3D-printed dermis-specific extracellular matrix mitigates scar contraction via inducing early angiogenesis and macrophage M2 polarization.

Scar contraction frequently happens in patients with deep burn injuries. Hitherto, porcine dermal extracellular matrix (dECM) has supplied microenvironments that assist in wound healing but fail to inhibit scar contraction. To overcome this drawback, we integrate dECM into three-dimensional (3D)-printed dermal analogues (PDA) to prevent scar contraction. We have developed thermally gelled, non-rheologically modified dECM powder (dECMp) inks and successfully transformed them into PDA that was endowed with a micron-scale spatial structure. The optimal crosslinked PDA exhibited desired structure, good mechanical properties as well as excellent biocompatibility. Moreover, in vivo experiments demonstrated that PDA could significantly reduced scar contraction and improved cosmetic upshots of split thickness skin grafts (STSG) than the commercially available dermal templates and STSG along. The PDA has also induced an early, intense neovascularization, and evoked a type-2-like immune response. PDA's superior beneficial effects may attribute to their desired porous structure, the well-balanced physicochemical properties, and the preserved dermis-specific ECM cues, which collectively modulated the expression of genes such as Wnt11, ATF3, and IL1ß, and influenced the crucial endogenous signalling pathways. The findings of this study suggest that PDA is a clinical translatable material that possess high potential in reducing scar contraction.

Self-Healing Thermoplastic Polyurethane Linked via Host-Guest Interactions.

High toughness with self-healing ability has become the ultimate goal in materials research. Herein, thermoplastic polyurethane (TPU) was linked via host-guest (HG) interactions to increase its mechanical properties and self-healing ability. TPU linked via HG interactions was prepared by the step-growth bulk polymerization of hexamethylene diisocyanate (HDI), tetraethylene glycol (TEG), and HG interactions between permethylated amino ßCD (PMeAmßCD) and adamantane amine (AdAm). TPU linked with 10 mol% of HG interactions (HG(10)) showed the highest rupture stress and fracture energy (GF) of 11 MPa and 25 MJ·m-3, which are almost 40-fold and 1500-fold, respectively, higher than those of non-functionalized TEG-based TPU (PU). Additionally, damaged HG(10) shows 87% recovery after heated for 7 min at 80 °C, and completely cut HG(10) shows 80% recovery after 60 min of reattachment at same temperature. The HG interactions in TPU are an important factor in stress dispersion, increasing both its mechanical and self-healing properties. The TPU linked via HG interactions has great promise for use in industrial materials in the near future.

Drug Loaded Nanoparticles of Metal-Organic Frameworks with High Colloidal Stability for Anticancer Application.

Nanoscale metal-organic frameworks are considered for drug delivery due to their ultrahigh porosity and intrinsic biodegradability. However, the poor colloidal dispersity of these nanocarriers in aqueous media has limited the further applications. In this study, a novel dextran-coated zeolitic imidazolate framework-8 (ZIF-8/Dex) nanoparticle was synthesized. The hydrated dextran shell, which was linked to frameworks through coordination bonds, improved the dispersity of particle and reduced the side effects caused by rapid disintegration. Furthermore, this nanosystem with pH-sensitive property may serve as a vehicle of doxorubicin hydrochloride with high loading efficiency and controlling release behavior. Interestingly, the drug-loaded nanocomposite (DOX@ZIF-8/Dex) exhibited synergistic anticancer activity against human breast carcinoma multidrug resistant cells, effectively avoided the efflux effect and reduced P-glycoprotein expression. The successful preparation of such therapeutic platforms promotes the clinical application for anti-tumor therapy.

Control of the threading ratio of cyclic molecules in polyrotaxanes consisting of poly(ethylene glycol) and α-cyclodextrins.

We demonstrated a feasible method for providing polyrotaxanes (PRxs) with a controlled threading ratio of cyclic molecules and chain length of linear polymers by extending the linear polymers in the pseudo-PRx. This method gave PRxs with a lower threading ratio and a higher mobility of cyclic molecules compared to usual methods used previously with a high threading ratio. In addition, our PRx improved the thermal stability of the linear polymers in PRx despite the low threading ratio.

Intelligent Mesoporous Materials for Selective Adsorption and Mechanical Release of Organic Pollutants from Water.

