Selective mycobacterial capture with ultraviolet-polymerized poly-dimethyldiallyl chloride functionalized surfaces.

Tuberculosis (TB) is the top cause of death from a single infectious pathogen after COVID-19. Despite molecular diagnostic advances, two-thirds of the 10 million annual TB cases are still diagnosed using direct smear microscopy which has ~50% sensitivity. To increase the analytical performance of smear microscopy, we developed and characterized a novel polymer (Polydiallyldimethylammonium chloride [PDADMAC]) engraftment on inexpensive polystyrene (PS) specifically functionalized for mycobacterial capture. Engraftment is achieved via UV photopolymerization of DADMAC monomer on plasma-activated PS. The platform was tested on sputum from presumptive TB cases in Kampala, Uganda (n = 50), with an increased overall sensitivity of 81.8% (27/33) vs. fluorescent smear microscopy 57% (19/33) compared to a molecular (Cepheid GeneXpert MTB/RIF) gold standard. Frugal smear diagnostic innovation that is rapid and does not require dedicated instrumentation may offer an important solution to bridge the TB diagnostic gap.

Wavelength-Selective Photo-Cycloadditions of Styryl-Anthracene.

Light-tunable covalent chemistry is highly urgent in the fields of chemistry, biology, and materials science, especially for the smart materials and surface, due to the spatiotemporal control and feasible operation. Here, a new type of wavelength-selective photo-cycloaddition of styryl-anthracene carboxylic acid (SACA) is reported. Upon the irradiation of 450 nm visible light or 365 nm UV light, SACA can undergo [2+2] or [2+4] photocycloaddition, respectively. Furthermore, the [2+2] photocycloaddition induced by vis-light of 450 nm is reversible and can be disrupted by 365 nm UV light to form dimer-24 which cannot be photo-cleavable. Owing to the feasibility and spatiotemporal characteristics of UV-vis light-controlled photocycloaddition, the SACA possesses potential applications in various areas such as self-assembly, dynamic wrinkles, and fluorescence patterns, which are also explored and exhibited in this work.

Aminoesterenamide Achieved by Three-Component Reaction Heading toward Tailoring Covalent Adaptable Network with Great Freedom.

Covalent adaptable networks (CANs) have recently received extensive interests due to their reprocessability and repairability. Rethinking the libraries of the published CANs, most of them are fabricated by one/two-component reactions and few cases utilize multi-component reactions to construct CANs while multi-component reactions are conductive to tailoring the properties of polymers due to their structural designability and flexible choice of raw materials. A novel kind of dynamic covalent bond named aminoesterenamide is presented through three-component reaction between acetoacetyl, amine and isocyanate. Aminoesterenamide exhibits thermal reversibility through dissociating into vinylogous urethane and isocyanate. When it is used to prepare CANs, the synthesized polymer networks can be reprocessed many times via the exchange reaction between aminoesterenamides. Moreover, the forming of aminoesterenamide involving three starting components imparts CANs with great freedom to tailor their properties. Therefore, the authors believe this method that utilizes three-component reaction to fabricate CANs would bring new stories and perspectives to the exploration of new types of CANs.

Ultralarge Nanosheets Fabricated by the Hierarchical Self-Assembly of Porphyrin-Ended Hyperbranched Poly (ether amine) (TPP-hPEA).

An ultralarge sheet with remarkable lateral dimensions of 10 µm × 10 µm-20 µm × 20 µm is fabricated by the hierarchical self-assembly of porphyrin-ended hyperbranched poly(ether amine) (tetraphenylporphyrin (TPP)-hPEA) in solution. The obtained TPP-hPEA amphiphiles can self-assemble from ultrathin single-layered nanosheets with a thickness of 4 nm to ultralarge multilayered nanosheets with thicknesses from 30 to 70 nm. The lateral dimensions increase from 2 × 2 µm to 5 × 5 µm, and eventually to 10 × 10 µm. In-situ dynamic light scattering and UV-vis spectroscopy studies suggest a hierarchical growth self-assembly mechanism with a self-assembly process that relies on π-π stacking. This 2D self-assembly method provides a significant potential guide for the preparation of ultralarge nanosheets in solution.

Improved siRNA delivery efficiency via solvent-induced condensation of micellar nanoparticles.

