9 research outputs found
Janus Reactors with Highly Efficient Enzymatic CO<sub>2</sub> Nanocascade at Air–Liquid Interface
Though
enzymatic cascade reactors have been the subject of intense research
over the past few years, their application is still limited by the
complicated fabrication protocols, unsatisfactory stability and lack
of effective reactor designs. In addition, the spatial positioning
of the cascade reactor has so far not been investigated, which is
of significant importance for biphase catalytic reaction systems.
Inspired by the Janus properties of the lipid cellular membrane, here
we show a highly efficient Janus gas–liquid reactor for CO<sub>2</sub> hydration and conversion. Within the Janus reactor, nanocascades
containing the nanoscale compartmentalized carbonic anhydrase and
formic dehydrogenase were positioned at a well-defined gas–liquid
interface, with a high substrate concentration gradient. The Janus
reactor exhibited 2.5 times higher CO<sub>2</sub> hydration efficiency
compared with the conventional gas–liquid contactor with pristine
membranes, and the formic acid conversion rate can reach approximately
90%. Through this work, we provide evidence that the spatial arrangement
of the nanocascade is also crucial to efficient reactions, and the
Janus reactor can be a promising candidate for the biphase catalytic
reactions in environmental, biological and energy aspects
Janus Reactors with Highly Efficient Enzymatic CO<sub>2</sub> Nanocascade at Air–Liquid Interface
Though
enzymatic cascade reactors have been the subject of intense research
over the past few years, their application is still limited by the
complicated fabrication protocols, unsatisfactory stability and lack
of effective reactor designs. In addition, the spatial positioning
of the cascade reactor has so far not been investigated, which is
of significant importance for biphase catalytic reaction systems.
Inspired by the Janus properties of the lipid cellular membrane, here
we show a highly efficient Janus gas–liquid reactor for CO<sub>2</sub> hydration and conversion. Within the Janus reactor, nanocascades
containing the nanoscale compartmentalized carbonic anhydrase and
formic dehydrogenase were positioned at a well-defined gas–liquid
interface, with a high substrate concentration gradient. The Janus
reactor exhibited 2.5 times higher CO<sub>2</sub> hydration efficiency
compared with the conventional gas–liquid contactor with pristine
membranes, and the formic acid conversion rate can reach approximately
90%. Through this work, we provide evidence that the spatial arrangement
of the nanocascade is also crucial to efficient reactions, and the
Janus reactor can be a promising candidate for the biphase catalytic
reactions in environmental, biological and energy aspects
Immobilization and Intracellular Delivery of an Anticancer Drug Using Mussel-Inspired Polydopamine Capsules
We report a facile approach to immobilize pH-cleavable
polymer-drug
conjugates in mussel-inspired polydopamine (PDA) capsules for intracellular
drug delivery. Our design takes advantage of the facile PDA coating
to form capsules, the chemical reactivity of PDA films, and the acid-labile
groups in polymer side chains for sustained pH-induced drug release.
The anticancer drug doxorubicin (Dox) was conjugated to thiolated
polyÂ(methacrylic acid) (PMA<sub>SH</sub>) with a pH-cleavable hydrazone
bond, and then immobilized in PDA capsules via robust thiol-catechol
reactions between the polymer-drug conjugate and capsule walls. The
loaded Dox showed limited release at physiological pH but significant
release (over 85%) at endosomal/lysosomal pH. Cell viability assays
showed that Dox-loaded PDA capsules enhanced the efficacy of eradicating
HeLa cancer cells compared with free drug under the same assay conditions.
