Multicolor, injectable BSA-based lanthanide luminescent hydrogels with biodegradability.

Protein hydrogels have attracted increasing attention because of their excellent biodegradability and biocompatibility, but frequently suffer from the single structures and functions. As a combination of luminescent materials and biomaterials, multifunctional protein luminescent hydrogels can exhibit wider applications in various fields. Herein, we report a novel, multicolor tunable, injectable, and biodegradable protein-based lanthanide luminescent hydrogel. In this work, urea was utilized to denature BSA to expose disulfide bonds, and tris(2-carboxyethyl)phosphine (TCEP) was employed to break the disulfide bonds in BSA to generate free thiols. A part of free thiols in BSA rearranged into disulfide bonds to form a crosslinked network. In addition, lanthanide complexes (Ln(4-VDPA)3), containing multiple active reaction sites, could react with the remaining thiols in BSA to form the second crosslinked network. The whole process avoids the use of nonenvironmentally friendly photoinitiators and free radical initiators. The rheological properties and structure of hydrogels were investigated, and the luminescent performances of hydrogels were studied in detail. Finally, the injectability and biodegradability of hydrogels were verified. This work will provide a feasible strategy for the design and fabrication of multifunctional protein luminescent hydrogels, which may have further applications in biomedicine, optoelectronics, and information technology.

Organophosphine as an Alkyl Transfer Shuttle for the Direct ß-Alkylation of Chalcones Using Alkyl Halides.

We report an efficient alkyl transfer strategy for the direct ß-alkylation of chalcones using commercially available alkyl bromides as alkyl reagents. In this transformation, the ortho-phosphanyl substituent in the chalcones is crucial for controlling their reactivity and selectivity. It also serves as a reliable alkyl transfer shuttle to transform electrophilic alkyl bromides into nucleophilic alkyl species in the form of quaternary phosphonium salts and transfer the alkyl group effectively to the ß-position of the chalcones. This alkyl transfer strategy can be further extended to the alkenylation of ortho-phosphanyl benzaldehydes to assemble functionalized polyenes.

Color-tunable, self-healing albumin-based lanthanide luminescent hydrogels fabricated by reductant-triggered gelation.

Luminescent hydrogels show extensive applications in many fields because of their excellent optical properties. Although there are many matrixes used to prepare luminescent hydrogels, the synthesis of protein-based luminescent hydrogels is still urgently needed to explore due to their good biodegradability and biocompatibility. In this work, a color-tunable, self-healing protein-based luminescent hydrogel consisting of bovine serum albumin (BSA) and lanthanide complexes is prepared via reductant-triggered gelation. Firstly, a bifunctional organic ligand named 4-(phenylsulfonyl)-pyridine-2,6-dicarboxylic acid (4-PSDPA) is synthesized, which can react with thiol groups and effectively sensitize the luminescence of Eu3+ and Tb3+ ions. Then, the BSA is treated with a reducing agent tris(2-carboxyethyl)phosphine (TCEP) to produce thiol groups. And the newly formed thiol groups can re-match to form disulfide bonds between two BSA molecules or react with Ln(4-PSDPA)3 complexes, resulting in the formation of an albumin-based luminescent hydrogel. Furthermore, the self-healing, biodegradability and biocompatibility of albumin-based hydrogels have also been demonstrated. We expect that the newly developed multifunctional protein-based hydrogels will find potential applications in the fields of biomedical engineering and optical devices.