A novel red-to-near-infrared AIE fluorescent probe for detection of Hg2+ with large Stokes shift in plant and living cells.

Due to the highly toxic nature of mercury ions to living organisms, accurately detecting Hg2+ in water samples and biological systems is of great significance. In this study, we designed and synthesized a novel red-to-near-infrared Aggregation-Induced Emission (AIE) fluorescent probe (named as DS) based Fluorene derivatives on specifically for Hg2+ detection. Probe DS can visually identify Hg2+ through an red-to-near-infrared fluorescence enhancement change, characterized by a large Stokes shift (130 nm) and AIE feature. This probe offers a fast response, high selectivity and sensitivity. The Hg2+-induced deprotection reaction of the thioketal mechanism was thoroughly investigated using nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS) and density functional theory (DFT) calculation. Additionly, dynamic light scattering (DLS) results indicated that the aggregation states changes of the molecular play a crucial role in the AIE fluorescence response of probe DS toward Hg2+. The red-to-near-infrared response with AIE feature not only avoids the interference of auto-fluorescence signals in complex environments, but also reduces the fluorescence quenching caused by probe molecular aggregation. This makes probe DS highly suitable for high-quality imaging detection of Hg2+ in aqueous environments. Furthermore, probe DS demonstrates the capability for visual fluorescence detection of Hg2+ concentrations in water sample, plant roots and living cells.

Sulfated lignocellulose nanofibril based composite aerogel towards adsorption-photocatalytic removal of tetracycline.

The design-on-demand of lignocellulose nanofibril-based materials for contaminant disposal is worth exploring. Herein, we mildly extract sulfated lignocellulose nanofibrils from bagasse via a deep eutectic solvent-based approach, and use them as a matrix for TiO2 nanoparticles (TNPs) towards adsorption-photocatalytic synergistic removal of tetracycline (TC). The resultant lignocellulose-based nanocomposite aerogel possessing a high specific surface area (95.3 m2/g), surface charge density (1.78 mmol/g) and well-preserved lignocellulosic structure, strongly adsorbed TC with a maximum adsorption capacity of 70 mg/g via a combination of intermolecular interactions (i.e., hydrogen bonding and π-π stacking) and electrostatic forces. Furthermore, the excellent photocatalytic activity of uniformly distributed TNPs in combination with the outstanding adsorption capacity of nanocomposite aerogel can synergistically remove TC in a dynamic and continuous process, during which ~90 % TC (10 mg/L) was efficiently removed within 40 min. HPLC-MS was performed to reveal the degradation pathways of TC. Meanwhile, our developed nanocomposite aerogel demonstrated favorable structural stability and recyclability, which together supported its durability for environmental remediation.

Cationic Lignocellulose Nanofibers from Agricultural Waste as High-Performing Adsorbents for the Removal of Dissolved and Colloidal Substances.

The accumulation of dissolved and colloidal substances (DCS) in the increasingly closed paper circulating water system can seriously lower the productivity and safety of papermaking machines, and it has been a challenge to develop an adsorbent with low cost, high adsorption efficiency and large adsorption capacity for DCS removal. In this study, cationic lignocellulose nanofibers (CLCNF) were obtained by cationic modification of agricultural waste bagasse in deep eutectic solvents (DES) followed by mechanical defibrillation, and then CLCNF were employed as an adsorbent for DCS model contaminant polygalacturonic acid (PGA) removal. CLCNF was characterized by transmission electron microscopy, Fourier transform infrared, elemental analysis, X-ray diffraction, and thermogravimetric analysis. The analytical results confirmed the successful preparation of CLCNF with 4.6-7.9 nm diameters and 0.97-1.76 mmol/g quaternary ammonium groups. The effects of quaternary ammonium group contents, pH, contact time and initial concentration of PGA on the adsorption were investigated in a batch adsorption study. According to the results, the cationic modification significantly enhanced the adsorption of PGA by CLCNF and the adsorption performance increased with the increase of the quaternary ammonium group contents. The adsorption of PGA on CLCNF followed the pseudo-second-order and the fitted Langmuir isotherm model. The adsorption showed fast initial kinetics and the experimental maximum adsorption capacity was 1054 mg/g, which is much higher than PGA adsorbents previously reported in the literature. Therefore, CLCNF with high cationic group content developed in this paper is a promising adsorbent for DCS removal.