Comparative Study of Gold and Carbon Nanoparticles in Nucleic Acid Lateral Flow Assay

Abstract

A lateral flow assay (LFA) is a paper-based, point-of-need test designed to detect a specific analyte in complex samples in low-resource settings. Although LFA has been successfully used in different applications, its use is still limited when high sensitivity is required, especially in the diagnosis of an early-stage condition. The limit of detection (LOD) is clearly related to the signal-generating system used to achieve the visual readout, in many cases involving nanoparticles coupled to a biomolecule, which, when combined, provides sensitivity and specificity, respectively. While colloidal gold is currently the most-used label, other detection systems are being developed. Carbon nanoparticles (CNPs) demonstrate outstanding features to improve the sensitivity of this technology by producing an increased contrast in the paper background. Based on the necessity of sensitivity improvement, the aim of this work is a comparative study, in terms of analytical performance, between commercial streptavidin gold nanoparticles (streptAv-AuNPs) and avidin carbon nanoparticles (Av-CNPs) in a nucleic acid lateral flow assay. The visual LOD of the method was calculated by serial dilution of the DNA template, ranging from 0.0 to 7 pg μL−1/1.5 × 104 CFU mL−1). The LFA achieved visual detection of as low as 2.2 × 10−2 pg μL−1 using Av-CNPs and 8.4 × 10−2 pg μL−1 using streptAv-AuNPs. These LODs could be obtained without the assistance of any instrumentation. The results demonstrate that CNPs showed an increased sensitivity, achieving the nanomolar range even by visual inspection. Furthermore, CNPs are the cheapest labels, and the suspensions are very stable and easy to modify.

Immunomagnetic Separation Improves the Detection of Mycobacteria by Paper-Based Lateral and Vertical Flow Immunochromatographic Assays

“…A valid test was considered when the streptAv-AuNPs also reacted with a biotinylated reporter located on the control dot. The reporter is a biotinylated reporter previously described by our research group [ 27 ], although good performance can be achieved by using other biotinylated proteins at higher concentration levels [ 29 ].…”

“…Even improved analytical features were achieved by combining double-tagging amplification with immunomagnetic separation (IMS) [ 19 ]. The integration of double-tagged amplicon to RDTs based on immunochromatography was also reported [ 27 , 28 ], showing a comparable sensitivity for the detection of double-tagged amplicons: electrochemical biosensing and lateral flow labeled with Au-NPs [ 28 ] and carbon nanoparticles [ 29 ].…”

Colorimetric Systems for the Detection of Bacterial Contamination: Strategy and Applications

“…The fifth route is based on NP accumulation reactions [ 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ]. This strategy has been generally used in flat substrate-based systems, such as the lateral flow assay (LFA), µ-paper-based analytical device (µ-PAD), and paper-based dipstick system [ 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ]. These systems rely on the capillary action of fluids and colored NPs.…”

Integrated Nanomaterials and Nanotechnologies in Lateral Flow Tests for Personalized Medicine Applications

“…The use of GNPs can be replaced in LFTs by that of other nanomaterials having stronger colorimetric contrast, such as carbon nanomaterials (see Figure 4 ) comprising different types of nanostructured products based on carbon black. The intrinsic black color of carbon nanomaterials ensures the highest possible visual contrast in the nitrocellulose membrane, thus providing improvement of the LFT sensitivity [ 42 , 43 , 44 ]. In particular, CNTs and CNPs have gained significant attention as labels for LFTs [ 45 ].…”

“…Porras and colleagues reported on a comparative study of GNPs and CNPs in nucleic acid LFA [ 44 ]. They presented the conjugation of avidin to CNPs (Av-CNPs) and the design of LFAs for the detection of PCR products in order to compare the performance of Av-CNPs to commercial streptavidin-conjugated GNPs (streptAv-GNPs).…”