18 research outputs found
Perfluorocarbon Nanodroplets for Dual Delivery with Ultrasound/GSH-Responsive Release of Model Drug and Passive Release of Nitric Oxide
Nitric oxide (NO) plays a critical role as an important signaling molecule for a variety of biological functions, particularly inhibiting cell proliferation or killing target pathogens. To deliver active radical NO gaseous molecule whose half-life is a few seconds in a stable state, the design and development of effective exogenous NO supply nanocarriers are essential. Additionally, the delivery of desired drugs with NO can produce synergistic effects. Herein, we report a new approach that allows for the fabrication of dual ultrasound (US)/glutathione (GSH)-responsive perfluorocarbon (PFC) nanodroplets for the controlled release of model drug and passive release of safely incorporated NO. The approach centers on the synthesis of a disulfide-labeled amphiphilic block copolymer and its use as a GSH-degradable macromolecular emulsifier for oil-in-water emulsification process of PFC. The fabricated PFC nanodroplets are colloidally stable and enable the encapsulation of both NO and model drugs. Encapsulated drug molecules are synergistically released when ultrasound and GSH are presented, while NO molecules are passively but rapidly released. Our preliminary results demonstrate that the approach is versatile and can be extended to not only GSH-responsive but also other stimuli-responsive block copolymers, thereby allowing for the fabrication of broad choices of stimuli-responsive (smart) PFC-nanodroplets in aqueous solution for dual delivery of drug and NO therapeutics
Multilayered Controlled Drug Release Silk Fibroin Nanofilm by Manipulating Secondary Structure
Many
studies of drug delivery nanoplatforms have explored drug
loading affinity and controlled release. The nanoplatforms can be
influenced by their inherent building blocks. Natural polypeptide
silk fibroin (SF) is an excellent nanoplatform material because of
its high biocompatibility and unique structural properties. SF secondary
structures have different properties that can be changed by external
stimuli. Thus, the characterization of SF-containing platforms is
strongly affected by secondary structure transformations. Structural
changes can occur spontaneously, which hinders the control of structural
variation in aqueous conditions. Herein, we successfully prepared
a controllable secondary structure composed of SF/heparin (HEP) layer-by-layer
assembled nanofilms using simple solvents (glycerol and methanol).
SF in the SF/HEP nanofilms takes up than 90%, which means configurations
of SF have a strong effect on the character of the nanofilms. We investigated
the degradation profiles of SF/HEP nanofilms depending on their β-sheet
contents and demonstrated an immediate correlation between the transformation
of secondary structures inside the nanofilms and the degree of degradation
of nanofilms. Finally, SF/HEP nanofilms were used as a delivery platform
for incorporating the anticancer drug epirubicin (EPI). We could control
the loading efficiency and release profile of EPI with various β-sheet
contents of the nanofilms
Perfluorocarbon Nanodroplets for Dual Delivery with Ultrasound/GSH-Responsive Release of Model Drug and Passive Release of Nitric Oxide
Nitric oxide (NO) plays a critical role as an important signaling molecule for a variety of biological functions, particularly inhibiting cell proliferation or killing target pathogens. To deliver active radical NO gaseous molecule whose half-life is a few seconds in a stable state, the design and development of effective exogenous NO supply nanocarriers are essential. Additionally, the delivery of desired drugs with NO can produce synergistic effects. Herein, we report a new approach that allows for the fabrication of dual ultrasound (US)/glutathione (GSH)-responsive perfluorocarbon (PFC) nanodroplets for the controlled release of model drug and passive release of safely incorporated NO. The approach centers on the synthesis of a disulfide-labeled amphiphilic block copolymer and its use as a GSH-degradable macromolecular emulsifier for oil-in-water emulsification process of PFC. The fabricated PFC nanodroplets are colloidally stable and enable the encapsulation of both NO and model drugs. Encapsulated drug molecules are synergistically released when ultrasound and GSH are presented, while NO molecules are passively but rapidly released. Our preliminary results demonstrate that the approach is versatile and can be extended to not only GSH-responsive but also other stimuli-responsive block copolymers, thereby allowing for the fabrication of broad choices of stimuli-responsive (smart) PFC-nanodroplets in aqueous solution for dual delivery of drug and NO therapeutics
Dual Changes in Conformation and Optical Properties of Fluorophores within a Metal–Organic Framework during Framework Construction and Associated Sensing Event
Microsized
chemosensor particle (CPP-16, CPP means coordination
polymer particle), which is made from a metal–organic framework
(MOF), is synthesized using pyrene-functionalized organic building
block. This building block contains three important parts, a framework
construction part, a Cu<sup>2+</sup> detection part, and a fluorophore
part. PXRD studies have revealed that CPP-16 has a 3D cubic structure
of MOF-5. During both MOF formation and sensing event, fluorophores
within CPP-16 undergo dual changes in conformation and optical properties.
