Bacterial infection poses a massive threat to our society, and bacterial biofilm is a major cause of chronic and recurrent infections. The treatment of bacterial biofilms represents a challenging task, and the development of antibacterial materials that can not only disperse bacterial biofilms but also kill bacteria is of increasing interest. Herein, we report the fabrication of well-defined nitric oxide (NO)-releasing amphiphiles, poly­(ethylene oxide)-b-polyCouNO (PEO-b-PCouNO), where CouNO is an N-nitrosoamine-based NO donor containing a coumarin chromophore, exhibiting visible-light-mediated and self-reporting NO-release behavior. Unlike conventional polymeric NO donors derived from N-diazeniumdiolate (NONOates) or N-nitrosothiol (SNOs) that could be only synthesized via the postmodification procedure due to poor stability, the newly developed N-nitrosoamine-based NO donors can be directly polymerized into amphiphiles using reversible addition-fragmentation chain transfer (RAFT) polymerization. The NO-releasing amphiphiles self-assembled into micelles and selective NO release in aqueous medium was achieved by irradiating the micelle solution with visible light, which was characterized by a remarkable fluorescence turn-on (>185-fold), thereby enabling in situ self-reporting NO release. The photoinduced NO release can efficiently disperse bacterial biofilm of Pseudomonas aeruginosa. Moreover, antibiotics (e.g., Ciprofloxacin, Cip) could be loaded into the NO-releasing micelles, and co-delivery of NO and Cip was achieved, allowing for simultaneous biofilm dispersal and bacterial killing. This work provides a new strategy to fabricate macromolecular NO donors, which can efficiently avoid uncontrolled NO leakage and display promising antibacterial applications.

Metal–organic frameworks (MOFs) comprising metal ions or clusters coordinated to organic ligands have become a class of emerging materials in the field of biomedical research due to their bespoke compositions, highly porous nanostructures, large surface areas, good biocompatibility, etc. So far, many MOFs have been developed for imaging and therapy purposes. The unique porous nanostructures render it possible to adsorb and store various substances, especially for gaseous molecules, which is rather challenging for other types of delivery vectors. In this review, we mainly focus on the recent development of MOFs for controlled release of three gaseous transmitters, namely, nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S). Although these gaseous molecules have been known as air pollutants for a long time, much evidence has been uncovered regarding their important physiological functions as signaling molecules. These signaling molecules could be either physically absorbed onto or covalently linked to MOFs, allowing for the release of loaded signaling molecules in a spontaneous or controlled manner. We highlight the designing concept by selective examples and display their potential applications in many fields such as cancer therapy, wound healing, and anti-inflammation. We hope more effort could be devoted to this emerging fields to develop signaling molecule-releasing MOFs with practical applications.

The development of new antibacterial agents that can efficiently eradicate biofilms is of crucial importance to combat persistent and chronic bacterial infections. Herein, the fabrication of photoresponsive vesicles capable of the sequential release of nitric oxide (NO) and gentamicin sulfate (GS) is reported, which can not only efficiently disperse Pseudomonas aeruginosa (P. aeruginosa) PAO1 biofilm but also kill the planktonic bacteria. Well‐defined amphiphilic diblockcopolymers of poly(ethylene oxide)‐b‐poly(4‐((2‐nitrobenzyl)(nitroso)amino)benzyl methacrylate) (PNO) is first synthesized through atom transfer radical polymerization (ATRP). The PNO diblock copolymer self‐assembled into vesicles in aqueous solution, and a hydrophilic antibiotic of GS is subsequently encapsulated into the aqueous lumens of vesicles. The vesicles undergo visible light‐mediated N‐NO cleavage, releasing NO and disintegrating the vesicles with the release of the GS payload. The sequential release of NO and GS efficiently eradicate P. aeruginosa PAO1 biofilm and kill the liberated bacteria, showing a better antibiofilm effect than that of NO or GS alone.

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