Label-Free and Regenerative Electrochemical Microfluidic Biosensors for Continual Monitoring of Cell Secretomes.

Development of an efficient sensing platform capable of continual monitoring of biomarkers is needed to assess the functionality of the in vitro organoids and to evaluate their biological responses toward pharmaceutical compounds or chemical species over extended periods of time. Here, a novel label-free microfluidic electrochemical (EC) biosensor with a unique built-in on-chip regeneration capability for continual measurement of cell-secreted soluble biomarkers from an organoid culture in a fully automated manner without attenuating the sensor sensitivity is reported. The microfluidic EC biosensors are integrated with a human liver-on-a-chip platform for continual monitoring of the metabolic activity of the organoids by measuring the levels of secreted biomarkers for up to 7 d, where the metabolic activity of the organoids is altered by a systemically applied drug. The variations in the biomarker levels are successfully measured by the microfluidic regenerative EC biosensors and agree well with cellular viability and enzyme-linked immunosorbent assay analyses, validating the accuracy of the unique sensing platform. It is believed that this versatile and robust microfluidic EC biosensor that is capable of automated and continual detection of soluble biomarkers will find widespread use for long-term monitoring of human organoids during drug toxicity studies or efficacy assessments of in vitro platforms.

Simple fabrication method for a porous poly(vinyl alcohol) matrix by multisolvent mixtures for an air-exposed model of the lung epithelial system.

We introduce a simple and easy method for fabricating a thin and porous matrix that can be used as an extracellular matrix (ECM). A porous poly(vinyl alcohol) (PVA) matrix was created through recrystallization by multiple solvents under distilled water (DW), isopropyl alcohol (IPA), and a combination of DW and IPA. The crysatllization was driven by precipitating and dissolving a solute in a solution of a solvent and a nonsolvent, which induced the formation of microspheres in the IPA. The crystal structure depended on the ratio of the solvent/nonsolvent and the concentration of the PVA aqueous solution; these properties were used to tune the thickness, size, and porosity of the matrices. The resulting PVA matrix was chemically stabilized through a reaction with glutaraldehyde in the IPA solution. We demonstrated that a very thin and porous PVA matrix provided an effective functional model of the lung epithelial system. Lung epithelial cells (A549) displayed a high affinity for this matrix, which was permeable to the culture medium. These properties facilitated culturing under the air environment.

Micro/Nanometer-scale fiber with highly ordered structures by mimicking the spinning process of silkworm.

A new method for the microfluidic spinning of ultrathin fibers with highly ordered structures is proposed by mimicking the spinning mechanism of silkworms. The self-aggregation is driven by dipole-dipole attractions between polar polymers upon contact with a low-polarity solvent to form fibers with nanostrands. The induction of Kelvin-Helmholtz instabilities at the dehydrating interface between two miscible fluids generates multi-scale fibers in a single microchannel.

Biomimetic and molecular level-based silicate bioactive glass-gelatin hybrid implants for loading-bearing bone fixation and repair.

Biomedical implants for successful bone fixation and repair should be biodegradable, and of matched mechanical strength, bone-bonding bioactivity and good biocompatibility. However, current bone implants in the clinic and research are usually not meeting the demands of ideal implants. Here, at low temperatures, we develop a biomimetic molecular level-based silicate bioactive glass-gelatin bone implant with matched physicochemical and biological properties. Our implant could mimic the physical structure at the molecular and nanoscale levels, and presents a high compressive strength (beyond 120 MPa), suitable modulus (300-600 MPa) and strain percent (30%). In addition, the biomimetic implants also showed a linear biodegradation behavior which indicated their stable biodegradation ability. An in vitro simulated body fluid (SBF) test showed that a uniform biomineralization layer was formed on the implant under short times, which shows the good bone-bonding bioactivity of the implants. An in vitro marrow stem cells (MSC) culture showed that our biomimetic implants possessed good biocompatibility by enhancing cell proliferation. These results indicated that our biomimetic hybrid implants may be competitive candidates for bone fixation and repair biomaterials.

