Synthesis and Lectin Recognition of Glyco Star Polymers Prepared by “Clicking” Thiocarbohydrates onto a Reactive Scaffold

Glycopolymers with a four-arm star architecture were prepared from poly(vinyl benzyl chloride) (PVBC) star polymers as reactive scaffold and 1-thio-β-d-glucose sodium salt. The star polymer was prepared via RAFT polymerization using 1,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene as a rate-retarding RAFT agent at a polymerization temperature of 120 °C. The occurrence of known side reactions such as star−star coupling was partly suppressed by optimizing the reaction conditions. The molecular weight distribution in the early stages of the polymerization (1H NMR, confirming full conversion after a reaction time of 110 h. Six different glyco star polymers with number of repeating units N ranging from 40 to 680 were tested regarding their ability to bind to Concanavalin A (ConA) using turbidity assay. The rate of reaction and t1/2, the time to reach half of the maximum absorption, was found to reach a maximum and minimum, respectively, at a medium molecular weight. The same molecular weight dependency was obtained using precipitation assay, which determines the amount of ConA conjugated to the glycopolymer. Comparison with linear glycopolymers reveals however that the amount of bound ConA and the rate of clustering are not superior in the star architecture

Ultralow Self-Cross-Linked Poly(<i>N</i>‑isopropylacrylamide) Microgels Prepared by Solvent Exchange

We found that the poly­(N-isopropylacrylamide) (PNIPAm) synthesized by free-radical polymerization in organic phase could also form stable microgels in water through solvent exchange without chemical cross-linkers. Dynamic light scattering and transmission electron microscopy showed the larger swelling ratio and higher deformability of these microgels. Nuclear magnetic resonance and infrared spectroscopy indicated that the self-cross-linking structures in these microgels were attributed to the hydrogen atom abstraction both from the isopropyl tert-carbon atoms and the vinyl tert-carbon atoms in PNIPAm chains and the organic solvents were important assistants in the hydrogen abstraction behavior. Our discovery revealed that the self-cross-linking of PNIPAm chains is a common phenomenon within their free-radical polymerization process, whether in aqueous phase or in organic phase. Besides, the addition of second monomers will not affect the cross-linkage of the PNIPAm portion, which may be of great significance for the synthesis of various functional ultralow cross-linking PNIPAm microgels

High Throughput Screening of Glycopolymers: Balance between Cytotoxicity and Antibacterial Property

To search for synthetic agents with low cytotoxicity and good antibacterial activity is essential for antimicrobial applications. Here we report a high throughput technique that carried out in multiwell plates via recyclable-catalyst-aided, opened-to-air, and sunlight-photolyzed RAFT (ROS-RAFT) polymerization. By using this method, three key monomers (MAG the sugar unit, DMAPMA the positively charged monomer, and DEMAA the hydrophobic monomer) can be polymerized in a controlled manner to afford glycopolymers. This simple high throughput technology is used to synthesize glycopolymers with variable compositions. The bacterial adhesion/killing ability and cytotoxicity of synthesized polymers have been evaluated, and glycopolymers with certain composition can achieve a balance of low cytotoxic and good antibacterial activity

Sunlight-Induced RAFT Synthesis of Multifaceted Glycopolymers with Surface Anchoring, In Situ AgNP Formation, and Antibacterial Properties

A multifaceted glycopolymer is designed for the convenient and universal fabrication of antibacterial surfaces. Sunlight-induced living-radical polymerization in the presence of a reversible addition–fragmentation chain-transfer agent without a photoinitiator was applied to obtain well-designed multifunctional glycopolymers containing three functional groups that can complex with a silver ion, bind to different surfaces, and form silver nanoparticles in situ. The polymerization behavior and the effects of the concentration of the three monomers have been investigated. The obtained polymers can be used to effectively modify a variety of surfaces [silicon wafer, poly­(dimethylsiloxane), and stainless steel] and the modification is characterized by contact-angle studies, Fourier transform infrared, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy. In addition, the effect of the composition of the polymers on the antibacterial properties of different surfaces has been studied

