Transferrin-Appended Nanocaplet for Transcellular siRNA Delivery into Deep Tissues

Abstract

Transferrin (Tf) is known to induce transcytosis, which is a consecutive endocytosis/exocytosis event. We developed a Tf-appended nanocaplet (TfNC⊃siRNA) for the purpose of realizing siRNA delivery into deep tissues and RNA interference (RNAi) subsequently. For obtaining TfNC⊃siRNA, a macromonomer (AzGu) bearing multiple guanidinium (Gu+) ion units, azide (N3) groups, and trityl (Trt)-protected thiol groups in the main chain, side chains, and termini, respectively, was newly designed. Because of a multivalent Gu+–phosphate salt-bridge interaction, AzGu can adhere to siRNA along its strand. When I2 was added to a preincubated mixture of AzGu and siRNA, oxidative polymerization of AzGu took place along the siRNA strand, affording AzNC⊃siRNA, the smallest siRNA-containing reactive nanocaplet so far reported. This conjugate was converted into Glue/BPNC⊃siRNA by the click reaction with a Gu+-appended bioadhesive dendron (Glue) followed by a benzophenone derivative (BP). Then, Tf was covalently immobilized onto Glue/BPNC⊃siRNA by Gu+-mediated adhesion followed by photochemical reaction with BP. With the help of Tf-induced transcytosis, TfNC⊃siRNA permeated deeply into a cancer spheroid, a 3D tissue model, at a depth of up to nearly 70 μm, unprecedentedly.

Nanocarrier‐Mediated Cytosolic Delivery of Biopharmaceuticals

“…For membrane translocation of NPs, factors such as size, charge, surface hydrophobicity, elasticity, and shape play an essential role. [ 157 ] Several NPs, such as carbon nanotubes, [ 158 ] oligonucleotide (ON) nanospheres with an average size of 45 nm, [ 159 ] transferrin (Tf)‐appended NPs with a diameter of 20 nm, [ 160 ] hollow casein spheres with a size of ≈500 nm, [ 161 ] and lipid‐covered hydrophobic NPs with diameters greater than 5 nm, [ 162 ] have the ability to cross the cell membrane and demonstrate potential for direct cytosol delivery of biologics. An increase in NP size hampers translocation, [ 163 ] as larger NPs must recruit more receptors to be fully wrapped by the cell membrane.…”

Single siRNA Nanocapsules for Effective siRNA Brain Delivery and Glioblastoma Treatment

“…[ 6 ] Viruses have shown excellent siRNA delivery capability, however, the mutagenic toxicity and immunogenicity seriously hinder their clinical applications. [ 7 ] Comparatively, nonviral vectors such as cationic liposomes, [ 8 ] polymeric, [ 9 ] and inorganic nanoparticles [ 10 ] are able to deliver siRNA, but they still face efficiency and safety issues. Remarkably, most nonviral delivery nanocarriers were cationic or lipid based materials that have excessive positive surface charge, which normally induce systemic toxicity and low selectively in vivo.…”

Intelligent Nanocomposites with Intrinsic Blood–Brain‐Barrier Crossing Ability Designed for Highly Specific MR Imaging and Sonodynamic Therapy of Glioblastoma

“…ii) O 2 generation derived from MnO 2 species in the tumor microenvironment alleviates hypoxia in the tumor region and simultaneously enables protoporphyrin to produce much more 1 O 2 under US irradiation . iii) The fascinating “sequential intercellular relay” property of holo‐Tf, which favors deep penetration of nanoparticles in tumor tissue, greatly increases the efficiency of sonodynamic therapy …”