14 research outputs found
Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving
Synthetic chemists have devoted tremendous effort towards the production of precision synthetic polymers with defined sequences and specific functions. However, the creation of a general technology that enables precise control over monomer sequence, with efficient isolation of the target polymers, is highly challenging. Here, we report a robust strategy for the production of sequence-defined synthetic polymers through a combination of liquid-phase synthesis and selective molecular sieving. The polymer is assembled in solution with real-time monitoring to ensure couplings proceed to completion, on a three-armed star-shaped macromolecule to maximize efficiency during the molecular sieving process. This approach is applied to the construction of sequence-defined polyethers, with side-arms at precisely defined locations that can undergo site-selective modification after polymerization. Using this versatile strategy, we have introduced structural and functional diversity into sequence-defined polyethers, unlocking their potential for real-life applications in nanotechnology, healthcare and information storage
Identification of potential key genes as diagnostic biomarkers for Kawasaki disease based on integrated bioinformatics analysis
Growing collaborations between Chinese and UK young scholars on chemical science and technology
Author Correction: Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving
Correction to: Nature Chemistry https://doi.org/10.1038/s41557-018-0169-6, published online 3 December 2018
Aligned macrocycle pores in ultrathin films for accurate molecular sieving
Jiang Z, Dong R, Evans AM, et al. Aligned macrocycle pores in ultrathin films for accurate molecular sieving. Nature. 2022;609(7925):58-64.Polymer membranes are widely used in separation processes including desalination1, organic solvent nanofiltration2,3 and crude oil fractionation4,5. Nevertheless, direct evidence of subnanometre pores and a feasible method of manipulating their size is still challenging because of the molecular fluctuations of poorly defined voids in polymers6. Macrocycles with intrinsic cavities could potentially tackle this challenge. However, unfunctionalized macrocycles with indistinguishable reactivities tend towards disordered packing in filmshundreds of nanometresthick7-9, hindering cavity interconnection and formation of through-pores. Here, we synthesized selectively functionalized macrocycles with differentiated reactivities that preferentially aligned to create well-defined pores across an ultrathin nanofilm. The ordered structure was enhanced by reducing the nanofilm thickness down to several nanometres. This orientated architecture enabled direct visualization of subnanometre macrocycle pores in the nanofilm surfaces, with the size tailored to angstromprecision by varying the macrocycle identity. Aligned macrocycle membranes provided twice the methanol permeance and higher selectivity compared to disordered counterparts. Used in high-value separations, exemplified here by enriching cannabidiol oil, they achieved one order of magnitude faster ethanol transport and threefold higher enrichment than commercial state-of-the-art membranes. This approach offers a feasible strategy for creating subnanometre channels in polymer membranes, and demonstrates their potential for accurate molecular separations. © 2022. The Author(s)
Supramolecular ABC Miktoarm Star Terpolymer Based on Host–Guest Inclusion Complexation
A facile strategy for the construction of supramolecular
star-shaped
ABC terpolymer was proposed and realized via the molecular recognition
between β-cyclodextrin- (β-CD-) based host and adamantane-
(AD-)Âmodified guest. In the first step, β-CD with two different
functional groups was prepared, which was further used to construct
a diblock copolymer host via “click” reaction with <i>alkynyl</i>-polyÂ(ethylene glycol) (<i>alkynyl</i>-PEG)
and atom transfer radical polymerization (ATRP) of dimethylaminoethyl
methacrylate (DMAEMA) monomer. On the other hand, the AD-modified
polymeric guest was obtained by ATRP of methyl methacrylate (MMA)
using an AD-modified initiator. Because of the molecular recognition
between β-CDs and adamantyl moieties, the polymeric host and
guest formed a star-shaped ABC miktoarm terpolymer via a simple mixing
procedure. The resultant ABC miktoarm star-shaped terpolymer was characterized
by two-dimensional NMR spectroscopy. This amphiphilic ABC miktoarm
terpolymer could self-assemble into micelles in aqueous solution,
and the reversible transition between assembly and disassembly of
this supramolecular ABC miktoarm star terpolymer could be readily
controlled by adding the competitive host or guest
Synthesis of a Cationic Supramolecular Block Copolymer with Covalent and Noncovalent Polymer Blocks for Gene Delivery
The
design and fabrication of safe and highly efficient nonviral
vectors is the key scientific issue for the achievement of clinical
gene therapy. Supramolecular cationic polymers have unique structures
and specific functions compared to covalent cationic polymers, such
as low cytotoxicity, excellent biodegradability, and smart environmental
responsiveness, thereby showing great application prospect for gene
therapy. However, supramolecular gene vectors are facile to be degraded
under physiological conditions, leading to a significant reduction
of gene transfection efficiency. In order to achieve highly efficient
gene expression, it is necessary for supramolecular gene vectors being
provided with appropriate biostability to overcome various cell obstacles.
