Proteins Adsorbing onto Surface-Modified Nanoparticles: Effect of Surface Curvature, pH, and the Interplay of Polymers and Proteins Acid–Base Equilibrium

Abstract

Protein adsorption onto nanomaterials is a process of vital significance and it is commonly controlled by functionalizing their surface with polymers. The efficiency of this strategy depends on the design parameters of the nanoconstruct. Although significant amount of work has been carried out on planar surfaces modified with different types of polymers, studies investigating the role of surface curvature are not as abundant. Here, we present a comprehensive and systematic study of the protein adsorption process, analyzing the effect of curvature and morphology, the grafting of polymer mixtures, the type of monomer (neutral, acidic, basic), the proteins in solution, and the conditions of the solution. The theoretical approach we employed is based on a molecular theory that allows to explicitly consider the acid–base reactions of the amino acids in the proteins and the monomers on the surface. The calculations showed that surface curvature modulates the molecular organization in space, but key variables are the bulk pH and salt concentration (in the millimolar range). When grafting the NP with acidic or basic polymers, the surface coating could disfavor or promote adsorption, depending on the solution’s conditions. When NPs are in contact with protein mixtures in solution, a nontrivial competitive adsorption process is observed. The calculations reflect the balance between molecular organization and chemical state of polymers and proteins, and how it is modulated by the curvature of the underlying surface.

Orientational Pathways during Protein Translocation through Polymer-Modified Nanopores

“…Previous theoretical calculations have also addressed this issue regarding the adsorption of proteins on charged surfaces of different geometries. 34,40,44 At pH = 8 (Figure 2A), both the polyelectrolyte brush and the protein have a negative net charge. The resulting electrostatic repulsions give rise to a barrier in the free energy as the protein translocates through the nanopore.…”

Passivating quantum dots against histag-displaying enzymes using blocking peptides: salient considerations for self-assembling quantum dot biosensors

“…Interestingly, the data suggest that the amount of BP needed to passivate QDs does not scale proportionally with surface area. This discrepancy is hypothesized to arise from variations in the completeness of CL4 ligand exchange, as well as the effects of QD curvature, 60 though differences in the ligand exchange process and uncertainty regarding the full composition of QD625 limit this to speculation.…”

Separation of the heme protein cytochrome C using a 3D structured graphene oxide bionanocomposite as an adsorbent

“…3 The comprehension of complex interactions between the surface of biological macromolecules and nanomaterials underlies the potential biomedical applications of novel nanomaterials and nanocomposites. 4 Several applications in biotechnology rely on protein adsorption, and interactions of proteins with nanomaterials can be exploited for tissue engineering, regenerative medicine, drug delivery, and biosensors development primarily due to their mechanical properties, versatility in functionalization, and high specific surface area. 5,6 Among the proteins evaluated in studies regarding the development of new materials applied to more efficient separation processes, there are the heme proteins, such as cytochrome C (Cyto C).…”