In vitro assessment of a novel polyrotaxane-based drug delivery system integrated with a cell-penetrating peptide

Abstract

In the development of anti-cancer drugs, it is important to yield selective cytotoxicity primarily against tumor tissues. To achieve this goal, the use of a polymer-drug conjugate appears to be appealing, simply because it can take the advantage of the so-called enhanced permeability and retention (EPR) effect due to vascular leak in tumors. Among various types of polymers, polyrotaxane (PR) is an interesting candidate and warrants further consideration. It is a self-assembled polymer made entirely of biocompatible components, by threading alpha-cyclodextrin (alpha-CD) molecules with the poly(ethylene glycol) (PEG) chain. The abundance in functional -OH groups on the CD residues renders PR the capability of carrying a large dose of small anti-tumor agents for delivery. Herein, we presented a novel PR-based delivery system using doxorubicin (DOX) as the model anti-cancer drug. Daunorubicin (DNR) was conjugated to the PR polymer via hydrolysable linkages, and upon hydrolysis, doxorubicin was released as the cytotoxic drug. To facilitate an intracellular uptake by the tumor cells of the PR-DOX conjugates, a cell-penetrating low molecular weight protamine (LMWP) peptide was further attached to the two termini of the PR chain. Using an innovative principle established in our laboratory, such as via the inhibition of the cell-penetrating activity by binding with heparin and reversal of this inhibition by subsequent addition of protamine, cellular uptake of the polymer-drug conjugates could be readily regulated. In this paper, we performed in vitro studies to demonstrate the feasibility of this delivery system. The LMWP-PR-DOX conjugates, which yielded a sustained release of DOX over a period of greater than 4 days, were successfully synthesized. Intracellular uptake of these conjugates by A2780 human ovarian cancer cells and regulation of such uptake by heparin and protamine were confirmed by using the MTT assay and also the confocal microscopy method.

Self-assembly Polyrotaxanes Nanoparticles as Carriers for Anticancer Drug Methotrexate Delivery

“…With the modification of hydroxyl groups on the CDs, anticancer drugs could be immobilized on polyrotaxanes via cleavable bonds to form drug-polyrotaxane conjugates [6,7]. The drug release was triggered by the broken of the cleavable bonds.…”

The Synthesis of a Multiblock Osteotropic Polyrotaxane by Copper(I)‐Catalyzed Huisgen 1,3‐Dipolar Cycloaddition

“…[28][29][30][31] Since its discovery in 1990, [29] this molecular assembly has been extensively scrutinized and has led to interesting developments of biodegradable polyrotaxanes for controlled drug delivery. [32][33][34][35] In these studies, drugs are typically conjugated to the a-CD rings post polyrotaxane formation and environment (e.g., low pH, enzymes) triggered decapping is employed as the drug releasing mechanism.…”

Supramolecular Polymers Based on Cyclodextrins for Drug and Gene Delivery

“…Based on a similar technology, another drug, anti-cancer drug doxorubincin (DOX), was also conjugated to a polyrotaxane polymer via hydrolyzable linkages, and a cell-penetrating low molecular weight protamine (LMWP) peptide was further attached to the chain end in order to facilitate the intracellular uptake of tumor cells [91]. Figure 14 illustrates the structure of DOX-polyrotaxane conjugate.…”