Synthesis of organic-solvent-soluble cellulose and preparation of fluorescent polyurethanes for the detection and removal of Hg+ ions

Modifying cellulose to obtain materials with favorable processing properties and functions is highly significant, especially, for the detection and removal of heavy metal ions. In this study, fluorescent cellulose-based polyurethane (PU) films containing naphthalimide fluorophore were synthesized and could use for the convenient detection and removal of Hg+ ions. Firstly, the microcrystalline cellulose was treated with SOCl2 to convert some -OH groups into -Cl. Simultaneously, a naphthalimide derivative (NAN) with -NH- groups was synthesized. Subsequently, a fluorescent cellulose-based probe (Cel-NAN) was prepared by utilizing the substitution reaction between -Cl on cellulose and -NH- on NAN. Finally, two cellulose-based fluorescent PU films (Cel-NAN-PU1 and Cel-NAN-PU2) were successfully synthesized by reacting the unreacted -OH groups on Cel-NAN with PEG-1000 and HDI/IPDI. These as-prepared PU films could serve as portable fluorescence test papers to Hg+ ions in aqueous solutions. Upon contact with Hg+ ions, the fluorescence was quenched, acting as a "turn-off" probe. Simultaneously, these films could serve as adsorbents for the removal of Hg+ ions from aqueous systems. Cel-NAN-PU1 film exhibited a removal efficiency over 80 % and an adsorption capacity of 8.4 mg·cm-2 for Hg+. These cellulose-based fluorescent PU films possess promising potential in the field of mercury pollution control.

Phenothiazine-chitosan based eco-adsorbents: A special design for mercury removal and fast naked eye detection

The aim of the paper was to investigate the ability of an eco-friendly luminescent xerogel prepared by chitosan crosslinking with a phenothiazine luminogen to detect and remove heavy metals. Its ability to give a divergent morphological and optical response towards fifteen environmental relevant metals was investigated by naked eye and UV lamp, fluorescence spectroscopy and scanning electron microscopy. A distinct response was noted for mercury, consisting in the transformation of the xerogel into a rubber-like material accompanied by the red shifting of the color of emitted light from yellow-green to greenish-yellow domain. The particularities of the metals anchoring into the xerogel were analyzed by FTIR spectroscopy and X-ray diffraction. The morphological changes and the metal uptake were analyzed by SEM-EDAX, swelling and gravimetric methods. It was concluded that mercury has a superior affinity towards this heteroatoms rich system, leading to a secondary crosslinking. This directed a great absorption capacity of 1673 mg/g and a specific morphological response for mercury ion concentrations up to 0.001 ppm.

Multifunctional polyurethane sponge for polymerase chain reaction enhancement

Selective filtering of target biomaterials from impurities is an important task in DNA amplification through polymerase chain reaction (PCR) enhancement and gene identification to save endangered animals and marine species. Conventional gene extraction methods require complicated steps, skilled persons, and expensive chemicals and instruments to improve DNA amplification. Herein, we proposed an alternative method for overcoming such challenges by imparting secondary functionality using commercially available polyurethane (PU) sponges and cost-effective fabrication approaches through polydopamine and polysiloxane coatings. The porous, highly flexible, and chemically modified superhydrophilic and superhydrophobic PU sponges allow large surface areas and mechanically stable frames for effective extraction of genomic DNA through selective filtering of fish tissues and oils. Furthermore, these chemically modified PU sponges allow separation of genes and improvement of PCR for DNA amplification for the identification of fish species. The combination of a simple fabrication method and functionalized PU sponges could be a useful platform for PCR enhancement and gene-based identification of species for practical applications.