New Twin-SERS Biosensor Improves miRNA Detection


MicroRNAs are helpful in early most cancers prognosis and prognosis. Therefore, creating miniaturized biosensors with excessive sensitivity for microRNAs is extremely fascinating. In an article revealed lately within the journal Analytica Chimica Acta, the researchers constructed a brand new microfluidic dual-SERS biosensor to detect microRNAs, integrating multifunctional nanosurface immobilized nanoparticles into the system.

New Dual-SERS Biosensor Improves miRNA Detection

Research: A microfluidic-based SERS biosensor with multifunctional nanosurface immobilized nanoparticles for delicate detection of MicroRNA. Picture Credit score: Love Worker/Shutterstock.com

The designed nanosurface was composed of porous anodic aluminum oxide (AAO) filled with gold nanoparticles (AuNPs) that served as floor enhanced Raman scattering (SERS) substrate. Silver-coated, p-mercaptobenzoic acid surface-decorated ultrasmall gold core-shell NPs ([email protected]) have been used as SERS nanotags. Moreover, a single normal DNA (ssDNA) was used to seize microRNA and immobilize the nanotags.

The accuracy of the constructed biosensor was improved by subdividing the AAO membrane into AAO/Au array and AAO/[email protected] array, the place the previous acted as the first detector and reactor, and the latter served as a secondary detector and collector. Twin-SERS mode on main and secondary detectors prevented false positives or false negatives throughout microRNA detection.

MicroRNA Detection Strategies

MicroRNAs are a category of endogenous ssRNAs with 19 to 23 base pairs. These microRNAs modulate the post-transcriptional gene expression in dwelling techniques. MicroRNAs are very important for numerous organic processes similar to repression, immune cell/system improvement, human tumor cell expression, and apoptosis.

The expression of microRNA gives very important data for the early detection of most cancers. However, the delicate detection of microRNA is difficult on account of its small dimension, sequence homology amongst relations, and low abundance in samples. Therefore, creating a microRNA detection method with excessive specificity, sensitivity, and stability is especially essential.

Northern blotting, polymerase chain response (PCR), and microarray strategies are typical applied sciences used to detect microRNA. Nonetheless, their detection means is restricted to tissues and is unsuitable for physique fluids. Most up-to-date approaches for microRNA detection embody colorimetry, fluorescence, electro-chemiluminescence, and SERS.

SERS is a strong analytical methodology usually utilized in biomarker detection. Its low background noise, anti-interference, and excessive sensitivity make it an appropriate method for classy environments. The foremost problem in creating a extremely environment friendly SERS strategy for detecting biomolecular targets is to arrange SERS lively substrate with good reproducibility and multi-level electromagnetic scorching spots.

AAOs are extremely ordered and simply managed nanostructures with tunable geometry which are ultimate nanotemplates to arrange SERS substrate. The three-dimensional (3D) construction of AAO and its extremely ordered porous nanostructure kind a SERS lively substrate with multi-level electromagnetic scorching spots and good reproducibility.

Duplex-specific nuclease (DSN)-assisted goal recycle amplification is a handy technique for delicate detection of microRNA on account of its means to cleave double-stranded (ds) DNA or DNA/RNA heteroduplexes. Beforehand used microRNA detection methods through sign amplification had excessive specificity, low detection restrict, and a large linear vary.

Microfluidic-based SERS Biosensor for Detection of MicroRNA

Within the current examine, AuNP-coated, extremely ordered porous AAO (AAO/Au) was used as a DSN-assisted goal recycle amplification reactor that served as a main detector for microRNA-sensitive detection.

The AAO array chamber, coated with [email protected] NPs, resulted in AAO/[email protected] nanoplatforms, which have been utilized to detect the SERS nanotags of their dissociated types, launched from the reactor, thereby not directly confirming microRNA focus. Right here, AAO/[email protected] nanosurface served as a collector and secondary detector.

The presence of microRNA close to the nanosurface triggered a hybridization response that facilitated the ssDNA to seize the microRNA, forming DNA/microRNA heteroduplexes. Then, the DSN-assisted goal recycle course of was initiated to cleave the freshly shaped DNA/microRNA heteroduplexes into DNA fragments and ss microRNA.

Initially, the SERS nanotags dissociating from the nanosurface resulted in a decreased SERS sign. After capturing the cleaved microRNA, the subsequent cycle of SERS nanotags launch was initiated, thus amplifying the detection sign, which correlated to the focus of microRNA. The microRNA detection was achieved with a pattern of 30 microliters and an enzyme of 10 microliters to acquire a large linear vary of concentrations between 10 femtomoles to 10 nanomoles.

The microfluidic dual-SERS detection technique has a single detection mode that reduces the potential of false-positive or unfavourable and permits the simultaneous detection of a number of microRNAs through integrating completely different probes.

Conclusion

In abstract, a microfluidic-based biosensor with a dual-SERS detection mode consisting a DSN-assisted goal recycle amplification technique and functionalized AAO substrate was constructed to detect microRNA in samples. Within the building of this biosensor, the functionalized AAO substrate was divided into two zones.

One zone with an AuNP-loaded AAO array with AuMBA@Ag SERS nanotags was used for the DSN-assisted goal recycle amplification course of. The opposite zone with [email protected] NP-decorated AAO array was used to gather and detect the disassociated SERS nanotags, thus not directly reaching microRNA detection within the pattern. Monitoring SERS sign in two completely different useful zones correlated to microRNA focus.

Reference

Ma, W., Liu, L., Zhang, X., Liu, X., Xu, Y., Li, S., Zeng, M. A microfluidic-based SERS biosensor with multifunctional nanosurface immobilized nanoparticles for delicate detection of microRNA. Analytica Chimica Acta. https://doi.org/10.1016/j.aca.2022.340139


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