The reported method provides a new platform for the application of
stimuli-responsive PDA capsules as drug delivery systems
Table_1_Simultaneous determination of nine phenolic compounds in imitation wild Dendrobium officinale samples using ultrahigh-performance liquid chromatography–tandem mass spectrometry.docx
Dendrobium officinale Kimura et Migo (D. officinale), one of the nine everlasting types of grass, has gained increasing attention owing to its important roles in alternative medicines and drug discovery. Due to its natural resources being in danger of being extinct, imitation wild planting is becoming increasingly common. To assess the product’s quality completely, an efficient ultrahigh performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-QQQ-MS/MS) method was established to simultaneously quantify nine phenolic compounds in D. officinale samples. The extraction parameters, including solvent, solvent concentration, solid–liquid ratio, and extraction time, were systematically optimized with the single-factor test. The results demonstrated that extraction with a 1:200 solid-to-liquid ratio of 80% methanol for 1.5 h was the most efficient condition for the extraction of flavonoids. Satisfactory retention times and resolution of the nine analytes were acquired on the Thermo Scientific Hypersil GOLD column with multiple reaction monitoring in negative ion scanning mode. The method was validated to demonstrate its selectivity, linearity, precision, accuracy, and robustness. Thus, the verified UHPLC-QQQ-MS/MS method was successfully applied to the quantification of phenolic components present in D. officinale samples. The results indicated that the quantity and composition of phenolic components in D. officinale from various provenances were significantly different. This work provides a theoretical foundation for the cultivation and assessment of wild D. officinale quality.</p
Fundamental Studies of Hybrid Poly(2-(diisopropylamino)ethyl methacrylate)/Poly(<i>N</i>‑vinylpyrrolidone) Films and Capsules
Hybrid and multicompartment carriers
are of significant interest
for the development of next-generation therapeutic drug carriers.
Herein, fundamental investigations on layer-by-layer (LbL) capsules
consisting of two different polymers are presented. The hybrid systems
were designed to have pH-responsive, charge-shifting polyÂ(2-(diisopropylamino)Âethyl
methacrylate) (PDPA) inner layers and low-fouling polyÂ(<i>N</i>-vinylpyrrolidone) (PVPON) outer layers. Planar hybrid films with
different layer ratios were studied by quartz crystal microgravimetry
(QCM) and atomic force microscopy (AFM). The information obtained
was translated to particulate templates to prepare hybrid capsules,
which were stabilized by click chemistry. The charge-shifting behavior
of PDPA improved the cargo encapsulation and initial retention of
a model CpG cargo, while outer layers of PVPON improved biofouling
properties compared to single-component PDPA capsules. The results
demonstrate the need to understand and design multifunctional systems
that can successfully embody different functionalities in a single,
stable construct for the fabrication of next-generation drug and gene
delivery carriers aimed at overcoming the challenges encountered in
biological systems
Tuning Particle Biodegradation through Polymer–Peptide Blend Composition
We
report the preparation of polymer–peptide blend replica
particles via the mesoporous silica (MS) templated assembly of polyÂ(ethylene
glycol)-<i>block</i>-polyÂ(2-diisopropylaminoethyl methacrylate-<i>co</i>-2-(2-(2-(prop-2-ynyloxy)Âethoxy)Âethoxy)Âethyl methacrylate)
(PEG<sub>45</sub>-<i>b</i>-PÂ(DPA<sub>55</sub>-<i>co</i>-PgTEGMA<sub>4</sub>)) and polyÂ(l-histidine) (PHis). PEG<sub>45</sub>-<i>b</i>-PÂ(DPA<sub>55</sub>-<i>co</i>-PgTEGMA<sub>4</sub>) was synthesized by atom transfer radical polymerization
(ATRP), and was coinfiltrated with PHis into polyÂ(methacrylic acid)
(PMA)-coated MS particles assembled from different peptide-to-polymer
ratios (1:1, 1:5, 1:10, or 1:15). Subsequent removal of the sacrificial
templates and PMA resulted in monodisperse, colloidally stable, noncovalently
cross-linked polymer–peptide blend replica particles that were
stabilized by a combination of hydrophobic interactions between the
PDPA and the PHis, hydrogen bonding between the PEG and PHis backbone,
and π–π stacking of the imidazole rings of PHis
side chains at physiological pH (pH ∼ 7.4). The synergistic charge-switchable properties of PDPA and PHis, and the enzymatic degradability of PHis, make these particles
responsive to pH and enzymes. In vitro studies, in simulated endosomal
conditions and inside cells, demonstrated that particle degradation
kinetics could be engineered (from 2 to 8 h inside dendritic cells)
based on simple adjustment of the peptide-to-polymer ratio used
Influence of Ionic Strength on the Deposition of Metal–Phenolic Networks
Metal–phenolic
networks (MPNs) are a versatile class of
self-assembled materials that are able to form functional thin films
on various substrates with potential applications in areas including
drug delivery and catalysis. Different metal ions (e.g., Fe<sup>III</sup>, Cu<sup>II</sup>) and phenols (e.g., tannic acid, gallic acid) have
been investigated for MPN film assembly; however, a mechanistic understanding
of the thermodynamics governing MPN formation remains largely unexplored.
