Mechanical Properties and Concentrations of Poly(ethylene glycol) in Hydrogels and Brushes Direct the Surface Transport of Staphylococcus aureus

Abstract

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.

Generation of Photopolymerized Microparticles Based on PEGDA Using Microfluidic Devices. Part 1. Initial Gelation Time and Mechanical Properties of the Material

“…Generally, the generation of microparticles based on polymers such as hydrogels made of Polyethylene Glycol Diacrylate (PEGDA), Figure 1 , are extensively used in the biotechnological field due to their minimal toxicity [ 5 ]. Different application fields have used hydrogels, such as biomedical devices [ 6 , 7 , 8 , 9 , 10 ], intelligent robotics [ 11 , 12 ], flexible electronics [ 13 ], mechanical metamaterials [ 14 , 15 , 16 , 17 ], activators [ 18 , 19 ] and the encapsulation of medicaments or biological agents where the hydrogel can be useful in protecting them or releasing them [ 20 ].…”

Satellite-Based Sensor for Environmental Heat-Stress Sweat Creatinine Monitoring: The Remote Artificial Intelligence-Assisted Epidermal Wearable Sensing for Health Evaluation

“…Recently, several novel materials , and polymer gels − in different electrochemical sensing paradigms have been embedded in wearable electronic textiles , used for promising emerging telehealth applications, such as human interactive sensors, motion trackers, sweat sensors for health monitoring . Integrated textile fabrics are easily stretched on the skin into many different configurations .…”

Salivary Creatinine Detection Using a Cu(I)/Cu(II) Catalyst Layer of a Supercapacitive Hybrid Sensor: A Wireless IoT Device To Monitor Kidney Diseases for Remote Medical Mobility

“…Several types of polymer gels ,− with chemical and physical properties tailored over a wide range of characteristics are being employed in different sensory architectures, − such as flexible silk–fibroin sponges with distinctive pore structure and excellent water uptake, the hybrid of silk fibroin and carbon nanotube for cardiomyocyte functionalities, to achieve highly sensitive biomaterials. Therefore, considering the importance of salivary creatinine monitoring for CKD patients with severely chronic stages, we anticipated the benefit of using a novel matrix of supramolecular gels with metal nanoparticles as sensing material equipped with portable electrochemical-based smartphones that can be monitored closely by doctors, physicians, or any qualified practitioners.…”