Numerical simulation of transport and adhesion of thermogenic nano-carriers in microvessels

Microfluidic-based skin-on-chip systems for safety assessment of nanomaterials

The skin is the body's largest organ, continuously exposed to and affected by natural and anthropogenic nanomaterials (materials with external and internal dimensions in the nanoscale range). This broad spectrum of insults gives rise to irreversible health effects (from skin corrosion to cancer). Organ-on-chip systems can recapitulate skin physiology with high fidelity and potentially revolutionize the safety assessment of nanomaterials. Here, we review current advances in skin-on-chip models and their potential to elucidate biological mechanisms. Further, strategies are discussed to recapitulate skin physiology on-chip, improving control over nanomaterials exposure and transport across cells. Finally, we highlight future opportunities and challenges from design and fabrication to acceptance by regulatory bodies and industry.

Experimental Investigation of Temperature Influence on Nanoparticle Adhesion in an Artificial Blood Vessel

Background

A good understanding of the adhesion behaviors of the nanocarriers in microvessels in chemo-hyperthermia synergistic therapy is conducive to nanocarrier design for targeted drug delivery.

Methods

In this study, we constructed an artificial blood vessel system using gelatins with a complete endothelial monolayer formed on the inner vessel wall. The numbers of adhered NPs under different conditions were measured, as well as the interaction forces between the arginine-glycine-aspartic acid (RGD) ligands and endothelial cells.

Results

The experimental results on the adhesion of ligand-coated nanoparticles (NPs) with different sizes and morphologies in the blood vessel verified that the gelatin-based artificial vessel possessed good cytocompatibility and mechanical properties, which are suitable for the investigation on NP adhesion characteristics in microvessels. When the temperature deviated from 37 °C, an increase or decrease in temperature resulted in a decrease in the number of adhered NPs, but the margination probability of NP adhesion increased at high temperatures due to the enhanced Brownian movement and flow disturbance. It is found that the effect of cooling was less than that of heating according to the observed changes in cell morphology and a decrease in cell activity under the static and perfusion culture conditions within the temperature range of 25 °C-43 °C. Furthermore, the measurement results of change in the RGD ligand-cell interaction with temperature showed good agreement with those in the number of adhered NPs.

Conclusion

The Findings suggest that designing ligands that can bind to the receptor and are least susceptible to temperature variation can be an effective means to enhance drug retention.

An Updated Review on EPR-Based Solid Tumor Targeting Nanocarriers for Cancer Treatment

The enhanced permeability and retention (EPR) effect in cancer treatment is one of the key mechanisms that enables drug accumulation at the tumor site. However, despite a plethora of virus/inorganic/organic-based nanocarriers designed to rely on the EPR effect to effectively target tumors, most have failed in the clinic. It seems that the non-compliance of research activities with clinical trials, goals unrelated to the EPR effect, and lack of awareness of the impact of solid tumor structure and interactions on the performance of drug nanocarriers have intensified this dissatisfaction. As such, the asymmetric growth and structural complexity of solid tumors, physicochemical properties of drug nanocarriers, EPR analytical combination tools, and EPR description goals should be considered to improve EPR-based cancer therapeutics. This review provides valuable insights into the limitations of the EPR effect in therapeutic efficacy and reports crucial perspectives on how the EPR effect can be modulated to improve the therapeutic effects of nanomedicine.

Splitting dynamics of ferrofluid droplets inside a microfluidic T-junction using a pulse-width modulated magnetic field in micro-magnetofluidics

Micro-magnetofluidics offers a promising tool for better control over the ferrofluid droplet manipulation which has been vastly utilized in biomedical applications in recent years. In this study, the ferrofluid droplet splitting under an asymmetric Pulse-Width-Modulated (PWM) magnetic field in a T-junction is numerically investigated using a finite volume method and VOF two-phase model. By utilizing the PWM magnetic field, two novel regimes of ferrofluid droplet splitting named as Flowing through the Same Branch (FSB) and Double Splitting (DS) have been observed for the first time. In the FSB regime, the daughter droplets move out of the same microchannel outlet, and in the DS regime, the droplet splitting occurs two times which results in generating three daughter droplets. The main problem related to the asymmetric droplet splitting under a steady magnetic field is daughter droplet trapping. By using a PWM magnetic field, this issue is resolved and the trapped/escaped regions are obtained in terms of the duty cycle and dimensionless magnetic field frequency. The effects of six important dimensionless parameters on the splitting ratio, including magnetic Bond number, duty cycle, dimensionless magnetic field frequency, capillary number, dimensionless mother droplet length, and dimensionless dipole position are investigated. The results showed that the splitting ratio increases with increasing magnetic Bond number or duty cycle, or decreasing the dimensionless magnetic field frequency. Eventually, a correlation is offered for the splitting ratio based on the dimensionless variables with an average relative error of 2.67%.