Polymers with Dual Light-Triggered Functions of Shape Memory and Healing Using Gold Nanoparticles

Shape-memory and stimuli-healable polymers (SMP and SHP) are two types of emerging smart materials. Among the many stimuli that can be used to control SMP and SHP, light is unique because of its unparalleled remote activation and spatial control. Generally, light-triggered shape memory and optically healable polymers are different polymers and it is challenging to endow the same polymer with the two light-triggered functions because of their structural incompatibility. In this paper, we describe a general polymer design that allows a single material to exhibit both light-controlled shape memory and optical healing capabilities. We show that by chemically cross-linking a crystalline polymer and loading it with a small amount of gold nanoparticles (AuNPs), the polymer displays optically controllable shape memory and fast optical healing based on the same localized heating effect arising from the surface plasmon resonance of AuNPs. The photothermal effect controls, on the one hand, the shape memory process by tuning the temperature with respect to <i>T</i>_m of the crystalline phase and, on the other hand, activates the damage healing through crystal melting and recrystallization. Moreover, we show that these two features can be triggered separately in a sequential manner

CO₂‑Switchable Supramolecular Block Glycopolypeptide Assemblies

A novel supramolecular block glycopolypeptide, designed to have the viral building blocks and be sensitive to CO₂, a physiological stimulus, was prepared via the orthogonal coupling of two end-functionalized biopolymers, dextran with β-cyclodextrin terminal (Dex-CD) and poly­(l-valine) with a benzimidazole tail (BzI-PVal), respectively, driven by the end-to-end host–guest interactions. Due to the CO₂-cleavable CD/BzI connection, both the vesicular and fibrous aggregates of this supramolecular block copolymer self-assembled in aqueous solution can undergo a reversible process of disassembly upon “breathing in” CO₂ and assembly upon “breathing out” CO₂, which mimics, to some extent, the disintegration and construction of viral capsid nanostructures

Poly(vinyl alcohol) Hydrogel Can Autonomously Self-Heal

It is discovered that poly­(vinyl alcohol) (PVA) hydrogel prepared using the freezing/thawing method can self-repair at room temperature without the need for any stimulus or healing agent. The autonomous self-healing process can be fast for mechanically strong PVA hydrogel yielding a high fracture stress. Investigation on the effect of the hydrogel preparation conditions points out that hydrogen bonding between PVA chains across the interface of the cut surfaces is at the origin of the phenomenon. The key for an effective self-healing is to have an appropriate balance between high concentration of free hydroxyl groups on PVA chains on the cut surfaces prior to contact and sufficient PVA chain mobility in the hydrogel

Porphyrin Derivative Conjugated with Gold Nanoparticles for Dual-Modality Photodynamic and Photothermal Therapies In Vitro

Gold nanoparticles (Au NPs) have been confirmed to show excellent photothermal conversion property for tumor theranostic applications. To improve the antitumor efficacy, a novel nanoplatform system composed of porphyrin derivative and Au NPs was fabricated to study the dual-modality photodynamic and photothermal therapy with laser irradiation. Modified chitosan was coated on the Au NPs surface via ligand exchange between thiol groups and Au. The chitosan-coated Au NPs (QCS-SH/Au NPs) were further conjugated with meso-tetrakis­(4-sulphonatophenyl)­porphyrin (TPPS) via electrostatic interaction to obtain the porphyrin-conjugated Au hybrid nanoparticles (TPPS/QCS-SH/Au NPs). Size, morphology, and properties of the prepared nanoparticles were confirmed by Zeta potential, nanoparticle size analyzer, transmission electron microscopy (TEM), and UV–vis spectroscopy. Moreover, both photothermal therapy (PTT) and photodynamic therapy (PDT) were investigated. Compared with alone Au NPs or TPPS, the hybrid TPPS/QCS-SH/Au NPs with lower cytotoxicity showed durable elevated temperature to around 56 °C and large amount of singlet oxygen (¹O₂) produced from TPPS. Thus, the hybrid nanoparticles showed a more significant synergistic therapy effect of hyperthermia from PTT as well as ¹O₂ from PDT, which has potential applications in the tumor therapy fields

