Porous organic polymers assisted aptamer signal amplification for enhanced photoeletrochemical detection of MUC1.

Mucin1 (MUC1) is an extensively glycosylated transmembrane protein that is widely distributed and overexpressed on the surface of cancer cells, playing an important role in tumor occurrence and metastasis. Therefore, highly sensitive detection of MUC1 is of great significance for early diagnosis, treatment monitoring, and prognosis of cancer. Here, an ultra-sensitive photoelectrochemical (PEC) sensing platform was developed based on an aptamer amplification strategy for highly selective and sensitive detection of MUC1 overexpressed in serum and on cancer cell surfaces. The sensing platform utilized copper phthalocyanine to fabricate porous organic polymers (CuPc POPs), and was effectively integrated with g-C3N4/MXene to form a ternary heterojunction material (g-C3N4/MXene/CuPc POPs). This material effectively improved electron transfer capability, significantly enhanced light utilization, and greatly enhanced photoelectric conversion efficiency, resulting in a dramatic increase in photocurrent response. MUC1 aptamer 1 was immobilized on a chitosan-modified photoelectrode for the selective capture of MUC1 or MCF-7 cancer cells. When the target substance was present, MUC1 aptamer 2 labeled with methylene blue (MB) was specifically adsorbed on the electrode surface, leading to enhanced photocurrent. The concentration of MUC1 directly correlated with the number of MB molecules attracted to the electrode surface, establishing a linear relationship between photocurrent intensity and MUC1 concentration. The PEC biosensor exhibited excellent sensitivity for MUC1 detection with a wide detection range from 1 × 10-7 to 10 ng/mL and a detection limit of 8.1 ag/mL. The detection range for MCF-7 cells was from 2 × 101 to 2 × 106 cells/mL, with the capability for detecting single MCF-7 cells. The aptamer amplification strategy significantly enhanced PEC performance, and open up a promising platform to establish high selectivity, stability, and ultrasensitive analytical techniques.

Development of an Effective Neutralizing Antibody Assay for SARS-CoV-2 Diagnosis.

Introduction: Neutralizing antibodies (NAbs) are essential for preventing reinfection with SARS-CoV-2 and the recurrence of COVID-19; nonetheless, the formation of NAbs following vaccination and infection remains enigmatic due to the lack of a practical and effective NAb assay in routine laboratory settings. In this study, we developed a convenient lateral flow assay for the rapid and precise measurement of serum NAb levels within 20 minutes. Methods: Receptor-binding domain-fragment crystallizable (RBD-Fc) and angiotensin-converting enzyme 2-histidine tag (ACE2-His) were expressed by the eukaryotic expression systems of Spodoptera frugiperda clone 9 and human embryonic kidney 293T, respectively. Then, colloidal gold was synthesized and conjugated with ACE2. After optimizing various operating parameters, an NAb lateral flow assay was constructed. Subsequently, its detection limit, specificity, and stability were systematically evaluated, and clinical samples were analyzed to validate its clinical feasibility. Results: RBD-Fc and ACE2-His were obtained with 94.01% and 90.05% purity, respectively. The synthesized colloidal gold had a uniform distribution with an average diameter of 24.15 ± 2.56 nm. With a detection limit of 2 µg/mL, the proposed assay demonstrated a sensitivity of 97.80% and a specificity of 100% in 684 uninfected clinical samples. By evaluating 356 specimens from infected individuals, we observed that the overall concordance rate between the proposed assay and conventional enzyme-linked immunosorbent assay was 95.22%, and we noticed that 16.57% (59/356) of individuals still did not produce NAbs after infection (both by ELISA and the proposed assay). All the above tests by this assay can obtain results within 20 minutes by the naked eye without any additional instruments or equipment. Conclusion: The proposed assay can expediently and reliably detect anti-SARS-CoV-2 NAbs after infection, and the results provide valuable data to facilitate effective prevention and control of SARS-CoV-2. Clinical trial registration: Serum and blood samples were used under approval from the Biomedical Research Ethics Subcommittee of Henan University, and the clinical trial registration number was HUSOM-2022-052. We confirm that this study complies with the Declaration of Helsinki.

Real-time quantification of fusion transcripts with ligase chain reaction by direct ligation of adjacent DNA probes at fusion junction.

Gene fusions, produced by aberrant juxtapositions of two or more genes even in different chromosomes, play important roles in the primary oncogenic mechanism and have been demonstrated to be typically associated with many cancers. So the fused genes or the transcripts can be specific predictive biomarkers for cancer diagnosis and therapy. Herein, we develop a direct ligation- and ligase chain reaction (LCR)-based method for a fusion transcript assay. In virtue of the high selectivity of ligase and the exponential amplification capacity of LCR, the proposed method can detect as low as 1 fM fusion transcripts with high specificity and has been successfully applied to real samples. With the real-time fluorescence measurements, the fusion transcripts can be assayed in a simple way. Therefore, the proposed method can provide a simple and cost-effective platform for fusion transcript detection in routine laboratories and clinical diagnosis.

Real-time detection of mRNA splicing variants with specifically designed reverse-transcription loop-mediated isothermal amplification.

Alternative splicing is a ubiquitous and crucial process in cellular processes and has a specific linkage with diseases. To date, developing cost-effective methods with high sensitivity and specificity for detection of splicing variants has been needed. Herein, we report a novel splicing variant assay based on specifically designed reverse-transcription loop-mediated isothermal amplification. After reverse transcribing the splicing variant into cDNA, four DNA primers are specifically designed to recognize six distinct regions. The four DNA primers can hybridize with corresponding sequences for extension and strand displacement DNA synthesis to form stem-loop DNA and then LAMP amplification is started. The proposed method can detect as low as 100 aM splicing variants in real-time fashion with high specificity, showing great potential in biological function and clinical studies.