Silver and gold enhancement methods for lateral flow immunoassays

Abstract

Sensitivity is the main concern at the development of rapid test by lateral flow immunoassays. On the other hand, low limits of detection are often required at medical diagnostics and other field of analysis. To overcome this drawback, several enhancement protocols have been described. In this paper, we have selected different silver enhancement methods and one dual gold conjugation, and we critically compared the amplification produced when applied to a gold-nanoparticle based lateral flow immunoassay for the detection of prostate specific antigen (PSA). The highest amplification was obtained by using an immersion method based on a solution of silver nitrate and hydroquinone/citrate buffer in proportion 1:1. Under these conditions, the system is capable of detecting PSA within 20 min at levels as low as 0.1 ng/mL, with a 3-fold sensitivity improvement.

Ways to Reach Lower Detection Limits of Lateral Flow Immunoassays

“…Anfossi et al [133] and Panferov et al [134,135] considered the possibilities of silver enhancement (restoration of the silver salt on the surface of a gold nanoparticle with an increase in its size) in LFIA. In a study by Rodriguez et al [136], the optimal regimes of silver and gold enhancements were determined to enhance the signal from the gold nanoparticles. Enzymatic amplification using alkaline phosphatase was studied by Panferov et al [137] for LFIA of potato virus X and by Kim et al [138] for LFIA of C-reactive protein.…”

Lateral flow based immunobiosensors for detection of food contaminants

“…In lateral flow tests, nitrocellulose membrane act as stationary phase, and aptamer, antibody or antigen are immobilized in the capture area. To visualize the interactions in capture area, different labels have been used including liposome, colloidal carbon, colloidal gold, fluorescent probes, quantum dots, phosphors, bioluminescent markers, enzyme labels, paramagnetic particles and latex particles (Takanashi, Okame et al 2008;Blazkova, Koets et al 2009;Quesada-González and Merkoçi 2015;Qi, Huang et al 2016;Rodríguez, Covián et al 2016;Zhao, Wang et al 2016), each of which has particular characteristic and their usage is dependent on the analyzed samples (Tse 2009). …”

“…Also, colloidal gold in unconjugated forms and conjugated forms can be easily found from a variety of commercial sources (Tse 2009). Besides, several investigations have been reported on the potential benefits of using different labels, for example, fluorescent dyes, liposomes encapsulating visible or fluorescent dyes, quantum dots, magnetic nanoparticles, and silver-gold nanoparticles (Goryacheva, Lenain et al 2013;Byzova, Smirnova et al 2014;Zhang, Huang et al 2015;Rodríguez, Covián et al 2016;Wu, Yuan et al 2016) A study using fluorescent immunoliposome as a label has been described by Khreich et al (Khreich, Lamourette et al 2008) for detection of Staphylococcus aureus enterotoxin B (SEB) in water and juice.…”

“…Mixing gold nanoparticles with silver can result in sharp signal enhancement (Liu, Liu et al 2011;Yang, Li et al 2011;Rodríguez, Covián et al 2016) on a nanoparticle-based immunoassay. In 2010, Liao and Li (Liao and Li 2010) used a mixture of gold and silver nanoparticles for detection of AFB1.…”

Silver-enhanced lateral flow immunoassay for highly-sensitive detection of potato leafroll virus

“…The silver enhancement is based on the reduction of silver ions on the surface of gold nanoparticles (GNP), and provides a significant increase of initial GNP-caused coloration. This approach was previously used successfully in other LFIAs (Byzova, Zherdev, Sveshnikov, Sadykhov, & Dzantiev, 2015;Drygin et al, 2012;Gupta, Huda, Kilpatrick, & Velev, 2007;Panferov et al, 2016;Rodriguez, Covian, Garcia, & Blanco-Lopez, 2016), but it has not been combined with PLRV immunodetection. Because the possibility of nonspecific background coloration is indicated as an important risk factor in silver enhancement, this assay procedure was modified to limit this process.…”