# Enhanced Drug Screening Efficacy in Zebrafish Using a Highly Oxygen-Permeable Culture Plate
## 1 Introduction  
Cell culture and drug screening are indispensable tools in the research domains of biology, physiology, pharmacology, toxicology, and medicine. Cell culture involves techniques for cultivating cells outside their natural habitats, under controlled and appropriate conditions. In basic scientific research, cell cultures are typically employed to analyze cellular structure and function, elucidate the mechanisms underlying cell proliferation and differentiation, and investigate the molecular pathways that regulate gene and protein expression. Cell cultures are crucial in pathological research, regenerative medicine, personalized therapies, and safety evaluations, directly affecting human health [1,2]. Drug screening is a crucial step in drug development, used to efficiently assess a wide rangeof compounds to identify those that specifically interact with target receptors or other biological entities. This process is vital for the discovery of new therapeutic agents, the evaluation of pharmacological effectiveness, and the assessment of toxicity. By employing cultured cells and model organisms, drug screening substantially contributes to the creation of safe and effective pharmaceuticals [3,4]. Sterile polystyrene (PS) plates are commonly used in cell culture drug screening owing to their convenience. However, cells in culture can swiftly generate hypoxic conditions in vitro, with a notable reduction in dissolved oxygen levels occurring within 1 h of either seeding or medium replacement [5]. An adequate supply of oxygen is essential for the metabolism and function of almost all cell types. For example, hepatocytes, especially primary hepatocytes, require relatively high levels of oxygen to sustain a physiological biomimetic environment [6]. Therefore, the gap between cell culture conditions and the actual physiological settings hinders biotechnological research. An uncomplicated yet efficient approach has been introduced to enhance oxygen delivery by incorporating oxygen-permeable substances, such as polydimethylsiloxane (PDMS) or 4-polymethyl-1-pentene polymer (PMP), at the base of culture plates. PDMS, an organic polymer derived from silicone, is recognized for its optical clarity and ability to allow gas passage. Its high oxygen permeability makes it a popular choice for cell culture and serves as an alternative to traditional PS-bottom surfaces [6,7]. Nevertheless, a major drawback is that hydrophobic molecules can be adsorbed on both the surface and within the bulk of PDMS [8]. Nile red has been shown to infiltrate PDMS, leading to an increase in fluorescence over time [9]. Moreover, PMP is increasingly utilized in cell culture applications owing to its excellent oxygen permeability, biocompatibility, chemical stability, and transparency [10]. Mitsui Chemicals, Inc. developed a next-generation cell culture solution called the InnoCellTM T-plate (hereafter referred to as the InnoCellTM plate). This plate features a base constructed from PMP, which is known for its excellent oxygen permeability and release properties. Comparing the oxygen consumption rates of primary rat hepatocytes cultured on InnoCellTM plates with those on conventional PS-bottom plates, PMP was found to exhibit an oxygen permeability coefficient up to 15 times greater than that of PS [11]. This corresponds to a 190-fold increase in the theoretical oxygen supply, calculated as the product of the bottom thickness and oxygen permeability coefficient. Additionally, the InnoCellTM plate exhibits low levels of chemical sorption [11]. The InnoCellTM plate-induced environment can also boost cytochrome P450 activity and enhance mitochondrial function. Therefore, this cutting-edge plate is considered a promising option for various drug-testing applications.