Caging Cationic Polymer Brush‐Coated Plasmonic Nanostructures for Traceable Selective Antimicrobial Activities

Abstract

Cationic polymers are under intense research to achieve prominent antimicrobial activity. However, the cellular and in vivo toxicity caused by nonspecific electrostatic interaction has become a major challenge for their practical applications. Here, the development of a “caging” strategy based on the use of a block copolymer consisting of a stealth block and an anionic block that undergoes degradation in presence of enzymes secreted by selective bacterial pathogens of interest is reported. The results have shown that antimicrobial cationic polymer brushes‐coated gold nanorods (AuNRs) can be caged by the block polymer of poly(ethylene glycol) and anionic, lipase‐degradable block of ε‐caprolactone and methacrylic acid copolymer to afford neutrally charged surfaces. The caged AuNRs are activated by lipase released by bacteria of interest to endow an excellent bactericidal effect but show minimal binding and toxicity against mammalian cells and nonspecific bacteria that do not produce lipase. In this design, AuNRs play multifunctional roles as the scaffolds for polymer brushes, photothermal transducers, and imaging probes for traceable delivery of the activation and delivery of bactericidal cationic polymer brushes. The caging strategy opens new opportunities for the safe delivery of antimicrobial materials for the treatment of bacterial infections.

Spacer Matters: All-Peptide-Based Ligand for Promoting Interfacial Proteolysis and Plasmonic Coupling

“…This plasmonic coupling led to protease concentration- and time-dependent color changes from red to pink/purple (Figure h). A typical blue colored aggregation, however, was not observed due to trade-off of the polyPro scaffold at improving enzyme accessibility while restricting close proximity of neighbor metallic cores. ,, It is not unusual that assay time at hour scale was needed to maximize color changes due to ( i ) a low k cat / K M and ( ii ) irregular enzymatic kinetic at cumbersome bio-NP interfaces. , Notably, ESI-MS measured the NP supernatant after proteolysis with the liberated Asp-rich fragment, D 4 AVLQ (Figure S 1s). In contrast, negative control monitored the CM-P 7 –AuNPs without M pro and showed no color change (Figure i).…”

“…7,60,61 It is not unusual that assay time at hour scale was needed to maximize color changes due to (i) a low k cat /K M 52 and (ii) irregular enzymatic kinetic at cumbersome bio-NP interfaces. 62,63 Notably, ESI-MS measured the NP supernatant after proteolysis with the liberated Asp-rich fragment, D 4 AVLQ (Figure S 1s). In contrast, negative control monitored the CM-P 7 −AuNPs without M pro and showed no color change (Figure 3i).…”

Recent advances in responsive antibacterial materials: design and application scenarios

“…In this case, PCL-containing anionic polymer could be used to neutralize the positive charge toxic cationic agents, whose antimicrobial activity could only be recovered once the PCL is degraded to remove the "cage" by lipase. Accordingly, cationic poly(2-(methylamino)ethyl methacrylate) (PDMA) 64 and Ga 3+ ions 65 were used in this strategy, respectively, exhibiting lipase-responsive release of cargos. In addition to PCL, fatty acid esters are the natural substrate of lipase, and the derived materials have also been utilized as lipase-sensitive carriers for the delivery of antibiotics.…”

Creating Anti‐Biofouling Surfaces by Degradable Main‐chain Polyphosphoester Polymer Brushes

“…[8][9][10] Degradable brushes have also been used as marine antifouling coatings and in separation technologies, catalysis, and sensing for e.g., micro-electronic devices. [11][12][13][14] One of the most prevalent polymers in antibiofouling brushes relies on poly(ethylene glycol) (PEG)-based brushes. PEG-based coatings have long been recognized for their capacity to block unspecific protein adsorption and cellular adhesion.…”