The glutathione-mediated retro Michael-type addition reaction is demonstrated to take place at the interface of small water-soluble maleimide-functionalized gold nanoparticles (Maleimide-AuNP). The retro Michael-type addition reaction can be blocked by hydrolyzing the Michael addition thioether adduct at the nanoparticle's interface under reaction conditions that do not cause AuNP decomposition. This procedure "locks" the molecule of interest onto the Maleimide-AuNP template for potential uses in medical imaging and bioconjugation, ensuring no loss of the molecular cargo from the nanocarrier. On the other hand, the glutathione-mediated retro Michael-type addition reaction can be exploited for delivering a molecular payload. As a proof of concept, a fluorogenic molecular cargo was incorporated onto a Maleimide-AuNP and delivered via the glutathione-mediated retro Michael-type addition reaction.

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3-Aryl-3-(trifluormethyl)diazirine functionalized highly fluorinated phosphonium salts (HFPS) were synthesized, characterized, and utilized as photoinduced carbene precursors for covalent attachment of the HFPS onto cotton/paper to impart hydrophobicity to these surfaces. Irradiation of cotton and paper, as proof of concept substrates, treated with the diazirine-HFPS leads to robust hydrophobic cotton and paper surfaces with antiwetting properties, whereas the corresponding control samples absorb water readily. The contact angles of water were determined to be 139° and 137° for cotton and paper, respectively. In contrast, water placed on the untreated or the control samples (those treated with the diazirine-HFPS but not irradiated) is simply absorbed into the surface. Additionaly, the chemically grafted hydrophobic coating showed high durability toward wash cycles and sonication in organic solvents. Because of the mode of activation to covalently tether the hydrophobic coating, it is amenable to photopatterning, which was demonstrated macroscopically.

A novel bioorthogonal gold nanoparticle (AuNP) template displaying interfacial nitrone functional groups for bioorthogonal interfacial strain-promoted alkyne–nitrone cycloaddition reactions has been synthesized. These nitrone–AuNPs were characterized in detail using 1H nuclear magnetic resonance spectroscopy, transmission electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy, and a nanoparticle raw formula was calculated. The ability to control the conjugation of molecules of interest at the molecular level onto the nitrone–AuNP template allowed us to create a novel methodology for the synthesis of AuNP-based radiolabeled probes.

Maleimide‐terminated triethylene glycol thiolate monolayer‐protected gold nanoparticles (Mal‐EG4‐AuNPs) with a core size of 2.5 ± 0.7 nm were prepared. Mal‐EG4‐AuNPs were modified in high yields via interfacial 1,3‐dipolar cycloaddition and Diels–Alder reactions with a variety of nitrones and dienes, respectively. The resulting cycloadduct‐modified AuNPs were characterized using 1H NMR spectroscopy and were verified by comparison of the spectra to those of the products of the model reactions with the same nitrones and dienes. TEM analysis showed that the reaction conditions did not affect the shape or size of the gold core, suggesting that this is an efficient methodology to modify small water soluble AuNPs under ambient pressure and biological temperature with high yields and a reasonable reaction time.

Photolysis of diazirine modified small (3.9 AE 0.9 nm) gold nanoparticles (AuNP) generates a reactive interfacial carbene that then reacts via an insertion reaction to covalently attach the AuNP onto glassy carbon (GC) electrodes. This yields GC surfaces that are densely and homogeneously functionalized with AuNP. The AuNP hybrid glassy carbon electrode has been characterised by atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The system is found to be robust to physical and electrochemical stresses due to the covalent bond between the AuNP and the surface formed through the carbene insertion reaction. The conductivity of the AuNP functionalized GC electrode is found to be similar to clean GC, and the AuNP serve to switch on electron transfer. The AuNP can be oxidatively desorbed from the electrode at surprisingly low potential (0.99 V). This yields a monolayer of insulator thiol/thiolate ligands that previously anchored the AuNP to the GC, which gives an interesting switch off effect of the electron transfer. We demonstrate that because the method is photoinitiated this methodology allows for spatial control and the AuNP, which can be photopatterned onto GC surfaces easily. The high stability, the good electrical conductivity, the facility of making patterns, and the ability to tune the physical and chemical properties of AuNP through its ligands, make this new functionalization method suitable for the development of sensors and electronic devices.

A bioorthogonal gold nanoparticle template displaying interfacial nitrone functional groups for bioorthogonal interfacial strain-promoted alkyne-nitrone cycloaddition (I-SPANC) reactions has been synthesized. The Nitrone-AuNPs were characterized in detail using ¹H NMR spectroscopy, TEM, TGA, and XPS and a nanoparticle raw formula was calculated. The ability to control the conjugation of molecules of interest at the molecular level onto the Nitrone-AuNPs template allowed us to create a methodology for the synthesis of AuNP-based radiolabeled probes with a high degree of loading using copper free, strained-promoted cycloaddition. To this end, we also describe the synthesis of a new prosthetic group containing a strained-alkyne capable of clicking hot ¹⁸F-label onto complementary azide or nitrone labelled agents.