Trading polymeric microspheres: Exchanging DNA molecules via microsphere interaction

Adhesive Sulfabetaine Polymer Hydrogels for the Sandwich Cell Culture

Sandwich culture systems are techniques that cultivate cells by sandwiching them between the top and bottom substrates. Since the substrates can be separated, the system is expected to be applied to the construct layering of patterned cells and to the isolation of stacked cells. In this study, we prepared hydrogels composed of zwitterionic sulfabetaine polymers, poly[2-(2-(methacryloyloxyethyl)dimethylammonio)ethyl-1-sulfate] (PZBMA). The ZBMA homopolymers have been shown to form aggregates in aqueous solutions due to their intermolecular interactions. The water content of the PZBMA hydrogels in water was ∼70% regardless of N,N'-methylenebis(acrylamide), BIS, content as the cross-linker. The results indicated that the intermolecular interaction contributed more to the swelling behaviors than the chemical cross-linker. However, PZBMA hydrogels with 0.1 mol % BIS showed not only high elongation (∼850%) properties but also high adhesiveness and self-healing properties. When this PZBMA hydrogel was impregnated with collagen and subjected to sandwich culture using Madin-Darby canine kidney (MDCK) cells, a three-dimensional morphology of MDCK cell aggregates was constructed. Such a sulfabetaine hydrogel is expected to be developed for regenerative medicine.

The microspheres/hydrogels scaffolds based on the proteins, nucleic acids, or polysaccharides composite as carriers for tissue repair: A review

There are many studies on specific macromolecules and their contributions to tissue repair. Macromolecules have supporting and protective effects in organisms and can help regrow, reshape, and promote self-repair and regeneration of damaged tissues. Macromolecules, such as proteins, nucleic acids, and polysaccharides, can be constructed into hydrogels for the preparation of slow-release drug agents, carriers for cell culture, and platforms for gene delivery. Hydrogels and microspheres are fabricated by chemical crosslinking or mixed co-deposition often used as scaffolds, drug carriers, or cell culture matrix, provide proper mechanical support and nutrient delivery, a well-conditioned environment that to promote the regeneration and repair of damaged tissues. This review provides a comprehensive overview of recent developments in the construction of macromolecules into hydrogels and microspheres based on the proteins, nucleic acids, polysaccharides and other polymer and their application in tissue repair. We then discuss the latest research trends regarding the advantages and disadvantages of these composites in repair tissue. Further, we examine the applications of microspheres/hydrogels in different tissue repairs, such as skin tissue, cartilage, tumor tissue, synovial, nerve tissue, and cardiac repair. The review closes by highlighting the challenges and prospects of microspheres/hydrogels composites.

Sulfobetaine polymers for effective permeability into multicellular tumor spheroids (MCTSs)

Multicellular tumor spheroids (MCTSs) are attractive for drug screening before animal tests because they emulate an in vivo microenvironment. The permeability of the MCTSs and tumor tissues towards the candidate drugs is not sufficient even though the drugs can penetrate monolayer cultured cells; therefore, nanocarriers are required to enhance permeability and deliver drugs. In this study, we prepared zwitterionic polymers of sulfobetaine methacrylates and (meth)acrylamides with or without hydroxy groups between the zwitterions to serve as highly permeable nanocarriers. In the sulfobetaine polymers, poly(2-hydroxy-3-((3-methacrylamidopropyl)dimethylammonio)propane-1-sulfonate), P(OH-MAAmSB), the hydroxy group containing methacrylamide polymer exhibited little cytotoxicity and membrane translocation ability against monolayer cultured cells. Moreover, the excellent permeability of the hepatocyte MCTS enabled P(OH-MAAmSB) to permeate it and reach the center region (∼325 μm in diameter) at approximately 150 s, although poly(trimethyl-2-methacroyloxyethylammonium), a cationic polymer, penetrated just 1 to 2 layers from the periphery. The superior permeability of P(OH-MAAmSB) might be due to its good solubility and side chain conformation. P(OH-MAAmSB) is a promising nanocarrier with membrane translocation and permeability.

