Exploring the Heterogeneity of Nanoparticles in Their Interactions with Plasma Coagulation Factor XII

Anionic Ultrasmall Gold Nanoparticles Bind to Coagulation Factors and Disturb Normal Hemostatic Balance

Ultrasmall gold nanoparticles (usNPs) and nanoclusters are an emerging class of nanomaterials exhibiting distinctive physicochemical properties and in vivo behaviors. Although understanding the interactions of usNPs with blood components is of fundamental importance to advance their clinical translation, currently, little is known about the way that usNPs interact with the hemostatic system. This study describes the effects of a model anionic p-mercaptobenzoic acid-coated usNP on the coagulation cascade, with particular emphasis on the contact pathway. It is found that in a purified system, the anionic usNPs bind to and activate factor XII (FXII). The formed usNP-FXII complexes are short-lived (residence time of ∼10 s) and characterized by an affinity constant of ∼200 nM. In human plasma, the anionic usNPs activate the contact pathway and promote coagulation. The usNPs also exhibit anticoagulant activity in plasma by interfering with the thrombin-mediated cleavage of fibrinogen. Taken together, these findings establish that anionic usNPs can disturb the normal hemostatic balance, which in turn may hinder their clinical translation. Finally, it is shown that usNPs can be designed to be nearly inert in plasma by surface coating with the natural peptide glutathione.

Hydrogel-Tissue Adhesion Using Blood Coagulation Induced by Silica Nanoparticle Coatings

The fixation of hydrogels to biological tissues is a major challenge conditioning the development of implants and surgical techniques. Here, coatings of procoagulant nanoparticles are devised which use the presence of blood to create adhesion between hydrogels and soft internal organs. Those nanostructured coatings are simply adsorbed at the hydrogel surfaces and can rapidly activate the formation of an interfacial blood clot acting as an adhesive joint. This concept is demonstrated on pig liver capsules with model poly(ethylene-glycol) membranes that are intrinsically poorly adhesive. In the absence of blood, ex vivo peeling tests show that coatings with aggregates of bare silica nanoparticles induce a 2- to 4-fold increase in adhesion energy as compared to the uncoated membrane (3 ± 2 J m^-2). This effect is found to scale with the specific surface area of the coating. The highest adhesion energies produced by these nanoparticle-coated membranes (10 ± 5 J m^-2) approach the value obtained with cyanoacrylate glue (33 ± 11 J m^-2) for which tearing of the tissue is observed. Ex vivo pull-off tests show an adhesion strength of coated membranes around 5 ± 1 kPa, which is significantly reduced when operating in vivo (1.0 ± 0.5 kPa). Nevertheless, when blood is introduced at the interface, the in vivo adhesion strength can be improved remarkably with silica coatings, reaching 4 ± 2 kPa after 40 min contact. In addition, these silica-coated membranes can seal and stop the bleeding produced by liver biopsies very rapidly (<30 s). Such a combination of coagulation and particle bridging opens promising routes for better biointegrated hydrogel implants and improved surgical adhesives, hemostats, and sealants.

Interactions of Surface-Functionalized Starch Nanoparticles with Pepsin and Trypsin in Simulated Gastrointestinal Fluids

Nanoparticles (NPs) can form a protein corona (PC) with proteins in biological fluids. We examined whether starch nanoparticles (SNPs) form a PC and interact with digestive enzymes in simulated gastric and intestinal fluids. We investigated the adsorption of pepsin and trypsin on unmodified, carboxyl-, and amino-modified SNPs (SNPs, COOH-SNPs, and NH₂-SNPs, respectively). Quartz crystal microbalance data showed that a tight and irreversible pepsin corona formed on the NH₂-SNPs, pepsin had little or no binding to the SNPs and COOH-SNPs, and trypsin had weak binding to all three kinds of NPs. Dynamic light scattering data showed that pepsin significantly increased the size of the NH₂-SNPs from 120 ± 2.6 to 203 ± 12.2 nm and decreased their surface potential from 23.2 ± 1.0 to 12.7 ± 0.2 mV. NH₂-SNPs could induce the fluorescence quenching of pepsin and change its secondary structures without affecting its activity.

Identification of physicochemical properties that modulate nanoparticle aggregation in blood

Inorganic materials are receiving significant interest in medicine given their usefulness for therapeutic applications such as targeted drug delivery, active pharmaceutical carriers and medical imaging. However, poor knowledge of the side effects related to their use is an obstacle to clinical translation. For the development of molecular drugs, the concept of safe-by-design has become an efficient pharmaceutical strategy with the aim of reducing costs, which can also accelerate the translation into the market. In the case of materials, the application these approaches is hampered by poor knowledge of how the physical and chemical properties of the material trigger the biological response. Hemocompatibility is a crucial aspect to take into consideration for those materials that are intended for medical applications. The formation of nanoparticle agglomerates can cause severe side effects that may induce occlusion of blood vessels and thrombotic events. Additionally, nanoparticles can interfere with the coagulation cascade causing both pro- and anti-coagulant properties. There is contrasting evidence on how the physicochemical properties of the material modulate these effects. In this work, we developed two sets of tailored carbon and silica nanoparticles with three different diameters in the 100-500 nm range with the purpose of investigating the role of surface curvature and chemistry on platelet aggregation, activation and adhesion. Substantial differences were found in the composition of the protein corona depending on the chemical nature of the nanoparticles, while the surface curvature was found to play a minor role. On the other hand, large carbon nanoparticles (but not small carbon nanoparticles or silica nanoparticles) have a clear tendency to form aggregates both in plasma and blood. This effect was observed both in the presence or absence of platelets and was independent of platelet activation. Overall, the results presented herein suggest the existence of independent modes of action that are differently affected by the physicochemical properties of the materials, potentially leading to vessel occlusion and/or formation of thrombi in vivo.