Dumpling-Like Nanocomplexes of Foldable Janus Polymer Sheets and Spheres

The formation of object complexes between Janus nanosheets and cross-linked polystyrene (PS) microspheres is reported. Sheets with one side tethered with PS chains and the other with poly­(2-vinyl pyridine) made from triblock terpolymers were confirmed to be foldable by the addition of acidic water to their dispersion in tetrahydrofuran (THF). When acidic water was added to a THF dispersion of the sheets in the presence of PS spheres of 226 nm, dumpling-like complexes of two different nanoobjects were obtained by wrapping the spheres with the sheets

Efficient Metal-Free “Grafting Onto” Method for Bottlebrush Polymers by Combining RAFT and Triazolinedione–Diene Click Reaction

An efficient metal-free “grafting onto” method was developed for preparing bottlebrush polymers based on the combination of reversible addition–fragmentation chain transfer polymerization (RAFT) and triazolinedione (TAD)–diene Diels–Alder cycloaddition reaction. In this approach, RAFT and a following postfunctionalization process were used to prepare the polyacrylate backbone with conjugated diene side group in each repeat unit (PHEA–diene) and the various TAD-terminated polymer sides including poly­(methyl methacrylate) (PMMA), poly­(<i>tert</i>-butyl acrylate) (P<i>t</i>BA), and polystyrene (PS). The TAD–diene Diels–Alder cycloaddition reaction was then employed to efficiently couple the resultant polymer backbone and side chains, which produced the corresponding bottlebrush polymers of PHEA₄₄₈-<i>g</i>-PMMA₂₇, PHEA₄₄₈-<i>g</i>-P<i>t</i>BA₂₅, and PHEA₄₄₈-<i>g</i>-PS₂₅ with a high grafting density above 90% in only 1 min in the presence of slight molar excess (1.2 times) of TAD to diene groups. The quantitative grafting density could be further achieved in less than 10 min coupling reaction. Atomic force microscopy (AFM) characterization visualized the worm-like molecular morphology for all cases

Synthesis of Cylindrical Polymer Brushes with Umbrella-Like Side Chains via a Combination of Grafting-from and Grafting-onto Methods

Cylindrical polymer brushes with umbrella-like side chains have been synthesized by a combination of grafting-from and grafting-onto methods. First, the polymer brushes with azido end-functionalized poly­(<i>tert</i>-butyl acrylate) (P<i>t</i>BA-N₃) side chains, PBIEM-<i>g</i>-(P<i>t</i>BA-N₃), were prepared by atom transfer radical polymerization (ATRP) of <i>t</i>BA monomers using polyinitiator PBIEM followed by a substitution of bromo-side terminals with sodium azide. Subsequently, polyamidoamino dendrons of three generations with a propargyl focal point (G<i>n</i>) were introduced onto the brush-shaped P<i>t</i>BA-N₃ by copper-catalyzed azide–alkyne cycloaddition (CuAAC) coupling reaction. The efficiency of CuAAC between P<i>t</i>BA-N₃ side chains and G<i>n</i> has showed a dependence on generation number <i>n</i> of the dendrons. At the feed ratio of [G<i>n</i>]:[N₃] = 1:1, the grafting efficiency of the first generation dendron (G1) reached above 95%, whereas that of G2 and G3 was at least 84% and 73%, respectively. AFM images indicated that diameter of the brushes hybridized with G3 increased obviously than that of the brushes without dendrons

Universal and Translational Nanoparticulate CpG Adjuvant

CpG, an agonist of toll-like receptor 9 (TLR9), has become a novel adjuvant that substantially potentiates cellular immunity. However, this agonist may increase systemic toxicity by diffusing into blood after administration and is difficult to be internalized by immune cells to reach TLR9 located in endosomes as a result of the characteristics of negative charge of CpG. Here, we applied a scalable and controllable flash nanocomplexation technology to prepare nanoparticulate CpG adjuvant (npCpG), CpG encapsulated in a physical cross-linking network of protamine and TPP. The nanoadjuvant could redirect CpG into draining lymph nodes to reduce systemic diffusion to improve safety. Further, a combination of npCpG and influenza H1N1 hemagglutinin antigen showed excellent humoral and cellular immunity, evoking high levels of antibodies and cytokines and inducing a great expansion of splenocytes in immunized mice. Also, the nanoadjuvant combined with ovalbumin antigen led to a potent cytotoxic T-cell response, substantially inhibited tumor growth, and improved the survival rate of mice in a melanoma model. This study showed the universal performances of npCpG in infectious disease prevention and tumor immunotherapy to demonstrate the translational potential

Simple, Clean Preparation Method for Cross-Linked α‑Cyclodextrin Nanoparticles via Inclusion Complexation

A simple, clean method was presented in this letter to prepare cross-linked α-cyclodextrin (α-CD) nanoparticles with a low dispersion. The nanoparticles were synthesized in water by cross-linking the inclusion complex of α-CDs and poly­(ethylene glycol) (PEG). The structure of the nanoparticles was characterized by ¹H NMR, nuclear overhauser enhancement spectroscopy (NOESY), and wide-angle X-ray diffraction (XRD). Spherical morphology was observed by scanning electron microscopy (SEM) for these nanoparticles. Their average hydrodynamic radius was determined to be 67 nm by dynamic light scattering (DLS). Small guest molecules could be included in the cross-linked α-CD nanoparticles, and anticancer drug cisplatin was used to evaluate the drug release behavior

