ELISA In the ELISA assay, recombinant plasminogen activator inhibitor (PAI-1) is coated around the plate and free binding sites are blocked with bovine serum albumin. serum was measured at 1000 nm. The particles were dispersed at 1 mg/mL and the absorbance was monitored for 25 hours. A significant decrease of the absorbance would LY2140023 (LY404039) show colloidal instability and precipitation of the nanoparticles.(DOCX) pone.0109475.s003.docx (240K) GUID:?4D7E4CC2-0F35-45BE-8B2F-B16AFDF8EA45 Physique S4: Transmission electron microscopy (TEM) LY2140023 (LY404039) image of the iron oxide nanoparticles (8.60.6 nm). Their size was determined by ImageJ software.(DOCX) pone.0109475.s004.docx (2.7M) GUID:?18F363ED-412D-44FD-A742-DBA9DF1B6DE0 Figure S5: The colloidal stability of the nanoparticle dispersions is excellent, even after 1 year of storage. The samples (5 mg/mL in water, pH 7) show above have the following coatings (molar percentages): A, 100% PEG10-OH; B, 10% PEG10-COOH 90% PEG10-OH; C, 25% PEG10-COOH 75% PEG10-OH; D, 50% PEG10-COOH 50% PEG10-OH.(DOCX) pone.0109475.s005.docx (2.1M) GUID:?AD9D6675-B4F3-4533-9FB7-DE49445B21DE Data Availability StatementThe authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper and its Supporting Information files. Abstract Ever since iron oxide nanoparticles have been recognized as encouraging scaffolds for biomedical applications, their surface functionalization has become even more important. We statement the synthesis of a novel polyethylene glycol-based ligand that combines multiple advantageous properties for these applications. The ligand is usually covalently bound to the surface via a siloxane group, while its polyethylene glycol backbone significantly enhances the colloidal stability of the particle in complex environments. End-capping the molecule LY2140023 (LY404039) with a carboxylic acid introduces a variety of coupling chemistry possibilities. In this study an antibody targeting LY2140023 (LY404039) plasminogen activator inhibitor-1 was coupled to the surface and its presence and binding activity was assessed by enzyme-linked immunosorbent assay and surface plasmon resonance experiments. The results indicate that this ligand has high potential towards biomedical applications where colloidal stability and advanced functionality is crucial. Introduction The potential of iron oxide nanoparticles (NP) in biomedical applications is usually widely recognized: they can act as magnetic resonance imaging (MRI) contrast agents, superparamagnetic service providers for drugs or are used in hyperthermia treatments. [1]C[6] By improving the synthesis of these particles, their quality and availability has largely increased. [7]C[12] When NP are used in biomedical applications, two requirements are often necessary. First, their colloidal stability in complex environments is crucial. If the particles become unstable in for instance blood, they will precipitate, possibly triggering severe inflammatory responses. [13]C[15] Secondly, they should possess accessible anchor points for molecules or proteins to be coupled onto. This allows NP to selectively interact with certain targets or to carry drugs close to a desired Rabbit polyclonal to ZNF10 location. However, functionalization of their surface has proven to be non-trivial. Although multiple different methods have been developed, most of them lack a certain degree of control. [16] Covering their surface with functional polymers is a straightforward method, but has crosslinking issues and allows little control over the thickness of the layer and orientation of functional groups. [17] Since they are not covalently attached to the surface, they could potentially detach, which would make the particles precipitate. Growing an additional silica layer around the iron oxide core, on the other hand, has several advantages: the shell thickness can be well controlled and it is chemically inert. [18] However, the diameter of such NP increases by several nanometers, which is usually often not desired for biomedical applications. [19] This problem was circumvented by the introduction of functional siloxane molecules on iron oxide NP. They also form a silicon dioxide shell, albeit very thin, and they contain a functional group, which can have several advantages or uses later on. [20], [21]. Even though multiple variants of these silanes are commercially available, they often do not have the desired structure or properties. This can very easily be related to the complicated handling of siloxane molecules. Since they react with water and are relatively intolerant to warmth, modification reactions have to be limited in LY2140023 (LY404039) time and workup. Tucker-Schwartz recently published an easy method to avoid this direct modification of the siloxanes,.