High-Performance PEBA2533-Functional MMT Mixed Matrix Membrane Containing High-Speed Facilitated Transport Channels for CO₂/N₂ Separation

A novel mixed matrix membrane was fabricated by establishing montmorillonite (MMT) functionalized with poly­(ethylene glycol) methyl ether (PEG) and aminosilane coupling agents in a PEBA membrane. The functional MMT played multiple roles in enhancing membrane performance. First, the MMT channels could be used as high-speed facilitated transport channels, in which the movable metal cations acted as carriers of CO₂ to increase the CO₂ permeability. Second, due to mobility of long-chain aminos and reversible reactions between CO₂ and amine groups, the functional MMT could actively catch the CO₂, not passively wait for arrival of CO₂, which can facilitate the CO₂ transport. At last, PEG consisting of EO groups had excellent affinity for CO₂ to enhance the CO₂/N₂ selectivity. Thus, the as-prepared functional MMMs exhibited good CO₂ permeability and CO₂/N₂ selectivity. The functional MMM doped with 40 wt % of MMT-HD702-PEG5000 displayed optimal gas separation with a CO₂ permeability of 448.45 Barrer and a CO₂/N₂ selectivity of 70.73, surpassing the upper bound lines of the Robeson study of 2008

Renal cortical dual labeled immunofluorescent staining for IL-18 and tubular epithelial cells following UUO.

<p><b>A.</b> Photographs (magnification 400X) depicting renal cortical IL-18 production (red) and distal tubular staining (Peanut Agglutinin; green) in vehicle treated and macrophage depleted mice exposed to sham operation or one week of UUO. White arrows indicate IL-18 staining overlying tubules. T = Tubules.</p

Renal cortical macrophage accumulation following UUO.

<p>Photographs (magnification 400X) depicting macrophage (brown stain; arrows) in vehicle treated and macrophage depleted mice exposed to sham operation or one week of UUO. T = tubule; G = glomerulus.</p

Renal cortical dual labeled immunofluorescent staining for IL-18R and tubular epithelial cells following UUO.

<p><b>A.</b> Photographs (magnification 400X) depicting renal cortical IL-18R production (red) and distal tubular staining (Peanut Agglutinin; green) in vehicle treated and macrophage depleted mice exposed to sham operation or one week of UUO. White arrows indicate IL-18R staining overlying tubules. T = Tubules.</p

Renal cortical active IL-18 production following UUO.

<p>Renal cortical active IL-18 protein levels in vehicle treated and macrophage depleted mice exposed to sham operation or one week of UUO.</p

Artificial Nacre from Supramolecular Assembly of Graphene Oxide

Inspired by the “brick-and-mortar” structure and remarkable mechanical performance of nacre, many efforts have been devoted to fabricating nacre-mimicking materials. Herein, a class of graphene oxide (GO) based artificial nacre material with quadruple hydrogen-bonding interactions was fabricated by functionalization of polydopamine-capped graphene oxide (PDG) with 2-ureido-4­[1<i>H</i>]-pyrimidinone (UPy) self-complementary quadruple hydrogen-bonding units followed by supramolecular assembly process. The artificial nacre displays a strict “brick-and-mortar” structure, with PDG nanosheets as the brick and UPy units as the mortar. The resultant nanocomposite shows an excellent balance of strength and toughness. Because of the strong strengthening via quadruple hydrogen bonding, the tensile strength and toughness can reach 325.6 ± 17.8 MPa and 11.1 ± 1.3 MJ m^–3, respectively, thus exceeding natural nacre, and reaching 3.6 and 10 times that of a pure GO artificial nacre. Furthermore, after further H₂O treatment, the resulting H₂O-treated PDG-UPy actuator displays significant bending actuations when driven by heat. This work provides a pathway for the development of artificial nacre for their potential applications in energy conversion, temperature sensor, and thermo-driven actuator