Mechanochromic luminescence of a bionanocomposite hydrogel

Abstract

Bionanocomposite hydrogels were prepared from gelatin hydrogel and subsequent ionic crosslinking in the presence of the smectite with adsorbed cyanine dye (pseudoisocyanine). In addition to the improved mechanical properties achieved...

Swelling-Induced Chromotropism of Bionanocomposite Hydrogel Beads

“…The PL changed from red to blue ( t = 0–6 min) upon swelling. The blue color is coming from the PIC monomer and gelatin through the aggregation-induced emission mechanism, as reported previously. ,− The change in the PL color between red and blue was induced by the swelling and deswelling of the gel beads, as confirmed by the absorption and PL spectra (Figure d, Movies S2 and S3). The decrease in the PL intensity due to the excimer at 580 nm was observed upon swelling in water, which was associated with an increase in the absorbance due to the monomer band in the absorption spectra (at 520 nm).…”

“…PIC was incorporated into the system by adsorbing it onto smectite (BN) through ion exchange in the aqueous mixture prior to mixing with the aqueous gelatin solution. The concentration of PIC (1.39 × 10 –6 mol PIC per 100 mL of the mixture) was below the Cation Exchange Capacity (CEC) (82 mequiv/100 g smectite) of the smectite in order to prevent the flocculation and to obtain a homogeneous suspension . By inducing the coil-to-helix transition of gelatin chains, physically cross-linked gel beads were successfully synthesized through the dropwise addition of an aqueous mixture in ice-cooled olive oil.…”

“…Biopolymer hydrogels warrant exploration for their application, particularly in the biomedical field, due to their biocompatible and environmentally friendly characteristics, which surpass those of synthetic polymers. The introduction of inorganic particles enhances the (bio)­chemical, thermal, and mechanical characteristics of hydrogels, ultimately resulting in adjustable functionalities. − The polymer nanocomposite hydrogels have been developed by Haraguchi et al to find large and reversible volume changes superior to the conventional chemically cross-linked hydrogels and impart stimuli-responsiveness using water-swellable clay minerals (smectite group of clay minerals as the common examples) and poly­( N -isopropylacrylamide). ,,− Taking advantage of the water-swellable clay minerals, the concept was extended recently to obtain a bionanocomposite containing gelatin with 1,1′-diethyl-2,2′-cyanine (pseudoisocyanine, PIC) adsorbed on smectite to find novel PL mechanochromism upon uniaxial stretching, and the phenomena was explained by the formation and the disruption of PIC J-aggregate on the smectite surface . We have reported the mechanochromic response of the PL from PIC adsorbed on smectite.…”

Mechanochromic luminescence of phase-separated hydrogels that contain cyclophane mechanophores

“…[1][2][3] The incorporation of a mechanism that enables the evaluation and visualisation of mechanical stimuli applied to hydrogels would be useful for understanding the nanomechanics in hydrogels, leading to longer lifetimes. Over the years, several mechanochromic hydrogels have been developed using fluorescence resonance energy transfer (FRET) pairs, 4 polarity-sensing dyes such as 8-anilino-1-naphthalenesulfonic acid (ANS), 5 dyegrafted prepolymer, 6 aggregation of fluorophores, 7 or structural colour change. 8 The introduction of mechanochromic mechanophores is another promising method for studying the force applied to polymer chains in hydrogels.…”

Recent Advances in Mechano-responsive Fluorescent Organic and Organometallic Compounds: Structural Diversity, Phase Transformation and Applications

“…[161] As a consequence of the slipping of LDH sheets, the molecular conformation of NFC anions and their intermolecular interactions with LDHs were easily tuned by applying perturbations. [162] XRD-based investigations conducted on the NFC/LDH system suggested that grinding resulted in an increase in the sample's interlayer spacing. This modification further influenced the samples' fluorescent properties.…”