POSS-Containing Bioinspired Adhesives with Enhanced Mechanical and Optical Properties for Biomedical Applications

Construction of Fluorescent Conjugated Polytriazole Containing Double-Decker Silsesquioxane: Click Polymerization and Thermal Stability

This study synthesized two azide-functionalized monomers through p-dichloro xylene and double-decker silsesquioxane (DDSQ) units with NaN₃ to form DB-N₃ and DDSQ-N₃ monomers, respectively. In addition, five different propargyl-functionalized monomers were also prepared from hydroquinone, bisphenol A, bis(4-hydroxyphenyl)methanone, 2,4-dihydroxybenzaldehyde (then reacted with hydrazine hydrate solution) and 1,2-bis(4-hydroxyphenyl)-1,2-diphenylethene with propargyl bromide to form P-B, P-BPA, P-CO, P-NP, and P-TPE monomers, respectively. As a result, various DDSQ-based main chain copolymers could be synthesized using Cu(I)-catalyzed click polymerization through DDSQ-N₃ with different propargyl-functionalized monomers, of which the chemical structure and molecular weight could be confirmed by using Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC) analyses. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy analyses also could characterize the thermal stability, morphology, and optical behaviors of these DDSQ-based copolymers. All results indicate that the incorporation of an inorganic DDSQ cage could improve the thermal stability such as thermal decomposition temperature and char yield, because of the DDSQ dispersion homogeneously in the copolymer matrix, and this would then affect the optical properties of NP and TPE units in this work.

Autonomous Bionanorobots via a Cage-Shaped Silsesquioxane Vehicle for In Vivo Heavy Metal Detoxification

Nanorobots hold great promise for integrated drug delivery systems that are responsive to molecular triggers. Herein, we successfully developed an automatic smart bionanorobot that has transport capability and recognizes and removes zinc ions from poisoned cells based on nanoscale polyhedral oligomeric silsesquioxane molecules. This intelligent bionanorobot can easily move inside and outside the cell and find zinc ions owing to its highly selective recognition to zinc ions and high cell permeability, especially the well-combined high penetration and strong binding energy. More importantly, it was also found that this intelligent bionanorobot can restore round HeLa cells to a normal fusiform cell morphology following high-concentration zinc treatment and does not interfere with cell proliferation and division. It was also shown by in vivo experiments that the bionanorobot can inhibit persistent enlargement of the liver caused by zinc ion poisoning.

Fluorescent and Antibacterial Aminobenzeneboronic Acid (ABA)-Modified Gold Nanoclusters for Self-Monitoring Residual Dosage and Smart Wound Care

The replacement of dressings may cause secondary damage to the wounds; thus, the real-time monitoring of the state of wound dressings is crucial for evaluating wound care processes. Herein, we report a smart dressing to self-monitor residue nanomedicine on it during the application. We load aminobenzeneboronic acid (ABA)-modified gold nanoclusters (A-GNCs) on bacterial cellulose (BC) membranes as an antibacterial wound dressing to display the amount of residual nanomedicine (A-GNCs) by in situ colorimetry during the application in remedying multi-drug-resistant (MDR) bacteria-infected wounds. A-GNCs emit bright orange fluorescence under UV light, whereas the BC membrane is transparent at a humidified state on the wounds. Thus, the BC-A-GNCs nanocomposite (BGN) shows decreasing intensity of orange fluorescence with the release of the A-GNCs, indicating the appropriate time points for the replacement of the dressing. The BGN, which can realize accurate self-monitoring in a simple, low-cost, and efficient way, thus holds great promise for broad clinical applications.

Inducing enantioselective crystallization with and self-assembly of star-shaped hybrid polymers prepared via "grafting to" strategy

Helical polymers present some interesting and distinctive properties, and one of the most distinguished applications of them is the chiral recognition and resolution of enantiomers. In this work, star-shaped hybrid helical poly (phenyl isocyanide) (PPI) with polyhedral oligomeric silsesquioxanes (POSS) as the core was designed and synthesized by "grafting to" strategy. The homoarm star-shaped hybrid POSS-(PPI)₈ was first obtained by the click reaction between azide-modified POSS (POSS-(N₃ )₈ ) and alkynyl-modified PPI (PPI-Alkynyl). The hybrid POSS-(PPI)₈ was with predominated left-handed helical conformation and exhibited excellent ability in the enantioselective crystallization of racemic compounds. In the meantime, heteroarm star-shaped hybrid (PEG)₄ -POSS-(PPI)₄ was prepared by the click reaction of POSS-(N₃ )₈ with PPI-Alkynyl and alkynyl-modified poly (ethylene glycol) (PEG-Alkynyl). The hybrid (PEG)₄ -POSS-(PPI)₄ was amphiphilic, and it could self-assemble to form spherical micelles in aqueous solutions.

