Noble metals can be ionized by electrochemical corrosion and transported by electrospray ionization. Mass spectrometry (MS) showed solvated metal ions as the main ionic constituent of the sprayed droplets. Collection of the electrospray plume on a surface yielded noble metal nanoparticles (NPs) under ambient conditions. The NPs were characterized by several techniques. Under typical conditions, capped-nanoparticle sizes averaged 2.2 nm for gold and 6.5 nm for silver. The gold nanoparticles showed high catalytic activity in the reduction of p-nitrophenol by NaBH4 . Efficient catalysis was also observed by simply directing the spray of solvated Au(+) onto the surface of an aqueous p-nitrophenol/NaBH4 mixture. Organometallic ions were generated by spiking ligands into the spray solvent: for example, Cu(I) bipyridine cations dominated the spray during Cu electrocorrosion in acetonitrile containing bipyridine. This organometallic reagent was shown to be effective in the radical polymerization of styrene.

Here, we report a simple method to control the location of nanoparticles in colloidal block-copolymer assemblies by using nanoparticles modified with mixed surface ligands. The binary self-assembly of amphiphilic polymers of polystyrene-b-poly(acrylic acid) (PS-b-PAA) and gold nanoparticles (AuNPs) modified with a hydrophobic ligand, dodecanethiol (DT), led to polymer micelles with nanoparticles segregated in the core of polymer micelles. On the other hand, AuNPs modified with mixed ligands of mercaptoundecanol (MUL) and DT were distributed at the PS−PAA interface, reducing the interfacial energy between the two polymers. This result was in good agreement with the prediction by the surface energy calculations. We also showed that the AuNPs with mixed ligands can decorate preformed polymer assemblies by the interfacial self-assembly. Furthermore, we demonstrated the compartmentalization of two different types of nanoparticles in colloidal polymer assemblies based on the strategy.

Relay electrospray ionization (rESI) from a capillary containing a sample solution (or from an array of such capillaries) is triggered by charge deposition onto the capillary. Suitable sources of primary ions, besides electrosprays, are plasma ion and piezoelectric discharge plasma sources. With no requirement for physical contact, high-throughput sample screening is enabled by rapidly addressing individual secondary (sample) capillaries. Sub-pL sample volumes can be loaded and sprayed. Polar analytes, including neurotransmitters, phosphopeptides, oligonucleotides, illicit drugs, and pharmaceutical compounds are successfully ionized by rESI with concentration sensitivities (0.1 ppb for acetylcholine) which are similar to nanoESI but absolute sensitivities are orders of magnitude better. Nonpolar analytes (steroids, alkynes) are ionized by rESI using an open-tube secondary capillary and injecting electrolytically generated metal cations from the primary electrospray.

Here, we report the formation of polymer vesicles (polymersomes) uniformly decorated with gold nanoparticles (AuNPs) through the interfacial self-assembly of 11-mercapto-1undecanol (MUL)-stabilized AuNPs and two prototypical amphiphilic polymers (i.e., polystyrene-block-poly(acrylic acid) (PS-b-PAA), poly(ethylene oxide)-block-polylactide (PEO-b-PLA)). The addition of MUL-capped nanoparticles during the self-assembly process was found to stabilize colloidal polymer assemblies that otherwise tend to form macroscopic aggregates in water. Multicompartment polymersomes with complex internal membrane structures were formed at high nanoparticle volume percent, demonstrating that the interfacial assembly of nanoparticles can be used to create interesting new types of polymer assemblies while providing additional functionalities. This strategy offers a simple method for the formation of nanoparticleloaded polymersomes that is applicable to various types of amphiphilic polymers.

Here, we report DNA-induced polymer segregation and DNA island formation in binary block copolymer assemblies. A DNA diblock copolymer of polymethylacrylate-block-DNA (PMA-b-DNA) and a triblock copolymer of poly(butadiene)-block-poly(ethylene oxide)-block-DNA (PBD-b-PEO-b-DNA) were synthesized and each was co-assembled with a prototypical amphiphilic polymer of poly(butadiene)-block-poly(ethylene oxide) (PBD-b-PEO). The binary self-assembly of PMA-b-DNA and PBD-b-PEO resulted in giant polymersomes with DNA uniformly distributed in the hydrophilic PEO shell. When giant polymersomes were connected through specific DNA interactions, DNA block-copolymers migrated to the junction area, forming DNA islands within polymersomes. These results indicate that DNA hybridization can induce effective lateral polymer segregation in mixed polymer assemblies. The polymer segregation and local DNA enrichment has important implications in DNA melting properties, as mixed block copolymer assemblies with low DNA block copolymer contents can still exhibit useful DNA melting properties that are characteristic of DNA nanostructures with high DNA density.