A TEM-traceable physiologically-functional gold nano-probe that permeates non-endocytic cells.

M. VICTORIA BERBERIAN*(CA); CRISTIAN A. POCOGNONI; LUIS S. MAYORGA

INTERNATIONAL JOURNAL OF NANOMEDICINE

DOVE MEDICAL PRESS LTD

Año: 2018 vol. 13 p. 8075 - 8086

1176-9114

Background: Nanoparticles´ intracellular fate requires proper internalization. Most cells make use of a battery of internalization pathways, but some are practically sealed, as they lack the biochemical machinery for cellular intake. Non-endocytic cells, such as mammals? spermatozoa, challenge standard drug-delivery strategies. Purpose: In this article, we present a gold nanoprobe that permeates the external and internal membranes of human sperm.Methods: Our design makes use of a gold nanoparticle functionalized with a membrane- permeable cysteine-rich recombinant protein. The chimeric protein contains two units of physiologically active metallothioneins (MT) that also provide binding motifs to gold and a cell-penetrating-peptide sequence (CPP) that confers cell permeability to the nanoparticle. Results: Transmission electron microscopy, indirect immunofluorescence, and functional assays show that the nanoprobe is readily internalized in sperm, without compromising cell integrity, while preserving MT´s physiological activity. Our findings highlight the potential of CPP-functionalized nanogold for investigating the physiology of otherwise impermeable non-endocytic cells. Keywords: human sperm, metallothionein, gold nanoparticles functionalization, cell-penetrating peptides, transmission electron microscopy