Despite recent advances in the porous materials for efficient removal of dissolved organic pollutants from water, the regeneration of porous characteristics for reuse with preventing secondary contamination remains a challenge. Here, novel supramolecular absorbents with hydrophobic pore are prepared by the self-assembly of propeller-shaped aromatic amphiphiles. The assembly of folded propeller provides a mesoporous environment within aromatic segments, which is suitable for the removal of organic pollutants from waste water. The removal efficiency is found to be 92% and 90% for ethinyl oestradiol (Eo) and bisphenol A (BPA). Notably, the folded architecture of propeller is observed to be flattened by the salt addition, which results in the strong π-π interaction driving the porous materials closed and forms solid fibers. It is found that most of the removed pollutants are spontaneously released by the dynamic porous assembly, and subsequent dialysis triggers the porous materials to be recovered.

Biocompatible surface modification of nano-scale zeolitic imidazolate frameworks for enhanced drug delivery.

Recently, nanoscale metal organic frameworks have attracted considerable attention as a novel drug delivery system platform owing to their highly efficient drug loading and delivery capacities. However, their low dispersity in aqueous media, poor biocompatibility, and non-active targeting ability seriously limit their further clinical application. To address these issues, a hyaluronic acid (HA)-coated ZIF-8 nanocomposite (CCM@ZIF-8/HA) was successfully developed for use in anti-cancer treatment through efficient curcumin (CCM) delivery. The resultant CCM@ZIF-8/HA showed a long-term pH-dependent controlled drug release based on the core-shell structure of the encapsulation by HA. Moreover, compared to bare CCM@ZIF-8, the obtained ternary assembly showed enhanced dispersity in PBS, promoted cellular uptake, and greater growth inhibition against HeLa cells. Thus, CCM@ZIF-8/HA can not only serve as an ideal drug carrier, but it can also provide a general surface modification strategy to promote the performance of metal organic frameworks for efficient drug delivery.

Flexible interlocked porous frameworks allow quantitative photoisomerization in a crystalline solid.

Photochromic molecules have shown much promise as molecular components of stimuli-responsive materials, but despite recent achievements in various photoresponsive materials, quantitative conversion in photochemical reactions in solids is hampered by the lack of intrinsic structural flexibility available to release stress and strain upon photochemical events. This issue remains one of the challenges in developing solid-state photoresponsive materials. Here, we report a strategy to realize photoresponsive crystalline materials showing quantitative reversible photochemical reactions upon ultraviolet and visible light irradiation by introducing structural flexibility into crystalline porous frameworks with a twofold interpenetration composed of a diarylethene-based ligand. The structural flexibility of the porous framework enables highly efficient photochemical electrocyclization in a single-crystal-to-single-crystal manner. CO2 sorption on the porous crystal at 195 K is reversibly modulated by light irradiation, and coincident X-ray powder diffraction/sorption measurements clearly demonstrate the flexible nature of the twofold interpenetrated frameworks.Organizing photochromic molecules into 3D networks is a key strategy to access photoresponsive materials, but framework rigidity typically limits conversion efficiency. Here, the authors exploit a flexible metal-organic framework to achieve quantitative and reversible photoisomerization in a porous crystalline solid.

Peptide assembly-driven metal-organic framework (MOF) motors for micro electric generators.

Peptide-metal-organic framework (Pep-MOF) motors, whose motions are driven by anisotropic surface tension gradients created via peptide self-assembly around frameworks, can rotate microscopic rotors and magnets fast enough to generate an electric power of 0.1 µW. A new rigid Pep-MOF motor can be recycled by refilling the peptide fuel into the nanopores of the MOF.

The densely fluorinated nanospace of a porous coordination polymer composed of perfluorobutyl-functionalized ligands.

A perfluorobutyl-functionalized two-dimensional porous coordination polymer (PCP), {[Cu(bpbtp)(L)(DMF)]·(DMF)}n (H2bpbtp = 2,5-bis(perfluorobutyl)terephthalic acid, L = 2,5-bis(perfluorobutyl)-1,4-bis(4-pyridyl)benzene, DMF = N,N-dimethylformamide) has been synthesized and structurally characterized. The pore surface of the PCP is decorated with pendant perfluorobutyl groups which fabricate a densely fluorinated nanospace resulting in unique gas sorption properties.

pH-responsive self-assembly by molecular recognition on a macroscopic scale.

