Modulus-tunable multifunctional hydrogel ink with nanofillers for 3D-Printed soft electronics.

Seamless integration and conformal contact of soft electronics with tissue surfaces have emerged as major challenges in realizing accurate monitoring of biological signals. However, the mechanical mismatch between the electronics and biological tissues impedes the conformal interfacing between them. Attempts have been made to utilize soft hydrogels as the bioelectronic materials to realize tissue-comfortable bioelectronics. However, hydrogels have several limitations in terms of their electrical and mechanical properties. In this study, we present the development of a 3D-printable modulus-tunable hydrogel with multiple functionalities. The hydrogel has a cross-linked double network, which greatly improves its mechanical properties. Functional fillers such as XLG or functionalized carbon nanotubes (fCNT) can be incorporated into the hydrogel to provide tunable mechanics (Young's modulus of 10-300 kPa) and electrical conductivity (electrical conductivity of ∼20 S/m). The developed hydrogel exhibits stretchability (∼1000% strain), self-healing ability (within 5 min), toughness (400-731 kJ/m3) viscoelasticity, tissue conformability, and biocompatibility. Upon examining the rheological properties in the modulated region, hydrogels can be 3D printed to customize the shape and design of the bioelectronics. These hydrogels can be fabricated into ring-shaped strain sensors for wearable sensor applications.

A Mechanically Resilient and Tissue-Conformable Hydrogel with Hemostatic and Antibacterial Capabilities for Wound Care.

Hydrogels are used in wound dressings because of their tissue-like softness and biocompatibility. However, the clinical translation of hydrogels remains challenging because of their long-term stability, water swellability, and poor tissue adhesiveness. Here, tannic acid (TA) is introduced into a double network (DN) hydrogel consisting of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) to realize a tough, self-healable, nonswellable, conformally tissue-adhesive, hemostatic, and antibacterial hydrogel. The TA within the DN hydrogel forms a dynamic network, enabling rapid self-healing (within 5 min) and offering effective energy dissipation for toughness and viscoelasticity. Furthermore, the hydrophobic moieties of TA provide a water-shielding effect, rendering the hydrogel nonswellable. A simple chemical modification to the hydrogel further strengthens its interfacial adhesion with tissues (shear strength of ≈31 kPa). Interestingly, the TA also can serve as an effective hemostatic (blood-clotting index of 58.40 ± 1.5) and antibacterial component, which are required for a successful wound dressing. The antibacterial effects of the hydrogel are tested against Escherichia coli and Staphylococcus aureus. Finally, the hydrogel is prepared in patch form and applied to a mouse model to test in vivo biocompatibility and hemostatic performances.

3D printing of mechanically tough and self-healing hydrogels with carbon nanotube fillers.

Hydrogels have the potential to play a crucial role in bioelectronics, as they share many properties with human tissues. However, to effectively bridge the gap between electronics and biological systems, hydrogels must possess multiple functionalities, including toughness, stretchability, self-healing ability, three-dimensional (3D) printability, and electrical conductivity. Fabricating such tough and self-healing materials has been reported, but it still remains a challenge to fulfill all of those features, and in particular, 3D printing of hydrogel is in the early stage of the research. In this paper, we present a 3D printable, tough, and self-healing multi-functional hydrogel in one platform made from a blend of poly(vinyl alcohol) (PVA), tannic acid (TA), and poly(acrylic acid) (PAA) hydrogel ink (PVA/TA/PAA hydrogel ink). Based on a reversible hydrogen-bond (H-bond)-based double network, the developed 3D printable hydrogel ink showed excellent printability via shear-thinning behavior, allowing high printing resolution (~100 µm) and successful fabrication of 3D-printed structure by layer-by-layer printing. Moreover, the PVA/TA/PAA hydrogel ink exhibited high toughness (tensile loading of up to ~45.6 kPa), stretchability (elongation of approximately 650%), tissue-like Young's modulus (~15 kPa), and self-healing ability within 5 min. Furthermore, carbon nanotube (CNT) fillers were successfully added to enhance the electrical conductivity of the hydrogel. We confirmed the practicality of the hydrogel inks for bioelectronics by demonstrating biocompatibility, tissue adhesiveness, and strain sensing ability through PVA/TA/PAA/CNT hydrogel ink.

Age- and sex-specific risk of urogenital infections in patients with type 2 diabetes treated with sodium-glucose co-transporter 2 inhibitors: A population-based self-controlled case-series study.

This study aimed to investigate the age- and sex-specific risk of urogenital infections in patients with type 2 diabetes mellitus (T2DM) treated with sodium-glucose co-transporter 2 (SGLT2) inhibitors. A self-controlled case series was conducted using annual national patient sample datasets from 2016 and 2017. Patients who were treated with SGLT2 inhibitors and who received antimicrobials for urogenital infections were included in the study. The incidence rate ratio (IRR) of urogenital infections during SGLT2 inhibitor exposure were compared with those in the non-exposure period. A total of 2,949 patients were included in the analysis, and 71.2% of the patients were women aged ≥ 50 years. Stratified analysis by age and sex showed that only women ≥ 50 years showed a significant increase in the risk of urinary tract infections (UTIs) (IRR 1.25, 95% CI 1.14-1.37) and genital infections (IRR 1.44, 95% CI 1.28-1.62). The highest risk of UTI risk was observed 8-14 days after initiating SGLT2 inhibitor therapy (IRR 1.49, 95% CI 1.07-2.08), and after 15-28 days for genital infections (IRR 2.11, 95% CI 1.66-2.67) in women ≥ 50. SGLT2 inhibitors increase the risk of urogenital infections in T2DM patients, especially in women aged ≥ 50 years. Monitoring of urogenital infections in women aged ≥ 50 years, especially during the first month after starting SGLT2 inhibitors, is recommended.