Enhanced Stability of Gold Magnetic Nanoparticles with Poly(4-styrenesulfonic acid-co-maleic acid): Tailored Optical Properties for Protein Detection

Abstract

Gold magnetic nanoparticles (GoldMag) have attracted great attention due to their unique physical and chemical performances combining those of individual Fe3O4 and Au nanoparticles. Coating GoldMag with polymers not only increases the stability of the composite particles suspended in buffer but also plays a key role for establishing point-of-care optical tests for clinically relevant biomolecules. In the present paper, poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA), a negatively charged polyelectrolyte with both sulfonate and carboxylate anionic groups, was used to coat the positively charged GoldMag (30 nm) surface. The PSS-MA-coated GoldMag complex has a stable plasmon resonance adsorption peak at 544 nm. A pair of anti-D-dimer antibodies has been coupled on this GoldMag composite nanoparticle surface, and a target protein, D-dimer was detected, in the range of 0.3–6 μg/mL. The shift of the characteristic peak, caused by the assembly of GoldMag due to the formation of D-dimer-antibody sandwich bridges, allowed the detection.

Sensitive T2 MRI Contrast Agents from the Rational Design of Iron Oxide Nanoparticle Surface Coatings

“…Notably, IONCs with carboxylate-containing encapsulation agents (oleic acid bilayer, PAA-LA, and PMAO–PEG) have a significantly reduced r 2 under highly acidic conditions (pH 3) and in the presence of high divalent salt concentrations (0.05–0.5 M CaCl 2 ) (Figure d,f and Figure b,d). As discussed above, carboxylate-containing surface coating agents become less stable at low pH and in the presence of divalent metal cations like Ca 2+ , leading to aggregation and a reduction in r 2 . , The sulfonated polymer coatings in contrast maintain good colloidal stability and high T 2 performance under all conditions–even at low pH and high CaCl 2 (0.05–0.5 M). − …”

“…Phase transferred nanocrystals with sulfonate-containing polymer coatings (PAMPS-LA) provide for the most stable suspensions under all conditionseven low pH and high CaCl 2 (0.05–0.5 M) conditions. This is to be expected for sulfonated polymers because of their low p K a (<2), hydrogen bond donor and acceptor properties, and lack of interaction with divalent cations. − As such, relatively novel sulfonated polymeric surface coatings like PAMPS-LA demonstrate significant promise in biomedical applications of nanomaterials. − , …”

Super-assembly of integrated gold magnetic assay with loop-mediated isothermal amplification for point-of-care testing

“…2(a). The characteristic peak at 585 cm −1 is related to Fe-O bond in GMNPs [40]. The characteristic absorption bands of 1,037 and 1,637 cm −1 correspond to the symmetric vibration of the sulfonate group (SO 3 − ) and the stretching vibration of C=C of Benzene [41].…”

2D Gadolinium Oxide Nanoplates as T1 Magnetic Resonance Imaging Contrast Agents

“…[82,83] Its sulfonic acid functional group ensures excellent colloidal stability over a wide range of conditions and we note that other sulfonated polymers are biocompatible www.advhealthmat.de at clinically relevant concentrations. [82][83][84][85] Also, more negatively charged surface coatings enhance the relaxivity of Gadoliniumcontaining nanocrystals. [20,38,86] Here we expect that the sulfonic acid groups will structure water around the nanoplates and accelerate second-sphere relaxation processes.…”