Peristalsis in the digestive tract is crucial to maintain physiological functions. It remains challenging to mimic the peristaltic microenvironment in gastrointestinal organoid culture. Here, we present a method to model the peristalsis for human colon tumor organoids on a microfluidic chip. The chip contains hundreds of lateral microwells and a surrounding pressure channel. Human colon tumor organoids growing in the microwell were cyclically contracted by pressure channel, mimicking the in vivo mechano-stimulus by intestinal muscles. The chip allows the control of peristalsis amplitude and rhythm and the high throughput culture of organoids simultaneously. By applying 8% amplitude with 8 ∼ 10 times min−1, we observed the enhanced expression of Lgr5 and Ki67. Moreover, ellipticine-loaded polymeric micelles showed reduced uptake in the organoids under peristalsis and resulted in compromised anti-tumor efficacy. The results indicate the importance of mechanical stimuli mimicking the physiological environment when using in vitro models to evaluate nanoparticles. This work provides a method for attaining more reliable and representative organoids models in nanomedicine.

Cellular uptake of nanoparticles plays a crucial role in cell-targeted biomedical applications. Despite abundant studies trying to understand the interaction between nanoparticles and cells, the influence of cell geometry traits such as cell spreading area and cell shape on the uptake of nanoparticles remains unclear. In this study, poly(vinyl alcohol) is micropatterned on polystyrene cell culture plates using ultraviolet photolithography to control the spreading area and shape of individual cells. The effects of these factors on the cellular uptake of poly(N-(2-hydroxypropyl)methacrylamide)-based micelles were investigated at a single-cell level. Human carcinoma MCF-7 and A549 cells as well as normal Hs-27 and MRC-5 fibroblasts were cultured on micropatterned surfaces. MCF-7 and A549 cells, both with larger sizes, had a higher total micelle uptake. However, the uptake of Hs-27 and MRC-5 cells decreased with increasing spreading area. In terms of cell shapes, MCF-7 and A549 cells with round shapes showed a higher micelle uptake, while those with a square shape had a lower cellular uptake. On the other hand, Hs-27 and MRC-5 cells showed opposite behaviors. The results indicate that the geometry of cells can influence the nanoparticle uptake and may shed light on the design of functional nanoparticles.

While the effects of nanoparticle properties such as shape and size on cellular uptake are widely studied, influences exerted by drug loading have so far been ignored. In this work, nanocellulose (NC) coated by Passerini reaction with poly(2hydroxy ethyl acrylate) (PHEA-g-NC) was loaded with various amounts of ellipticine (EPT) by electrostatic interactions. The drug-loading content was determined by UV−vis spectroscopy to range between 1.68 and 8.07 wt %. Dynamic light scattering and small-angle neutron scattering revealed an increased dehydration of the polymer shell with increasing drug-loading content, which led to higher protein adsorption and more aggregation. The nanoparticle with the highest drug-loading content, NC-EPT8.0, displayed reduced cellular uptake in U87MG glioma cells and MRC-5 fibroblasts. This also translated into reduced toxicity in these cell lines as well as the breast cancer MCF-7 and the macrophage RAW264.7 cell lines. Additionally, the toxicity in U87MG cancer spheroids was unfavorable. The nanoparticle with the best performance was found to have intermediate drug-loading content where the cellular uptake was adequately high while each nanoparticle was able to deliver a sufficiently toxic amount into the cells. Medium drug loading did not hinder uptake into cells while maintaining sufficiently toxic drug concentrations. It was concluded that while striving for a high drug-loading content is appropriate when designing clinically relevant nanoparticles, it needs to be considered that the drug can cause changes in the physicochemical properties of the nanoparticles that might cause unfavorable effects.

Polymeric micelles are widely used as multifunctional drug carriers of poorly water‐soluble drugs, but the role of drug loading content is often overlooked. The purpose of this study is to investigate the cellular uptake and penetration of polymeric micelles with different drug loading contents and their effects on biological activities. In this study, poly(N‐(2‐hydroxypropyl) methacrylamide‐co‐methacrylic acid)‐block‐poly methyl methacrylate P(HPMA‐co‐MAA)‐b‐PMMA micelles are used as a nanocarrier for the encapsulation of the potent anticancer agent ellipticine (EPT). The micelles are loaded with various amounts of EPT and the physicochemical characteristics such as particle size, morphology, and zeta potential of blank and EPT loaded nanoparticles are studied. Moreover, fluorescent lifetime studies confirm that hydrophobic EPT is indeed in the PMMA micelle core. In vitro cytotoxicity tests using the glioma cell line U87MG reveal lower IC50 values when the cells are incubated with micelle with high drug loading content. The higher toxicity in micelles with higher drug loading content is associated with higher cellular uptake, which is monitored using laser scanning confocal microscopy and flow cytometry. Moreover, higher activity of micelles with higher drug loading is also observed in U87MG multicellular tumor spheroids although the difference is not significant.