To date, MPNs have been deposited at low ionic strengths (<5 mM),
resulting in films with typical thicknesses of ∼10 nm, and
it is still unclear how a bulk complexation reaction results in homogeneous
thin films when a substrate is present. Herein we explore the influence
of ionic strength (0–2 M NaCl) on the conformation of MPN precursors
in solution and how this determines the final thickness and morphology
of MPN films. Specifically, the film thickness increases from 10 nm
in 0 M NaCl to 12 nm in 0.5 M NaCl and 15 nm in 1 M NaCl, after which
the films grow rougher rather than thicker. For example, the root-mean-square
roughness values of the films are constant below 1 M NaCl at 1.5 nm;
in contrast, the roughness is 3 nm at 1 M NaCl and increases to 5
nm at 2 M NaCl. Small-angle X-ray scattering and molecular dynamics
simulations allow for comparisons to be made with chelated metals
and polyelectrolyte thin films. For example, at a higher ionic strength
(2 M NaCl), sodium ions shield the galloyl groups of tannic acid,
allowing them to extend away from the Fe<sup>III</sup> center and
interact with other MPN complexes in solution to form thicker and
rougher films. As the properties of films determine their final performance
and application, the ability to tune both thickness and roughness
using salts may allow for new applications of MPNs
Organophosphate Esters in Sediment of the Great Lakes
This
is the first study on organophosphate ester (OPEs) flame retardants
and plasticizers in the sediment of the Great Lakes. Concentrations
of 14 OPEs were measured in three sediment cores and 88 Ponar surface
grabs collected from Lakes Ontario, Michigan, and Superior of North
America. The sum of these OPEs (Σ<sub>14</sub>OPEs) in Ponar
grabs averaged 2.2, 4.7, and 16.6 ng g<sup>–1</sup> dw in Lakes
Superior, Michigan, and Ontario, respectively. Multiple linear regression
analyses demonstrated statistically significant associations between
logarithm concentrations of Σ<sub>14</sub>OPEs as well as selected
congeners in surface grab samples and sediment organic carbon content
as well as a newly developed urban distance factor. Temporal trends
observed in dated sediment cores from Lake Michigan demonstrated that
the recent increase in depositional flux to sediment is dominated
by chlorinated OPEs, particularly trisÂ(2-chloroisopropyl) phosphate
(TCPP), which has a doubling time of about 20 years. Downward diffusion
within sediment may have caused vertical fractionation of OPEs over
time. Two relatively hydrophilic OPEs including TCPP had much higher
concentrations in sediment than estimated based on equilibria between
water and sediment organic carbon. Approximately a quarter (17 tonnes)
of the estimated total OPE burden (63 tonnes) in Lake Michigan resides
in sediment, which may act as a secondary source releasing OPEs to
the water column for years to come
Engineering Poly(ethylene glycol) Particles for Improved Biodistribution
We report the engineering of poly(ethylene glycol) (PEG) hydrogel particles using a mesoporous silica (MS) templating method <i>via</i> tuning the PEG molecular weight, particle size, and the presence or absence of the template and investigate the cell association and biodistribution of these particles. An <i>ex vivo</i> assay based on human whole blood that is more sensitive and relevant than traditional cell-line based assays for predicting <i>in vivo</i> circulation behavior is introduced. The association of MS@PEG particles (template present) with granulocytes and monocytes is higher compared with PEG particles (template absent). Increasing the PEG molecular weight (from 10 to 40 kDa) or decreasing the PEG particle size (from 1400 to 150 nm) reduces phagocytic blood cell association of the PEG particles. Mice biodistribution studies show that the PEG particles exhibit extended circulation times (>12 h) compared with the MS@PEG particles and that the retention of smaller PEG particles (150 nm) in blood, when compared with larger PEG particles (>400 nm), is increased at least 4-fold at 12 h after injection. Our findings highlight the influence of unique aspects of polymer hydrogel particles on biological interactions. The reported PEG hydrogel particles represent a new class of polymer carriers with potential biomedical applications