5 research outputs found
Microneedles Integrated with ZnO Quantum-Dot-Capped Mesoporous Bioactive Glasses for Glucose-Mediated Insulin Delivery
A self-responsive
insulin delivery system is highly desirable because
of its high sensitivity dependent on blood glucose levels. Herein,
a smart pH-triggered and glucose-mediated transdermal delivery system,
insulin-loaded and ZnO quantum dots (ZnO QDs) capped mesoporous bioactive
glasses (MBGs) integrated with microneedles (MNs), was developed to
achieve control and painless administration. ZnO QDs as a promise
pH-responsive switch were employed to cap the nanopores of MBGs via
electrostatic interaction. The drug (insulin) and glucose-responsive
factor (glucose oxidase/catalase, GO<sub><i>x</i></sub>/CAT)
were sealed into the pores of MBGs. GO<sub><i>x</i></sub>/CAT in the MBGs could catalyze glucose to form gluconic acid, resulting
decrease in the local pH. The ZnO QDs on the surface of the MBGs could
be dissolved in the acidic condition, leading to disassembly of the
pH-sensitive MBGs and then release of preloaded insulin from the MBGs.
As a result of administration in a diabetic model, an excellent hypoglycemic
effect and lower hypoglycemia risk were obtained. These results indicate
that as-prepared pH-triggered and glucose-mediated transdermal delivery
systems have hopeful applications in the treatment of diabetes
Corona Liquid Crystalline Order Helps to Form Single Crystals When Self-Assembly Takes Place in the Crystalline/Liquid Crystalline Block Copolymers
Crystalline/ionic
liquid crystalline block copolymers (BCPs) with
various compositions have been successfully prepared by sequential
reactions. The effect of corona liquid crystalline order on self-assembly
of BCPs in selective solvent is investigated in detail. It is found
that two-dimensional single crystals with well-developed shapes are
formed when the liquid crystalline order is present. By contrast,
ill-developed platelets with small size or one-dimensional worm-like
micelles are assembled if the liquid crystalline order of the corona
segments is lost. It is speculated that the preferred parallel arrangement
of liquid crystalline block enables it to expose more growth front
of crystals. Accordingly, epitaxial crystallization will proceed readily,
leading to fabrication of the well-defined single crystals
Separable Microneedles for Near-Infrared Light-Triggered Transdermal Delivery of Metformin in Diabetic Rats
Near-infrared
(NIR) light-triggered and separable segmented microneedles
(MNs), consisting of lauric acid and polycaprolactone (LA/PCL) arrowheads
and poly(vinyl alcohol) and polycaprolactone (PVA/PVP) supporting
bases, have been fabricated. A hypoglycemic drug (metformin) and photothermal
conversion factor (Cu<sub>7</sub>S<sub>4</sub> nanoparticles) are
encapsulated into LA/PCL arrowheads. Due to the dissolution of soluble
supporting bases after the absorption of tissue fluid, the separable
MNs arrowheads can be embedded into skin after insertion. Under the
NIR-light irradiation, the LA/PCL arrowheads exhibit an excellent
thermal-ablation change with a low amount of Cu<sub>7</sub>S<sub>4</sub> nanoparticles (0.1 wt %) due to the low melting point of LA and
PCL, thus enabling the release behavior of the encapsulated model
drug to be photothermally triggered. Compared to the hypodermic injection
of metformin, the thermal ablation of separable MNs triggered by NIR
irradiation in the current research exhibit an excellent hypoglycemic
effect in vivo. It suggests that the NIR-induced thermal-ablation
MNs comprise a prospective transdermal drug-delivery system for the
precise control of the timing and dosage of a drug that is dependent
on NIR administration
Design and Synthesis of Fluorinated Amphiphile as <sup>19</sup>F MRI/Fluorescence Dual-Imaging Agent by Tuning the Self-Assembly
Both <sup>19</sup>F MRI and optical imaging are powerful noninvasive
molecular imaging modalities in biomedical applications. To integrate
these two complementary imaging modalities, the design and synthesis
of a novel <sup>19</sup>F MRI/fluorescence dual-modal imaging agent
is reported herein. Through Sonogashira coupling reaction between
the fluorinated phenylacetylene and 1,2,4,5-tetraiodobenzene, a fluorophore
with 48 symmetrical fluorines at its periphery was constructed with
high efficacy. High aqueous solubility was achieved by PEGylation
of the fluorophore with monodisperse PEGs. However, an unexpected
self-assembly of the PEGylated amphiphilic fluorophore in water “turned
off” the <sup>19</sup>F NMR signal. However, hydrogenation
of the triple bonds or introduction of branched monodisperse PEGs
was able to efficiently tune the self-assembly, resulting in the “turning
on” of the <sup>19</sup>F NMR signal. One of these amphiphiles
combines the advantages of label-free fluorescence, high <sup>19</sup>F MRI sensitivity, biocompatibility, and excellent aqueous solubility.
The results demonstrate the great potential of such amphiphiles for
real-time <sup>19</sup>F MRI and fluorescence dual-modality imaging
Surfactant-Mediated Crystallization-Driven Self-Assembly of Crystalline/Ionic Complexed Block Copolymers in Aqueous Solution
A series of crystalline/ionic
complexed block copolymers (BCPs)
with various compositions
have been prepared by sequential reactions. The BCPs with different
hydrophilic fractions can self-assemble into various morphologies,
such as spindlelike, rodlike, and spherical micelles with different
crystallinity of the core. Bis(2-ethylhexyl) sulfosuccinate sodium
salt (AOT) is added as a surfactant to induce the morphological transition
of BCPs in aqueous media. The introduced AOT can be tightly bound
to the cationic units, and a water-insoluble unit in the corona forms,
leading to a reduced tethering density. Consequently, morphological
variety changing from rods to platelets to fibril to dendrite-like
micelles can be observed