Establishing the 3D microscale organization of cells has numerous practical applications, such as in determining cell fate (e.g., proliferation, migration, differentiation, and apoptosis) and in making functional tissue constructs. One approach to spatially pattern cells is by dielectrophoresis (DEP). DEP has characteristics that are important for cell manipulation, such as high accuracy, speed, scalability, and the ability to handle both adherent and non-adherent cells. However, widespread application of this method is largely restricted because there is a limited number of suitable hydrogels for cell encapsulation. To date, polyethylene glycol-diacrylate (PEG-DA) and agarose have been used extensively for dielectric patterning of cells. In this study, we propose gelatin methacrylate (GelMA) as a promising hydrogel for use in cell dielectropatterning because of its biocompatibility and low viscosity. Compared to PEG hydrogels, GelMA hydrogels showed superior performance when making cell patterns for myoblast (C2C12) and endothelial (HUVEC) cells as well as in maintaining cell viability and growth. We also developed a simple and robust protocol for co-culture of these cells. Combined application of the GelMA hydrogels and the DEP technique is suitable for creating highly complex microscale tissues with important applications in fundamental cell biology and regenerative medicine in a rapid, accurate, and scalable manner.

No abstract

No abstract

Concentrations down to 3 nM of the rhS100A4 protein, associated with human tumor development, have been detected in undiluted urine using an integrated sensor based on microring resonators in the emerging Al 2 O 3 photonic platform. The fabricated microrings were designed for operation in the C-band (λ = 1565 nm) and exhibited a high-quality factor in air of 3.2 × 10 5. The bulk refractive index sensitivity of the devices was ~100 nm/RIU (for TM polarization) with a limit of detection of ~10 −6 RIU. A surface functionalization protocol was developed to allow for the selective binding of the monoclonal antibodies designed to capture the target biomarker to the surface of the Al 2 O 3 microrings. The detection of rhS100A4 proteins at clinically relevant concentrations in urine is a big milestone towards the use of biosensors for the screening and early diagnosis of different cancers. Biosensors based on this microring technology can lead to portable, multiplexed and easy-to-use point of care devices.

No abstract