Quantum dot‐mediated delivery of siRNA to inhibit sphingomyelinase activities in brain‐derived cells

Abstract

The use of RNAi to suppress protein synthesis offers a potential way of reducing the level of enzymes or the synthesis of mutant toxic proteins but there are few tools currently available for their delivery. To address this problem, bioconjugated quantum dots (QDs) containing a hydrophobic component (N-palmitate) and a sequence VKIKK designed to traverse across cell membranes and visualize drug delivery were developed and tested on cell lines of brain origin. We used the Zn outer shell of the QD to bind HIS6 in JB577 (W•G•Dap(N-Palmitoyl)•VKIKK•P9•G2•H6) and by a gel-shift assay showed that siRNAs would bind to the positively charged KIKK sequence. By comparing many peptides and QD coatings, we showed that the QD-JB577-siRNA construct was taken up by cells of nervous system origin, distributed throughout the cytosol, and inhibited protein synthesis, implying that JB577 was also promoting endosome egress. By attaching siRNA for luciferase in a cell line over-expressing luciferase, we showed 70% inhibition of mRNA after 24–48 h. To show more specific effects, we synthesized siRNA for neutral (NSMase2), acid (lysosomal ASMase) sphingomyelinase, and sphingosine kinase 1 (SK1), we demonstrated a dose-dependent inhibition of activity. These data suggest that QDs are a useful siRNA delivery tool and QD-siRNA could be a potential theranostic for a variety of diseases.

<p>Exosomes as Actively Targeted Nanocarriers for Cancer Therapy</p>

“…In general, traditional nanocarriers can be divided into two categories (Tables 1 and 2): organic nanocarriers (such as liposomes, [97][98][99] micelles, [100][101][102] etc.) and inorganic nanocarriers (eg, mesoporous silica nanoparticles, 103-105 graphene, 106,107 magnetic nanoparticles, [108][109][110] gold nanoparticles, [111][112][113] quantum dots, 114,115 and layered double hydroxides, 116-118 etc.). Compared with conventional nanocarriers, exosomes have several their own advantages and enormous potential in clinical tumor treatment.…”

New copolymers as hosts of ribosomal RNA

“…However, it is necessary to improve these materials and develop new materials to avoid gene delivery problems. Additionally, it is important to consider the protection of DNA, ease of fabrication, ability to target specific cell types, inexpensive synthesis, facile purification, stability, internalization, endolysosomal escape, efficient unpackaging, nontoxicity, and nonimmunogenicity [13].…”

Self-assembled nanoparticle-enzyme aggregates enhance functional protein production in pure transcription-translation systems

“…To provide the QDs with colloidal stability, we utilized the zwitterionic compact ligand (CL4), see Fig 2A for the chemical structure [ 65 ]. QDs displaying this surface ligand have been shown to remain stable across a wide range of pH and ion concentrations along with multiple applications in challenging in vivo biological environments [ 66 , 67 ]. More pertinently, the small size of this ligand still allows His n -appended proteins to penetrate through and self-assemble to the QD’s Zn-overcoated surface.…”