Capture of Soft Particles on Electrostatically Heterogeneous Collectors: Brushy Particles

Abstract

This work investigated how particle softness can influence the initial adhesive capture of submicrometer colloidal particles from flow onto collecting surfaces. The study focused on the case dominated by potential attractions at the particle periphery (rather than, for instance, steric stabilization, requiring entropically costly deformations to access shorter-range van der Waals attractions.) The particles, "spherical polyelectrolyte brushes" with diameters in the range of 150-200 nm depending on the ionic strength, consisted of a polystyrene core and a corona of grafted poly(acrylic acid) chains, producing a relatively thick (20-40 nm) negative brushy layer. The adhesion of these particles was studied on electrostatically heterogeneous collecting surfaces: negatively charged substrates carrying flat polycationic patches made by irreversibly adsorbing the poly-l-lysine (PLL) polyelectrolyte. Variation in the amount of adsorbed PLL changed the net collector charge from completely negatively charged (repulsive) to positively charged (attractive). Adjustments in ionic strength varied the range of the electrostatic interactions. Comparing capture kinetics of soft brushy particles to those of similarly sized and similarly charged silica particles revealed nearly identical particle capture kinetics over the full range of collecting surface compositions at high ionic strengths. Even though the brushy particles contained an average of 5 vol % PAA in the brushy shell, with the rest being water under these conditions, their capture was indistinguishable from that of similarly charged rigid spheres. The brushy particles were, however, considerably less adherent at low ionic strengths where the brush was more extended, suggesting an influence of particle deformability or reduced interfacial charge. These findings, that the short time adhesion of brushy particles can resemble that of rigid particles, suggest that for bacteria and cell capture, modeling the cells as rigid particles can, in some instances, be a good approximation.

Patterned and Specific Attachment of Bacteria on Biohybrid Bacteria‐Driven Microswimmers

“…[24] Comparing the capture kinetics of half-soft brushy Janus to the equivalent size and charged Janus particles without SAMs could be a good approximation, revealing nearly identical bacterial capture kinetics over the full range of collecting surface compositions at same ionic strength. [27] All adhesion experiments were carried out in motility media because the influence of ionic strength of motility media on the maturation of adhesion after initial cell capture supports a mechanism of electrostatically driven "tightening" of the bacteria onto the surface. [28] This adhesive tightening does not need to involve living processes or bacteria metabolism, but depends upon surface charge distribution.…”

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

“…This initial interaction involves adhesive groups across an interface at short times. Particle or wall deformation is not needed for this initial binding step and, indeed, previous studies provide examples of conditions where deformable particles are captured from flow at the same rates as rigid particles, 63 suggesting that any deformations, if they occur, might not influence capture. In the current study, it is unclear if deformation does or can occur on the timescales of particle− surface approach.…”

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.…”