Conducting hydrogels have attracted much attention for the emerging field of hydrogel bioelectronics, especially poly(3,4‐ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) based hydrogels, because of their great biocompatibility and stability. However, the electrical conductivities of hydrogels are often lower than 1 S cm−1 which are not suitable for digital circuits or applications in bioelectronics. Introducing conductive inorganic fillers into the hydrogels can improve their electrical conductivities. However, it may lead to compromises in compliance, biocompatibility, deformability, biodegradability, etc. Herein, a series of highly conductive ionic liquid (IL) doped PEDOT:PSS hydrogels without any conductive fillers is reported. These hydrogels exhibit high conductivities up to ≈305 S cm−1, which is ≈8 times higher than the record of polymeric hydrogels without conductive fillers in literature. The high electrical conductivity results in enhanced areal thermoelectric output power for hydrogel‐based thermoelectric devices, and high specific electromagnetic interference (EMI) shielding efficiency which is about an order in magnitude higher than that of state‐of‐the‐art conductive hydrogels in literature. Furthermore, these stretchable (strain >30%) hydrogels exhibit fast self‐healing, and shape/size‐tunable properties, which are desirable for hydrogel bioelectronics and wearable organic devices. The results indicate that these highly conductive hydrogels are promising in applications such as sensing, thermoelectrics, EMI shielding, etc.
In this paper, we present a 3D printed tumor spheroidal model suitable for drug discovery. This model is based on a hydroxyethyl cellulose/alginate/gelatin (HCSG) composite biomaterial that has three distinct properties: (1) the HCSG is similar to the commercial basement membrane extract in Ki67, MUC1, and PARP1 expressions of MCF-7 cells for embedding culture; (2) the HCSG is printable at room temperature; and (3) the HCSG can be large-scale manufactured at an ultralow cost.We printed a 3D MCF-7 spheroid model with HCSG and characterized it in terms of cell viability, spheroid size, key protein expression, and mitochondrial metabolic activity. We used the 3D MCF-7 spheroid model to evaluate the anti-breast cancer activity of 13 amino acid-based flavone phosphoramidates and found that the alanine structure induced a stronger drug resistance, whereas phenylalanine hardly caused drug resistance in the MCF-7 cells. This is the first time that 3D bioprinting technology has been used in a structure-activity relationship study.
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