Modified POSS nano-structures as novel co-initiator-crosslinker: Synthesis and characterization

OBJECTIVE

To synthesize an amine-modified polyhedral oligomeric silsesquioxane (POSS) nano-structure as a novel co-initiator-crosslinker (co-Ini-Linker) and to determine the effect of the co-Ini-linker on the physical and mechanical behavior of an experimental dental composite.

METHODS

The amine-methacrylate POSS nano-structures (AMA-POSS) were chemically synthesized by anchoring a tertiary amine functionality on the methacrylate POSS (MA-POSS) branches. Three types of AMA-POSS, having different amine branches in their structures, were synthesized through the Aza Michael reaction. The chemical structure of AMA-POSSs were evaluated by¹H-NMR spectroscopy. Afterward, the AMA-POSS was incorporated into a dental resin system composed of Bis-GMA, TEGDMA, and photo-initiator. Three resin systems with different AMA-POSS types were then prepared, and their properties were compared with a resin containing DMAEMA as a conventional co-initiator. The degree of conversion evaluated by FTIR spectroscopy and the shrinkage kinetics of the resins were determined through the bonded-disk technique. The flexural properties of the photopolymerized resins were also investigated. The distribution of nano-structures in the matrix resin was analyzed using EDX analysis.

RESULTS

The modified POSS structure and the number of amine branches were confirmed with¹H-NMR spectroscopy. The resin containing 8 amine branches (P8) showed the same degree of conversion (DC%) as the resin containing DMAEMA (P > 0.05). Decreasing the amine branches in the POSS structure, however, revealed an increasing trend in DC%. The resin containing P8 showed the lowest shrinkage strain. By incorporating AMA-POSS into the resin system, the water sorption significantly decreased (P < 0.05). The flexural strength and modulus increased by adding P3 into the resin system (P < 0.05). EDX Si-map revealed that the co-Ini-linker was well dispersed in the resin matrix.

SIGNIFICANCE

The synthesized novel amine-methacrylate POSS nanostructures not only act as an amine co-initiator but also work as a reinforcing filler and a cross-linking agent.

Novel multifunctional nano-hybrid polyhedral oligomeric silsesquioxane-based molecules with high cell permeability: molecular design and application for diagnosis and treatment of tumors

Chemotherapy mostly functions as a carrier for direct drug delivery to the tumor, which may induce secondary damage to healthy tissue cells around the tumor. To avoid this side effect, using multifunctional drugs with high cell permeability during chemotherapy is crucial to achieve significant antitumor efficacy. In this study, polyhedral oligomeric silsesquioxane-based multifunctional organic-inorganic hybrid molecules with potential for recognition, imaging, and treatment were designed and successfully synthesized through a facile and efficient one-pot reaction process. The structure and properties of the synthesized multifunctional molecules were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, mass spectrometry, fluorescence spectroscopy, cytotoxicity assay, surface tension testing, cell compatibility testing, hematoxylin and eosin staining, as well as in vivo and in vitro studies. The results demonstrated that these multifunctional molecules can be effectively used for delivering precisely-targeted imaging and therapeutic agents and exhibited considerable cell permeability. The excellent synergy between high permeability and precise targeting results in multifunctional molecules with superior diagnostic performance.

Synthesis of Monoacryloxypropyl-POSS-based Hybrid Epoxyacrylate Copolymers and Their Application in Thermally Curable Structural Self-Adhesive Tapes

New organic-inorganic hybrid copolymers (EA-POSSs) based on butyl acrylate, glycidyl methacylate, hydroxybutyl acrylate, acryloiloxybenzophenone and acryloxypropyl-heptaisobutyl-POSS (A-POSS) were prepared via free-radical solution polymerization (FRP) and applied as a component of thermally curable structural self-adhesive tapes (SATs). The EA-POSS with 0.25, 0.5 or 1 mol % of A-POSS exhibited significantly higher dynamic viscosity (ca. +104%), Mw (+61%) and polydispersity (+109%; measured using gel permeation chromatography) as well as lower Tg value (-16 °C) in relation to the A-POSS-free copolymer (EA-0). Differential scanning calorimetry (DSC) measurements (one glass transition process) confirmed statistic chain structure of the EA-POSS materials. Replacement of EA-0 by the EA-POSS copolymers in a SATs recipe caused simultaneous improvement of their self-adhesive features, i.e., adhesion (+70%), tack (+21%) and cohesion (+1590%). Moreover, the POSS-based copolymers improved the shear strength of thermally cured Al/SAT/Al overlap joints; the best mechanical resistance (before and after accelerated ageing tests) was observed for the sample containing 0.5 mol % of A-POSS (an increment range of 50-294% in relation to the A-POSS-free joints). Thermogravimetric analysis (TGA) revealed markedly improved thermal stability of the A-POSS-based SATs as well.

