Lipofection with estrone-based luminophores featuring aggregation-induced emission properties

Abstract

In this communication we present the use of a novel class of luminophores with aggregation-induced emission (AIE) properties based on the steroid estrone. These molecules were equipped with cationic residues yielding amphiphiles suitable for lipofection. To this end, self-assembled luminescent structures were formed in aqueous media and mixed with a red-fluorescent protein expressing plasmid, yielding lipoplexes with increased emission intensity. These luminescent lipoplexes were able to efficiently transfect HeLa and HEK 293T cells and were able to be tracked due to the aggregation induced-emission properties.

Scheme 1. Self-assembly of AIE active amphiphiles followed by the formation of luminescent lipoplexes in the presence of plasmid DNA as well their ability to transfect cells. The schematic presentation is not to scale.

Scheme 2. Molecular structures of the estrone-based AIE-active transfection vectors used in this study.

Fig. 1. X-ray structure of [F] × 1 DMF. Displacement ellipsoids are drawn at 50% probability levels.

Fig. 2. (A) Emission of compound [1] as pure sample and in the presence of the mRFP plasmid, (B) photographs of [1] as pure sample and in the presence of the mRFP plasmid under UV-light irradiation (λ = 365 nm), (C) DLS spectra of [1] and [1] in the presence of the pH2B-mRFP plasmid, c[1] = 100 μM, c(pH2B-mRFP plasmid) = 10 μg mL⁻¹ (D) TEM images of [1] and (E) [1] in the presence of RFP plasmid. c[1] = 500 μM, c(pH2B-mRFP plasmid) = 50 μg mL⁻¹.

Fig. 3. Confocal images of HEK 293T (upper panels) and HeLa cells (lower panels) 16 h after transfection of pH2B-mRFP (red) with [1]. Scale bar: 100 μm (concentrations: [1] = 48 μM, pH2B-mRFP plasmid = 2.4 μg mL⁻¹).

Fig. 4. Concentration-dependent cytotoxicity as determined by an MTS assay of compounds [1–4] compared with lipofectamine™ 2000 as reference.