4 research outputs found
Synthesis and Characterization of Functional Nanofilm-Coated Live Immune Cells
Layer-by-layer
(LbL) assembly techniques have been extensively studied in cell biology
because of their simplicity of preparation and versatility. The applications
of the LbL platform technology using polysaccharides, silicon, and
graphene have been investigated. However, the applications of the
above-mentioned technology using living cells remain to be fully understood.
This study demonstrates a living cell-based LbL platform using various
types of living cells. In addition, it confirms that the surplus charge
on the outer surface of the coated cells can be used to bind the target
protein. We develop a living cell-based LbL platform technology by
stacking layers of hyaluronic acid (HA) and poly-l-lysine
(PLL). The HA/PLL stacking results in three bilayers with a thickness
of 4 Ā± 1 nm on the cell surface. Furthermore, the multilayer
nanofilms on the cells are completely degraded after 3 days of the
application of the LbL method. We also evaluate and visualize three
bilayers of the nanofilm on adherent (AML-12 cells)-, nonadherent
(trypsin-treated AML-12 cells)-, and circulation type [peripheral
blood mononuclear cells (PBMCs)] cells by analyzing the zeta potential,
cell viability, and imaging via scanning electron microscopy and confocal
microscopy. Finally, we study the cytotoxicity of the nanofilm and
characteristic functions of the immune cells after the nanofilm coating.
The multilayer nanofilms are not acutely cytotoxic and did not inhibit
the immune response of the PBMCs against stimulant. We conclude that
a two bilayer nanofilm would be ideal for further study in any cell
type. The living cell-based LbL platform is expected to be useful
for a variety of applications in cell biology
Enhanced Doubly Activated Dual Emission Fluorescent Probes for Selective Imaging of Glutathione or Cysteine in Living Systems
The development of
novel fluorescent probes for monitoring the
concentration of various biomolecules in living systems has great
potential for eventual early diagnosis and disease intervention. Selective
detection of competitive species in biological systems is a great
challenge for the design and development of fluorescent probes. To
improve on the design of fluorescent coumarin-based biothiol sensing
technologies, we have developed herein an enhanced dual emission doubly
activated system (<b>DACP-1</b> and the closely related <b>DACP-2</b>) for the selective detection of glutathione (GSH) through
the use of one optical channel and the detection of cysteine (Cys)
by another channel. A phenylselenium group present at the 4-position
completely quenches the fluorescence of the probe via photoinduced
electron transfer to give a nonfluorescent species. Probes are selective
for glutathione (GSH) in the red region and for cysteine/homocysteine
(Cys/Hcy) in the green region. When they were treated with GSH, <b>DACP-1</b> and <b>DACP-2</b> showed strong fluorescence
enhancement in comparison to that for closely related species such
as amino acids, including Cys/Hcy. Fluorescence quantum yields (Ī¦<sub>F</sub>) increased for the red channel (<0.001 to 0.52 (<b>DACP-1</b>) and 0.48 (<b>DACP-2</b>)) and green channel
(Cys) (<0.001 to 0.030 (<b>DACP-1</b>) and 0.026 (<b>DACP-2</b>)), respectively. Competing fluorescent enhancements upon addition
of closely related species were negligible. Fast responses, improved
water solubility, and good cell membrane permeability were all properly
established with the use of <b>DACP-1</b> and <b>DACP-2</b>. Live human lung cancer cells and fibroblasts imaged by confocal
microscopy, as well as live mice tumor model imaging, confirmed selective
detection
Facile Solvothermal Preparation of Monodisperse Gold Nanoparticles and Their Engineered Assembly of FerritināGold Nanoclusters
Herein,
we report a quick and simple synthesis of water-soluble gold nanoparticles
using a HAuCl<sub>4</sub> and oleylamine mixture. Oleylamine serves
as a reduction agent as well as a stabilizer for nanoparticle surfaces.
The particle sizes can be adjusted by modulating reaction temperature
and time. Solvothermal reduction of HAuCl<sub>4</sub> with oleylamine
can be confirmed by measuring the product in Fourier transform infrared
(FTIR) spectroscopy. The plasmon band shifting from yellow to red
confirms a nanosized particle formation. Amide bonds on the surface
of the nanoparticles formed hydrogen bonds with one another, resulting
in a hydrophobic monolayer. Particles dispersed well in nonpolar organic
solvents, such as in hexane or toluene, by brief sonication. Next,
we demonstrated the transfer of gold nanoparticles into water by lipid
capsulation using 1-myristoyl-2-hydroxy-<i>sn</i>-glycero-3-phosphocholine
(MHPC), 1,2-distearoyl-<i>sn</i>-glycero-3-phosphoethanolamine-<i>N</i>-(methoxy polyethylene glycol)-2000 (DPPE-PEG2k), and 1,2-dioleoyl-<i>sn</i>-glycero-3-<i>N</i>-{5-amino-1-carboxypentyl}Āiminodiacetic
acid succinyl nickel salt [DGS-NTAĀ(Ni)]. The particle concentration
can be obtained using an absorbance in ultravioletāvisible
(UVāvis) spectra (at 420 nm). Instrumental analyses using transmission
electron microscopy (TEM), energy-dispersive X-ray (EDX) analysis,
dynamic light scattering (DLS), and FTIR confirmed successful production
of gold nanoparticles and fair solubility in water. Prepared gold
particles were selectively clustered via engineered ferritin nanocages
that provide multiple conjugation moieties. A total of 5ā6
gold nanoparticles were clustered on a single ferritin nanocage confirmed
in TEM. Reported solvothermal synthesis and preparation of gold nanoclusters
may serve as an efficient, alternate way of preparing water-soluble
gold nanoparticles, which can be used in a wide variety of biomedical
applications
Mesoporous Silica-Coated Hollow Manganese Oxide Nanoparticles as Positive <i>T</i><sub>1</sub> Contrast Agents for Labeling and MRI Tracking of Adipose-Derived Mesenchymal Stem Cells
Mesoporous silica-coated hollow manganese oxide (HMnO@mSiO<sub>2</sub>) nanoparticles were developed as a novel <i>T</i><sub>1</sub> magnetic resonance imaging (MRI) contrast agent. We hypothesized that the mesoporous structure of the nanoparticle shell enables optimal access of water molecules to the magnetic core, and consequently, an effective longitudinal (<i>R</i><sub>1</sub>) relaxation enhancement of water protons, which value was measured to be 0.99 (mM<sup>ā1</sup>s<sup>ā1</sup>) at 11.7 T. Adipose-derived mesenchymal stem cells (MSCs) were efficiently labeled using electroporation, with much shorter <i>T</i><sub>1</sub> values as compared to direct incubation without electroporation, which was also evidenced by signal enhancement on <i>T</i><sub>1</sub>-weighted MR images in vitro. Intracranial grafting of HMnO@mSiO<sub>2</sub>-labeled MSCs enabled serial MR monitoring of cell transplants over 14 days. These novel nanoparticles may extend the arsenal of currently available nanoparticle MR contrast agents by providing positive contrast on <i>T</i><sub>1</sub>-weighted images at high magnetic field strengths