Microfluidic spinning of flat alginate fibers with grooves for cell-aligning scaffolds.

Alginate microribbons with longitudinally grooved microstructures are continuously fabricated by means of a microfluidic system. The number and dimensions of the microgroovesare successfully controlled by regulation of the slit-shaped channel (yellow in figure). This method opens up the possibility of mass production of scaffolds for tissue engineering purposes, as it is proved that the grooved flat fibers can be used to align other types of cells in culture.

Beta-lactam antibiotic sensitization and its relationship to allergic diseases in tertiary hospital nurses.

PURPOSE: Skin allergies through type 1 and 4 hypersensitivity reactions are the most frequent manifestations of drug allergies. We had previously experienced a case of a nurse with cefotiam-induced contact urticaria syndrome. To aid in preventing the progression of drug-induced allergic disease in nurses, we conducted a survey of tertiary hospital nurses who were likely to have been exposed professionally to antibiotics. METHODS: All 539 staff nurses at a tertiary hospital were asked to respond to a questionnaire regarding antibiotic exposure. Of the 457 nurses (84.8%) who responded, 427 (79.2%) received a physical examination of the hands and 318 (59.0%) received skin prick tests with the beta-lactam antibiotics cefotiam, cefoperazone, ceftizoxime, flomoxef, piperacillin and penicillin G. RESULTS: A positive response to at least one of the antibiotics occurred in 8 (2.6%) of the 311 subjects included in the analysis and stages 1 and 2 contact urticaria syndrome were observed in 38 (8.9%) and 3 (0.7%) of 427 nurses, respectively. The frequencies of a positive antibiotic skin test (6.9 versus 1.3%, chi(2)=7.15, P=0.018), stage 1 contact urticaria syndrome (14.4 versus 7.4%, chi(2)=4.33, P=0.038) and drug allergy (15.3 versus 3.6%, chi(2)=18.28, P=0.000) were higher in subjects with a positive skin allergy history than in those without. Allergic rhinitis (P=0.02, OR=3.86, CI=1.23-12.06), night cough (P=0.04, OR=3.12, CI=1.03-9.41) and food allergy (P=0.00, OR=9.90, CI=3.38-29.98) were significant risk factors for drug allergy. CONCLUSIONS: Antibiotic sensitization and drug allergy occurred more frequently in nurses with a positive skin allergy history. Atopy may be an important risk factor for drug allergy.

Oil droplet generation in PDMS microchannel using an amphiphilic continuous phase.

This paper reports an amphiphilic solution can be used as a new continuous phase to generate double droplet emulsions (water/oil/IPA) with neither surface treatment nor surfactant in PDMS microfluidic chip. The affinity of various amphiphilic solutions in the microchannel was influenced by the polarity ratio and the size of molecules. The polarity ratio of isopropyl alcohol (IPA) was closest to that of the recovered PDMS surface and the chain length of IPA was also suitable for high affinity. IPA showed the highest affinity for the recovered PDMS and was selected as the continuous phase to form oil droplets in a PDMS microchannel. With this new continuous phase solution, IPA, we could successfully generate not only oil droplets but also double emulsions in the PDMS microfluidic chips.

Using the chorions of fertilized zebrafish eggs as a biomaterial for the attachment and differentiation of mouse stem cells.

The development of proper biomaterials is critical for the success of cell therapy and modern tissue engineering. Here, we extruded the yolk and remaining inner mass from fertilized zebrafish eggs and used the resulting chorions as a biomaterial for the differentiation and attachment of mouse P19 embryonic carcinoma (EC) cells. Cells inserted into the chorion showed the spontaneous formation of embryoid body due to the repulsive cell adhesion of the chorion and differentiated specifically into neural cells and cardiomyocytes. In contrast, dissolved chorion extracellular matrix (ECM) conferred enhanced cell attachment on it, suggesting that a unique property of the zebrafish chorion with nanoporous structure appears to be responsible for the simple and controllable embryoid formation for stem cell differentiation. These results indicate that chorions from fertilized zebrafish eggs may be used as an extracellular matrix alternative and applied for stem cell differentiation to specific cell lineages.