Multiplexed electrochemical nucleic acid sensor based on visible light-mediated metal-free thiol-yne click reaction for simultaneous detection of different nucleic acid targets

Simultaneous detection of multiple tumor biomarkers with a simple and low-cost assay is crucial for early cancer detection and diagnosis. Herein, we presented a low-cost and simple assay for multiplexed detection of tumor biomarkers using a spatially separated electrodes strategy. The sensor is fabricated based on a metal-free thiol-yne click reaction, which is mediated by visible light, on commercially available indium tin oxide (ITO) electrodes. Four biomarkers, including p53 DNA, Brca2 DNA, K-ras DNA, and MicroRNA-204 RNA, were used as model analytes, and the corresponding oligonucleotide probes were modified on the desired electrode units sequentially with 530 nm irradiation light in the presence of photosensitizer Eosin Y. By this visible light-mediated coupling reaction, oligonucleotide probe densities of up to 9.2 ± 0.7 × 1010 molecules/cm2 were readily obtained on the ITO electrode surface. The proposed multiplexed E-NA sensor could detect four different nucleic acid targets concurrently without crosstalk among adjacent electrodes and was also successfully applied for detecting targets in a 20% fetal calf serum sample. The detection limits for p53 DNA, Brca2 DNA, K-ras DNA, and MicroRNA-204 RNA were 0.72 nM, 0.97 nM, 2.15 nM, and 1.73 nM, respectively. The developed approach not only has a great potential for developing cost-effective biosensors on affordable substrates for nucleic acid target detection, but also be easily extended to detect other targets by modifying the specific oligonucleotide probes anchored on the electrode.

Rational design of genotyping nanodevice for HPV subtype distinction

There are more than 200 subtypes of human papillomavirus (HPV), and high-risk HPVs are a leading cause of cervical cancer. Identifying the genotypes of HPV is significant for clinical diagnosis and cancer control. Herein, we used programmable and modified DNA as the backbone to construct fluorescent genotyping nanodevice for HPV subtype distinction. In our strategy, the dye-labeled single-stranded recognize-DNA (R-DNA) was hybridized with Black Hole Quencher (BHQ) labeled single-stranded link-DNA (L-DNA) to form three functionalized DNA (RL-DNA). Through the extension of polycytosine (poly-C) in L-DNA, three RL-DNAs can be more firmly adsorbed on graphene oxide to construct reliable genotyping nanodevice. The genotyping nanodevice had low background noise since the dual energy transfer, including Förster resonance energy transfer (FRET) from dye to BHQ and the resonance energy transfer (RET) from dye to graphene oxide. Meanwhile, the programmability of DNA allows the proposed strategy to simultaneously and selectively distinguish several HPV subtypes in solution using DNA labeled with different dyes. To demonstrate clinical potential, we show multiplexed assay of HPV subtypes in cervical scrapes, and it has been successfully applied in HPV-DNA analysis in cervical scrapes samples. The genotyping nanodevice could be developed for simultaneous and multiplex analysis of several oligonucleotides in a homogeneous solution by adjusting the recognition sequence, demonstrating its potential application in the rapid screening of multiple biomarkers.

Alpha-Based Multiplexed Assay for Identifying SH2 Domain Antagonists

Constitutive activation of STAT3/5b frequently occurs in various human malignancies. STAT3/5b activation involves dimerization via intermolecular pTyr-SH2 binding; therefore, antagonizing this interaction is a feasible approach to inhibit STAT3/5b activation for cancer therapy. We have developed a multiplexed assay to assess STAT3- and STAT5b-SH2 binding in a single well by combining AlphaLISA and AlphaScreen beads. In this chapter, we describe application of the method for the purpose of identifying new STAT3 and STAT5b antagonists.

Multiplex profiling of glycoproteins using a novel bead-based lectin array

Lectin array is becoming important in profiling targeted glycan/glycoprotein, but weak interaction between lectin and glycan causes low sensitivity of the approach. This study aims to develop a bead-based lectin array for improving the sensitivity of glycosylation profiling. Lectins are chemically coupled to fluorescent dye coated microbeads, and glycan-lectin recognition is carried out three dimensionally. The performance of this platform was evaluated, and the LOD of lectin Ricinus communis agglutinin 120 (RCA120) was 50 pg/mL (1 pM) of asialofetuin, providing the bead-based lectin microarray with the highest sensitivity among the reported lectin microarrays. Furthermore, multiplexed assay was performed, which allowed the simultaneous detection of multiple carbohydrate epitopes in a single reaction vessel. The glycosylation patterns of hepatocellular carcinoma associated immunoglobulin G were analyzed, and increased (α-1,6) core fucosylation and (α-2,6) sialylation patterns were observed, which may provide significant clinical evidence for disease diagnosis.

Nanostructures as analytical tools in bioassays

We critically evaluate the usefulness of different nanostructures described as labels, nanoscaffolds or separation media in immunoassays and nucleic-acid hybridization assays. Many of the great number of publications describe only theoretical aspects of using these nanostructures or nanoparticles, but do not verify their applicability in the presence of potential interferents that can be present in the sample matrix. We attempt a systematic study of the advantages and the limitations of using these new reagents in bioassays, the different assay formats for individual and multiplexed detection, and the capability of these assays in analyzing real samples.