Plasmonic Nanomaterials for Colorimetric Biosensing: A Review

Abstract

In the last few decades, plasmonic colorimetric biosensors raised increasing interest in bioanalytics thanks to their cost-effectiveness, responsiveness, and simplicity as compared to conventional laboratory techniques. Potential high-throughput screening and easy-to-use assay procedures make them also suitable for realizing point of care devices. Nevertheless, several challenges such as fabrication complexity, laborious biofunctionalization, and poor sensitivity compromise their technological transfer from research laboratories to industry and, hence, still hamper their adoption on large-scale. However, newly-developing plasmonic colorimetric biosensors boast impressive sensing performance in terms of sensitivity, dynamic range, limit of detection, reliability, and specificity thereby continuously encouraging further researches. In this review, recently reported plasmonic colorimetric biosensors are discussed with a focus on the following categories: (i) on-platform-based (localized surface plasmon resonance, coupled plasmon resonance and surface lattice resonance); (ii) colloid aggregation-based (label-based and label free); (iii) colloid non-aggregation-based (nanozyme, etching-based and growth-based).

Bio-Tailored Sensing at the Nanoscale: Biochemical Aspects and Applications

“…Upon binding with the target analyte, i.e., the epithelial sodium channel, a secondary fluorescent antibody can be used to detect the complex formed. In these conditions, the samples containing the epithelial sodium channel treated with AuNPs-antibodies probes show a much larger intensity if compared to samples treated only with anti-epithelial sodium channel antibodies; this result is likely due to the plasmonic effect occurring on the surface of the metal NPs that affects the optical properties of the neighboring fluorophores [ 108 ]. To note, in this configuration the distance between the antibodies and the metal surface provided by indirect conjugation through 3-mercaptopropionic acid as a short ligand is propaedeutic for avoiding the quenching effect that is induced by the plasmonic nanostructures at very small distances from the fluorophore.…”

Recent advances in optical biosensing and imaging of telomerase activity and relevant signal amplification strategies

“…It is fast and sensitive; however, it has intrinsic drawbacks of complicated operation and false positive signals. 8 To solve these problems, a variety of PCR-free methods have been developed, including electrochemical, 9 fluorometric, 10 colorimetric, 11 and surface-enhanced Raman scattering (SERS) methods, 12 among which optical techniques are diverse and have remarkable advantages of simple equip-ment, high sensitivity, and good specificity. Due to the extremely low level of telomerase and the complexity of total proteins in single cells, signal amplification strategies are frequently employed to enhance the sensitivity for telomerase activity detection.…”

Color Transferability from Solution to Solid Using Silica Coated Silver Nanoparticles

“…Silver nanoparticles can replace organic dyes to produce colored fabrics with antimicrobial properties. 1 Plasmonic colorimetric sensors can quantify changes in color intensity and color shade 2 and are particularly attractive for point of care (POC) diagnostics. 3 These kinds of tests demand simplicity because even the slightest change in color shade can be perceived by our eyes and lead to misinterpretations.…”