Intracellularly Actuated Quantum Dot–Peptide–Doxorubicin Nanobioconjugates for Controlled Drug Delivery via the Endocytic Pathway

Abstract

Nanoparticle (NP)-mediated drug delivery (NMDD) has emerged as a novel method to overcome the limitations of traditional systemic delivery of therapeutics, including the controlled release of the NP-associated drug cargo. Currently, our most advanced understanding of how to control NP-associated cargos is in the context of soft nanoparticles (e.g., liposomes), but less is known about controlling the release of cargos from the surface of hard NPs (e.g., gold NPs). Here we employ a semiconductor quantum dot (QD) as a prototypical hard NP platform and use intracellularly triggered actuation to achieve spatiotemporal control of drug release and modulation of drug efficacy. Conjugated to the QD are two peptides: (1) a cell-penetrating peptide (CPP) that facilitates uptake of the conjugate into the endocytic pathway and (2) a display peptide conjugated to doxorubicin (DOX) via three different linkages (ester, disulfide, and hydrazone) that are responsive to enzymatic cleavage, reducing conditions, and low pH, respectively. Formation of the QD-[peptide-DOX]-CPP complex is driven by self-assembly that allows control over both the ratio of each peptide species conjugated to the QD and the eventual drug dose delivered to cells. Förster resonance energy transfer assays confirmed successful assembly of the QD-peptide complexes and functionality of the linkages. Confocal microscopy was employed to visualize residence of the QD-[peptide-DOX]-CPP complexes in the endocytic pathway, and distinct differences in DOX localization were noted for the ester linkage, which showed clear signs of nuclear delivery versus the hydrazone, disulfide, and amide control. Finally, delivery of the QD-[peptide-DOX]-CPP conjugate resulted in cytotoxicity for the ester linkage that was comparable to free DOX. Attachment of DOX via the hydrazone linkage facilitated intermediary toxicity, while the disulfide and amide control linkages showed minimal toxicity. Our data demonstrate the utility of hard NP-peptide bioconjugates to function as multifunctional scaffolds for simultaneous control over cellular drug uptake and toxicity and the vital role played by the nature of the chemical linkage that appends the drug to the NP carrier.

In Situ Self‐Assembly of Quantum Dots at the Plasma Membrane Mediates Energy Transfer‐Based Activation of Channelrhodopsin

“…It is also worth noting that over the four days of the experimental time course, the cells remained healthy and functional, consistent with our previous work that showed minimal impact on viability when cells are simultaneously transfected with plasmid DNA and interfaced with QDs at various cellular locations. [29,23,24,26,27]…”

DNA Microsystems for Biodiagnosis

“…Furthermore, electrochemical DNA sensors offer a faster, more specific, sensitive, and versatile detection modality for target pathogen molecules [137]. Moreover, nanocarriers can bind to commonly used drugs such as doxorubicin to reduce side effects, toxicity, and drug resistance in cancer therapy [138][139][140][141]. Nanorobots can be used to carry thrombin and stop blood flow in tumor vessels, while DNA-based signal amplification methods combined with DNA-integrated gold nanomaterials accurately detect tumor biomarkers [138].…”

Toxicological assessment of nanoparticle interactions with the pulmonary system

“…They efficiently allow for multidrug or combinational therapy targeting (Wang et al 2016;Costa-Gouveia et al 2017;Zhang et al 2017;Yan et al 2018) achieving synergistic, or multi-targeting, or theranostic applications. Functionalized NPs can deliver the active substance intracellularly (Medina et al 2009Sangtani et al 2018. Furthermore, NPs could be modulated with mechanisms to target only the diseased tissue or cells, either passively, through the enhanced permeability and retention effect (EPR) (increased local blood supply tends to pool the NPs as in case of tumor sites), or actively, through targeting molecules like antibodies (here the tumor cells selectively intake the NPs) (Zimmer 2002;Zamboni et al 2012).…”