International Journal of Nanomedicine (Nov 2018)
A TEM-traceable physiologically functional gold nanoprobe that permeates non-endocytic cells
Abstract
Maria Victoria Berberian,1 Cristian A Pocognoni,2 Luis S Mayorga1,2 1Institute of Histology and Embryology of Mendoza – CONICET, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina; 2Institute of Histology and Embryology of Mendoza – CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina 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
