Size-dependent Cellular Uptake Research Articles

Gold Nanoparticle-Enhanced and Size-Dependent Generation of Reactive Oxygen Species from Protoporphyrin IX

Photosensitizer, protoporphyrin IX (PpIX), was conjugated with Au nanoparticles (Au NPs) of 19, 66, and 106 nm diameter to study the size-dependent enhancement of reactive oxygen species (ROS) formation enabled by Au NPs. The ROS enhancement ratio is determined to be 1:2.56:4.72 in order of increasing Au NP size, in general agreement with theoretically calculated field enhancement to the fourth power. The convergence of the experimental and simulated results suggests that Au NP-enhanced and size-dependent ROS formation can be attributed directly to the localized electromagnetic field as a result of surface plasmonic resonance of Au NPs under light irradiation. In vitro study on the ROS formation enabled by PpIX-conjugated Au NPs in human breast cancer cells (MDA-MB-231) revealed the similar size-dependent enhancement of intracellular ROS formation, while the enhancement greatly depended on cellular uptake of Au NPs. Cellular photodynamic therapy revealed that cell destruction significantly increased in the presence of Au NPs. Compared to the untreated control (0% destruction), 22.6% cell destruction was seen in the PpIX alone group and more than 50% cell destruction was obtained for all PpIX-conjugated Au NPs. The 66 nm Au NPs yielded the highest cell destruction, consistent with the highest cellular uptake and highest ROS formation. Clearly, the complex cellular environment, size-dependent cellular uptake of Au NPs, and ROS generations are vital contributors to the overall cellular PDT efficacy.

Size dependent cellular uptake, in vivo fate and light–heat conversion efficiency of gold nanoshells on silica nanorattles

Despite advances in photothermal therapy of gold nanoshells, reliable evaluations of their size dependence on the relative biological effects are needed. We report the size effects of PEGylated gold nanoshells on silica nanorattles (pGSNs) on their cellular uptake, in vivo fate and light-heat conversion efficiency in this study. The results indicate that smaller pGSNs have enhanced cellular uptake by the MCF-7 cells. For in vivo biodistribution study, pGSNs of different particle sizes (84-315 nm) distribute mainly in the liver and spleen in MCF-7 tumor-bearing BALB/c nude mice. Smaller pGSNs have a longer blood-circulation lifetime and higher light-heat conversion efficiency both in vitro and in vivo compared with larger ones. All three sizes of pGSNs can be excreted from the mice body at a slow rate and do not cause tissue toxicity after intravenous injection at a dosage of 20 mg kg(-1) for three times. The data support the feasibility of optimizing the therapeutic process for photothermal cell killing by plasmonic gold nanoshells.

A physical model for the size-dependent cellular uptake of nanoparticles modified with cationic surfactants

BackgroundThe aim of this work was to improve oral bioavailability. The uptake of a series of quaternary ammonium salt didodecyl dimethylammonium bromide (DMAB)-modified nanoparticles (with uniform sizes ranging from 50 nm to 300 nm) into heterogeneous human epithelial colorectal adenocarcinoma cells (Caco-2) and human colon adenocarcinoma cells (HT-29) was investigated.MethodsCoumarin-6 (C6) loaded poly (lactide-co-glycolide) (PLGA) nanoparticles were prepared with DMAB using the emulsion solvent diffusion method. The physicochemical properties and cellular uptake of these nanoparticles were studied. Deserno’s model was applied to explain the experimental observations.ResultsThe results showed that the surface modification of PLGA nanoparticles with DMAB notably improved the cellular uptake. The cellular uptake was size-dependent and had an optimal particle size of 100 nm. The experimental data was integrated numerically, and was in agreement with the theoretical model.ConclusionThese results indicated that the interactions between the charged nanoparticles and the cells resulted from various forces (eg, electrostatic forces, hydrophobic forces, bending and stretching forces, and limited receptor-mediated endocytosis), and the uptake of the nanoparticles occurred as a result of competition.