More Like this

1. Polymer Ligands with Quaternary Ammonium Binding Motifs on Metal Nanoparticles Enable Selective Ion Transport for CO ₂ Electroreduction

   https://doi.org/10.1002/ange.202516071  

   Muhuri, Debasmita; Sarkar, Manthan; Duan, Hanyi; Hanson, Lindsey A; He, Jie (September 2025, Angewandte Chemie)

   Abstract We report a new class of hydrophobic polymer ligands with quaternary ammonium head groups for surface modification of noble metal nanoparticles (NPs). Quaternary ammonium ligands bind NPs through non‐covalent electrostatic interactions, producing polymer‐grafted NPs with high colloidal and chemical stability. These polymers having charged head groups offer powerful strategies to tailor the structure and function of metal‐electrolyte interfaces in electrocatalytic systems. The ammonium head groups serve as ionic reservoirs that preconcentrate bicarbonate counterions at the surface of nanocatalysts, while the hydrophobic polymer backbones restructure local hydrogen‐bonding networks, modulating water and ion transport dynamics. These interfacial effects promote CO₂electroreduction, particularly under diffusion‐limited conditions, resulting in a CO Faradaic efficiency (FE) exceeding 90%. 

   more » « less
2. Polymers on plasmonic metal nanoparticles: From symmetric coating to asymmetric surface patterning

   https://doi.org/10.1016/j.polymer.2024.127115  

   Duan, Hanyi; Muhuri, Debasmita; He, Jie (May 2024, Polymer)

   We summarize recent advances in the design of hybrid nanostructures through the combination of synthetic polymers and plasmonic nanoparticles (NPs). We categorize the synthetic methods of those polymer-coated metal NPs into two main strategies: direct encapsulation and chemical grafting, based on how NPs interact with polymers. In direct encapsulation, NPs with hydrophobic ligands are physically encapsulated into polymer micelles, primarily through hydrophobic interactions. We discuss strategies for controlling the loading numbers and locations of NPs within polymer micelles. On the other hand, polymer-grafted NPs (PGNPs) have synthetic polymers as ligands chemically grafted on NPs. We highlight that polymer ligands can asymmetrically coat metal NPs through hydrophobicity-driven phase segregation using homopolymers, BCPs and blocky random copolymers. This review provides insights into the methodologies and mechanisms to design new nanostructures of polymers and NPs, aiming to enhance the understanding of this rapidly evolving field. 

   more » « less
3. Do polymer ligands block the catalysis of metal nanoparticles? Unexpected importance of binding motifs in improving catalytic activity

   https://doi.org/10.1039/D0TA03906C  

   Zhang, Lei; Wei, Zichao; Meng, Michael; Ung, Gaël; He, Jie (August 2020, Journal of Materials Chemistry A)

   null (Ed.)

   Metal nanoparticles (NPs) tethered by synthetic polymers are of broad interest for self-assembly, nanomedicine and catalysis. The binding motifs in polymer ligands usually as the end functional groups of polymers are mostly limited to thiolates. Since the binding motif only represents a tiny fraction of many repeating units in polymers, its importance is often ignored. We herein report the uniqueness of polymeric N-heterocyclic carbene (NHC) ligands in providing oxidative stability and promoting the catalytic activity of noble metal NPs. Two “grafting to” methods were developed for polymer NHCs for pre-synthesized metal NPs in various solvents and with different sizes. Remarkably, imidazolium-terminated polystyrene can modify gold NPs (AuNPs) within 2 min while reaching a similar grafting density to polystyrene-thiol (SH) requiring 6 h modification. We demonstrate that polymer NHCs are extremely stable at high temperature in air. Interestingly, the binding motifs of polymer ligands dominate the catalytic activity of metal NPs. Polymer NHC modified metal NPs showed improved activity regardless of the surface crowdedness. In the case of AuNPs, AuNPs modified with polystyrene NHCs are approximately 5.2 times more active than citrate-capped ones and 22 times more active than those modified with polystyrene thiolates. In view of ligand-controlled catalytic properties of metal NPs, our results illustrate the importance of binding motifs that has been overlooked in the past. 

   more » « less
4. Aggregation and gelation in a tunable aqueous colloid–polymer bridging system

   https://doi.org/10.1063/5.0101697  

   Gallegos, Mariah J.; Soetrisno, Diego D.; Park, Nayoung; Conrad, Jacinta C. (September 2022, The Journal of Chemical Physics)

   We report a colloid–polymer model system with tunable bridging interactions for microscopic studies of structure and dynamics using confocal imaging. The interactions between trifluoroethyl methacrylate-co-tert-butyl methacrylate copolymer particles and poly(acrylic acid) (PAA) polymers were controllable via polymer concentration and pH. The strength of adsorption of PAA on the particles, driven by pH-dependent interactions with polymer brush stabilizers on the particle surfaces, was tuned via solution pH. Particle–polymer suspensions formulated at low pH, where polymers strongly adsorbed to the particles, contained clusters or weak gels at particle volume fractions of ϕ = 0.15 and ϕ = 0.40. At high pH, where the PAA only weakly adsorbed to the particle surface, particles largely remained dispersed, and the suspensions behaved as a dense fluid. The ability to visualize the suspension structure is likely to provide insight into the role of polymer-driven bridging interactions in the behavior of colloidal suspensions. 

   more » « less
5. Robust Synthesis of Targeting Glyco‐Nanoparticles for Surface Enhanced Resonance Raman Based Image‐Guided Tumor Surgery

   https://doi.org/10.1002/smsc.202300154  

   Liu, Kunli; Ullah, A. K.; Juhong, Aniwat; Yang, Chia‐Wei; Yao, Cheng‐You; Li, Xiaoyan; Bumpers, Harvey L.; Qiu, Zhen; Huang, Xuefei (February 2024, Small Science)

   Surface enhanced resonance Raman (SERS) is a powerful optical technique, which can help enhance the sensitivity of Raman spectroscopy aided by noble metal nanoparticles (NPs). However, current SERS‐NPs are often suboptimal, which can aggregate under physiological conditions with much reduced SERS enhancement. Herein, a robust one‐pot method has been developed to synthesize SERS‐NPs with more uniform core diameters of 50 nm, which is applicable to both non‐resonant and resonant Raman dyes. The resulting SERS‐NPs are colloidally stable and bright, enabling NP detection with low‐femtomolar sensitivity. An algorithm has been established, which can accurately unmix multiple types of SERS‐NPs enabling potential multiplex detection. Furthermore, a new liposome‐based approach has been developed to install a targeting carbohydrate ligand, i.e., hyaluronan, onto the SERS‐NPs bestowing significantly enhanced binding affinity to its biological receptor CD44 overexpressed on tumor cell surface. The liposomal hyaluronan (HA)‐SERS‐NPs enabled visualization of spontaneously developed breast cancer in mice in real time guiding complete surgical removal of the tumor, highlighting the translational potential of these new glyco‐SERS‐NPs. 

   more » « less