Amoxicillin coated gold nanoparticles with photo-antibacterial action on antibiotic resistant strains

ROCCA D; SILVERO MJ; AIASSA V; SCAIANO JC; BECERRA M C

Carlos Paz

Congreso; XIII ELAFOT; 2017

Grupo Argentino de Fotobiología

Amoxicillin coatedgold nanoparticles with photo-antibacterial action on antibiotic resistantstrains Diamela María Roccaa, María Jazmín Silveroa, Virginia Aiassab, Juan C. Scaianoc, María Cecilia Becerraa  aIMBIV-CONICET, Dpto. Farmacia. Fac. Cs. Químicas. UNC.Córdoba, Argentina; E-mail: diamelarocca@gmail.com; E-mail: jazmincompagnucci@gmail.combUNITEFA-CONICET, Dpto. Farmacia. Fac. Cs. Químicas. UNC. Córdoba,Argentina.cDep. of Chem. and Biom. Sc. and CCRI, Ottawa U., 10 Marie Curie Priv., Ottawa, Canada  e-mail : diamelarocca@gmail.com  Novel antibacterial strategiesare badly needed as a consequence of the growing resistance of bacteria toconventional antibiotics. Photodynamic Antibacterial Chemotherapy (PACT) hasrecently proved to be an effective therapy when the photosensitizer presentsselectivity for prokaryotic cells [1] . In fact, in the present work, goldnanoparticles were synthesized and stabilized with amoxicillin (amoxi@AuNP),which is a beta-lactamic antibiotic with high affinity for the bacterial wall.Amoxi@AuNP were prepared by 1-step synthesis at 50°C for 18 minutes. TEMrevealed that the majority of the population is composed of nano-spheres(average 50 nm). However triangular and hexagonal micro-plates (50 to 90 nm)were also observed. The binding of amoxicillin (slightly modified) to thenanoparticle was confirmed through FT-IR and TGA. Importantly, the active siteof the molecule, the beta-lactamic ring, was preserved intact [2]. Theantibacterial activity of amoxi@AuNP against methicillin-sensitive Staphylococcus aureus ATCC 29213 (MSSAATCC 29213) and methicillin-resistant clinical isolate of Staphylococcus aureus (MRSA 9455) was tested. Briefly, 100 µL ofbacterial suspension (106 CFU/mL) and 100 µL of the tested solutions(37.5% PBS, 1.5 µg/mL amoxi@AuNP, 0.15 µg/mL amoxi@AuNP and amoxicillin atminimum inhibitory concentration (MIC): 2 µg/mL for MSSA and 32 µg/mL for MRSA) were mixed in a 96wellplate. All samples were irradiated for a total of 90 min under white light(from blue, red and yellow LED combined) at 37 °C. An identical well plate was kept in the dark as a control. Aliquots ofeach samples were properly diluted and seeded on tryptic soy agar (TSA) plates forColonies Forming Unit (CFU) counting. The 1.5 µg/mL amoxi@AuNP were able toinhibit bacterial growth of both MSSA and MRSA completely after just 30 min ofirradiation. The same concentration of amoxi@AuNP was able to kill all the MSSA, but not the MRSA, after 90 min under dark conditions. Thismay be due to synergistic effect between the antibiotic and nanoparticles,because the amoxicillin itself was not bactericidal in this short period oftime.In summary, this study has demonstrated that PACT with amoxi@AuNP havean excellent potential in treatment of infectious diseases. Additionally, ourgroup have reported their high biocompatibility and non-toxic properties to thehost [3]. Further research would includeevaluation of their effects in biofilms.  References[1] C Fasciani, MJ Silvero, MAAnghel, GA Argüello, MC Becerra, JC Scaiano, J Am Chem Soc. 2014, 136, 17394; [2] C. Bisson-Boutelliez, S.Fontanay, C. Finance, F. Kedzierewicz. AAPSPharmSciTech. 2010, 11, 574; [3] Silvero MJ, Rocca DM, Aiassa V, Artur dela Villarmois E, Scaiano JC, Pérez MF, Becerra MC. 2nd Int. Caparica Conf. in Antibiotic Resistance IC2AR 2017. Lisbon, Portugal.Acknowledgements: This work wassupported by grants of FONCYT, CONICET and SECyT.