Thiol–yne and Thiol–ene “Click” Chemistry as a Tool for a Variety of Platinum Drug Delivery Carriers, from Statistical Copolymers to Crosslinked Micelles

Statistical and block copolymers based on poly(2-hydroxyethyl methacrylate) (PHEMA) and poly[oligo(ethylene glycol) methylether methacrylate] (POEGMEMA) were modified with 4-pentenoic anhydride or 4-oxo-4-(prop-2-ynyloxy)butanoic anhydride to generate polymers with pendant vinyl or acetylene, respectively. Subsequent thiol–ene or thiol–yne reaction with thioglycolic acid or 2-mercaptosuccinic acid leads to polymers with carboxylate functionalities, which were conjugated with cisplatin (cis-diamminedichloroplatinum(II) (CDDP)) to generate a drug carrier for Pt-drugs. Only the polymers modified with 2-mercaptosuccinic acid resulted in the formation of soluble well-defined polymers with gel formation being prevented. Due to the hydrophobicity of the drug, the block copolymers took on amphiphilic character leading to micelle formation. The micelles were in addition crosslinked to further stabilize their structure. Pt-containing statistical copolymer, micelles, and crosslinked micelles were then tested regarding their cellular uptake by the A549 lung cancer cell line to show a superior uptake of crosslinked micelles. However, due to the better Pt release of the statistical copolymer, the highest cytotoxicity was observed with this type of polymer architecture

Macromolecular Cobalt Carbonyl Complexes Encapsulated in a <i>Click</i>-Cross-Linked Micelle Structure as a Nanoparticle To Deliver Cobalt Pharmaceuticals

Block copolymers poly(trimethylsilyl propargyl methacrylate)-block-poly(poly(ethylene glycol) methyl ether methacrylate) (P(TMS-PAMA)-b-P(PEGMA)) were synthesized using reversible addition−fragmentation chain transfer (RAFT) polymerization. Subsequent removal of the trimethylsilyl protective groups on the P(TMS-PAMA)24-b-P(PEGMA)40 polymer with tetra-n-butylammonium fluoride hydrate lead to the polymer P(PAMA)24-b-P(PEGMA)40 with pendant alkyne groups, which self-assembled in aqueous solution into micelles with hydrodynamic diameters of less than 20 nm. The alkyne groups in the core took on two functions, acting as a ligand for Co2(CO)8 to generate a derivative of the antitumor agents based on (alkyne)Co2(CO)6 as well as an anchor point for the cross-linking of micelles via click chemistry. The click process was shown to be highly efficient with the two types of cross-linker employed: 1,2-bis-(2-azidoethoxy)ethane and bis-(azidoethyl)disulfide, with almost all of the cross-linker reacting with the micelle at room temperature. The cross-linking density was influenced by the amount of added cross-linker leaving a well-defined amount of alkyne groups that were utilized in the formation of the cobalt complexes. The successful complexation was confirmed via UV/vis and FT-IR spectroscopy. With the formation of (alkyne)Co2(CO)6 moieties in the core, the un-cross-linked and cross-linked micelles were found to almost double in size. The resulting Co-loaded un-cross-linked micelles were observed to be highly toxic to L929 fibroblast cells, while the cross-linking of the micelle was shown to reduce the toxicity

Multifunctional, Degradable Wearable Sensors Prepared with an Initiator and Crosslinker-Free Method