Efficient delivery of short interfering RNA (siRNA) remains one of the primary challenges of RNA interference therapy. Polyethylene glycol (PEG)ylated polycationic carriers have been widely used for the condensation of DNA and RNA molecules into complex-core micelles. The PEG corona of such nanoparticles can significantly improve their colloidal stability in serum, but PEGylation of the carriers also reduces their condensation capacity, hindering the generation of micellar particles with sufficient complex stability. This presents a particularly significant challenge for packaging siRNA into complex micelles, as it has a much smaller size and more rigid chain structure than DNA plasmids. Here, we report a new method to enhance the condensation of siRNA with PEGylated linear polyethylenimine using organic solvent and to prepare smaller siRNA nanoparticles with a more extended PEG corona and consequently higher stability. As a proof of principle, we have demonstrated the improved gene knockdown efficiency resulting from the reduced siRNA micelle size in mice livers following intravenous administration.

Hyperbranched poly(ether amine) (hPEA)/poly(vinyl alcohol) (PVA) interpenetrating network (IPN) for selective adsorption and separation of guest homologues.

We here reported that hyperbranched poly(ether amine) (hPEA) and poly(vinyl alcohol) (PVA) interpenetrating network (hPEA/PVA-IPN) can be used for the selective adsorption and separation of guest homologues. A series of hyperbranched poly(ether amine) and poly(vinyl alcohol) interpenetrating networks (hPEA/PVA-IPNs) were fabricated by introducing poly(vinyl alcohol) chains into network of hyperbranched poly(ether amine), in which two independent networks of hyperbranched poly(ether amine) and poly(vinyl alcohol) were cross-linked through photodimerization of coumarin groups of hyperbranched poly(ether amine) and aldol condensation reaction between hydroxyl groups of poly(vinyl alcohol) and glutaraldehyde, respectively. The mechanical strength of interpenetrating networks can be enhanced by the introduction of poly(vinyl alcohol), and the tensile strength of interpenetrating networks increased with tens of times in compared with the pure hyperbranched poly(ether amine) network. The adsorption behavior of seven fluorescein dyes sharing with the same backbone and charge state onto hyperbranched poly(ether amine) and poly(vinyl alcohol) interpenetrating networks was then investigated in detail. Regardless of their charge states, these interpenetrating networks exhibited the quick adsorption to Rose Bengal (RB), Erythrosin B (ETB), Eosin B (EB), 4',5'-dibromofluorescein (DBF), and 4,5,6,7-tetrachlorofluorescein (TCF), with high adsorption capacity (Qeq) and very low adsorption of Calcein (Cal) and fluorescein (FR). The adsorption process was found to follow the pseudo-second-order kinetics, and the introduction of poly(vinyl alcohol) has no obvious effect on the adsorption behavior in this study. The big difference in the adsorption is indicative of the selective adsorption of hyperbranched poly(ether amine) and poly(vinyl alcohol) interpenetrating networks to fluorescein dyes. Based on the unique selective adsorption, the separation of several mixtures of fluorescein dyes such as RB/Cal, RB/FR, ETB/FR, and ETB/Cal was achieved by using hPEA/PVA-IPN as adsorbent.

Functional binary micropattern of hyperbranched poly(ether amine) (hPEA-AN) network and poly(ether amine) (PEA) brush for recognition of guest molecules.

A binary micropattern of anthracene-contained hyperbranched poly(ether amine) (hPEA-AN) network and poly(ether amine) (PEA) brush on gold surface was developed and explored. First, a micropatterned hPEA-AN network array on gold surface was fabricated by photolithography via photodimerization of anthracene moieties, and a PEA brush was subsequently immobilized on the remaining free gold surface areas by chemical adsorption of thiol groups. The patterned hPEA-AN network exhibits selectivity with respect to the adsorption of hydrophilic dyes: Methyl orange is strongly adsorbed, but rhodamine 6G is not, as indicated by the fluorescence response. The PEA brush domain exhibits excellent protein adsorption repellency, whereas the hPEA-AN network layer readily adsorbs protein. These characteristics make the binary hPEA-AN network and PEA brush array sensitive to different kinds of dyes and proteins, which open up pathways to potential applications as microsensors, biochips, and bioassays.

Photodimerization induced hierarchical and asymmetric iontronic micropatterns.

Micropatterning various ion-based modality materials offers compelling advantages for functionality enhancement in iontronic pressure sensing, piezoionic mechanoreception, and skin-interfaced electrode adhesion. However, most existing patterning techniques for iontronic materials suffer from low flexibility and limited modulation capability. Herein, we propose a facile and robust method to fabricate hierarchical and asymmetrical iontronic micropatterns (denoted as HAIMs) through programmed regulation of the internal stress distribution and the local ionic migration among an iontronic host. The resultant HAIMs with arbitrarily regulated morphologies and region-dependent ionic electrical performance can be readily made via localized photodimerization of an anthracene-functionalized ionic liquid copolymer (denoted as An-PIL) and subsequent vapor oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT). Based on the piezoionic effect within the resultant distinct doped PEDOT, HAIMs can serve as a scalable iontronic potential generator. Successful syntheses of these fascinating micropatterns may accelerate the development of patterned iontronic materials in a flexible, programmable, and functionally adaptive form.