POSS Hybrid Robust Biomass IPN Hydrogels with Temperature Responsiveness

In order to improve the performance of traditional sodium alginate (SA) hydrogels cross-linked by Ca2+ ions to meet greater application demand, a strategy was designed to structure novel SA-based gels (named OP-PN gels) to achieve both stimulus responsiveness and improved mechanical strength. In this strategy, the SA chains are co-cross-linked by CaCl₂ and cationic octa-ammonium polyhedral oligomeric silsesquioxane (Oa-POSS) particles as the first network, and an organically cross-linked poly(N-isopropyl acrylamide) (PNIPA) network is introduced into the gels as the second network. Several main results are obtained from the synthesis and characterization of the gels. For OP-PN gels, their properties depend on the content of both uniformly dispersed Oa-POSS and PNIPA network directly. The increased Oa-POSS and PNIPA network content significantly improves both the strength and resilience of gels. Relatively, the increased Oa-POSS is greatly beneficial to the modulus of gels, and the increased PNIPA network is more favorable to advancing the tensile deformation of gels. The gels with hydrophilic PNIPA network exhibit better swelling ability and remarkable temperature responsiveness, and their volume phase transition temperature can be adjusted by altering the content of Oa-POSS. The deswelling rate of gels increases gradually with the increase of POSS content due to the hydrophobic Si⁻O skeleton of POSS. Moreover, the enhanced drug loading and sustained release ability of the target drug bovine serum albumin displays great potential for this hybrid gel in the biomedical field.

Synthesis, self-assembly and self-healing properties of organic–inorganic ABA triblock copolymers with poly(POSS acrylate) endblocks

A novel organic–inorganic ABA triblock copolymer with a poly(acrylate amide) (PAA) midblock and poly(POSS acrylate) [P(POSS)] endblocks was synthesized via sequential reversible addition–fragmentation chain transfer (RAFT) polymerization.

Functional Polyimide/Polyhedral Oligomeric Silsesquioxane Nanocomposites

The preparation of hybrid nanocomposite materials derived from polyhedral oligomeric silsesquioxane (POSS) nanoparticles and polyimide (PI) has recently attracted much attention from both academia and industry, because such materials can display low water absorption, high thermal stability, good mechanical characteristics, low dielectric constant, flame retardance, chemical resistance, thermo-redox stability, surface hydrophobicity, and excellent electrical properties. Herein, we discussed the various methods that have been used to insert POSS nanoparticles into PI matrices, through covalent chemical bonding and physical blending, as well as the influence of the POSS units on the physical properties of the PIs.

Self-Assembly and Applications of Amphiphilic Hybrid POSS Copolymers

Understanding the mechanism of molecular self-assembly to form well-organized nanostructures is essential in the field of supramolecular chemistry. Particularly, amphiphilic copolymers incorporated with polyhedral oligomeric silsesquioxanes (POSSs) have been one of the most promising materials in material science, engineering, and biomedical fields. In this review, new ideas and research works which have been carried out over the last several years in this relatively new area with a main focus on their mechanism in self-assembly and applications are discussed. In addition, insights into the unique role of POSSs in synthesis, microphase separation, and confined size were encompassed. Finally, perspectives and challenges related to the further advancement of POSS-based amphiphilics are discussed, followed by the proposed design considerations to address the challenges that we may face in the future.

Hyperbranched Polysiloxanes Based on Polyhedral Oligomeric Silsesquioxane Cages with Ultra-High Molecular Weight and Structural Tuneability

Hyperbranched siloxane-based polymers with ultra-high molecular weight were synthesized by the Piers–Rubinsztajn reaction between octakis(dimethylsiloxy) octasilsesquioxane with different dialkoxysilanes, using tris(pentafluorophenyl) borane as the catalyst. The origin of the high molecular weight is explained by the high reactivity of the catalyst and strain energy of isolated small molecule in which all eight silane groups close into rings on the sides of a single cubic cage. The structural tuneability was further demonstrated by use of methyl(3-chloropropyl)diethoxysilane, which generates a polymer with similar ultra-high molecular weight. Introduction of phosphonate groups through the chloropropyl sites later leads to functionalized polymers which can encapsulate various transition metal nanoparticles.

