Algae Adhesion onto Silicone is Sensitive to Environment-Induced Surface Restructuring.

Resistance to algae contamination is an important characteristic of insulators used in overhead power distribution in coastal environments. It is therefore important to understand the parameters governing algae adhesion onto polymer insulator materials such as silicone. Flow cell-based shear experiments were conducted in order to characterize the adhesion strength of algae onto polydimethylsiloxane surfaces, comparing fresh polymer substrates with those that have been soaked in water and saline solutions for 1 month. Both freshwater algae and seawater species could withstand considerably less drag force and were therefore more easily removed when the polymer was soaked in salt water. The polymer surface was found to be unaltered in terms of its roughness, contact angle, and lack of water uptake; no macroscopic surface characterization was therefore able to account for the differences in cell adhesion strength resulting from the soaking treatment. Surface-specific nonlinear vibrational spectroscopy, however, revealed subtle differences in the orientation of surface methyl groups that resulted from the water and saline exposure.

Automated fabrication of a scalable heart-on-a-chip device by 3D printing of thermoplastic elastomer nanocomposite and hot embossing.

The successful translation of organ-on-a-chip devices requires the development of an automated workflow for device fabrication, which is challenged by the need for precise deposition of multiple classes of materials in micro-meter scaled configurations. Many current heart-on-a-chip devices are produced manually, requiring the expertise and dexterity of skilled operators. Here, we devised an automated and scalable fabrication method to engineer a Biowire II multiwell platform to generate human iPSC-derived cardiac tissues. This high-throughput heart-on-a-chip platform incorporated fluorescent nanocomposite microwires as force sensors, produced from quantum dots and thermoplastic elastomer, and 3D printed on top of a polystyrene tissue culture base patterned by hot embossing. An array of built-in carbon electrodes was embedded in a single step into the base, flanking the microwells on both sides. The facile and rapid 3D printing approach efficiently and seamlessly scaled up the Biowire II system from an 8-well chip to a 24-well and a 96-well format, resulting in an increase of platform fabrication efficiency by 17,5000-69,000% per well. The device's compatibility with long-term electrical stimulation in each well facilitated the targeted generation of mature human iPSC-derived cardiac tissues, evident through a positive force-frequency relationship, post-rest potentiation, and well-aligned sarcomeric apparatus. This system's ease of use and its capacity to gauge drug responses in matured cardiac tissue make it a powerful and reliable platform for rapid preclinical drug screening and development.

A plug-and-play modular microcapillary platform for the generation of multicompartmental double emulsions using glass or fluorocarbon capillaries.

Although multiple emulsions have a wide range of applications in biology, medicine, chemistry and cosmetics, the use of microfluidic devices to generate them remains limited to specialist laboratories. This is because of the expertise required to design and operate these technologies. Here we show a plug-and-play microcapillary platform for the generation of multicompartmental double emulsions which only requires a low cost 3D printer for fabrication and syringe pumps for operation. Our microcapillary platform is modular because we fabricate junction boxes from a flexible resin to hold and align any type of standard glass capillary or piece of tubing for droplet formation without the need for capillary alignment. The flexible resin enables total sealing of the capillaries without the need for gaskets or adhesives, and the ability to use any type of capillary or tubing means that surface treatment is not required. We show how our microcapillary platform is able to generate water-in-oil-in-water, oil-in-water-in-oil, and oil-in-oil-in-water multicompartmental double emulsions with between 1 and 10 inner droplets with high accuracy and reproducibility using standard oils (FC40, mineral oil) and inexpensive surfactants (sodium dodecyl sulfate, SDS or 1H,1H,2H,2H-perfluoro-1-octanol, PFO). Additionally, we show the formation of binary multicompartmental double emulsions, where two types of inner phase droplets can be encapsulated in the multicompartmental emulsions. Our results demonstrate how simple and accessible tools can be employed to generate a powerful modular microcapillary platform. We anticipate that the simplicity of fabrication and operation of this platform, coupled with its ability to make a wide variety of different types of emulsions, will be attractive both to microfluidic laboratories and to those without microfluidic expertise who need an enabling tool for multicompartmental double emulsion formation.

Programmed assembly of bespoke prototissues on a microfluidic platform.

The precise assembly of protocell building blocks into prototissues that are stable in water, capable of sensing the external environment and which display collective behaviours remains a considerable challenge in prototissue engineering. We have designed a microfluidic platform that enables us to build bespoke prototissues from predetermined compositions of two types of protein-polymer protocells. We can accurately control their size, composition and create unique Janus configurations in a way that is not possible with traditional methods. Because we can control the number and type of the protocells that compose the prototissue, we can hence modulate the collective behaviours of this biomaterial. We show control over both the amplitude of thermally induced contractions in the biomaterial and its collective endogenous biochemical reactivity. Our results show that microfluidic technologies enable a new route to the precise and high-throughput fabrication of tissue-like materials with programmable collective properties that can be tuned through careful assembly of protocell building blocks of different types. We anticipate that our bespoke prototissues will be a starting point for the development of more sophisticated artificial tissues for use in medicine, soft robotics, and environmentally beneficial bioreactor technologies.