A Near-Infrared-Triggered Dynamic Wrinkling Biointerface for Noninvasive Harvesting of Practical Cell Sheets.

Cell sheet engineering represents a new era of precise and efficient regenerative medicine, but its efficacy is limited by the elaborative preparation and the weak mechanics. Herein, a near-infrared (NIR)-triggered dynamic wrinkling biointerface was designed for rapid acquisition of practical cell sheets. The biocompatible NIR can initiate the photothermal-mechanical linkage cascade to efficiently dissolve the collagen supporting layer and release the high-quality cell sheets. The interfacial shear force generates with the dynamic wrinkling, playing an active role in accelerating the cell sheet release. High-quality and self-supporting cell sheets can be harvested within a few minutes, demonstrating a new paradigm of photothermal-mechanical manipulation. The transplantable cell sheets with outstanding physiological and mechanical performances were proven to promote wound healing in skin regeneration. This method may open a completely new front in thermal and mechanical responsive cascade to harvest cell sheets, facilitating their wide applications in regenerative medicine.

Surface-immobilization of adhesion peptides on substrate for ex vivo expansion of cryopreserved umbilical cord blood CD34+ cells.

The interaction between integrins and extracellular matrix proteins play an important role in the regulation of hematopoiesis. Human hematopoietic progenitor cells express very late antigen-4 (VLA-4) and VLA-5, which mediate their interaction with fibronectin by recognizing the connecting segment-1 (CS-1 and RGD motifs, respectively. In this study, we investigated the ex vivo expansion of human umbilical cord blood (UCB) CD34+ cells on synthetic substrates surface-immobilized with peptides containing the CS-1 binding motif (EILDVPST) and the RGD motif (GRGDSPC). These peptides were covalently conjugated to poly(ethylene terephthalate) (PET) film at a surface density of 2.0-2.3 nmol/cm2. UCB CD34+ cells were cultured for 10 days in serum-free medium supplemented with recombinant human thrombopoietin, stem cell factor, flt3-ligand and interleukin 3. The highest cell expansion fold was observed on the CS-1 peptide-modified surface, where total nucleated cells, total colony forming unit, and long-term culture initiating cells were expanded by 589.6+/-58.6 (mean+/-s.d.), 76.5+/-8.8, and 3.2+/-0.9-fold, respectively, compared to unexpanded cells. All substrates surface-immobilized with peptides, including the control peptides, were more efficient in supporting the expansion of CD34+, CFU-GEMM and LTC-ICs than tissue culture polystyrene surface. Nevertheless, after 10-days of ex vivo expansion from 600 CD34+ cells, only cells cultured on CS-1-immobilized surface yielded positive engraftment, even though the frequency was low. PET surface immobilized with RGD peptide was less efficient than that with CS-1 peptide. Our results suggest that covalently immobilized adhesion peptides can significantly influence the proliferation characteristics of cultured UCB CD34+ cells.

Photoinitiated synthesis of polymer brush from dendritic photoinitiator electrostatic self-assembly.

We report on a simple and effective method to prepare polymer brush by electrostatic self-assembly of dendritic macrophotoinitiator and photoinitiated polymerization.

Hybrid POSS-containing brush on gold surfaces for protein resistance.

A hybrid polymer brush containing poly(ethylene glycol) (PEG) chains and polyhedral oligosilsesquioxane (POSS) on a gold surface is presented that exhibits an excellent protein resistance and long-term stability. A series of hybrid polymer brushes with different length and numbers of PEG chains are fabricated through chemisorption of PEG-POSS-SH on the gold surface. Protein adsorption of these hybrid brushes is investigated. The amount of protein adsorption decreases with increasing lengths and numbers of PEG chains. After immersion in BSA solution for two months, the PPS4 brushes retain their protein resistance, while a PEG-SH layer loses its non-fouling performance. These POSS-containing hybrid polymer brushes might offer an alternative for modification of gold surface with an excellent protein resistance for long-term applications.

Ultrafast generation of thick poly(ether amine) (PEA) brush on a gold surface and its protein resistance.

We demonstrate an ultrafast, convenient and universal approach to fabricate a poly(ether amine) (PEA) brush on a gold surface, which exhibited excellent performance of protein resistance with long-term stability.

Facile approach to patterned binary polymer brush through photolithography and surface-initiated photopolymerization.

