A simple method to synthesize phosphine-stabilized gold nanoparticles (AuNPs) of narrow size dispersion using the mild reducing agent 9-borabicyclo[3.3.1]nonane (9-BBN) is described. The methodology produces particles 1.2-2.8 nm in size depending on the reaction conditions and the phosphine ligand used. The phosphine-stabilized AuNPs exhibit size dependent localized surface plasmon resonance (LSPR) behavior as measured by UV-visible spectroscopy. (31)P NMR spectroscopy analysis of triphenylphosphine-AuNPs (TPP-AuNPs) shows a peak shift to 63.0 ppm compared to pure TPP at -5.4 ppm which is attributed to adsorption of TPP on the AuNP surface. Synthesis of trioctylphosphine-stabilized AuNPs demonstrates the versatility of the 9-BBN-based method. We present initial investigations of using TPP-AuNPs as precursor materials for nanoparticles functionalized with other ligands through ligand exchange reactions with dodecanethiol (DDT) and 11-mercaptoundecanoic acid (MUA).

We report a simple route to produce fluorophore-encapsulated gold nanoparticles (AuNPs) in a single step under aqueous conditions using the fluorophore 1-pyrenemethylamine (PMA). Different amounts of PMA were used and the resulting core-shell gold nanoparticles were analyzed using UV-visible absorption spectroscopy, fluorescence spectroscopy, and transmission and scanning electron microscopy. Electron microscopy analysis shows nanoparticles consisting of a gold nanoparticle core which is encapsulated with a lower contrast shell. In the UV-visible spectra, we observed a significant red shift (37 nm) of the localized surface plasmon resonance (LSPR) absorption maximum (lambda(max)) compared to citrate-stabilized AuNPs of a similar size. We attribute the prominent LSPR wavelength shift for PMA-AuNP conjugates to the increase in the local dielectric environment near the gold nanoparticles due to the shell formation. This simple, aqueous-based synthesis is a new approach to the production of fluorophore-encapsulated AuNPs that could be applicable in biological sensing systems and photonic device fabrication.

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Over the years, there has been a greater emphasis on chemical safety than on chemical security training in academic institutions in Kenya a trend that has continued in the industry where chemical safety training is emphasized. The gaps in chemical security awareness and implementation have resulted in reported cases of theft and attacks involving chemicals. To fill this gap, over the past 5 years, the Kenya Chemical Society has conducted chemical security trainings and outreach campaigns for chemical security practitioners from academia and industry. The engagements have uncovered a lack of basic knowledge among chemical practitioners about chemical security, as they are unable to appropriate or implement chemical security best practices to prevent misuse, theft, and diversion of hazardous and dual-use chemicals. This Case Study presents efforts, successes, challenges, and opportunities for the adoption of chemical security best practices and culture in Kenya.

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