6 research outputs found
Iodinated Photosensitizing Chitosan: Self-Assembly into Tumor-Homing Nanoparticles with Enhanced Singlet Oxygen Generation
A novel iodinated chitosan-backboned conjugate (GC–I–Ce6)
was designed and prepared to fabricate self-assembled biopolymeric
nanoparticles with heavy atom-effected enhanced singlet oxygen generation
as well as biological merits. The heavy atom-rich nature of the hydrophobic
particle interior was characterized with X-ray absorption and the
modified photophysical properties of a chemically embedded photosensitizer,
chlorin e6 (Ce6). From the comparative spectroscopic studies as well
as cellular and animal experiments, it has been shown that the self-assembled
GC–I–Ce6 nanoparticles have enhanced capability of singlet
oxygen generation by the intraparticle heavy-atom effect, along with
high tumor targetability in vitro and in vivo thanks to the glycol
chitosan-surfaced exterior with biocompatible, positively charged
and tumor-homing characteristics. Actual efficacy improvement in the
photodynamic therapy of a human breast cancer cell line (MDA-MB-231)
demonstrates potential of our photophysically and pharmaceutically
motivated hybrid bioconjugate approach for nanomedicine applications
DNA Amplification in Neutral Liposomes for Safe and Efficient Gene Delivery
In general, traditional gene carriers contain strong cationic charges to efficiently load anionic genes, but this cationic character also leads to destabilization of plasma membranes and causes severe cytotoxicity. Here, we developed a PCR-based nanofactory as a safe gene delivery system. A few template plasmid DNA can be amplified by PCR inside liposomes about 200 nm in diameter, and the quantity of loaded genes highly increased by more than 8.8-fold. The liposome membrane was composed of neutral lipids free from cationic charges. Consequently, this system is nontoxic, unlike other traditional cationic gene carriers. Intense red fluorescent protein (RFP) expression in CHO-K1 cells showed that the amplified genes could be successfully transfected to cells. Animal experiments with the luciferase gene also showed <i>in vivo</i> gene expression by our system without toxicity. We think that this PCR-based nanofactory system can overcome the toxicity problem that is the critical limitation of current gene delivery to clinical application
Tumor-Targeting Transferrin Nanoparticles for Systemic Polymerized siRNA Delivery in Tumor-Bearing Mice
Transferrin (TF) is widely used as
a tumor-targeting ligand for
the delivery of anticancer drugs because the TF receptor is overexpressed
on the surface of various fast-growing cancer cells. In this article,
we report on TF nanoparticles as an siRNA delivery carrier for in
vivo tumor-specific gene silencing. To produce siRNA carrying TF nanoparticles
(NPs), both TF and siRNA were chemically modified with sulfhydryl
groups that can build up self-cross-linked siRNA-TF NPs. Self-polymerized
5′-end thiol-modified siRNA (poly siRNA, psi) and thiolated
transferrin (tTF) were spontaneously cross-linked to form stable NPs
(psi-tTF NPs) under optimized conditions, and they could be reversibly
degraded to release functional monomeric siRNA molecules under reductive
conditions. Receptor-mediated endocytosis of TF induced rapid tumor-cell-specific
uptake of the psi-tTF NPs, and the internalized NPs resulted in a
downregulation of the target protein in red-fluorescent-protein-expressing
melanoma cancer cells (RFP/B16F10) with negligible cytotoxicity. After
systemic administration, the psi-tTF NPs showed marked accumulation
at the tumor, leading to successful target-gene silencing in vivo.