Taking advantage of the photobleaching and co-initiating properties of the dendritic thioxanthone (TX) photoinitiator, we developed a general and facile approach to fabricate patterned binary polymer brushes by combining photolithography and surface-initiated photopolymerization (SIPP). The dendritic TX photoinitiator monolayer was immobilized covalently on a silicon slide surface, followed by photobleaching through a mask. The resulting slides could initiate photopolymerization of methyl methacrylate (MMA) to generate a patterned poly (methyl methacrylate) (PMMA) brush, and subsequently initiate styrene (St) in the presence of TX to obtain patterned binary poly (methyl methacrylate)-polystyrene (PMMA-PS) brushes. This general and facile method could be of use in large-scale patterned binary polymer brush fabrication.

Well-defined PMMA brush on silica particles fabricated by surface-initiated photopolymerization (SIPP).

The photochemical method is a convenient and simple way to synthesize the polymer brush on surface. We presented here a facile approach to fabricate PMMA brush on silica particles (SPs) by combination of self-assembly monolayer of hyperbranched polymeric thioxanthone (HPTX) and surface-initiated photopolymerization (SIPP). HPTX was immobilized on the surface of silica particles (SPs) through nucleophilic addition between amine and epoxy groups, and then initiated photopolymerization of MMA to generate PMMA brush on SPs at room temperature. The whole process was well-traced by FT-IR, TGA, SEM, and TEM. The results show that it is easy to create PMMA brushes of tunable thickness under UV irradiation. Especially, TEM images reveal the obvious formation of well-defined hybrid particles with SPs as the core and PMMA layers as the shell. The obtained hybrid particles can be implanted into PMMA matrix to produce PMMA composite with enhanced thermal and mechanical properties.

Multi-responsive amphiphilic gold nanoparticles (AuNPs) protected by poly(ether amine) (PEA).

Multi-responsive amphiphilic gold nanoparticles (AuNPs) protected by graft poly(ether amine) have been prepared simply by a one-pot photochemical synthesis in the presence of thio-graft poly(ether amine) (gPEA-SH) and the mechanism was studied in detail.

Responsive polymer nanoparticles formed by poly(ether amine) containing coumarin units and a poly(ethylene oxide) short chain.

We reported a novel poly(ether amine) (PEAC) containing poly(ethylene oxide) (PEO) short blocks and coumarin units, which was synthesized by nucleophilic addition/ring-opening polymerization of diepoxy and diamine monomers. PEAC can be directly dispersed in aqueous solution as uniformly sized nanoparticles 50-60 nm in diameter. The whole process for aggregation of PEAC was revealed by transmission electron microscopy (TEM) and ultraviolet-visible (UV-vis) spectra. The results show that these polymeric nanoparticles possess a very sharp response to temperature and light, and can form complex micromicelles with nanoparticles inside.

Facile approach to the fabrication of a micropattern possessing nanoscale substructure.

On the basis of the combined technologies of photolithography and reaction-induced phase separation (RIPS), a facile approach has been successfully developed for the fabrication of a micropattern possessing nanoscale substructure on the thin film surface. This approach involves three steps. In the first step, a thin film was prepared by spin coating from a solution of a commercial random copolymer, polystyrene-r-poly(methyl methacrylate) (PS-r-PMMA) and a commercial crosslinker, trimethylolpropane triacrylate (TMPTA). In the second step, photolithograph was performed with the thin film using a 250 W high-pressure mercury lamp to produce the micropattern. Finally, the resulting micropattern was annealed at 200 degrees C for a certain time, and reaction-induced phase separation occurred. After soaking in chloroform for 4 h, nanoscale substructure was obtained. The whole processes were traced by atomic force microscopy (AFM), X-ray photoelectron spectrometry (XPS), and Fourier transform infrared (FTIR) spectroscopy, and the results supported the proposed structure.

Studies on functionalization of poly(epsilon-caprolactone) by a cholesteryl moiety.

Biodegradable polymers/oligomers based on epsilon-caprolactone (CL) were end-functionalized by a cholesteryl moiety. The functionalized polymers/oligomers, Chol-(CL)n, were synthesized through ring-opening polymerization initiated by cholesterol with a hydroxyl group. The chemical structure of end-functionalized polymers/oligomers was confirmed by FT-IR and 1H-NMR. The molecular weight of the functionalized polymer/oligomer increases with decreasing feed ratio of the initiator cholesterol to the monomer CL. Incorporation of the cholesteryl moiety to the polymer chain results in liquid crystallinity for the resultant oligomers when their molecular chains are not very long. The enzymatic degradation of the functionalized polymers/oligomers was investigated. The microsphere drug-delivery system of a functionalized oligomer was fabricated and its drug release properties were evaluated. The cell-culture experiment indicates the incorporation of cholesteryl moiety to the polymer chain results in improved cell proliferation.