Simple, Clean Preparation Method for Cross-Linked α‑Cyclodextrin Nanoparticles via Inclusion Complexation

A simple, clean method was presented in this letter to prepare cross-linked α-cyclodextrin (α-CD) nanoparticles with a low dispersion. The nanoparticles were synthesized in water by cross-linking the inclusion complex of α-CDs and poly­(ethylene glycol) (PEG). The structure of the nanoparticles was characterized by ¹H NMR, nuclear overhauser enhancement spectroscopy (NOESY), and wide-angle X-ray diffraction (XRD). Spherical morphology was observed by scanning electron microscopy (SEM) for these nanoparticles. Their average hydrodynamic radius was determined to be 67 nm by dynamic light scattering (DLS). Small guest molecules could be included in the cross-linked α-CD nanoparticles, and anticancer drug cisplatin was used to evaluate the drug release behavior

Simple, Clean Preparation Method for Cross-Linked α‑Cyclodextrin Nanoparticles via Inclusion Complexation

A simple, clean method was presented in this letter to prepare cross-linked α-cyclodextrin (α-CD) nanoparticles with a low dispersion. The nanoparticles were synthesized in water by cross-linking the inclusion complex of α-CDs and poly­(ethylene glycol) (PEG). The structure of the nanoparticles was characterized by ¹H NMR, nuclear overhauser enhancement spectroscopy (NOESY), and wide-angle X-ray diffraction (XRD). Spherical morphology was observed by scanning electron microscopy (SEM) for these nanoparticles. Their average hydrodynamic radius was determined to be 67 nm by dynamic light scattering (DLS). Small guest molecules could be included in the cross-linked α-CD nanoparticles, and anticancer drug cisplatin was used to evaluate the drug release behavior

Simple, Clean Preparation Method for Cross-Linked α‑Cyclodextrin Nanoparticles via Inclusion Complexation

A simple, clean method was presented in this letter to prepare cross-linked α-cyclodextrin (α-CD) nanoparticles with a low dispersion. The nanoparticles were synthesized in water by cross-linking the inclusion complex of α-CDs and poly­(ethylene glycol) (PEG). The structure of the nanoparticles was characterized by ¹H NMR, nuclear overhauser enhancement spectroscopy (NOESY), and wide-angle X-ray diffraction (XRD). Spherical morphology was observed by scanning electron microscopy (SEM) for these nanoparticles. Their average hydrodynamic radius was determined to be 67 nm by dynamic light scattering (DLS). Small guest molecules could be included in the cross-linked α-CD nanoparticles, and anticancer drug cisplatin was used to evaluate the drug release behavior

Well-Defined Poly(α-amino-δ-valerolactone) via Living Ring-Opening Polymerization

This article demonstrates the synthesis of a new kind of cationic poly­(δ-valerolactone) with primary amino groups at α-positions (poly­(α-NH₂-VL)) via ring-opening polymerization (ROP) of α-NHBoc-valerolactone (α-NHB-VL) followed by a simple deprotection reaction. The ROP of α-NHB-VL using benzyl alcohol as an initiator and DBU/TU (1,8-diazabicyclo[5.4.0]­undec-7-ene/thiourea) as a catalytic system in THF at room temperature afforded poly­(α-NHB-VL) with narrow molecular weight distribution. The ¹H NMR and MALDI-TOF MS analysis of poly­(α-NHB-VL) indicated that each polymeric chain was capped by the initiator. Kinetic experiments confirmed the living nature of the DBU/TU-catalyzed ROP of α-NHB-VL in THF. The copolymerization result indicated that the polymerization activity of α-NHB-VL is comparable to that of ε-caprolactone (CL) and VL. In addition, block copolymers containing poly­(α-NHB-VL) were successfully synthesized regardless of whether hydrophilic PEG or hydrophobic PCL was used as the macroinitiator. Moreover, water-soluble poly­(α-NH₂-VL) was obtained by treatment with trifluoroacetic acid (TFA). It was found that poly­(α-NH₂-VL) degraded more slowly at pH 5.5 than at pH 7.4 through a hydrolysis kinetics study

How Big Is Big Enough? Effect of Length and Shape of Side Chains on the Single-Chain Enthalpic Elasticity of a Macromolecule

Polymers with a carbon–carbon (C–C) backbone are an important class of polymers, which can be regarded as the derivatives of polyethylene (PE). To investigate the effect of side chains on the single-chain enthalpic elasticity (SCEE) of polymers with a C–C backbone, several polymers with pendants or side chains of different lengths and shapes have been studied by single-molecule AFM. We find that both length and shape of the side chains count: only the side chains that are both long and bulky (i.e., bulky dendrons of second or higher generation as side chains) affect the SCEE. Thus, only rare polymers have special SCEE. For the vast majority of polymers, the SCEE is identical to that of PE, which means that the SCEE is determined by the nature of the C–C backbone. It is expected that this conclusion can also be popularized to all polymers with various backbones. This study is an important update to the understanding of polymers at the single-chain level