Exploiting Stokes and anti‐Stokes type emission profiles of aptamer‐functionalized luminescent nanoprobes for multiplex sensing applications

Abstract

Multiplex biosensing of four types of bacterial food pathogens in one pot is described. Stokes and anti-Stokes type photoluminescence (PL) of two quantum dots (QD) and two upconverting nanoparticles (UCNP) were utilised for realisation of the multiplex detection. The biosensing system was composed of aptamer-functionalized QD and UCNP nanoprobes that were conjugated with partially complementary DNAmodified magnetic beads for separation. PL signals of the conjugates were collected before and after incubation with target pathogens in one pot through the sequential excitations at 335 nm for QD probes and 980 nm for UCNP probes. The limit of detection values achieved were 28, 15, 12 and 25 cfu·mL À1 for Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium and Pseudomonas aeruginosa, respectively. Efforts for extending the multiplex detection up to five pathogens were also presented even though the PL signal cross-talk of a third QD nanoprobe hindered the detection. This work empowers co-deployment of QDs and UCNPs and paves the way for future studies in multiplex sensing, labelling, and bioimaging fields.

Current Perspectives on Aptamers as Diagnostic Tools and Therapeutic Agents

“…Additionally, these methods could be labor-intensive and time-consuming [ 25 ]. Therefore, due to their higher sensitivity i.e., the ability to detect quite low quantities of their targets [ 7 , 8 ], aptamers have become an emerging and promising tool for cancer diagnosis and imaging. Aptamers were used to identify as low as 10 cancer cells [ 38 ].…”

“…Antibodies are usually bound to proteins for diagnostic procedures, such as enzyme-linked immunosorbent assay (ELISA). However, aptamers can bind to a variety of targets such as bacteria/pathogens [ 7 , 8 ], proteins [ 9 ], toxins [ 10 ], viruses [ 11 ], live cancer cells [ 12 ], and tissues [ 13 ]. They are stable in a range of ionic conditions, temperature, and pH.…”

“…Additionally, in vitro selection of aptamers helps to avoid complications arising from the use of animals. Aptamers can be chemically modified with functional groups or chemicals or nanoparticles that make them a perfect material for diagnostic applications [ 5 , 8 ]. The small size of the aptamer oligonucleotides ensures their penetration into tumor cells, as compared to antibodiesAs we reviewed earlier [ 14 ], aptamers could be conjugated with non-coding RNAs, drugs, nanoparticles, and proteins for sensing, imaging, and targeted drug delivery purposes.…”

Recent Advances in Aptamer-Based Biosensors for Detection of Pseudomonas aeruginosa

“…Illustration of the multiplex-detection of conjugates of luminescent upconversion nanoparticles and quantum dots (a), luminescence emission profiles of the conjugates before interaction with the targets (b), addition of the targets into the conjugate solution (c), binding of the luminescent aptamer-nanoparticle probes to the targets (d), separation of the unbound conjugates (e), and luminescence emission profiles of the conjugates after interaction with the targets (f) (Yüce et al, 2018). (B) Schematic illustration of the fabrication of dual-aptamer-labeled polydopamine-polyethyleneimine (PDA-PEI) probe (a), and the detection procedure for P. aeruginosa (b) (Zhong et al, 2020).…”

“…For the simultaneous detection of four types of bacteria (Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium, and P. aeruginosa), an aptasensor exploiting Stokes and anti-Stokes photoluminescence of two QDs and two UCNPs was developed ( Figure 3A) (Yüce et al, 2018). The system was composed of aptamer-modified QD and UCNP probes and partially complementary DNA-modified magnetic beads (MBs).…”