Bioelectronic Energy Storage: A Pseudocapacitive Hydrogel Composed of Endogenous Biomolecules

Advances in bioelectronics have produced implantable devices for in vivo biosensing and therapeutics, but batteries for implantable devices currently require bulky metal cases to sequester toxic electrolytes and immunogenic active materials; therefore, development of new materials is paramount for safety and miniaturization. Implantable batteries could be fully biocompatible if they exclusively comprised endogenous materials. Accordingly, we present an energy-storage material fabricated entirely from endogenous biomolecules via one-step carbodiimide conjugation of dopamine (DA) to hyaluronic acid (HA). The DAHA composite can be electropolymerized to create a pseudocapacitive biopolymer, p­(DAHA), that exhibits catechol–quinone interconversion, stability, long-term electroactivity for 400 cycles, and high pseudocapacitance (up to ∼900 F g^–1) and discharge capacity (∼130 mAh g^–1 at ∼10 A g^–1). These characteristics predispose it for bioelectronic energy storage, i.e., as a supercapacitor or, when coupled with an implantable Ag/AgCl electrode, a biobattery with an operating voltage of ∼0.85 V

Community-based monitoring of diarrhea in urban Brazilian children: incidence and associated pathogens.

Community-based monitoring was conducted in order to investigate the occurrence of diarrhea in 'sentinel areas' of Salvador, Brazil, and to establish a preliminary profile of the most common pathogens present in children's diarrhea by screening stool samples. This report describes the results obtained from twice weekly home visits to identify and follow diarrhea episodes and testing of carer-requested stool sample collection over a 6-month period. Participants were selected from a large longitudinal study in 21 areas representing the city's poorer socioeconomic and sanitary conditions. Fecal samples were examined for the presence of pathogenic bacteria, viruses and protozoa. The mean incidence of diarrhea was 4.97 episodes per child-year, and longitudinal prevalence was 13.6 days per child-year (3.7%). Pathogens were found in 44% of the fecal samples examined. Bacteria were the most frequently encountered pathogens (isolated in 22% of samples), followed by protozoa (19.5%) and viruses (16%). Viral and bacterial pathogens were associated with episodes of severe diarrhea, while viral and protozoan pathogens were associated with longer episodes. The study demonstrated the importance of a public health monitoring system based on 'sentinel areas'