The present zwitterionic hydrogel-based wearable sensor exhibits various limitations, such as limited degradation capacity, unavoidable toxicity resulting from initiators, and poor mechanical properties that cannot satisfy practical demands. Herein, we present an initiator and crosslinker-free approach to prepare polyethylene glycol (PEG)@poly­[2-(methacryloyloxy)­ethyl] dimethyl-(3-sulfopropyl) (PSBMA) interpenetrating polymer network (IPN) hydrogels that are self-polymerized via sunlight-induced and non-covalent crosslinking through electrostatic interaction and hydrogen bonding among polymer chains. The PEG@PSBMA IPN hydrogel possesses tissue-like softness, superior stretchability (∼2344.6% elongation), enhanced fracture strength (∼39.5 kPa), excellent biocompatibility, antibacterial property, reliable adhesion, and ionic conductivity. Furthermore, the sensor based on the IPN hydrogel demonstrates good sensitivity and cyclic stability, enabling effective real-time monitoring of human body activities. Moreover, it is worth noting that the excellent degradability in the saline solution within 8 h makes the prepared hydrogel-based wearable sensor free from the electronic device contamination. We believe that the proposed strategy for preparing physical zwitterionic hydrogels will pave the way for fabricating eco-friendly wearable devices

Multifunctional, Degradable Wearable Sensors Prepared with an Initiator and Crosslinker-Free Method

The present zwitterionic hydrogel-based wearable sensor exhibits various limitations, such as limited degradation capacity, unavoidable toxicity resulting from initiators, and poor mechanical properties that cannot satisfy practical demands. Herein, we present an initiator and crosslinker-free approach to prepare polyethylene glycol (PEG)@poly­[2-(methacryloyloxy)­ethyl] dimethyl-(3-sulfopropyl) (PSBMA) interpenetrating polymer network (IPN) hydrogels that are self-polymerized via sunlight-induced and non-covalent crosslinking through electrostatic interaction and hydrogen bonding among polymer chains. The PEG@PSBMA IPN hydrogel possesses tissue-like softness, superior stretchability (∼2344.6% elongation), enhanced fracture strength (∼39.5 kPa), excellent biocompatibility, antibacterial property, reliable adhesion, and ionic conductivity. Furthermore, the sensor based on the IPN hydrogel demonstrates good sensitivity and cyclic stability, enabling effective real-time monitoring of human body activities. Moreover, it is worth noting that the excellent degradability in the saline solution within 8 h makes the prepared hydrogel-based wearable sensor free from the electronic device contamination. We believe that the proposed strategy for preparing physical zwitterionic hydrogels will pave the way for fabricating eco-friendly wearable devices

Synthetic Sugar-Only Polymers with Double-Shoulder Task: Bioactivity and Imaging

The search for novel fluorescent materials has attracted the attention of many researchers. Numerous bioimaging materials based on the aggregation-induced emission (AIE) units have been surging and could be employed in wide areas during the past two decades. In recent few years, the appearance of nonconventional fluorescence emitters without aromatic conjugated structures provides another bioimaging candidate which has the advantage of enhanced biodegradability and relatively low cost, and their luminescent mechanism can be explained by clustering-triggered emission (CTE) like AIE. In our contribution, we utilize nonaromatic sugar as a monomer to prepare a series of glycopolymers with designed components through sunlight-induced reversible addition fragmentation chain transfer polymerization; these glycopolymers can be employed in bioimaging fields due to the bioactivity coming from sugar and CTE capacity

Well-Defined Oligo(azobenzene-<i>graft</i>-mannose): Photostimuli Supramolecular Self-Assembly and Immune Effect Regulation

The immune system can recognize and respond to pathogens of various shapes. Synthetic materials that can change their shape have the potential to be used in vaccines and immune regulation. The ability of supramolecular assemblies to undergo reversible transformations in response to environmental stimuli allows for dynamic changes in their shapes and functionalities. A meticulously designed oligo­(azobenzene-graft-mannose) was synthesized using a stepwise iterative method and “click” chemistry. This involved integrating hydrophobic and photoresponsive azobenzene units with hydrophilic and bioactive mannose units. The resulting oligomer, with its precise structure, displayed versatile assembly morphologies and chiralities that were responsive to light. These varying assembly morphologies demonstrated distinct capabilities in terms of inhibiting the proliferation of cancer cells and stimulating the maturation of dendritic cells. These discoveries contribute to the theoretical comprehension and advancement of photoswitchable bioactive materials