Silica nanoparticles embedded with water insoluble phthalocyanines for the photoinactivation of microorganisms

BAIGORRIA, ESTEFANIA; REYNOSO, EUGENIA; ALVAREZ, M. GABRIELA; MILANESIO, M. ELISA; DURANTINI, EDGARDO N.

Photodiagnosis Photodynamic Therapy

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 vol. 23 p. 261 - 269

1572-1000

Silica nanoparticles (SiNPs) embedded with Zn(II) 2,9,16,23-tetrakis(methoxy)phthalocyanine(SiNPZnPcOCH3), Zn(II) 2,9,16,23-tetrakis(4-pyridyloxy) phthalocyanine (SiNPZnPcOPy) and Zn(II)2,9,16,23-tetrakis(t-butyl) phthalocyanine (SiNPZnPctBu) were synthesized in the nonpolar core of AOT/1-butanol/water micelles using triethoxyvinylsilane and 3-aminopropyltriethoxysilane. These SiNPs-Pcpresented an average diameter of about 20-25 nm. UV-visible absorption spectra presented the characteristicSoret and Q bands of phthalocyanines embedded into the nanoparticles. Moreover, red fluorescence emissionof SiNPs bearing phthalocyanines was detected in water. The SiNPs-Pc produced the photodecomposition of2,2´-(anthracene-9,10-diyl)bis(methylmalonic acid), which was used to sense the singlet molecular oxygenO2(1g) generation in aqueous medium. Also, the formation of superoxide anion radical was detected by nitroblue tetrazolium reduction in the presence of NADH. Photoinactivation of microorganisms was investigatedin Staphylococcus aureus and Candida albicans. In vitro experiments showed that photosensitized inactivationinduced by SiNPZnPcOCH3 and SiNPZnPctBu improved with an increase of irradiation times. After 30 minirradiation, over 7 log reduction was found for S. aureus. Also, these SiNPs-Pc produced a decrease of 2.5 login C. albicans after 60 min irradiation. In both cases, a lower photoinactivation activity was found forSiNPZnPcOPy. Studies of photodynamic action mechanism showed that the photokilling of microbial cellswas protected in the presence of sodium azide and diazabicyclo[2.2.2]octane. Also, a reduction on the cellphotodamage was found with the addition of D-mannitol. Therefore, the photodynamic activity sensitized bySiNPZnPcOCH3 and SiNPZnPctBu in microbial cells was mediated by a contribution of both type I and typeII photooxidative mechanisms. Thus, silica nanoparticles are interesting material to vehicle ZnPcOCH3 andZnPctBu in aqueous media to photoeradicate microorganisms