Synthesis and adhesion control of glucose-based bioadhesive via strain-promoted azide–alkyne cycloaddition

A glucose-based bioadhesive has been synthesized by radical polymerization. The adhesion was significantly enhanced by biologically safe SPAAC crosslinking after initial attachment on a substrate.

Nanoscale considerations responsible for diverse macroscopic phase behavior in monosubstituted isobutyl-POSS/poly(ethylene oxide) blends

Nanocomposites prepared by incorporating functionalized polyhedral oligomeric silsesquioxane (POSS) into polymer matrices afford a wide range of versatile hybrid materials for use in technologies ranging from cosmetics and pharmaceuticals to sensors and batteries. Here, we investigate the phase behavior of nanocomposites composed of poly(ethylene oxide) (PEO) and monosubstituted isobutyl POSS (iPOSS) modified with different functional moieties. Microscopic analyses of blends containing these iPOSS variants reveal the existence of different macroscopic morphologies and surface topologies. In the presence of octa-iPOSS, a POSS-rich surface cell motif reminiscent of breath patterns develops, whereas addition of allyl-iPOSS promotes the formation of surface plates. While aminopropyl-iPOSS forms dispersed aggregates, maleamic acid-iPOSS disperses in PEO with little effect on PEO crystal morphology. We perform rotational isomeric state Monte Carlo simulations to discern the effect of monosubstitution on the interaction energy between iPOSS and PEO, and establish the molecular-level origin for these observed differences in phase behavior.

Composites of Bacterial Cellulose and Small Molecule-Decorated Gold Nanoparticles for Treating Gram-Negative Bacteria-Infected Wounds

Bacterial infections, especially multidrug-resistant bacterial infections, are an increasingly serious problem in the field of wound healing. Herein, bacterial cellulose (BC) decorated by 4,6-diamino-2-pyrimidinethiol (DAPT)-modified gold nanoparticles (Au-DAPT NPs) is presented as a dressing (BC-Au-DAPT nanocomposites) for treating bacterially infected wounds. BC-Au-DAPT nanocomposites have better efficacy (measured in terms of reduced minimum inhibition concentration) than most of the antibiotics (cefazolin/sulfamethoxazole) against Gram-negative bacteria, while maintaining excellent physicochemical properties including water uptake capability, mechanical strain, and biocompatibility. On Escherichia coli- or Pseudomonas aeruginosa-infected full-thickness skin wounds on rats, the BC-Au-DAPT nanocomposites inhibit bacterial growth and promote wound repair. Thus, the BC-Au-DAPT nanocomposite system is a promising platform for treating superbug-infected wounds.

POSS-Appended Diphenylalanine: Self-Cleaning, Pollution-Protective, and Fire-Retardant Hybrid Molecular Material

Ordered self-assemblies of hybrid molecules have potential as protective umbrellas against environmental pollution and corrosion. This article describes the design and fabrication of a new self-cleaning hybrid molecular material containing polyhedral oligomeric silsesquioxane (POSS) and diphenylalanine as hydrophobic and pollution-protective coating. The colorless organic-inorganic hybrid materials, in which the diphenylalanine motif controls the self-assembly, exhibit unique water resistance property and enhance mechanical strength of paper 1.5-fold. The hybrid building blocks self-assemble in antiparallel sheet manner through noncovalent interactions to form a supramolecular layerlike surface with enhanced roughness. The hybrid material is soluble in organic solvents at room temperature that makes it easy to coat on paper, wood, or metal surfaces. The coating is effective against rusting, corrosion, environmental pollution, and bacterial attack. The coating has been used as fire retardant and enhances fire safety. The sustainable molecular material is promising for the packaging industry and metal industry and artifact preservation.

Catechol- and ketone-containing multifunctional bottlebrush polymers for oxime ligation and hydrogel formation

We report the synthesis of a highly-functional macromonomer, and subsequent crosslinkable poly(ethylene glycol) (PEG)-based bottlebrush polymers prepared via graft-through ring-opening metathesis polymerization (ROMP).

Photo-responsive bio-inspired adhesives: facile control of adhesion strength via a photocleavable crosslinker

A photo-responsive bio-inspired terpolymer adhesives consisting of a zwitterionic polymer, catechol moiety, and nitrobenzyl crosslinker was synthesized for convenient control of adhesion strength under UV irradiation.