Printable electrodes have advantages in mass production and disposable biosensor applications. A mobile electrochemical detector has been developed to use printable electrodes. Electrochemical DNA detection was originally developed without immobilization of DNA onto electrodes. The PCR process can be monitored in real time and used for detection of pathogens such as Salmonella, O-157, and the flu virus; genetically modified organisms; and the origin of meats. Microfluidic PCR and RT-PCR chips were useful for rapid detection with our electrochemical DNA sensor method. Gold nanoparticle and antibodies can be linked for a novel type of electrochemical immunoassay, gold linked electrochemical immunoassay. Highly sensitive detection of human chorionic gonadotropin (0.36pg⁄mL) and insulin (0.1ng⁄mL) was achieved. These nanoporous structures were transferred to the cyclo-olefin polymer film surface from the porous mold using a thermal nanoimprinting process. A plasmonic substrate was fabricated by sputtering a thin layer of gold onto this nanopillar polymer structure, and the refractive index response in a variety of media was evaluated. Finally, the biosensing capacity of this novel plasmonic substrate was verified by analysis of human immunoglobulin; a minimum detection limit of 1.0ng⁄mL was achieved. With the advantage of mass production with consistent reproducibility derived from the nanoimprinting fabrication process, our gold-capped polymeric pillars are ready for transition from academic interest into commercialization of systems for practical use in diagnostic applications.
Control of the cell adhesion properties of culture substrates is essential to produce complex cell cultures for development of cell-based products for regenerative medicine. Various established techniques in the printing industry (e.g., coating, patterning, surface treatment) can be used for this purpose. In this paper, two types of material⁄process combinations are discussed. In the first case, polyethylene glycol was used as a base material to modify cell-adhesiveness. Polyethylene glycol coatings naturally prevent cell adhesion, but can be changed to be cell-adhesive when decomposed by UV irradiation, based on the irradiation power. Cells cultured on such adhesive-modified substrates were successfully transferred to biological materials such as collagen by simply stacking for transplantation use. Pattern-wise UV irradiation was also performed to prepare cell-adhesive patterns for cultivating human iPS cells. The experimental results suggested that differentiation directions depended on the pattern dimensions. Temperature-responsive cell culture substrates, the key device for cell sheet technology, are also discussed. In this case, cell adhesiveness can be varied by changing the electron beam irradiation conditions.
The development of printing technology has been investigated for applications in various fields such as industry, food processing, and surgery. In the medical field, transplantation is performed for patients with serious conditions, but a shortage of donors for such surgeries has been a serious problem in recent years. As a solution to this issue, development of a new treatment is urgently required. Printing technology, in particular, is being developed for the manufacture of tissues and organs in the field of tissue engineering. Recently, a "bio-three-dimensional (3D) printer," which uses biomaterials such as cells or biopolymers, has drawn much attention in this area. This review will introduce fabrication methods for cell constructs produced by bio-3D printing that we invented in our laboratory. We have achieved good results, such that we expect to be able to make cell constructs in the form of organs such as cartilage, blood vessels, and liver tissue. We consider the potential for producing transplantable organs for patients using their own cells with our system in the near future.
A novel bioassay system using ink jet printing technology and a paper substrate is under development. Ink jet printing has potential for high-precision metered dispensing of bacteria and nutrients in various conditions. Paper has the potential to be used as a container to accommodate bacteria and nutrients and is easily disposed of by combustion after use. Filter paper was first immersed in a toluene solution of polystyrene and hydrophobized after drying. Toluene was printed on a few sections of the filter paper to make them hydrophilic again. An agar medium with its viscosity adjusted by acid hydrolysis was printed on the hydrophilic sections. Bacteria were manually dispensed onto the medium, and the colonies of the bacteria were observed to grow for at least 24 h before the medium dried. Recombinant E. Coli was also successfully dispensed by ink jet printing and grew steadily with a high survival rate. This bioassay system is expected to be applied for a variety of bacterial and yeast spores, and enzymes.
Recently, smartphones and tablets have been used for collecting records of patients' compliance with drug regimens at medical sites. However, it is difficult for many elderly patients to operate these devices. Most medical facilities are also unable to prepare and distribute these devices to all patients. In this study, we have introduced a novel and simple electronic device system to evaluate its usefulness to patients. This new device is a paper card device equipped with an electric circuit board and a memory chip, which is employed to record the times at which patients take medications and the patients' condition. These simple paper electric devices have the potential to be used in various scenarios for monitoring medical and daily life activities. Using the new devices would enable effective and cost-effective medical care.
Photoreactive materials are fundamental materials in printing technology and their applications have expanded to various other fields. The photoinitiator is an important component of a photoreactive material. This concept has expanded to the photo-X-generator (PXG). Based on the concept of the PXG, the photo ampholyte compound generator (PAmG) and photoreactive solubilizer (PRS) are proposed and studied here. The PAmG acts as a photoreactive fluorescence probe or a photo-control reagent with pH in aqueous solutions. A photochromic system was applied to a PRS of carbon nano-materials. PAmGs have the potential to increase the resolution in nanolithography processes. PRS could be used for photo direct patterning. These functional materials enhance the fusion of various technical fields and sciences including printing technology.