No abstract

Dry epidermal electrodes that can always form conformal contact with skin can be used for continuous long-term biopotential monitoring, which can provide vital information for disease diagnosis and rehabilitation. But, this application has been limited by the poor contact of dry electrodes on wet skin. Herein, we report a biocompatible fully organic dry electrode that can form conformal contact with both dry and wet skin even during physical movement. The dry electrodes are prepared by drop casting an aqueous solution consisting of poly­(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), poly­(vinyl alcohol) (PVA), tannic acid (TA), and ethylene glycol (EG). The electrodes can exhibit a conductivity of 122 S cm–1 and a mechanical stretchability of 54%. Moreover, they are self-adhesive to not only dry skin but also wet skin. As a result, they can exhibit a lower contact impedance to skin than commercial Ag/AgCl gel electrodes on both dry and sweat skins. They can be used as dry epidermal electrodes to accurately detect biopotential signals including electrocardiogram (ECG) and electromyogram (EMG) on both dry and wet skins for the users at rest or during physical movement. This is the first time to demonstrate dry epidermal electrodes self-adhesive to wet skin for accurate biopotential detection.

As a reductionist approach, patient‐derived in vitro tumor models are inherently still too simplistic for personalized drug testing as they do not capture many characteristics of the tumor microenvironment (TME), such as tumor architecture and stromal heterogeneity. This is especially problematic for assessing stromal‐targeting drugs such as immunotherapies in which the density and distribution of immune and other stromal cells determine drug efficacy. On the other end, in vivo models are typically costly, low‐throughput, and time‐consuming to establish. Ex vivo patient‐derived tumor explant (PDE) cultures involve the culture of resected tumor fragments that potentially retain the intact  TME of the original tumor. Although developed decades ago, PDE cultures have not been widely adopted likely because of their low‐throughput and poor long‐term viability. However, with growing recognition of the importance of patient‐specific TME in mediating drug response, especially in the field of immune‐oncology, there is an urgent need to resurrect these holistic cultures. In this Review, the key limitations of patient‐derived tumor explant cultures are outlined and technologies that have been developed or could be employed to address these limitations are discussed. Engineered holistic tumor explant cultures may truly realize the concept of personalized medicine for cancer patients.

In Vitro Tumor Models The success of personalized cancer therapy hinges on a timely clinical decision and a preclinical model that can recapitulate tumor and stromal heterogeneity for clinically relevant drug profiling. In article 2202279, Eliza Li Shan Fong and co‐workers review how by transcending the existential reductionist approaches, bioengineered patient‐derived explant (PDE) models can truly replicate the tumor features in vivo and allow clinicians to rapidly offer and strategize specific care and treatment for each cancer patient.