4 research outputs found

    Silicification of Genipin-Cross-Linked Polypeptide Hydrogels Toward Biohybrid Materials and Mesoporous Oxides

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    A simple and versatile approach is proposed to use cross-linked polypeptide hydrogels as templates for silica mineralization, allowing the synthesis of polypeptide–silica hybrid hydrogels and mesoporous silica (meso-SiO<sub>2</sub>) by subsequent calcination. The experimental data revealed that the cross-linked polypeptide hydrogels comprised of interconnected, membranous network served as templates for the high-fidelity transcription of silica replicas spanning from nanoscale to microscale, resulting in hybrid network comprised of interpenetrated polypeptide nanodomains and silica. The mechanical properties of these as-prepared polypeptide–silica hybrid hydrogels were found to vary with polypeptide chain length and composition. The synergy between cross-link, hydrophobic interaction, and silica deposition can lead to the enhancement of their mechanical properties. The polypeptide–silica hybrid hydrogel with polypeptide and silica content as low as 1.1 wt % can achieve 114 kN/m<sup>2</sup> of compressive strength. By removing the polypeptide nanodomains, mesoporous silicas with average pore sizes ranged between 2 nm and 6 nm can be obtained, depending on polypeptide chain length and composition. The polypeptide–silica hybrid hydrogels demonstrated good cell compatibility and can support cell attachment/proliferation. With the versatility of polymer chemistry and feasibility of amine-catalyzed sol–gel chemistry, the present method is facile for the synthesis of green nanocomposites and biomaterials

    Alkyl Chain-Grafted Poly(l‑lysine) Vesicles with Tunable Molecular Assembly and Membrane Permeability

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    The preparation of alkyl chain-grafted poly­(l-lysine) (PLL) vesicles with tunable molecular assembly in aqueous solution and the evaluation of their membrane permeability by drug release experiments have been investigated. Upon grafting long alkyl chains, polypeptides confined in the assembled nanostructures adopted ordered conformations such as α-helices or β-sheets/turns, leading to the dense packing of membranes and, consequently, the decreases in vesicular size and membrane permeability. The vesicles can also be cross-linked by genipin to form stable structures with tunable membrane permeability. Additionally, these vesicles exhibited noticeable pH-sensitive behavior, depending on the grafted alkyl chain and cross-linking

    Novel Highly Selective and Reversible Chemosensors Based on Dual-Ratiometric Fluorescent Electrospun Nanofibers with pH- and Fe<sup>3+</sup>-Modulated Multicolor Fluorescence Emission

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    Novel dual-ratiometric fluorescent electrospun (ES) nanofibers featuring high sensitivity for pH and ferric ion (Fe<sup>3+</sup>) were prepared using binary blends of poly­(2-hydroxyethyl methacrylate<i>-<i>co</i>-N</i>-methylolacrylamide<i>-<i>co</i>-</i>nitrobenzoxadiazolyl derivative) (poly­(HEMA<i>-<i>co</i>-</i>NMA<i>-<i>co</i>-</i>NBD)) and a spirolactam rhodamine derivative (SRhBOH) by employing a single-capillary spinneret. The HEMA, NMA, and NBD moieties were designed to exhibit hydrophilic properties, chemical cross-linking, and fluorescence (fluorescence resonance energy transfer (FRET) donor), respectively. The fluorescence emission of SRhBOH was highly selective for pH and Fe<sup>3+</sup>; when SRhBOH detected acidic media and Fe<sup>3+</sup>, the spirocyclic form of SRhBOH, which is nonfluorescent, was transformed into the opened cyclic form and exhibited strong fluorescence emission. The emission colors of ES nanofibers in acidic or Fe<sup>3+</sup> aqueous solutions changed from green to red because of FRET from NBD (donor) to SRhBOH (acceptor). The off/on switching of the FRET process was modulated by adjusting the SRhBOH blending ratio, pH, and Fe<sup>3+</sup> concentration. Poly­(HEMA<i>-<i>co</i>-</i>NMA<i>-<i>co</i>-</i>NBD) ES fibers blended with 20% SRhBOH showed high sensitivity in sensing Fe<sup>3+</sup> and pH because of the substantial 57 nm red shift in emission as well as substantial reversible dual photoluminescence. The prepared FRET-based dual-ratiometric fluorescent ES nanofibrous membranes can be used as “naked eye” sensors and have potential for application in multifunctional environment sensing devices
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