5 research outputs found
Enhancing Passive Transport of Micro/Nano Particles into Cells by Oxidized Carbon Black
Uses of micro-/nano-sized particles
to deliver biologically active
entities into cells are common for medical therapeutics and prophylactics
and also for cellular experiments. Enhancing cellular uptake and avoiding
destruction by lysosomes are desirable for general particulate drug
delivery systems. Here, we show that the relatively nontoxic, negatively
charged oxidized carbon black particles (OCBs) can enhance cellular
penetration of micro- and nano-particles. Experiments with retinal-grafted
chitosan particles (PRPs) with hydrodynamic sizes of 1200 ± 51.5,
540 ± 29.0, and 430 ± 11.0 nm (three-sized model particles)
indicate that only the sub-micron-sized particles can penetrate the
first layer of multilayered liposomes. However, in the presence of
OCBs, the micron-sized PRPs and the two submicron-sized PRPs can rapidly
enter the interiors of all layers of the multilayered liposomes. Very
low cellular uptakes of micro- and submicron-sized PRPs into keratinocytes
cells are usually observed. However, in the presence of OCBs, faster
and higher cellular uptakes of all of the three-sized PRPs are clearly
noticed. Intracellular traffic monitoring of PRP uptake into HepG2
cells in the presence of OCBs revealed that the PRPs did not co-localize
with endosomes, suggesting a nonendocytic uptake process. This demonstration
of OCB’s ability to enhance cellular uptake of micro- and submicron-particles
should open up an easy strategy to effectively send various carriers
into cells
Enhancing Passive Transport of Micro/Nano Particles into Cells by Oxidized Carbon Black
Uses of micro-/nano-sized particles
to deliver biologically active
entities into cells are common for medical therapeutics and prophylactics
and also for cellular experiments. Enhancing cellular uptake and avoiding
destruction by lysosomes are desirable for general particulate drug
delivery systems. Here, we show that the relatively nontoxic, negatively
charged oxidized carbon black particles (OCBs) can enhance cellular
penetration of micro- and nano-particles. Experiments with retinal-grafted
chitosan particles (PRPs) with hydrodynamic sizes of 1200 ± 51.5,
540 ± 29.0, and 430 ± 11.0 nm (three-sized model particles)
indicate that only the sub-micron-sized particles can penetrate the
first layer of multilayered liposomes. However, in the presence of
OCBs, the micron-sized PRPs and the two submicron-sized PRPs can rapidly
enter the interiors of all layers of the multilayered liposomes. Very
low cellular uptakes of micro- and submicron-sized PRPs into keratinocytes
cells are usually observed. However, in the presence of OCBs, faster
and higher cellular uptakes of all of the three-sized PRPs are clearly
noticed. Intracellular traffic monitoring of PRP uptake into HepG2
cells in the presence of OCBs revealed that the PRPs did not co-localize
with endosomes, suggesting a nonendocytic uptake process. This demonstration
of OCB’s ability to enhance cellular uptake of micro- and submicron-particles
should open up an easy strategy to effectively send various carriers
into cells
Shape Effect on Particle-Lipid Bilayer Membrane Association, Cellular Uptake, and Cytotoxicity
Although computer simulation and
cell culture experiments have shown that elongated spherical particles
can be taken up into cells more efficiently than spherical particles,
experimental investigation on effects of these different shapes over
the particle–membrane association has never been reported.
