Escherichia coli (E. coli) is a large and diverse bacteria group that inhabits the intestinal tract of many mammals. Most E. coli strains are harmless, however some of them are pathogenic, meaning they can make one sick if ingested. By being in the feces of animals and humans, its presence in water and food is used as indicator of fecal contamination. The main method for this microorganism detection is the bacterial culture medium that is time-consuming and requires a laboratory with specialized personnel. Other sophisticated methods are still not fast enough because they require sending samples to a laboratory and with a high cost of analysis. In this paper, a gold-coated U-shaped plastic optical fiber (POF) biosensor for E. coli bacteria detection is presented. The biosensor works by intensity modulation principle excited by monochromatic light where the power absorption is imposed by predominant effect of either bending loss or surface plasmon resonance (SPR), depending on the gold thickness. Bacterial selectivity is obtained by antibody immobilization on the fiber surface. The biosensor showed a detection limit of 1.5 × 103 colony-forming units (CFU)/mL, demonstrating that the technology can be a portable, fast response and low-cost alternative to conventional methodologies for quality analysis of water and food.

This study assessed the effect of whey protein substitution with isolated soy protein in protein bar (PB) formulations at 25% (PB2), 50% (PB3), or 75% (PB1) weight/weight on the proximate and mineral composition, sensory, and antidiabetic properties. Sensory evaluation was conducted within diabetic (DB) and non-diabetic (NDB) consumers by preference ranking and acceptance test. The formulations were analysed in terms of moisture, ash, protein, lipid, carbohydrates, fibers and mineral content. The consumers did not distinguish the formulations by preference ranking test. However, the acceptability test showed a rating of 9 most frequent for PB1 (36.30%), followed by PB2 and PB3 (both 34.09%), among DB consumers. The PB1 and PB3 showed higher content of total, soluble and insoluble fibers and, PB 2 presented higher carbohydrate content. Potassium, sodium and calcium showed the highest mineral content in the formulations. PB3 was assessed for glycaemic and lipidemic control in diabetics and non-diabetics female Wistar rats, for this 20% of PB was added in the ration consumed ad libitum, besides, the rats received 100 mg/kg b. w. by gavage daily. The treatment did not reduce significantly fasting glucose, lipid profile, or peripheral glucose disposal in DB or NDB rats. However, it significantly improved insulin tolerance test values in diabetic rats. The results suggest that the formulations showed good acceptance and potentially ameliorate insulin resistance both in control group and in animal model of type II diabetes.

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This paper describes, for the first time to our knowledge, a fast-response and specific biosensor for detection of Taenia solium, a parasite responsible for neurocysticercosis disease that affects the central nervous system. The biosensor is based on the localized surface plasmon resonance (LSPR) technique on gold nanoparticles (AuNPs) in colloidal suspension that were functionalized and activated with antibodies to perform an immuno-capture effect. The AuNPs were synthetized by Turkevich and seed-mediated growth methods. A variety of concentrations of T. solium antigen were added to test the detection and the dose-response profile. Small antigen concentrations were detected indicating that the limit of detection is lower than 0.1 µg/mL of antigen. The results demonstrate the potential of the AuNPs LSPR biosensor as a clinical tool for neurocysticercosis diagnostic.

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