After MOF construction, pyrene moieties experience an unusual complete
conversion from monomer to excimer form. This conversion takes place
due to a confinement effect induced by space limitations within the
MOF structure. The selective sensing ability of CPP-16 on Cu<sup>2+</sup> over many other metal ions is verified by emission spectra and is
also visually identified by fluorescence microscopy images. Specific
interaction of Cu<sup>2+</sup> with binding sites within CPP-16 causes
a second conformational change of the fluorophores, where they change
from stacked excimer (CPP-16) to quenched excimer states (CPP-16·Cu<sup>2+</sup>)
Hollow Metal–Organic Framework Microparticles Assembled via a Self-Templated Formation Mechanism
Hollow
particles are considered to be fascinating materials due to their
useful applications and unique properties. Understanding the formation
mechanism of hollow structures is critical for their controlled formation.
Herein, we demonstrate the fabrication of hollow metal–organic
framework (hollow MOF) microparticles via a one-step solvothermal
reaction of ZnÂ(NO<sub>3</sub>)<sub>2</sub> and 1,3,5-benzenetricarboxylic
acid (H<sub>3</sub>BTC) without extra template materials. The formation
mechanism study of the hollow MOF reveals a unique self-templated
formation mechanism consisting of three stages: (1) spherical microparticles
are initially formed during the early stage of the reaction, (2) the
initially formed spherical microparticles act as self-templates for
the growth of new crystalline MOF materials during the middle stage
of the reaction, and (3) the initially formed spherical microparticles
spontaneously disappear for the formation of hollow MOFs during the
late stage of the reaction
Effect of Urethane Crosslinking by Blocked Isocyanates with Pyrazole-Based Blocking Agents on Rheological and Mechanical Performance of Clearcoats
A novel blocked isocyanate crosslinker was synthesized, and its applicability was investigated for the low-temperature curing of automotive clearcoats. Various pyrazole derivatives were prepared as blocking agents in isocyanate crosslinkers, which strongly affect the deblocking and curing properties of the urethane-bonded coating systems. The thermal curing properties of clearcoat samples containing a pyrazole-based blocked isocyanate crosslinker and polyol resin were characterized under two different temperature conditions (120 and 150 °C). The decrease in the amount of hydroxyl groups in the polyol before and after curing was expressed by the change in OH stretching frequency in the Fourier transform infrared (FT-IR) spectra. The real-time rheological storage moduli of the bulk clearcoat mixtures were measured via a rotational rheometer to determine the effect of pyrazole-based blocking agents on the curing dynamics. In addition, a rigid-body pendulum tester (RPT) was employed to investigate the curing behavior in the thin film form. The nano-indentation and the nano-scratch tests were conducted to examine the surface hardness and scratch resistance characteristics of the cured clearcoat films. The results show that a low-temperature curing system of clearcoats can be realized by tuning the curing temperature and reactivity of isocyanate crosslinkers blocked with pyrazole-based substituents
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 ± 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