4 research outputs found
Silicification of Genipin-Cross-Linked Polypeptide Hydrogels Toward Biohybrid Materials and Mesoporous Oxides
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
The preparation of alkyl chain-grafted
polyÂ(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
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
polyÂ(2-hydroxyethyl methacrylate<i>-<i>co</i>-N</i>-methylolacrylamide<i>-<i>co</i>-</i>nitrobenzoxadiazolyl
derivative) (polyÂ(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.
PolyÂ(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