Biogenic selenium nanoparticles: characterization, antimicrobial activity and effects on human dendritic cells and fibroblasts

Abstract

SummaryTailored nanoparticles offer a novel approach to fight antibiotic‐resistant microorganisms. We analysed biogenic selenium nanoparticles (SeNPs) of bacterial origin to determine their antimicrobial activity against selected pathogens in their planktonic and biofilm states. SeNPs synthesized by Gram‐negative Stenotrophomonas maltophilia [Sm‐SeNPs(−)] and Gram‐positive Bacillus mycoides [Bm‐SeNPs(+)] were active at low minimum inhibitory concentrations against a number of clinical isolates of Pseudomonas aeruginosa but did not inhibit clinical isolates of the yeast species Candida albicans and C. parapsilosis. However, the SeNPs were able to inhibit biofilm formation and also to disaggregate the mature glycocalyx in both P. aeruginosa and Candida spp. The Sm‐SeNPs(−) and Bm‐SeNPs(+) both achieved much stronger antimicrobial effects than synthetic selenium nanoparticles (Ch‐SeNPs). Dendritic cells and fibroblasts exposed to Sm‐SeNPs(−), Bm‐SeNPs(+) and Ch‐SeNPs did not show any loss of cell viability, any increase in the release of reactive oxygen species or any significant increase in the secretion of pro‐inflammatory and immunostimulatory cytokines. Biogenic SeNPs therefore appear to be reliable candidates for safe medical applications, alone or in association with traditional antibiotics, to inhibit the growth of clinical isolates of P. aeruginosa or to facilitate the penetration of P. aeruginosa and Candida spp. biofilms by antimicrobial agents.

Biogenic selenium nanoparticles synthesized by Stenotrophomonas maltophilia SeITE02 loose antibacterial and antibiofilm efficacy as a result of the progressive alteration of their organic coating layer

“…As reported in previous studies (Jain et al ., 2015; Cremonini et al ., 2016; Lampis et al ., 2017), biogenic SeNPs from the bacterial strain Stenotrophomonas maltophilia SeITE02 present a complex organic cap consisting of different biomolecules such as proteins, lipids and carbohydrates. In order to evaluate the possible influence of such an organic coating layer on the biological reactivity of these biogenic SeNPs (here called SeNPs‐24 and also untreated SeNPs), different and progressively more aggressive denaturants were applied to the nanoparticles.…”

“…In this scenario, selenium nanoparticles either of biogenic origin or chemically synthesized have been proven to possess surprising antibacterial and antibiofilm capabilities (Cihalova et al ., 2015; Cremonini et al ., 2016; Huang et al ., 2016). …”

“…(2016) reported on comparative tests carried out with selenium nanoparticles (SeNPs) of biogenic nature, produced by two environmental bacterial strains [namely, Bacillus mycoides SeITE01 and Stenotrophomonas maltophilia (SeITE02) and chemically synthesized selenium nanoparticles (Ch‐SeNPS)]. Biogenic SeNPs showed a higher antibacterial activity against a number of clinical strains of Pseudomonas aeruginosa as well as a significant inhibition of biofilm formation along with disaggregation capacity towards already established bacterial biofilms.…”

“…Biogenic SeNPs showed a higher antibacterial activity against a number of clinical strains of Pseudomonas aeruginosa as well as a significant inhibition of biofilm formation along with disaggregation capacity towards already established bacterial biofilms. Furthermore, biogenic SeNPs showed no toxic effects in cell cultures of human dendritic cell (DCs) or fibroblasts and did not elicit production of pro‐inflammatory and immune‐stimulatory cytokines (Cremonini et al ., 2016). …”

Inhibition of Pseudomonas aeruginosa secreted virulence factors reduces lung inflammation in CF mice

“…P. aeruginosa laboratory strain PAO1 and clinical strains VR1, VR2, CFC20, CFC21 [15,43] were used in this study. Clinical isolates were previously collected from sputum samples of patients followed at the Cystic Fibrosis Center of Verona, Italy.…”