Transport of a comb-like polymer across a nanochannel subject to a pulling force.

We investigate the dynamics of comb-like polymer translocation through a nanochannel using three-dimensional Langevin dynamics simulations based on a coarse-grained chain model. A comprehensive set of simulations are performed to examine the effects of system parameters such as the grafting densityρof the side chains, the polymer chain length, the nanochannel dimensions, and the magnitude of the pulling force on the translocation dynamics. For a given polymer chain length, keeping the backbone length is constant while varyingρ, we have found that the dependence of the mean translocation time⟨τ⟩onρis non-monotonic, with a maximum translocation time for a specificρat which the translocation is the slowest. The simulation results also show that⟨τ⟩is not significantly affected by the channel width above a certain radius, while the comb-like polymer translocation is hindered by a narrower channel due to increased interactions between the chain monomers and the channel. In addition,⟨τ⟩increases linearly with the nanochannel length. A linear scaling relationship between the mean translocation time⟨τ⟩and the chain lengthNof polymer is obtained,⟨τ⟩∼N. Similarly, the dependence of⟨τ⟩on the backbone chain sizeNbbhas a quasi-linear dependence,⟨τ⟩∼Nbb. On the other hand, the translocation velocityvfollows a power-law relationship with the polymer chain lengthNasv∼N-1. The mean translocation time also shows an inverse linear relationship with the magnitude of the pulling forceF,⟨τ⟩∼F-1. The power-law relationships discovered in this study contribute to the fundamental understanding of the comb polymer translocation dynamics and to establishing a framework for further investigations in this field.

A New Approach Utilizing Aza-Michael Addition for Hydrolysis-Resistance Non-Ionic Waterborne Polyester.

This work first synthesized a series of linear polyesters by step-growth polycondensation, then an amino-terminated hydrophilic polyether was grafted to the polyester as side-chains through aza-Michael addition to prepare a self-dispersible, non-ionic waterborne comb-like polyester (NWCPE). In contrast to traditional functionalization methods that usually require harsh reaction conditions and complex catalysts, the aza-Michael addition proceeds efficiently at room temperature without a catalyst. In this facile and mild way, the NWCPE samples with number-average molecular weight (Mn) of about 8000 g mol-1 were obtained. All dispersions showed excellent storage stability, reflected by no delamination observed after 6 months of storage. The NWCPE dispersion displayed better hydrolysis resistance than an ionic waterborne polyester, as was indicated by a more slight change in pH value and Mn after a period of storage. In addition, the film obtained after the NWCPE dispersion was cross-linked with the curing agent, it exhibited good water resistance, adhesion, and mechanical properties.

Comb-like Pseudopeptides Enable Very Rapid and Efficient Intracellular Trehalose Delivery for Enhanced Cryopreservation of Erythrocytes.

Cell cryopreservation plays a key role in the development of reproducible and cost-effective cell-based therapies. Trehalose accumulated in freezing- and desiccation-tolerant organisms in nature has been sought as an attractive nontoxic cryoprotectant. Herein, we report a coincubation method for very rapid and efficient delivery of membrane-impermeable trehalose into ovine erythrocytes through reversible membrane permeabilization using pH-responsive, comb-like pseudopeptides. The pseudopeptidic polymers containing relatively long alkyl side chains were synthesized to mimic membrane-anchoring fusogenic proteins. The intracellular trehalose delivery efficiency was optimized by manipulating the side chain length, degree of substitution, and concentration of the pseudopeptides with different hydrophobic alkyl side chains, the pH, temperature, and time of incubation, as well as the polymer-to-cell ratio and the concentration of extracellular trehalose. Treatment of erythrocytes with the comb-like pseudopeptides for only 15 min yielded an intracellular trehalose concentration of 177.9 ± 8.6 mM, which resulted in 90.3 ± 0.7% survival after freeze-thaw. The very rapid and efficient delivery was found to be attributed to the reversible, pronounced membrane curvature change as a result of strong membrane insertion of the comb-like pseudopeptides. The pseudopeptides can enable efficient intracellular delivery of not only trehalose for improved cell cryopreservation but also other membrane-impermeable cargos.

Light-to-Thermal Conversion and Thermoregulated Capability of Coaxial Fibers with a Combined Influence from Comb-like Polymeric Phase Change Material and Carbon Nanotube.

A series of coaxial fibers with poly(ethylene terephthalate) (PET) as sheath and poly(tetradecyl acrylate) (PTA) comb-like polymeric phase change material as core have been prepared via an electrospinning technology with carbon nanotube (CNT) dispersed into a core component, denoted as PET/PTA- x CNT, where x is the mass fraction of CNT. The morphology, structure, and thermal performance of coaxial fibers are characterized. Good thermal stability below 300 °C is shown due to the sheath-core structure for PET/PTA- x CNT coaxial fibers. Light-to-thermal conversion effect is contributed from the wide UV-vis light absorbance of CNT and phase change of PTA, and PET/PTA-2% CNT reaches 60 °C after 600 s illumination under 100 mW/cm2. Furthermore, a comparable temperature variation is proved for the covered bottle with PET composite membrane containing PET/PTA-2% CNT coaxial fibers, and after 900 s illumination, the inner temperature of the bottle gets to 38 °C, which is 3 °C higher than that of the PET-covered one. The investigations of light-to-thermal conversion and thermoregulated ability of fibers guide an approach to thermal management material and greenhouse film application.

Chitosan composite microencapsulated comb-like polymeric phase change material via coacervation microencapsulation.

