I. ANTIMICROBIAL PHOTODYNAMIC INACTIVATION TARGETING MULTIDRUG RESISTANCE WITH GALLIUM-HEMOGLOBIN-COATED SILVER NANOPARTICLES II. SYNTHESIS AND PROPERTIES OF MAGNETIC GOLD NANOPARTICLES

Abstract

I. Gallium-hemoglobin Coated Silver\nNanoparticles for Antimicrobial Photodynamic Therapy Against Bacterial\nPathogens One of\nthe mechanisms for bacterial pathogens’ hemin acquisition is through\ncell-surface hemin receptors (CSHRs), which are responsible for rapid hemin\nrecognition. GaPpIX, as a hemin analog, can be rapidly taken up by\nCSHR-expressing bacteria, such as Staphylococcus\naureus (S.aureus). Previous works\nshown that GaPpIX has aPDI activity at micromolar level of concentration\nfollowing 10 seconds of 405-nm light exposure using LED array. The\nphotosensitizing ability of GaPpIX can be further enhanced by incorporating\nwith hemoglobin (GaHb) and 10 nm silver nanoparticles (AgNP). The results\nsuggested a higher aPDI activity of GaHb-AgNP than any of its components\nagainst MRSA strains and neglectable cytotoxicity against keratinocytes.\nGaHb-AgNPs were also found having aPDI activity against intracellular MRSA and Mycobacterium abscessus but not\neffective against S. aureus biofilm.\nGaHb-AgNPs have no significant toxicity toward macrophages with concentrations\nlower than 22.64 μg/mL.\n\n \n\nII. Synthesis and Properties of Magnetic Gold Nanoparticles\n\n Superparamagnetic\ngold nanoparticles support hybrid magnetic and plasmonic properties that\ncan be exploited for a variety of applications. In this paper we present new\ninsights on the synthesis of magnetic gold nanoparticles (MGNPs) with an\nemphasis on efficiency, scalability, and waste reduction, supported by a\ncomprehensive analysis of their physical and materials properties. Aqueous\nsuspensions of colloidal Fe3O4 are conditioned with 5-kDa\npolyethylene glycol and L-histidine\nto mediate the nucleation and growth of gold by a mild reducing agent.\nIsotropic MGNPs on the order of 100 nm can be synthesized using scalable\nreaction conditions with Au:Fe mole ratios as low as 1:2 and cleansed with\ngenerally regarded as safe (GRAS) chemicals for the removal of residual iron\noxide. High-resolution energy-dispersive x-ray imaging of individual MGNCs\nrevealed these to be ultrafine composites of gold and SPIO rather than core–shell structures. The\nattenuated total reflectance infrared (ATR-IR) spectroscopy and Raman\nspectroscopy indicated that the cleansing step does change the optical\nproperties of the synthesized MGNPs. Magnetometry of MGNCs in bulk powder form\nconfirmed their superparamagnetic nature, with bulk moments between 6 to 7\nemu/g.