Layer‐by‐Layer Coated Gold Nanoparticles: Size‐Dependent Delivery of DNA into Cells

Abstract

Because nanoparticles are finding uses in myriad biomedical applications, including the delivery of nucleic acids, a detailed knowledge of their interaction with the biological system is of utmost importance. Here the size-dependent uptake of gold nanoparticles (AuNPs) (20, 30, 50 and 80 nm), coated with a layer-by-layer approach with nucleic acid and poly(ethylene imine) (PEI), into a variety of mammalian cell lines is studied. In contrast to other studies, the optimal particle diameter for cellular uptake is determined but also the number of therapeutic cargo molecules per cell. It is found that 20 nm AuNPs, with diameters of about 32 nm after the coating process and about 88 nm including the protein corona after incubation in cell culture medium, yield the highest number of nanoparticles and therapeutic DNA molecules per cell. Interestingly, PEI, which is known for its toxicity, can be applied at significantly higher concentrations than its IC(50) value, most likely because it is tightly bound to the AuNP surface and/or covered by a protein corona. These results are important for the future design of nanomaterials for the delivery of nucleic acids in two ways. They demonstrate that changes in the nanoparticle size can lead to significant differences in the number of therapeutic molecules delivered per cell, and they reveal that the toxicity of polyelectrolytes can be modulated by an appropriate binding to the nanoparticle surface.

Particle size- and number-dependent delivery to cells by layered double hydroxide nanoparticles

“…Our findings are consistent with our previous observation in HEK-293T cells [49], suggesting that partial complexation of DNA by L-LDH NPs at this mass ratio is detrimental to gene delivery efficiency. This observation seems to be similar to the report by Elbakry et al [63] that far more DNA molecules were delivered to one cell by 20 nm Au NPs than 80 nm ones.…”

Inclusion of a pH-responsive amino acid-based amphiphile in methotrexate-loaded chitosan nanoparticles as a delivery strategy in cancer therapy

“…It is worth pointing out that these NPs with LMW-CS and 77KS have a diameter almost 2-fold lower than the NPs prepared with MMW-CS and 77KL (Nogueira et al 2013). The small size of nanocarriers may constitute a great feature to improve the drug delivery to the tumor tissues and, more specifically, to the intracellular compartments of tumor cells (Elbakry et al 2012;Huang et al 2012). Concerning the NP surface charge, positive ZP values (> 22 mV) were detected for all formulations.…”

The biodistribution and pharmacokinetic evaluation of choline-bound gold nanoparticles in a human prostate tumor xenograft model

“…e culture medium was then replaced with 200 µL of solution containing a mixture of fresh medium and a choline-gold nanoparticle solution prepared in deionized water. e e ects of 0.32 µM native PEI, 2.0 mM choline chloride and choline-GNPs were examined representing a PEI containing GNP concentration greater than a previously published concentration using GNPs bound with PEI [26]. Control wells containing the same cell density received only 200 µL of fresh culture medium.…”

“…e incorporation of PEI onto a GNP surface results in a positively charged nanoparticle [26]. Nanoparticles with a net positive charge have been purported to have improved cancer cell uptake [22,26].…”

“…e "proton sponge" nature of PEI is thought to provide buering within the endosomes, improving PEI bound GNP stability a er cellular internalization [23][24][25][26][27]. Furthermore, the steric hindrance imparted by PEI surface functionalization imparts added colloidal stability for the gold in solution [27].…”