Staining Traditional Colloidal Gold Test Strips with Pt Nanoshell Enables Quantitative Point-of-Care Testing with Simple and Portable Pressure Meter Readout

Abstract

Traditional immunochromatographic test strips based on colloidal gold are effective devices for portable and low-cost point-of-care (POC) testing. Nevertheless, they still suffer from the limitation of qualitative or semiquantitative tests via naked-eye detection. Replacement of gold with other signal entities, such as magnetic particles or fluorescent particles, requires professional instrumentation to obtain quantitative results. A pressure-based assay with platinum nanoparticles (PtNPs) can provide quantitative results using a portable pressure meter but is also hampered by the long-term instability of PtNPs. Consequently, we developed a Pt-staining method based on test strips to create platinum nanoshells on the surface of colloidal gold. This method not only preserves the original advantages of colloidal gold with easy synthesis and decoration but also introduces PtNPs with excellent catalytic activity as signal labels to achieve sensitive quantitative detection. Myoglobin was tested as a model target, and the limit of detection was 5.47 ng/mL in 20% diluted serum samples, which satisfies the requirements for clinical monitoring of acute myocardial infarction. In addition, the two most common colloidal gold strips available in the marketplace were applied to demonstrate the compatibility of Pt-staining. Taking advantage of low cost, user-friendliness, compatibility, simplicity, and stability, colloidal gold test strips with Pt-staining are expected to satisfy the need for quantitative POC testing of biomarkers, especially in resource-limited regions.

Controlled copper in situ growth-amplified lateral flow sensors for sensitive, reliable, and field-deployable infectious disease diagnostics

“…Signal amplification technologies, such as metal in-situ growth (MISG) ( Huang et al, 2018a ; Kim et al, 2017b ), NP accumulation ( Tang et al, 2009 ), and enzyme catalytic deposition ( Loynachan et al, 2018 ), are attracting considerable attention due to their strong signal amplification capability to improve the sensitivity of traditional AuNP-LFS. MISG strategies exhibit potential in practical applications due to their superior signal amplification and simple operation.…”

A nanoenzyme linked immunochromatographic sensor for rapid and quantitative detection of SARS-CoV-2 nucleocapsid protein in human blood

“… [25] , [26] The nanozymes, such as Au@PtNPs, are nanomaterial with intrinsic enzyme mimicking activity, which have good catalytic activity and stability, presenting low cost and easy coupling, thus widely used in the various biosensors. [27] , [28] , [29] Compared with gold nanoparticles (AuNPs), the gold-platinum nanoparticles (Au@PtNPs) realized the signal amplification on color reaction, consequently the sensitivity was greatly improved. In comparison with Au@PtNPs, natural protease, such as horseradish peroxidase (HRP), has low storage stability, complicated preparation process, and lower sensitivity.…”

Comparative Study of In Situ Techniques to Enlarge Gold Nanoparticles for Highly Sensitive Lateral Flow Immunoassay of SARS-CoV-2

“…To overcome the limitations of the initial size of Au NPs, various methods for post-assay modifications (including enlargement [15], change of shape [16], and chemical composition-the overgrowth of Ag [17], Pt [18], and Cu [19]) have been reported. Among them, the deposition of a silver layer over Au NP seeds (silver enhancement) is a common method for LOD reduction, which is widely used in LFIA and other techniques [20].…”