Development of light-emitting polymers is usually hampered by inherent drawbacks such as photobleaching, stability, and functionalization issues. Formation of biocompatible, luminescent polymer particles often entails hazardous chemical cross-linking processes and/or doping with fluorophores susceptible to leaching and photobleaching. Here we describe the formation of size-tunable phosphorescent particles via self-assembly of chitosan and other linear polymers that bear positive surface charges upon polyelectrolytic complexation to a polyanionic gold(I) phosphor (AuP). The in situ self-assembly of phosphorescent chitosan nanoparticles is enabled by AuP that performs a quadruple role: a physical cross-linker, light emitter, sensor of polysaccharide rings with structures akin to those of some cancer markers, and contrast agent for electron microscopy. Size tunability in phosphorescent chitosan particles was achieved by systematic variations in pH or reactant concentrations. AuP exhibits “on–off” photoluminescence (PL) switching induced by several amine-bearing linear polymers, rendering the phosphorescent nanocomposites particularly attractive for biological imaging and sensing applications. Finally, combination of AuP-chitosan with a Pt-based orange-red phosphor leads to white-emitting thin films with high color-rendering index, remarkable stability, and PL quantum yields as high as 78% with <2% photobleaching. These properties render such thin films useful for applications in lighting and electronic displays.

The synthesis of medium-ring heterocycles remains a challenge largely due to unfavorable energetic factors. We are reporting syntheses of 7–9-member diaza heterocycles that go to completion in 5 min, require no solvents, and are quantitative with the only byproducts being acetone and water. The reaction products could be isolated in pure form by simply placing the mixture under vacuum. The reaction sequence possesses many of the hallmarks of a click reaction.

Biological screening of one-bead, one-compound (OBOC) combinatorial peptide libraries is routinely carried out with the peptide remaining bound to the resin bead during screening. After a hit is identified, the bead is isolated, the peptide is cleaved from the bead, and its sequence is determined. We have developed a new technique for cleavage of peptides from resin beads whereby exposure of a 4-hydroxymethyl benzoic acid (HMBA)-linked peptide to high-pressure ammonia gas led to efficient cleavage in as little as 5 min. Here we also report a new method of extracting peptide from individual library beads for its introduction into a mass spectrometer that uses nanomanipulation combined with nanoelectrospray ionization mass spectrometry (NSI MS). Single beads analyzed by nanomanipulation/NSI MS were found to give identical MS results to those of bulk samples. Detection of 18 unique cleaved peptides 1 to 8 amino acids in length, and sequencing of 14 different peptide sequences 4 to 8 amino acids in length, was demonstrated on a combination of bulk samples and ones from individual beads of an OBOC library. The method was highly reproducible, with 100% of attempts to extract peptide resulting in high-quality MS data. This new collection of techniques allows rapid, reliable, environmentally responsible sequencing of hit beads from combinatorial peptide libraries.