Building NanoSPR Biosensor Systems Based on Gold Magnetic Composite Nanoparticles

Abstract

Composite Fe3O4/Au nanoparticles are attracting considerable interest in developing visual and specific detection of biomolecular due to their unique physical and chemical properties. Here, two localize surface plasmon resonance (LSPR) probes based on Fe3O4/Au nanoparticles (nanoSPR biosensors) were fabricated by exploring 11-mercaptoundecanoic acid (MUA) and poly acrylic acid (PAA) as surface modification agents and subsequently conjugating rabbit IgG with the modified particles' surface. Comparative investigations showed the differences between MUA-particles and PAA-particles, as well as sensitivity of the two as-prepared nanoSPR biosensors when used in target goat anti-rabbit IgG colorimetric detection. Particles coated with PAA were in a better dispersion and showed an ionic independent stability, indicating PAA-particles have a potential application in colorimetric detection. In contrast, the MUA-particle probes revealed a higher sensitivity in SPR detection (50 nmol/L), and further kinetic studies showed the reactions between probes and target followed the second order and the reaction rate of MUA-probes was twice the rate of PAA-probes at the same temperature and condition. Such proof-of concept works reported here demonstrated that the protocol to build nanoSPR biosensors was favored in developing molecular probes, and the novel composite nanoparticles might serve as ideal probes for sensitive, selective and real time detection.

Apolipoprotein E genotyping using PCR-GoldMag lateral flow assay and its clinical applications

“…This shift is likely to be caused by the surface chemistry change of the nanoparticles from PSS to antibody (33). The optimization of PGMNs-antibody conjugates was defined by the protein concentration assay as described in a previous report (23), and the appropriate amount of anti-digoxin or anti-FITC antibodies immobilized on the PGMNs was about 60 and 48 µg/mg, respectively.…”

“…A blocking buffer (1X PB buffer, pH 7.2, containing 3% BSA and 5% calf serum) was added to the conjugates, and the mixture was incubated for 1 h. After incubation for 2 h, anti-digoxin antibody or anti-FITC antibody functionalized PSS-GMNs conjugates, were magnetically separated and then suspended in buffer (1X PB, pH 7.2, containing 1% BSA) at 2–8°C prior to use. The conjugation efficiency was calculated by determining the concentration of anti-digoxin or anti-FITC antibody in the solution prior to and following coupling using the Lowry protein concentration assay, with BSA as a protein standard (23). …”

Optical-Based (Bio) Sensing Systems Using Magnetic Nanoparticles

“…Until now, decorating SPR surfaces with MNPs seems to be the most widely attested. Especially the application of MNPs in SPR sensing has attracted great focus owing to advantages which are (1) capture of the target molecules from the complex sample and (2) high refractive index and high molecular weight of MNPs to recruit the SPR signal [41,42]. Due to the aforementioned desired properties of MNPs, these compounds are widely used for environmental monitoring, biomedical applications, food analysis, etc.…”

Development of Aequorin-Based Mast Cell Nanosensor for Rapid Identification of Botulinum Neurotoxin Type B

“…15 18-20 These are promising techniques that could be applied in many fields such as in the diagnosis of infectious diseases, the monitoring of the environment and in the detection of potential bioterrorism agents. [21][22][23][24][25] Mast cells have excellent potential in biosensor applications because they undergo a dramatic activation in response to antigenic stimulation within minutes. Allergens bind specifically to immunoglobulin E (IgE), which is linked to the high-affinity receptor for IgE (Fc RI) leading to the crosslinking of membranous Fc RI, and consequently stimulation of a series of cellular events.…”