Therefore, whether the higher cellular uptake of an elongated spherical
particles is a result of a better particle–membrane association
as suggested by some calculation works or a consequence of its influence
on other cellular trans-membrane components involved in particle translocation
process, cannot be concluded. Here, we study the effect of particle
shape on the particle–membrane interaction by monitoring the
association between particles of various shapes and lipid bilayer
membrane of artificial cell-sized liposomes. Among the three shaped
lanthanide-doped NaYF<sub>4</sub> particles, all with high shape purity
and uniformity, similar crystal phase, and surface chemistry, the
elongated spherical particle shows the highest level of membrane association,
followed by the spherical particle with a similar radius, and the
hexagonal prism-shaped particle, respectively. The free energy of
membrane curvature calculated based on a membrane indentation induced
by a particle association indicates that among the three particle
shapes, the elongated spherical particle give the most stable membrane
curvature. The elongated spherical particles show the highest cellular
uptake into cytosol of human melanoma (A-375) and human liver carcinoma
(HepG2) cells when observed through a confocal laser scanning fluorescence
microscope. Quantitative study using flow cytometry also gives the
same result. The elongated spherical particles also possess the highest
cytotoxicity in A-375 and normal skin (WI-38) cell lines, comparing
to the other two shaped particles
Hydrophilic and Cell-Penetrable Pyrrolidinyl Peptide Nucleic Acid via Post-synthetic Modification with Hydrophilic Side Chains
Peptide nucleic acid (PNA) is a nucleic acid mimic in which the
deoxyribose–phosphate was replaced by a peptide-like backbone.
The absence of negative charge in the PNA backbone leads to several
unique behaviors including a stronger binding and salt independency
of the PNA–DNA duplex stability. However, PNA possesses poor
aqueous solubility and cannot directly penetrate cell membranes. These
are major obstacles that limit in vivo applications of PNA. In previous
strategies, the PNA can be conjugated to macromolecular carriers or
modified with positively charged side chains such as guanidinium groups
to improve the aqueous solubility and cell permeability. In general,
a preformed modified PNA monomer was required. In this study, a new
approach for post-synthetic modification of PNA backbone with one
or more hydrophilic groups was proposed. The PNA used in this study
was the conformationally constrained pyrrolidinyl PNA with prolyl-2-aminocyclopentanecarboxylic
acid dipeptide backbone (acpcPNA) that shows several advantages over
the conventional PNA. The aldehyde modifiers carrying different linkers
(alkylene and oligoÂ(ethylene glycol)) and end groups (−OH,
−NH<sub>2</sub>, and guanidinium) were synthesized and attached
to the backbone of modified acpcPNA by reductive alkylation. The hybrids
between the modified acpcPNAs and DNA exhibited comparable or superior
thermal stability with base-pairing specificity similar to those of
unmodified acpcPNA. Moreover, the modified apcPNAs also showed the
improvement of aqueous solubility (10–20 folds compared to
unmodified PNA) and readily penetrate cell membranes without requiring
any special delivery agents. This study not only demonstrates the
practicality of the proposed post-synthetic modification approach
for PNA modification, which could be readily applied to other systems,
but also opens up opportunities for using pyrrolidinyl PNA in various
applications such as intracellular RNA sensing, specific gene detection,
and antisense and antigene therapy
Bringing Macromolecules into Cells and Evading Endosomes by Oxidized Carbon Nanoparticles
A great challenge exists in finding
safe, simple, and effective delivery strategies to bring matters across
cell membrane. Popular methods such as viral vectors, positively charged
particles and cell penetrating peptides possess some of the following
drawbacks: safety issues, lysosome trapping, limited loading capacity,
and toxicity, whereas electroporation produces severe damages on both
cargoes and cells. Here, we show that a serendipitously discovered,
relatively nontoxic, water dispersible, stable, negatively charged,
oxidized carbon nanoparticle, prepared from graphite, could deliver
macromolecules into cells, without getting trapped in a lysosome.
The ability of the particles to induce transient pores on lipid bilayer
membranes of cell-sized liposomes was demonstrated. Delivering 12-base-long
pyrrolidinyl peptide nucleic acids with d-prolyl-(1<i>S</i>,2<i>S</i>)-2-aminocyclopentanecarboxylic acid
backbone (acpcPNA) complementary to the antisense strand of the NF-κB
binding site in the promoter region of the <i>Il6</i> gene
into the macrophage cell line, RAW 264.7, by our particles resulted
in an obvious accumulation of the acpcPNAs in the nucleus and decreased <i>Il6</i> mRNA and IL-6 protein levels upon stimulation. We anticipate
this work to be a starting point in a new drug delivery strategy,
which involves the nanoparticle that can induce a transient pore on
the lipid bilayer membrane