Bioaffinity detection of pathogens on surfaces

Abstract

The demand for improved technologies capable of rapidly detecting pathogens with high sensitivity and selectivity in complex environments continues to be a significant challenge that helps drive the development of new analytical techniques. Surface-based detection platforms are particularly attractive as multiple bioaffinity interactions between different targets and corresponding probe molecules can be monitored simultaneously in a single measurement. Furthermore, the possibilities for developing new signal transduction mechanisms alongside novel signal amplification strategies are much more varied. In this article, we describe some of the latest advances in the use of surface bioaffinity detection of pathogens. Three major sections will be discussed: (i) a brief overview on the choice of probe molecules such as antibodies, proteins and aptamers specific to pathogens and surface attachment chemistries to immobilize those probes onto various substrates, (ii) highlighting examples among the current generation of surface biosensors, and (iii) exploring emerging technologies that are highly promising and likely to form the basis of the next generation of pathogenic sensors.

Keywords: Lab-on-a-chip; Label-free detection; Nanomaterials; Pathogen detection; Surface biosensors.

Fig. 1

Timeline describing the development of pathogen detection methods.

Fig. 2

Schematic overview of surface-based optical detection platforms for pathogen detection; (a) fluorescence microscopy, (b) surface plasmon resonance (SPR), (c) quartz crystal microbalance (QCM), (d) optical waveguide sensors and (e) atomic force microscopy (AFM).

Fig. 3

Schematic of SPR imaging set-up with the inset showing a representative SPR difference image showing the hybridization adsorption of 2 nM 16S rRNA from E. coli onto a three-component DNA array. The array element C is the 25mer DNA probe sequence complementary to E. coli RNA. Inset data is adapted with permission from ref. .

Fig. 4

(A) Schematic diagram showing the detection of respiratory virus based on surface enhanced Raman scattering (SERS) using silver nanorod array substrates. (B) SERS spectra showing a) uninfected vero cell lysate, b) RSV-infected cell lysate and c) purified RSV. Distinctive spectral bands assigned at 1066 cm⁻¹ (C–N stretch), 835 cm⁻¹ (tyrosine), and a doublet at 545 cm⁻¹ and 523 cm⁻¹ (S–S) appear in the RSV-infected cell lysate samples but not in the uninfected cell lysates. Adapted with permission from ref. .

Fig. 5

Schematic of nanoparticle-enhanced diffraction grating setup for the detection of pathogens using various probes including aptamers, antibodies and short oligomers immobilized on gold line grating surfaces. Biofunctionalized gold nanoparticles (incl. nanorods) can be utilized to enhance the diffraction signal in a sandwich format where the surface probe interacts with the target pathogen followed by the recognition of biomolecules coated on the nanomaterials. Briefly, p-polarized white light through a narrowband pass filter is impinged onto a prism/grating chip/flow cell assembly at a fixed incidence angle. Next, either the +1, 0 and −1 orders can then be imaged on a CCD camera or the +1 diffraction beam can be passed through a lens and detected using an avalanche photodiode (APD). The left bottom inset is the 3D image of the +1, 0, −1 orders. The right inset is a representative TEM image of gold nanorods with peak maxima at 510 nm and 720 nm.

Fig. 6

(a) Schematic depicting an In₂O₃ nanowire device for SARS virus detection. The nanowire was functionalized with Fn probes which can specifically bind the target N protein. Bovine serum albumin (BSA) was used to prevent any nonspecific binding events. (b) Response curve for the N protein interacting with the Fn probe molecules immobilized on the surface of nanowire device. The arrows are the times when a given concentration of N protein solution was injected. The inset on the left side is to show the plateau and the definition of response time. Adapted with permission from ref. .

Fig. 7

Schematics showing (a) the arrangement of droplets on a PCB printed circuit board, and (b) droplet manipulation using magnetic forces through a series of processes on a perfluorinated surface. G is the perfluorinated glass substrate, M is the permanent magnet, T is the miniaturized thermocycler indicating one of four donut-shaped circles, Sa is the raw sample solution spiked with in vitro transcribed HPAI H5N1 RNA including lysis/binding/enhancer solution and silica particles, W1 and W2 are the washing solution 1 and 2, R is the RT-PCR mixture covered by mineral oil. Adapted with permission from ref. .