Biodegradable zwitterionic nanoparticles with tunable UCST-type phase separation under physiological conditions

Thermo-responsive polymeric nanoparticles (NPs) are emerging as a powerful tool in nanomedicine for the fabrication of advanced drug delivery systems. In addition to their size and biodegradation rate, phase separation of NPs upon application of a thermal stimulus provides an additional switch to control the rate of release of active components. Among the materials currently developed for biomedical applications, NPs stabilized by zwitterionic polymers are gaining increasing interest due to their high stability and ability to escape the body immune response. Yet, biodegradable zwitterionic NPs with temperature response under physiological conditions are currently not available. Here, we develop a new class of biodegradable zwitterionic NPs that exhibit UCST phase transition in the biological temperature range (T = 30-45 °C) and in physiological solution (i.e. 0.9% w/w NaCl). We design a strategy that relies on the self-assembly of block copolymers produced via reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization. These copolymers comprise a zwitterionic portion exhibiting an upper critical solution temperature (UCST) and a biodegradable hydrophobic block consisting of oligoesters functionalized with a vinyl group. This modular macromolecular architecture allows us to independently control a variety of NP properties by modifying the individual components of the copolymer. In particular, the zwitterionic block of the copolymers controls the UCST-type phase separation behavior, while the number of the oligoester repeating units governs the size of the NPs and the length of the oligoester dictates the degradation rate. After demonstrating the synthesis of highly controlled degradable NPs, we show the potential of this new class of materials in the context of drug delivery by controlling the release of a drug-mimic molecule upon temperature variations in a broad time range from few minutes to 20 hours.

Electrostatically Driven Guest Binding in a Self-Assembled Porous Network at the Liquid/Solid Interface

We present here the construction of a self-assembled two-dimensional (2D) porous monolayer bearing a highly polar 2D space to study guest co-adsorption through electrostatic interactions at the liquid/solid interface. For this purpose, a dehydrobenzo[12]annulene (DBA) derivative, DBA-TeEG, having tetraethylene glycol (TeEG) groups at the end of the three alternating alkoxy chains connected by p-phenylene linkers was synthesized. As a reference host molecule, DBA-C10, having nonpolar C₁₀ alkyl chains at three alternating terminals, was employed. As guest molecules, hexagonal phenylene-ethynylene macrocycles (PEMs) attached by triethylene glycol (TEG) ester and hexyl ester groups, PEM-TEG and PEM-C6, respectively, at each vertex of the macrocyclic periphery were used. Scanning tunneling microscopy observations at the 1,2,4-trichlorobenzene/highly oriented pyrolytic graphite interface revealed that PEM-TEG was immobilized in the pores formed by DBA-TeEG at higher probability because of electrostatic interactions such as dipole-dipole and hydrogen bonding interactions between oligoether units of the host and guest, in comparison to PEM-C6 with nonpolar groups. These observations are discussed based on molecular mechanics simulations to investigate the role of the polar functional groups. When a nonpolar host matrix formed by DBA-C10 was used, however, only phase separation and preferential adsorption were observed; virtually no host-guest complexation was discernible. This is ascribed to the strong affinity between the guest molecules which form by themselves densely packed van der Waals networks on the surface.

Design and synthesis of fluorescence-labeled nucleotide with a cleavable azo linker for DNA sequencing

A cleavable azo linker was synthesized and reacted with 5-(6)-carboxytetramethyl rhodamine succinimidyl ester, followed by further reactions with di(N-succinimidyl) carbonate and 5-(3-amino-1-propynyl)-2'-deoxyuridine 5'-triphosphate [dUTP(AP3)] to obtain the terminal product dUTP-azo linker-TAMRA as a potential reversible terminator for DNA sequencing by synthesis with no need for 3'-OH blocking.