In order to reduce environmental pollution during microencapsulating phase change materials and expand their applications as well, a novel eco-friendly microencapsulated/nanoencapsulated phase change materials (Micro/NanoPCMs) and the corresponding encapsulation method were proposed and discussed in this study, where the natural chitosan and side-chain crystallizable comb-like polymer were selected as shell material and core material, respectively. During the encapsulating process via coacervation, the effects of different core-shell ratios on the morphology and thermal storage properties of microcapsules were discussed. FE-SEM and TEM was employed to investigate the morphology and microstructure of the microcapsules. The thermodynamics performance of microcapsules was studied using TGA and DSC. The encapsulation efficiency of microcapsules ranged from 49.82% to 68.99%, and the thermal stability temperature of microcapsules was measured to be 243.2 °C. The fabrication process where natural raw materials were employed and showing promising applications in such fields as medical treatment.

Microencapsulated Comb-Like Polymeric Solid-Solid Phase Change Materials via In-Situ Polymerization.

To enhance the thermal stability and permeability resistance, a comb-like polymer with crystallizable side chains was fabricated as solid-solid phase change materials (PCMs) inside the cores of microcapsules and nanocapsules prepared via in-situ polymerization. In this study, the effects on the surface morphology and microstructure of micro/nanocapsules caused by microencapsulating different types of core materials (i.e., n-hexadecane, ethyl hexadecanoate, hexadecyl acrylate and poly(hexadecyl acrylate)) were systematically studied via field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The confined crystallization behavior of comb-like polymer PCMs cores was investigated via differential scanning calorimeter (DSC). Comparing with low molecular organic PCMs cores, the thermal stability of PCMs microencapsulated comb-like polymer enhanced significantly, and the permeability resistance improved obviously as well. Based on these resultant analysis, the microencapsulated comb-like polymeric PCMs with excellent thermal stability and permeability resistance showed promising foreground in the field of organic solution spun, melt processing and organic coating.

Amphiphilic ionic complexes of hyaluronic acid with organophosphonium compounds and their antimicrobial activity.

Amphiphilic ionic complexes of hyaluronic acid and alkyltrimethylphosphonium soaps with alkyl chains containing even numbers of carbons from 12 to 22 have been produced. The complexes have a nearly stoichiometric composition, are non-water soluble, and are stable to heat up to temperatures above 200 °C. These complexes are amphiphilic and able to adopt a biphasic structure with the paraffinic and polysaccharide phases ordered arranged with a periodicity ranging between 3 and 5 nm depending on n. The paraffinic phase in complexes with n ≥ 18 was crystallized and showed melting at temperatures between 58 and 70 °C depending on the n value. The complexes decomposed upon incubation in water under physiological conditions, and undergone extensive biodegradation by the action of hyaluronidases. Biocide assays carried out in both solid and liquid media demonstrated a high antimicrobial activity of the complexes against Gram-positive S. aureus but moderate against Gram-negative E. coli and C. albicans fungi.

Membrane-Anchoring, Comb-Like Pseudopeptides for Efficient, pH-Mediated Membrane Destabilization and Intracellular Delivery.

Endosomal release has been identified as a rate-limiting step for intracellular delivery of therapeutic agents, in particular macromolecular drugs. Herein, we report a series of synthetic pH-responsive, membrane-anchoring polymers exhibiting dramatic endosomolytic activity for efficient intracellular delivery. The comb-like pseudopeptidic polymers were synthesized by grafting different amounts of decylamine (NDA), which act as hydrophobic membrane anchors, onto the pendant carboxylic acid groups of a pseudopeptide, poly(l-lysine iso-phthalamide). The effects of the hydrophobic relatively long alkyl side chains on aqueous solution properties, cell membrane destabilization activity, and in-vitro cytotoxicity were investigated. The optimal polymer containing 18 mol % NDA exhibited limited hemolysis at pH 7.4 but induced nearly complete membrane destabilization at endosomal pH within only 20 min. The mechanistic investigation of membrane destabilization suggests the polymer-mediated pore formation. It has been demonstrated that the polymer with hydrophobic side chains displayed a considerable endosomolytic ability to release endocytosed materials into the cytoplasm of various cell lines, which is of critical importance for intracellular drug delivery applications.

A Tailor-Made Synthetic Polymer for Cell Encapsulation: Design Rationale, Synthesis, Chemical-Physics and Biological Characterizations.

This study presents a custom-made in situ gelling polymeric precursor for cell encapsulation. Composed of poly((2-hydroxyethyl)methacrylate-co-(3-aminopropyl)methacrylamide) (P(HEMA-co-APM) mother backbone and RGD-mimicking poly(amidoamine) (PAA) moiteis, the comb-like structured polymeric precursor is tailored to gather the advantages of the two families of synthetic polymers, i.e., the good mechanical integrity of PHEMA-based polymers and the biocompatibility and biodegradability of PAAs. The role of P(HEMA-co-APM) in the regulation of the chemico-physical properties of P(HEMA-co-APM)/PAA hydrogels is thoroughly investigated. On the basis of obtained results, namely the capability of maintaining vital NIH3T3 cell line in vitro for 2 d in a 3D cell culture, the in vivo biocompatibility in murine model for 16 d, and the ability of finely tuning mechanical properties and degradation kinetics, it can be assessed that P(HEMA-co-APM)/PAAs offer a cost-effective valid alternative to the so far studied natural polymer-based systems for cell encapsulation.