ABSTRACT
The rapid uptake of nanomaterials in life sciences calls for the development of universal, high-yield techniques for their production and interfacing with biomolecules. Top-down methods take advantage of the existing variety of bulk and thin-film solid-state materials for improved prediction and control of the resultant nanomaterial properties. We demonstrate the power of this approach using high-energy ball milling (HEBM) of alumina (Al2O3). Nanoalumina particles with a mean size of 25 nm in their most stable α-crystallographic phase were produced in gram quantities, suitable for biological and biomedical applications. Nanomaterial contamination from zirconia balls used in HEBM was reduced from 19 to 2% using a selective acid etching procedure. The biocompatibility of the milled nanomaterial was demonstrated by forming stable colloids in water and physiological buffers, corroborated by zeta potentials of +40 mV and -40 mV and characterized by in vitro cytotoxicity assays. Finally, the feasibility of a milled nanoalumina surface in anchoring a host of functional groups and biomolecules was demonstrated by the functionalization of their surface using facile silane chemistry, resulting in the decoration of the nanoparticle surface with amino groups suitable for further conjugation of biomolecules.
Subject(s)
Aluminum Oxide/chemistry , Biocompatible Materials/chemistry , Nanoparticles/chemistry , Nanotechnology/methods , Aluminum Oxide/toxicity , Animals , Biocompatible Materials/toxicity , Cell Line, Tumor , Cell Survival/drug effects , Colloids , Drug Stability , Mice , Particle Size , Surface Properties , Time Factors , Zirconium/chemistryABSTRACT
We investigate the intracellular uptake of 7.3 nm, 21.2 nm and 31.3 nm average size pure colloidal gold nanoparticles synthesized using femtosecond laser ablation technique in pure water. Dark-field imaging, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) was used to assess the uptake of these pure gold nanoparticles in the pancreatic tumor cell line. We show that these ligand-free gold nanoparticles are non-toxic to these cells. The nanoparticles and cell images indicated that unmodified gold nanoparticles interacted with the cells, despite negative surface charge on both the cells and the nanoparticles. We also demonstrate that the uptake of the gold nanoparticles is size-dependent.
Subject(s)
Endocytosis , Gold/chemistry , Laser Therapy/methods , Metal Nanoparticles/chemistry , Pancreatic Neoplasms/metabolism , Animals , Cell Line, Tumor , Centrifugation , Metal Nanoparticles/ultrastructure , Particle Size , Rats , Spectrometry, X-Ray Emission , Trypan BlueABSTRACT
We report a systematic empirical study of nanoparticle internalization into cells via non-specific pathways. The nanoparticles were comprised of commercial quantum dots (QDs) that were highly visible under a fluorescence confocal microscope. Surface-modified QDs with basic biologically significant moieties, e.g. carboxyl, amino, and streptavidin, were used, in combination with surface derivatization with polyethylene glycol (PEG) for a range of immortalized cell lines. Internalization rates were derived from image analysis and a detailed discussion about the effect of nanoparticle size, charge and surface groups is presented. We find that PEG derivatization dramatically suppresses the non-specific uptake while PEG-free carboxyl and amine functional groups promote QD internalization. These uptake variations displayed a remarkable consistency across different cell types. The reported results are important for experiments concerned with cellular uptake of surface-functionalized nanomaterials, both when non-specific internalization is undesirable and when it is intended for material to be internalized as efficiently as possible.
