A density-based threshold model for evaluating the separation of particles in heterogeneous mixtures with curvilinear microfluidic channels

Artificial tumor matrices and bioengineered tools for tumoroid generation

The tumor microenvironment (TME) is critical for tumor growth and metastasis. The TME contains cancer-associated cells, tumor matrix, and tumor secretory factors. The fabrication of artificial tumors, so-called tumoroids, is of great significance for the understanding of tumorigenesis and clinical cancer therapy. The assembly of multiple tumor cells and matrix components through interdisciplinary techniques is necessary for the preparation of various tumoroids. This article discusses current methods for constructing tumoroids (tumor tissue slices and tumor cell co-culture) for pre-clinical use. This article focuses on the artificial matrix materials (natural and synthetic materials) and biofabrication techniques (cell assembly, bioengineered tools, bioprinting, and microfluidic devices) used in tumoroids. This article also points out the shortcomings of current tumoroids and potential solutions. This article aims to promotes the next-generation tumoroids and the potential of them in basic research and clinical application.

Oxidative stress induced by Etoposide anti-cancer chemotherapy drives the emergence of tumor-associated bacteria resistance to fluoroquinolones

INTRODUCTION

Antibiotic-resistant bacterial infections, such as Pseudomonas aeruginosa and Staphylococcus aureus, are prevalent in lung cancer patients, resulting in poor clinical outcomes and high mortality. Etoposide (ETO) is an FDA-approved chemotherapy drug that kills cancer cells by damaging DNA through oxidative stress. However, it is unclear if ETO can cause unintentional side effects on tumor-associated microbial pathogens, such as inducing antibiotic resistance.

OBJECTIVES

We aimed to show that prolonged ETO treatment could unintendedly confer fluoroquinolone antibiotic resistance to P. aeruginosa, and evaluate the effect of tumor-associated P. aeruginosa on tumor progression.

METHODS

We employed experimental evolution assay to treat P. aeruginosa with prolonged ETO exposure, evaluated the ciprofloxacin resistance, and elucidated the gene mutations by DNA sequencing. We also established a lung tumor-P. aeruginosa bacterial model to study the role of ETO-evolved intra-tumoral bacteria in tumor progression using immunostaining and confocal microscopy.

RESULTS

ETO could generate oxidative stress and lead to gene mutations in P. aeruginosa, especially the gyrase (gyrA) gene, resulting in acquired fluoroquinolone resistance. We further demonstrated using a microfluidic-based lung tumor-P. aeruginosa coculture model that bacteria can evolve ciprofloxacin (CIP) resistance in a tumor microenvironment. Moreover, ETO-induced CIP-resistant (EICR) mutants could form multicellular biofilms which protected tumor cells from ETO killing and enabled tumor progression.

CONCLUSION

Overall, our preclinical proof-of-concept provides insights into how anti-cancer chemotherapy could inadvertently allow tumor-associated bacteria to acquire antibiotic resistance mutations and shed new light on the development of novel anti-cancer treatments based on anti-bacterial strategies.

Gravity-based focusing and size-dependent separation of metal microparticles in lubricating oil

The separation of wear microparticles in lubricating oil is crucial for improving the accuracy and throughput of the subsequent detection. However, there are few kinds of research on the separation of high-density metallic microparticles in high-viscosity lubricating oil. In this paper, a passive method for separating the metallic microparticles in oil is proposed. Gravity sedimentation was adopted to realize three-dimensional (3D) focusing of the particle by using an inclined capillary. The gravity-based 3D focusing made the sheath flow no longer responsible for the particle focusing and effectively reduced the sheath flow. Then, the separation of different-sized metallic microparticles was achieved in a horizontal channel with the aid of a sheath flow based on the different driving forces. The present method solved the problem of nonsynchronous separation of the particle in comparison to the traditional methods. This device has a simple structure with high separation efficiency, and it is easy to integrate with the detection channel. The influence of numerous parameters on the gravity-based focusing and separation was systematically studied by the numerical simulation and the experiment. The design criteria were established, which is useful in designing and employing the device, expanding its application to other non-neutral buoyancy particle separation cases, and opening up more prospects for microfluidic technology.