobicity of the monomers in the series, while binding experiments through fluorescence quenching demonstrated that all polymers, regardless of hydrophobicity, bound EGFP similarly. Interestingly, cellular uptake of EGFP into Jurkat T cells, measured by flow cytometry, revealed that intermediately hydrophobic PTDMs facilitated optimal EGFP uptake despite similar binding observed for all PTDMs, suggesting that PTDM hydrophobicity has more influence over cellular uptake than cargo binding.

Modulating the hydrophobicity of cell penetrating peptide mimics for binding and intracellular delivery of protein cargo

253rd National Meeting (2017)

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