Tuning Cellular Uptake of Molecular Probes by Rational Design of Their Assembly into Supramolecular Nanoprobes

Abstract

Intracellular sensing of pathologically relevant biomolecules could provide essential information for accurate evaluation of disease staging and progression, yet the poor cellular uptake of water-soluble molecular probes limits their use as protease sensors. In other cases such as extracellular sensing, cellular uptake should be effectively inhibited. Self-assembly of molecular probes into supramolecular nanoprobes presents a potential strategy to alter their interaction mechanisms with cells to promote or reduce their cellular uptake. Here, we report on the design, synthesis, and assembly of peptide-based molecular beacons into supramolecular protease sensors of either spherical or filamentous shapes. We found that positively charged spherical nanobeacons demonstrate much higher cellular uptake efficiency than its monomeric form, thus making them most suitable for intracellular sensing of the lysosomal protease cathepsin B. Our results also suggest that assembly into filamentous nanobeacons significantly reduces their internalization by cancer cells, an important property that can be utilized for probing extracellular protease activities. These studies provide important guiding principles for rational design of supramolecular nanoprobes with tunable cellular uptake characteristics.

Filomicelles Deliver a Chemo-Differentiation Combination of Paclitaxel and Retinoic Acid That Durably Represses Carcinomas in Liver to Prolong Survival

“…Interestingly, others have shown that filamentous nanostructures such as those of peptide conjugates have reduced cellular uptake compared to free drug in vitro. 54 However, our lab has previously shown that uptake can lead to a “depot effect” with more drug in a cell at a critical time (e.g., mitosis) compared to free drug. 6 …”

Self-assembling prodrugs

“…Discher and co-workers observed the enhanced ability of polyethylene glycol (PEG)-coated, block copolymer filomicelles to circulate longer in the bloodstream than their spherical counterparts. 189–191 In a study by Lock et al, 192 the self-assembled arrangement of positively charged spherical nanobeacons exhibited a much higher cellular uptake ability compared to their monomeric form. Furthermore, it was shown that assembly into filamentous nanobeacons reduced their overall internalization capacity, regardless of the surface charge status.…”

“…To do so would require an alteration in processing conditions such that two or more morphologies could be created from a single conjugate, as in Cui’s study on nanobeacons. 192 An alternative strategy could encompass the study of isomeric species in which the spatial location of elements are varied, a method shown in the study of peptide-based amphiphiles to induce morphological or self-assembly behaviour variations through a simple switch in the amino acid order. 204, 205 The rationale here is that the relocation of a particular amino acid can influence the intermolecular interactions that govern the self-assembly pathway.…”

Protease-Sensitive Nanomaterials for Cancer Therapeutics and Imaging

“…(D) Confocal laser scanning microscopy of PC3-Flu cells after 1 h incubation with 5 μM nanobeacons with different surface charges and shapes (a–f). Adapted with permission from ref (101). Copyright 2016 American Chemical Society.…”