2 research outputs found
Modular Fabrication of Polymer Brush Coated Magnetic Nanoparticles: Engineering the Interface for Targeted Cellular Imaging
Development of efficient and rapid
protocols for diversification
of functional magnetic nanoparticles (MNPs) would enable identification
of promising candidates using high-throughput protocols for applications
such as diagnostics and cure through early detection and localized
delivery. Polymer brush coated magnetic nanoparticles find use in
many such applications. A protocol that allows modular diversification
of a pool of parent polymer coated nanoparticles will lead to a library
of functional materials with improved uniformity. In the present study,
polymer brush coated parent magnetic nanoparticles obtained using
reversible addition–fragmentation chain transfer (RAFT) polymerization
are modified to obtain nanoparticles with different “clickable”
groups. In this design, trithiocarbonate group terminated polymer
brushes are “grafted from” MNPs using a catechol group
bearing initiator. A postpolymerization radical exchange reaction
allows installation of “clickable” functional groups
like azides and maleimides on the chain ends of the polymers. Thus,
modified MNPs can be functionalized using alkyne-containing and thiol-containing
moieties like peptides and dyes using the alkyne–azide cycloaddition
and the thiol–ene conjugation, respectively. Using the approach
outlined here, a cell surface receptor targeting cyclic peptide and
a fluorescent dye are attached onto nanoparticle surface. This multifunctional
construct allows selective recognition of cancer cells that overexpress
integrin receptors. Furthermore, the approach outlined here is not
limited to the installation of azide and maleimide functional groups
but can be expanded to a variety of “clickable” groups
to allow nanoparticle modification using a broad range of chemical
conjugations
Functionalization of Reduced Graphene Oxide via Thiol–Maleimide “Click” Chemistry: Facile Fabrication of Targeted Drug Delivery Vehicles
Materials based on
reduced graphene oxide
(rGO) have shown to be amenable to noncovalent functionalization through
hydrophobic interactions. The scaffold, however, does not provide
sufficient covalent linkage given the low number of reactive carboxyl
and alcohol groups typically available on the rGO. The integration
of clickable groups, particularly the ones that can undergo efficient
conjugation without any metal catalyst, would allow facile functionalization
of these materials. This study reports on the noncovalent association
of a maleimide-containing catechol (dopa-MAL) surface anchor onto
the rGO. Thiol–maleimide chemistry allows thereafter the facile
attachment of thiol-containing molecules under ambient metal-free
conditions. Although the attachment of glutathione and 6-(ferrocenyl)Âhexanethiol
was used as model thiols, the attachment of a cancer cell targeting
cyclic peptide, cÂ(RGDfC), opened the possibility of using the dopa-MAL-modified
rGO as a targeted drug delivery system for doxorubicin (DOX). Although
free DOX showed to be more effective at killing the human cervical
cancer cells (HeLa) over human breast adenocarcinoma cancer cells
(MDA-MB-231), the DOX-loaded rGO/dopa-MAL-c (RGDfC) nanostructure
showed an opposite effect being notably more effective at targeting
and killing the MDA-MB-231 cells. The effect is enhanced upon laser
irradiation for 10 min at 2 W cm<sup>–2</sup>. The facile fabrication
and functionalization to readily obtain a functional material in a
modular fashion make this clickable-rGO construct an attractive platform
for various applications