Understanding nanoparticle flow with a new in vitro experimental and computational approach using hydrogel channels.

Nanoparticles (NPs) are considered as one of the most promising drug delivery vehicles and a next-generation solution for current medical challenges. In this context, variables related to flow of NPs such as the quantity of NPs lost during transport and flow trajectory greatly affect the clinical efficiency of NP drug delivery systems. Currently, there is little knowledge of the physical mechanisms dominating NP flow inside the human body due to the limitations of available experimental tools for mimicking complex physiological environments at the preclinical stage. Here, we report a coupled experimental and computational fluid dynamics (CFD)-based novel in vitro approach to predict the flow velocity and binding of NP drug delivery systems during transport through vasculature. Poly(hydroxyethyl)methacrylate hydrogels were used to form soft cylindrical constructs mimicking vascular sections as flow channels for synthesized iron oxide NPs in these first-of-its-kind transport experiments. Brownian dynamics and material of the flow channels played key roles in NP flow, based on the measurements of NP flow velocity over seven different mass concentrations. A fully developed laminar flow of the NPs under these conditions was simultaneously predicted using CFD. Results from the mass loss of NPs during flow indicated a diffusion-dominated flow at higher particle concentrations but a flow controlled by the surrounding fluid and Brownian dynamics at the lowest NP concentrations. The CFD model predicted a mass loss of 1.341% and 6.253% for the 4.12 g·mL-1 and 2.008 g·mL-1 inlet mass concentrations of the NPs, in close confirmation with the experimental results. This further highlights the reliability of our new in vitro technique in providing mechanistic insights of NP flow for potential preclinical stage applications.

Numerical Simulation of Tidal Breathing Through the Human Respiratory Tract.

The objective of this study is to explore the complexity of airflow through the human respiratory tract by carrying out computational fluid dynamics simulation. In order to capture the detailed physics of the flow in this complex system, large eddy simulation (LES) is performed. The crucial step in this analysis is to investigate the impact of breathing transience on the flow field. In this connection, simulations are carried out for transient breathing in addition to peak inspiration and expiration. To enable a fair comparison, the flowrates for constant inspiration/expiration are selected to be identical to the peak flowrates during the transient breathing. Physiologically appropriate regional ventilation for two different flowrates is induced. The velocity field and turbulent flow features are discussed for both flowrates. The airflow through the larynx is observed to be significantly complex with high turbulence level, recirculation, and secondary flow while the level of turbulence decreases through the higher bifurcations.

Enhanced legume root growth with pre-soaking in α-Fe2O3 nanoparticle fertilizer.

The rising demand for food and energy crops has triggered interest in the use of nanoparticles for agronomy. Specifically, iron oxide-based engineered nanoparticles are promising candidates for next-generation iron-deficiency fertilizers. We used iron oxide and hybrid Pt-decorated iron oxide nanoparticles, at low and high concentrations, and at varied pHs, to model seed pre-soaking solutions for investigation of their effect on embryonic root growth in legumes. This is an environmentally friendly approach, as it uses less fertilizer, therefore less nanoparticles in contact with the soil. Analysis from varied material characterization techniques combined with a statistical analysis method found that iron oxide nanoparticles could enhance root growth by 88-366% at low concentrations (5.54 × 10-3 mg L-1 Fe). Hybrid Pt-decorated iron oxide nanoparticles and a higher concentration of iron oxide nanoparticles (27.7 mg L-1 Fe) showed reduced root growth. The combined materials characterization and statistical analysis used here can be applied to address many environmental factors to finely tune the development of vital nanofertilizers for high efficiency food production.