Macroscopic pH-responsive self-assembly is successfully constructed by polyacrylamide(pAAm)-based gels carrying dansyl (Dns) and ß-cyclodextrin (ßCD) residues, which are represented as Dns-gel and ßCD-gel, respectively. Dns-gel and ßCD-gel assemble together at pH ≥ 4.0, but disassemble at pH ≤ 3.0. The adhesion strengths for pairs of Dns-gel/ßCD-gel increase with increasing pH. The fluorescence study on the model system of pAAm modified with 1 mol% Dns moieties (pAAm/Dns) reveals that Dns residues are protonated at a lower pH, which results in the reduction in binding constant (K) for Dns residues and ßCD.

Interaction of cyclodextrins with pyrene-modified polyacrylamide in a mixed solvent of water and dimethyl sulfoxide as studied by steady-state fluorescence.

The interaction of ß- and γ-cyclodextrins (ß-CD and γ-CD, respectively) with polyacrylamide modified with pyrenyl (Py) residues (pAAmPy) was investigated in a mixed solvent of water and dimethyl sulfoxide (DMSO) by steady-state fluorescence. In the absence of CD, the fluorescence spectra indicated that the formation of Py dimers became less favorable with increasing volume fraction of DMSO (x(DMSO)). The fluorescence spectra at varying x(DMSO) and CD concentrations indicated that ß-CD and γ-CD included monomeric and dimeric Py residues, respectively. Using the fluorescence spectra, equilibrium constants of the formation of Py dimers and the complexation of ß-CD and γ-CD with Py residues were roughly estimated based on simplified equilibrium schemes.

Switching of macroscopic molecular recognition selectivity using a mixed solvent system.

The formation of macroscopic assemblies based on molecular recognition is promising in a wide variety of fields of materials science. Switching of the selectivity of macroscopic assemblies is of increasing importance to produce highly functional materials. Here we show macroscopic assembly based on molecular recognition using polyacrylamide gel modified with pyrenyl (Py) moiety (Py-gel) and gels possessing CD moieties (αCD-gel, ßCD-gel and γCD-gel) in a mixed solvent of water and dimethyl sulfoxide. Changing the composition of the mixed solvent can switch the selectivity of Py-gel, because the fractions of the monomer and dimer of the Py moieties on the gel surface depend on the mixed solvent composition. The monomer and dimer of the Py moieties prefer ßCD and γCD moieties, respectively.

Temperature-Sensitive Macroscopic Assembly Based on Molecular Recognition.

The interaction of polyacrylamide(pAAm)-based gel modified with benzyl (Bz) moiety (Bz(x)-gel, where x denotes the mol % content of Bz moiety) with a pAAm-based gel possessing cyclodextrin (CD) moieties (αCD-gel, ßCD-gel, and γCD-gel) was investigated at various temperatures to elucidate the effect of temperature on the formation of macroscopic assembly. The interaction of Bz(x)-gel with CD-gels was stronger at a lower temperature, consistent with the binding constants for the model system of pAAm modified with 1 mol % Bz moiety and native CDs. Bz(15)-gel interacted only with ßCD-gel at a higher temperature (

Macroscopic observations of molecular recognition: discrimination of the substituted position on the naphthyl group by polyacrylamide gel modified with ß-cyclodextrin.

Macroscopic molecular recognition observations were realized using polyacrylamide-based gels modified with α-cyclodextrin (α-CD), ß-cyclodextrin (ß-CD), 1-naphthylmethyl (1Np), and 2-naphthylmethyl (2Np) moieties, which are denoted as αCD(x)-gel, ßCD(x)-gel, 1Np(y)-gel, and 2Np(y)-gel, where x and y indicate the mol % of CD and Np moieties, respectively. The αCD(5)-gel did not adhere to either the 1Np(5)-gel or 2Np(5)-gel, whereas the ßCD(5)-gel interacted with both to form alternating or checkered assemblies. Although the difference in the association constants of ß-CD for the model polymers was small, the ßCD(x)-gel successfully discriminated between 1Np(y)-gel and 2Np(y)-gel at the appropriate x and y.