Delivery and Tracking of Quantum Dot Peptide Bioconjugates in an Intact Developing Avian Brain

Abstract

Luminescent semiconductor ~9.5 nm nanoparticles (quantum dots: QDs) have intrinsic physiochemical and optical properties which enable us to begin to understand the mechanisms of nanoparticle mediated chemical/drug delivery. Here, we demonstrate the ability of CdSe/ZnS core/shell QDs surface functionalized with a zwitterionic compact ligand to deliver a cell-penetrating lipopeptide to the developing chick embryo brain without any apparent toxicity. Functionalized QDs were conjugated to the palmitoylated peptide WGDap-(Palmitoyl)VKIKKP9GGH6, previously shown to uniquely facilitate endosomal escape, and microinjected into the embryonic chick spinal cord canal at embryo day 4 (E4). We were subsequently able to follow the labeling of spinal cord extension into the ventricles, migratory neuroblasts, maturing brain cells, and complex structures such as the choroid plexus. QD intensity extended throughout the brain, and peaked between E8 and E11 when fluorescence was concentrated in the choroid plexus before declining to hatching (E21/P0). We observed no abnormalities in embryonic patterning or embryo survival, and mRNA in situ hybridization confirmed that, at key developmental stages, the expression pattern of genes associated with different brain cell types (brain lipid binding protein, Sox-2, proteolipid protein and Class III-β-Tubulin) all showed a normal labeling pattern and intensity. Our findings suggest that we can use chemically modified QDs to identify and track neural stem cells as they migrate, that the choroid plexus clears these injected QDs/nanoparticles from the brain after E15, and that they can deliver drugs and peptides to the developing brain.

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

“…; Agarwal et al . ). When injected into the intact developing chick brain, the QD‐JB577 conjugates appear in neural precursor cells of developing chick embryo.…”

Design, fabrication, and biomedical applications of bioinspired peptide–inorganic nanomaterial hybrids

“…1 25 In this peptide-inspired synthesis approach, homogeneous surface of peptides coating the AuNPs was achieved due to the highly organized distribution of protonated amino groups. More typically, many inorganic nanoparticles (NPs) could be firstly functionalized by introducing zwitterionic compact ligand 26,27 or specific polymers 4 as linkers such as polyethylene glycol (PEG), thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA) and tiopronin. However, these surface ligands are likely to influence the second structures of adsorbed peptide, and could change the properties of peptide at the NP surface in the presence of reactive functional groups.…”

“…In another study, Agarwal et al designed a long peptide sequence containing (His) 6 fragment to binds the Zn molecules on the CdSe/ZnS core/shell QDs surface and thereby mediated long-term peptide attachment to the QD. 26 Hereafter, a lot of similar studies emerged, in which peptide was used to modify or functionalize QDs. In conclusion, peptides play double roles, namely, surface stabilization of QDs and self-assemble template for constructed well-defined hybrids.…”

Nanoparticle Technologies in the Spinal Cord

“…However, because of their small size and fluorescent properties, these probes have been used for cell imaging research in the spinal cord. QDs were injected into chick embryo spinal cords, and their migration during development was charted using fluorescent imaging [Agarwal et al, 2015]. Silica-coated ZnO QDs are used for imaging neurons in the mouse spinal cord [Matsuyama et al, 2013].…”