This psi-tTF NP system provided a safe and effective strategy for
in vivo systemic siRNA delivery for cancer therapy
pH-Controlled Gas-Generating Mineralized Nanoparticles: A Theranostic Agent for Ultrasound Imaging and Therapy of Cancers
We report a theranostic nanoparticle that can express ultrasound (US) imaging and simultaneous therapeutic functions for cancer treatment. We developed doxorubicin-loaded calcium carbonate (CaCO<sub>3</sub>) hybrid nanoparticles (DOX-CaCO<sub>3</sub>-MNPs) through a block copolymer templated <i>in situ</i> mineralization approach. The nanoparticles exhibited strong echogenic signals at tumoral acid pH by producing carbon dioxide (CO<sub>2</sub>) bubbles and showed excellent echo persistence. <i>In vivo</i> results demonstrated that the DOX-CaCO<sub>3</sub>-MNPs generated CO<sub>2</sub> bubbles at tumor tissues sufficient for echogenic reflectivity under a US field. In contrast, the DOX-CaCO<sub>3</sub>-MNPs located in the liver or tumor-free subcutaneous area did not generate the CO<sub>2</sub> bubbles necessary for US contrast. The DOX-CaCO<sub>3</sub>-MNPs could also trigger the DOX release simultaneously with CO<sub>2</sub> bubble generation at the acidic tumoral environment. The DOX-CaCO<sub>3</sub>-MNPs displayed effective antitumor therapeutic activity in tumor-bearing mice. The concept described in this work may serve as a useful guide for development of various theranostic nanoparticles for US imaging and therapy of various cancers
Chemical Tumor-Targeting of Nanoparticles Based on Metabolic Glycoengineering and Click Chemistry
Tumor-targeting strategies for nanoparticles have been predominantly based on optimization of physical properties or conjugation with biological ligands. However, their tumor-targeting abilities remain limited and insufficient. Furthermore, traditional biological binding molecules have intrinsic limitations originating from the limited amount of cellular receptors and the heterogeneity of tumor cells. Our two-step <i>in vivo</i> tumor-targeting strategy for nanoparticles is based on metabolic glycoengineering and click chemistry. First, an intravenous injection of precursor-loaded glycol chitosan nanoparticles generates azide groups on tumor tissue specifically by the enhanced permeation and retention (EPR) effect followed by metabolic glycoengineering. These ‘receptor-like’ chemical groups then enhance the tumor-targeting ability of drug-containing nanoparticles by copper-free click chemistry <i>in vivo</i> during a second intravenous injection. The advantage of this protocol over traditional binding molecules is that there are significantly more binding molecules on the surface of most tumor cells regardless of cell type. The subsequent enhanced tumor-targeting ability can significantly enhance the cancer therapeutic efficacy in animal studies
Facile Method To Radiolabel Glycol Chitosan Nanoparticles with <sup>64</sup>Cu via Copper-Free Click Chemistry for MicroPET Imaging
An efficient and straightforward
method for radiolabeling nanoparticles
is urgently needed to understand the <i>in vivo</i> biodistribution
of nanoparticles. Herein, we investigated a facile and highly efficient
strategy to prepare radiolabeled glycol chitosan nanoparticles with <sup>64</sup>Cu via a strain-promoted azide–alkyne cycloaddition
strategy, which is often referred to as click chemistry. First, the
azide (N<sub>3</sub>) group, which allows for the preparation of radiolabeled
nanoparticles by copper-free click chemistry, was incorporated to
glycol chitosan nanoparticles (CNPs). Second, the strained cyclooctyne
derivative, dibenzyl cyclooctyne (DBCO) conjugated with a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic
acid (DOTA) chelator, was synthesized for preparing the preradiolabeled
alkyne complex with <sup>64</sup>Cu radionuclide. Following incubation
with the <sup>64</sup>Cu-radiolabeled DBCO complex (DBCO-PEG<sub>4</sub>-Lys-DOTA-<sup>64</sup>Cu with high specific activity, 18.5 GBq/μmol),
the azide-functionalized CNPs were radiolabeled successfully with <sup>64</sup>Cu, with a high radiolabeling efficiency and a high radiolabeling
yield (>98%). Importantly, the radiolabeling of CNPs by copper-free
click chemistry was accomplished within 30 min, with great efficiency
in aqueous conditions. In addition, we found that the <sup>64</sup>Cu-radiolabeled CNPs (<sup>64</sup>Cu-CNPs) did not show any significant
effect on the physicochemical properties, such as size, zeta potential,
or spherical morphology. After <sup>64</sup>Cu-CNPs were intravenously
administered to tumor-bearing mice, the real-time, <i>in vivo</i> biodistribution and tumor-targeting ability of <sup>64</sup>Cu-CNPs
were quantitatively evaluated by microPET images of tumor-bearing
mice. These results demonstrate the benefit of copper-free click chemistry
as a facile, preradiolabeling approach to conveniently radiolabel
nanoparticles for evaluating the real-time <i>in vivo</i> biodistribution of nanoparticles