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Surface-associated transport of flowing bacteria, including cell rolling, is a mechanism for otherwise immobile bacteria to migrate on surfaces and could be associated with biofilm formation or the spread of infection. This work demonstrates how the moduli and/or local polymer concentration play critical roles in sustaining contact, dynamic adhesion, and transport of bacterial cells along a hydrogel or hydrated brush surface. In particular, stiffer more concentrated hydrogels and brushes maintained the greatest dynamic contact, still allowing cells to travel along the surface in flow. This study addressed how the mechanical properties, molecular architectures, and thicknesses of minimally adhesive poly(ethylene glycol) (PEG)-based coatings influence the flow-driven surface motion of Staphylococcus aureus MS2 cells. Three protein-repellant PEG-dimethylacrylate hydrogel films (~100 μm thick) and two protein-repellant PEG brushes (8–16 nm thick) were sufficiently fouling-resistant to prevent the accumulation of flowing bacteria. However, the rolling or hopping-like motions of gently flowing S. aureus cells along the surfaces were specific to the particular hydrogel or brush, distinguishing these coatings in terms of their mechanical properties (with moduli from 2 to 1300 kPa) or local PEG concentrations (in the range 10–50% PEG). On the stiffer hydrogel coatings having higher PEG concentrations, S. aureus exhibited long runs of surface rolling, 20–50 μm in length, an increased tendency of cells to repeatedly return to some surfaces after rolling and escaping, and relatively long integrated contact times. By contrast, on the softer more dilute hydrogels, bacteria tended to encounter the surface for brief periods before escaping without return. The dynamic adhesion and motion signatures of the cells on the two brushes were bracketed by those on the soft and stiff hydrogels, demonstrating that PEG coating thickness was not important in these studies where the vertically oriented surfaces minimized the impact of gravitational forces. Control studies with similarly sized poly(ethylene oxide)-coated rigid spherical microparticles, that also did not arrest on the PEG coatings, established that the bacterial skipping and rolling signatures were specific to the S. aureus cells and not simply diffusive. Dynamic adhesion of the S. aureus cells on the PEG hydrogel surfaces correlated well with quiescent 24 h adhesion studies in the literature, despite the orientation of the flow studies that eliminated the influence of gravity on bacteria-coating normal forces.

Wearable human sweat sensors have offered a great prospect in epidermal detection for self-monitoring and health evaluation. These on-body epidermal sensors can be integrated with the Internet of Things (IoT) as augmented diagnostics tools for telehealth applications, especially for noninvasive health monitoring without using blood contents. One of many great benefits in utilizing sweat as biofluid is the capability of instantaneously continuous diagnosis during normal day-to-day activities. Here, we revealed a textile-based sweat sensor selective for perspired creatinine that is prepared by coating poly­(vinyl alcohol) (PVA)-Cu2+-poly­(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) and cuprous oxide nanoparticles on stretchable nylon, is equipped with heart rate monitoring and a satellite-communication device to locate wearers, and incorporates machine learning to predict the levels of environmental heat stress. Electrochemical impedance spectroscopy (EIS) was used to investigate different charge-transfer resistances of PVA and PEDOT:PSS with cuprous and cuprite ions induced by single-chain and ionic cross-linking. Furthermore, density function theory (DFT) studies predicted the catalytic binding of sweat creatinine with the sensing materials that occurred at thiophene rings. The hybrid sensor successfully achieved 96.3% selectivity efficacy toward the determination of creatinine contents from 0.4 to 960 μM in the presence of interfering species of glucose, urea, uric acid, and NaCl as well as retained 92.1% selectivity efficacy in the existence of unspecified human sweat interference. Ultimately, the hand-grip portable device can offer the great benefit of continuous health monitoring and provide the location of any wearer. This augmented telemedicine sensor may represent the first remote low-cost and artificial-intelligence-based sensing device selective for heat-stress sweat creatinine.

The stress-free electrochemical-based sensor equipped with the Internet of Things (IoT) device for salivary creatinine determination was fabricated for point-of-care (POC) diagnosis of advanced kidney disorders. Beneficial and realtime data readout for preventive diagnosis and clinical evaluation of chronic kidney diseases (CKD) at different stages and renal dysfunction can be acquired by noninvasive monitoring of the creatinine amounts in saliva. The direct determination and real-time response of salivary creatinine can be attained using the supercapacitor-based sensor of cuprous oxide nanoparticles entrapped by the synergistically cross-linked poly(acrylic acid) (PAA) gel−Cu 2+ and Nafion perfluorinated membrane fabricated on a screen-printed carbon electrode (SPCE). Here, we demonstrated that the degree of renal illness could be evaluated using salivary creatinine detection via a catalytic mechanism as Cu 2+ ions bound irreversibly with CN functional groups of creatinine. Besides, the computer simulation was performed to study the interaction between 5 functional groups of creatinine toward acrylic gel−Cu 2+. The linear increment between the obtained anodic currents and creatinine concentrations varying from 1 to 2000 μM was accomplished with a selectivity efficiency of 97.2%. Nyquist plots obtained by electrochemical impedance spectroscopy (EIS) validated that the increment of impedance changes strongly dependent on the amount of detected creatinine both in artificial and in human saliva. The porosity features were observed in this interconnected nanocomposite and correlated with Nafion doping. Successively, the friendly portable device was invented and integrated saliva sampling with miniaturized, low-cost IoT electronics of world-location mapping, representing the first remote medical sensor focusing on salivary creatinine sensing.