Polypyrrole (PPy) is a well-known intrinsically conductive polymer broadly used in cardiac tissue engineering due to its excellent biocompatibility, radical scavenging capacity and antimicrobial activity. However, the lack of proper processability of PPy motivated the development of hybrid materials using different biocompatible polymers and techniques. Motivated by these limitations, a thermoplastic polyurethane (TPU) was used as matrix for preparing two PPy hybrid conductive materials: a coated 3D printed TPU scaffold and melt-mixed composite films. The PPy was synthesized in presence of FeCl3, acting as an initiator and further providing dopant agents. The as-synthesized PPy exhibited a conductivity of 1000 S/m, while coated PPy/TPU presented a conductivity of 1 S/m and the percolated TPU composite containing 25 w/w% of PPy showed a value of 10⁻⁵ S/m. Regarding the mechanical properties, although coated samples did not present a relevant change in the tensile mechanical behavior as compared with pure TPU, composites drastically increased the stiffness until a 1000%, although increasing the brittleness. Our results show that the antioxidant activity of PPy was rendered to the coated and composite TPU samples. Regarding the antibacterial activity, PPy displayed high antimicrobial activity against E. coli and S. aureus as measured by inhibition zone tests, although depending on the amount of dopants used in the synthesis. Under antibacterial contact tests, coated TPU samples presented high activity against both strains, while the composite was only active against S. aureus. Noteworthy, coated and composited TPU/PPy displayed antimicrobial activity on planktonic bacteria but did not inhibit bacterial adhesion, highlighting the relevance of the de-doping process from PPy. Regarding the biocompatibility of hybrid samples toward cardiac TE, coated TPU samples enhanced cardiomyocytes viability compared to pure TPU, whereas composite showed reduced viability. These results underscore the potential of PPy-based hybrid materials for the design of electroactive and antibacterial biomaterials giving key antecedents about its mechanisms and the differences between PPy coatings and PPy composite materials. This strategy allowed us to develop biocompatible materials having conductivity, radical scavenging capacity, antimicrobial activity, and cardiomyocyte viability.

Polypyrrole (PPy) is a well-known intrinsically conductive polymer broadly used in cardiac tissue engineering due to its excellent biocompatibility, radical scavenging capacity and antimicrobial activity. However, the lack of proper processability of PPy motivated the development of hybrid materials using different biocompatible polymers and techniques. Motivated by these limitations, a thermoplastic polyurethane (TPU) was used as matrix for preparing two PPy hybrid conductive materials: a coated 3D printed TPU scaffold and melt-mixed composite films. The PPy was synthesized in presence of FeCl3, acting as an initiator and further providing dopant agents. The as-synthesized PPy exhibited a conductivity of 1000 S/m, while coated PPy/TPU presented a conductivity of 1 S/m and the percolated TPU composite containing 25 w/w% of PPy showed a value of 10⁻⁵ S/m. Regarding the mechanical properties, although coated samples did not present a relevant change in the tensile mechanical behavior as compared with pure TPU, composites drastically increased the stiffness until a 1000%, although increasing the brittleness. Our results show that the antioxidant activity of PPy was rendered to the coated and composite TPU samples. Regarding the antibacterial activity, PPy displayed high antimicrobial activity against E. coli and S. aureus as measured by inhibition zone tests, although depending on the amount of dopants used in the synthesis. Under antibacterial contact tests, coated TPU samples presented high activity against both strains, while the composite was only active against S. aureus. Noteworthy, coated and composited TPU/PPy displayed antimicrobial activity on planktonic bacteria but did not inhibit bacterial adhesion, highlighting the relevance of the de-doping process from PPy. Regarding the biocompatibility of hybrid samples toward cardiac TE, coated TPU samples enhanced cardiomyocytes viability compared to pure TPU, whereas composite showed reduced viability. These results underscore the potential of PPy-based hybrid materials for the design of electroactive and antibacterial biomaterials giving key antecedents about its mechanisms and the differences between PPy coatings and PPy composite materials. This strategy allowed us to develop biocompatible materials having conductivity, radical scavenging capacity, antimicrobial activity, and cardiomyocyte viability.

Cellulose is a well-known biopolymer with excellent properties for a broad range of applications, including piezoelectricity for the development of nanogenerators. However, similar to other piezoelectric materials, the voltage outputs currently reported from cellulose-based piezoelectric nanogenerators (PENGs) could be overestimated due to the appearance of triboelectric processes. To understand the appearance of both phenomena, cellulose films and aerogels that had undergone several modifications to improve their piezoelectric behavior (i.e., thermal treatment and presence of piezoelectric/conductive particles) were developed and characterized. Our results show that these modifications significantly changed the dielectric properties (ε) and the piezoelectric coefficients (d₃₃), with increments as high as a factor of 4, although without a clear tendency regarding the sample characteristics. Under finger-tapping mechanical stimulation, nanogenerators (NGs) using pure cellulose films generated 6 V, whereas the modified cellulose films and aerogels either increased or decreased this value, with outputs between 2 and 10 V. Notably, ternary composites, having both conductive and piezoelectric ZnO particles, increased the generation up to 24 V. There was no correlation between the voltage generated and d₃₃ or d₃₃/ε values, although some relationship with ε was observed, meaning that a pure piezoelectric phenomenon was not observed. This lack of correlation and the drastic decrease in the voltage generated (around 0.2 V) after changing the NG configuration show that a triboelectric phenomenon from the multilayered structure significantly contributes to the voltage generation from cellulose samples.