To this end, a novel cationic supramolecular block copolymer composed
of a conventional polymer and a noncovalent polymer was constructed
through robust β-cyclodextrin/ferrocene host–guest recognition.
The resultant supramolecular block copolymer perfectly combines the
advantages of both conventional polymers and supramolecular polymers
ranging from structures to functions. This supramolecular copolymer
not only has the ability to effectively condense pDNA for enhanced
cell uptake, but also releases pDNA inside cancer cells triggered
by H<sub>2</sub>O<sub>2</sub>, which can be utilized as a prospective
nonviral delivery vehicle for gene delivery. The block polymer exhibited
low cytotoxicity, good biostability, excellent biodegradability, and
intelligent responsiveness, ascribing to the dynamic/reversible nature
of noncovalent linkages. In vitro studies further illustrated that
the supramolecular block polymer exhibited greatly improved gene transfection
efficiency in cancer cells. This work offers an alternative platform
for the exploitation of smart nonviral vehicles for specific cancer
gene therapy in the future
Synthesis and Self-Assembly of Amphiphilic Aptamer-Functionalized Hyperbranched Multiarm Copolymers for Targeted Cancer Imaging
A novel targeting cancer imaging
platform based on aptamer-functionalized
amphiphilic hyperbranched copolymer conjugates, which can self-assemble
into nanoscopic micelles with a core–shell structure and a
narrow size distribution, has been designed and synthesized. The size,
morphology, fluorescence performance, and cytotoxicity of micelles
were studied by dynamic light scattering, transmission electron microscopy,
fluorescence spectroscopy, and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide colorimetric assay. The results indicate that these micelles
have low cytotoxicity against MCF-7 cells and can be easily internalized
by MCF-7 cells. In addition, they also exhibit enhanced cell uptake,
excellent fluorescence properties, and smart targeting capability <i>in vitro</i>, indicating great potential to be promising carriers
for bioimaging and cancer specific delivery
Multicolor Fluorescent Polymers Inspired from Green Fluorescent Protein
Mimicking
the green fluorescent protein (GFP), multicolor fluorescent polymers
possessing enhanced fluorescence have been developed and applied to
single-excitation cell imaging. The GFP core chromophore was covalently
linked to the azide-functionalized amphiphilic block polymer polyÂ(ethylene
glycol)–azide–polyÂ(methyl methacrylate). Through macromolecular
assembly into micelles, the fluorescence enhanced and further increased
with the elongation of polyÂ(methyl methacrylate) chain due to the
segmentation effect of the polymeric framework, which could reduce
strong π–π interaction and suppress the chromophore’s
conformational motion. By a combination of chemically tailoring the
core chromophore and macromolecular assembly strategy, multicolor
fluorescent polymers showing a color palette from blue to orange were
achieved under similar excitation conditions with the highest emission
quantum yield approaching 8%, which is more than 80-fold larger than
that of the core chromophore. Moreover, fluorescent emission color
could be regulated by tuning the coassembling constitution of green
and orange fluorescent polymers, generating three new types of emission
color. Owing to their low cytotoxicity and good photostability, GFP-mimicking
fluorescent polymers were suitable for single-excitation multicolor
cell imaging, exhibiting maximum Stokes shift of 202 nm, ascribing
to the effect of excited-state proton transfer (ESPT). More importantly,
green, yellow, and orange fluorescent cell images were obtained from
one single visual field, demonstrating identical information on examined
cells, which would improve the accuracy and reliability of biological
analysis