This paper describes the physiochemical, optical and biological activity of chitosan-chromone derivative. The chitosan-chromone derivative gels were prepared by reacting chitosan with chromone-3-carbaldehyde, followed by solvent exchange, filtration and drying by evaporation. The identity of Schiff base was confirmed by UV-Vis absorption spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. The chitosan-chromone derivative was evaluated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), photoluminescence (PL) and circular dichroism (CD). The CD spectrum showed the chitosan-chromone derivative had a secondary helical structure. Microbiological screening results demonstrated the chitosan-chromone derivative had antimicrobial activity against Escherichia coli bacteria. The chitosan-chromone derivative did not have any adverse effect on the cellular proliferation of mouse embryonic fibroblasts (MEF) and did not lead to cellular toxicity in MEFs. These results suggest that the chitosan-chromone derivative gels may open a new perspective in biomedical applications.

Hydrogen peroxide (H(2)O(2)) is an endogenous molecule that plays diverse physiological and pathological roles in living systems. Here we report multimolecule integrated nanoprobes with the enhanced chemiluminescence (CL) response to H(2)O(2) that is produced in cells and in vivo. This approach is based on the nanoscopic coaggregation of a dye exhibiting aggregation-enhanced fluorescence (AEF) with a H(2)O(2)-responsive peroxalate that can convert chemical reaction energy into electronic excitation. The coaggregated CL nanoparticles (FPOA NPs) with an average size of ~20 nm were formulated by aqueous self-assembly of a ternary mixture of a surfactant (Pluronic F-127) and concentrated hydrophobic dye/peroxalte payloads. Spectroscopic studies manifest that FPOA NPs as a reagent-concentrated nanoreactor possess the signal enhancement effect by AEF, as well as the optimized efficiencies for H(2)O(2) peroxalate reaction and subsequent intraparticle energy transfer to the dye aggregates, to yield greatly enhanced CL generation with a prolonged lifetime. It is shown that the enhanced CL signal thereby is capable of detecting intracellular H(2)O(2) overproduced during immune response. We also demonstrate that the densely integrated nature of FPOA NPs facilitates further intraparticle CL energy transfer to a low-energy dopant to red shift the spectrum toward the biologically more transparent optical window, which enables the high-sensitivity in vivo visualization of H(2)O(2) associated with early stage inflammation.

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