One of the most common worries about titanium dioxide is that it could be a cancer-causing agent. The link between cancer and titanium dioxide traces back to a 1985 study where rats were exposed to high levels of titanium dioxide for two years, causing lung cancer. However, not all experts are convinced by this study.
CSPI’s Chemical Cuisine is the web’s definitive rating of the chemicals used to preserve foods and affect their taste, texture, or appearance. Besides titanium dioxide, the group recommends avoiding artificial sweeteners like aspartame, acesulfame potassium, and sucralose, as well as synthetic food dyes like Yellow 5 and Red 3. CSPI and others have recently asked the Food and Drug Administration to ban the latter dye in foods and ingested drugs because the FDA has already determined that it is a carcinogen unsafe for use in cosmetics.
The first study addressing the experimental convergence between in vitro spiking neurons and spiking memristors was attempted in 2013 (Gater et al., 2013). A few years later, Gupta et al. (2016) used TiO2 memristors to compress information on biological neural spikes recorded in real time. In these in vitro studies electrical communication with biological cells, as well as their incubation, was investigated using multielectrode arrays (MEAs). Alternatively, TiO2 thin films may serve as an interface material in various biohybrid devices. The bio- and neurocompatibility of a TiO2 film has been demonstrated in terms of its excellent adsorption of polylysine and primary neuronal cultures, high vitality, and electrophysiological activity (Roncador et al., 2017). Thus, TiO2 can be implemented as a nanobiointerface coating and integrated with memristive electronics either as a planar configuration of memristors and electrodes (Illarionov et al., 2019) or as a functionalization of MEAs to provide good cell adhesion and signal transmission. The known examples are electrolyte/TiO2/Si(p-type) capacitors (Schoen and Fromherz, 2008) or capacitive TiO2/Al electrodes (Serb et al., 2020). As a demonstration of the state of the art, an attempt at memristive interlinking between the brain and brain-inspired devices has been recently reported (Serb et al., 2020). The long-term potentiation and depression of TiO2-based memristive synapses have been demonstrated in relation to the neuronal firing rates of biologically active cells. Further advancement in this area is expected to result in scalable on-node processors for brain–chip interfaces (Gupta et al., 2016). As of 2017, the state of the art of, and perspectives on, coupling between the resistive switching devices and biological neurons have been reviewed (Chiolerio et al., 2017).