Three-Dimensional Human Liver-Chip Emulating Premetastatic Niche Formation by Breast Cancer-Derived Extracellular Vesicles.

The liver is one of the most common sites of breast cancer metastasis and is associated with high lethality. Although the interaction between tumor cells and their microenvironment at metastatic sites has been recognized as a key regulator of tumor progression, the underlying mechanism is not fully elucidated. Here, we describe a three-dimensional (3D) microfluidic human liver-on-a-chip (liver-chip) that emulates the formation of a premetastatic niche to investigate the roles of breast cancer-derived extracellular vesicles (EVs) in liver metastasis. We demonstrate that breast cancer-derived EVs activate liver sinusoidal endothelial cells (LSECs) in the liver-chip, inducing endothelial to mesenchymal transition and destruction of vessel barriers. In addition, we show that transforming growth factor ß1 (TGFß1) in breast cancer-derived EVs upregulates fibronectin, an adhesive extracellular matrix protein, on LSECs, which facilitates the adhesion of breast cancer cells to the liver microenvironment. Furthermore, we observed that EVs isolated from triple-negative breast cancer (TNBC) patients with liver metastasis contain higher TGFß1 levels and induce adhesion of more breast cancer cells to the 3D human liver-chip than do EVs isolated from healthy donors or nonmetastatic TNBC patients. These findings provide a better understanding of the mechanisms through which breast cancer-derived EVs guide secondary metastasis to the liver. Furthermore, the 3D human liver-chip described in this study provides a platform to investigate the mechanisms underlying secondary metastasis to the liver and possible therapeutic strategies.

Cross-linked chitosan biofunctionalized paper-based microfluidic device towards long term stabilization of blood typing antibodies.

Long term stability of antibodies at room temperature is a major challenge in the commercialization of point-of-care devices for diagnostics. Since chitosan has been proven to be an excellent biofunctionalization material, the effects of four different biofunctionalization processes were studied to improve the room temperature stability of antibodies immobilized on chitosan modified paper-based microfluidic devices using blood typing antibodies as candidates. The devices used in this work have a flower-shaped design with 4 test zones at each corner. In three zones Anti-A, Anti-B, and Anti-D (Anti-Rh) antibodies are immobilized and the fouth zone represents the control (no antibodies) after biofunctionalization. The biofunctionalization of the paper devices was done with chitosan and chitosan cross-linked with sodium triphosphate pentabasic, glutaraldehyde, and sodium hydroxide. These devices were used for blood typing assays using real blood samples. A similar assay was also performed on unmodified (non-biofunctionalized) paper devices for comparison. Chitosan based biofunctionalized paper-devices showed better stability, up to 100 days as compared to 14 days on unmodified paper, at room temperature. Such biofunctionalized paper-based devices will be suitable for on-field and remote testing without any technical expertise and requirement for the cold chain.

A fidget spinner for the point-of-care diagnosis of urinary tract infection.

The point-of-care detection of pathogens in biological samples in resource-limited settings should be inexpensive, rapid, portable, simple and accurate. Here, we describe a custom-made fidget spinner that rapidly concentrates pathogens in 1-ml samples of undiluted urine by more than 100-fold for the on-device colorimetric detection of bacterial load and pathogen identification. In Tiruchirappalli, India, the device enabled the on-site detection of infection with the naked eye within 50 min in urine samples from 39 patients suspected of having a urinary tract infection. We also show that, in 30 clinical samples of urinary tract infection, the device can be used to perform an antimicrobial susceptibility test for the antimicrobial drugs ciprofloxacin and cefazolin within 120 min. The fidget spinner could be used in low-resource settings as an inexpensive handheld point-of-care device for the rapid concentration and detection of pathogens in urine samples.

Surface-Engineered Paper Hanging Drop Chip for 3D Spheroid Culture and Analysis.

Protein corona coated onto the hydrophilic cellulose fiber turns into hydrophobic upon UV irradiation without hindering the porosity of the paper while simultaneously reducing nonspecific adsorption. Taking advantage of the biofouling-resistant, hydrophobic, and fluid transport through property, we demonstrated hanging drop three-dimensional (3D) spheroid culture and in-site analysis, including drug testing, time-dependent detection of secreted protein, and fluorescence staining without disturbing the spheroids. This single hanging drop system can also be extended to a networked hanging drop chip to mimic in vivo microphysiology by combining with wax-patterned microfluidic channels, where well-to-well interaction can be accurately controlled in a passive manner. As a proof of concept, the effects of a concentration gradient of nutrient and variable dosage of anticancer drugs were studied in the 3D spheroids cultured on paper. The experimental results suggested that a complex network device could be fabricated on a large scale on demand at a minimal cost for 3D spheroid culture. Our method demonstrates a future possibility for paper as a low cost, high-throughput 3D spheroid-based "body-on-a-chip" platform material.

Cloaked Exosomes: Biocompatible, Durable, and Degradable Encapsulation.

Exosomes-nanosized extracellular vesicles (EVs) naturally secreted from cells-have emerged as promising biomarkers and potential therapeutic vehicles, but methods to manipulate them for engineering purposes remain elusive. Among the technical obstacles are the small size and surface complexity of exosomes and the complex processing steps required, which reduce the biocompatibility of currently available methods. The encapsulation of exosomes with a nanofilm of supramolecular complexes of ferric ions (Fe3+ ) and tannic acid is demonstrated here. The resulting natural polyphenol, ≈10 nm thick, protects exosomes from external aggressors such as UV-C irradiation or heat and is controllably degraded on demand. Furthermore, gold nanoparticles can be covalently attached for single-exosome level visualization. To fully exploit their therapeutic potential, chemotherapeutic drug-loaded EVs are functionalized to achieve the targeted, selective killing of cancer cells preferentially over normal cells. This nanofilm not only preserves the native size and chemical makeup of the intrinsic exosomes, but also confers new capabilities for efficient tumor targeting and pH-controlled release of drugs. Demonstrating a scalable method to produce biocompatible, durable, on-demand degradable, and chemically controllable shields for exosome modification and functionalization, the methods introduced here are expected to bring the potential of exosome-based nanomedicine applications closer to reality.

Challenges and Opportunities of Centrifugal Microfluidics for Extreme Point-of-Care Testing.

The advantages offered by centrifugal microfluidic systems have encouraged its rapid adaptation in the fields of in vitro diagnostics, clinical chemistry, immunoassays, and nucleic acid tests. Centrifugal microfluidic devices are currently used in both clinical and point-of-care settings. Recent studies have shown that this new diagnostic platform could be potentially used in extreme point-of-care settings like remote villages in the Indian subcontinent and in Africa. Several technological inventions have decentralized diagnostics in developing countries; however, very few microfluidic technologies have been successful in meeting the demand. By identifying the finest difference between the point-of-care testing and extreme point-of-care infrastructure, this review captures the evolving diagnostic needs of developing countries paired with infrastructural challenges with technological hurdles to healthcare delivery in extreme point-of-care settings. In particular, the requirements for making centrifugal diagnostic devices viable in developing countries are discussed based on a detailed analysis of the demands in different clinical settings including the distinctive needs of extreme point-of-care settings.