I. Antimicrobial Photodynamic Inactivation Targeting Multidrug Resistance with Gallium-hemoglobin-Coated Silver Nanoparticles Ii. Synthesis and Properties of Magnetic Gold Nanoparticles

Lu Lin, Purdue University

Abstract

I. Gallium-hemoglobin Coated Silver Nanoparticles for Antimicrobial Photodynamic Therapy Against Bacterial Pathogens One of the mechanisms for bacterial pathogens’ hemin acquisition is through cell-surface hemin receptors (CSHRs), which are responsible for rapid hemin recognition. GaPpIX, as a hemin analog, can be rapidly taken up by CSHR-expressing bacteria, such as Staphylococcus aureus (S.aureus). Previous works shown that GaPpIX has aPDI activity at micromolar level of concentration following 10 seconds of 405-nm light exposure using LED array. The photosensitizing ability of GaPpIX can be further enhanced by incorporating with hemoglobin (GaHb) and 10 nm silver nanoparticles (AgNP). The results suggested a higher aPDI activity of GaHb-AgNP than any of its components against MRSA strains and neglectable cytotoxicity against keratinocytes. GaHb-AgNPs were also found having aPDI activity against intracellular MRSA and Mycobacterium abscessus but not effective against S. aureus biofilm. GaHb-AgNPs have no significant toxicity toward macrophages with concentrations lower than 22.64 μg/mL. II. Synthesis and Properties of Magnetic Gold Nanoparticles Superparamagnetic gold nanoparticles support hybrid magnetic and plasmonic properties that can be exploited for a variety of applications. In this paper we present new insights on the synthesis of magnetic gold nanoparticles (MGNPs) with an emphasis on efficiency, scalability, and waste reduction, supported by a comprehensive analysis of their physical and materials properties. Aqueous suspensions of colloidal Fe3O4 are conditioned with 5-kDa polyethylene glycol and L-histidine to mediate the nucleation and growth of gold by a mild reducing agent. Isotropic MGNPs on the order of 100 nm can be synthesized using scalable reaction conditions with Au:Fe mole ratios as low as 1:2 and cleansed with generally regarded as safe (GRAS) chemicals for the removal of residual iron oxide. High-resolution energy-dispersive x-ray imaging of individual MGNCs revealed these to be ultrafine composites of gold and SPIO rather than core– shell structures. The attenuated total reflectance infrared (ATR-IR) spectroscopy and Raman spectroscopy indicated that the cleansing step does change the optical properties of the synthesized MGNPs. Magnetometry of MGNCs in bulk powder form confirmed their superparamagnetic nature, with bulk moments between 6 to 7 emu/g.

Degree

Ph.D.

Advisors

Wei, Purdue University.

Subject Area

Analytical chemistry|Cellular biology|Chemistry|Microbiology|Optics|Pathology|Pharmaceutical sciences|Pharmacology|Therapy|Toxicology

COinS