An Electroanalytical Flexible Biosensor Based on Reduced Graphene Oxide-DNA Hybrids for the Early Detection of Human Papillomavirus-16

Highly sensitive and specific detection of human papillomavirus type 16 using CRISPR/Cas12a assay coupled with an enhanced single nanoparticle dark-field microscopy imaging technique

Human papillomavirus (HPV) is a prevalent sexually transmitted pathogen associated with cervical cancer. Detecting high-risk HPV (hr-HPV) infections is crucial for cervical cancer prevention, particularly in resource-limited settings. Here, we present a highly sensitive and specific sensor for HPV-16 detection based on CRISPR/Cas12a coupled with enhanced single nanoparticle dark-field microscopy (DFM) imaging techniques. Ag-Au satellites were assembled through the hybridization of AgNPs-based spherical nucleic acid (Ag-SNA) and AuNPs-based spherical nucleic acid (Au-SNA), and their disassembly upon target-mediated cleavage by the Cas12a protein was monitored using DFM for HPV-16 quantification. To enhance the cleavage efficiency and detection sensitivity, the composition of the ssDNA sequences on Ag-SNA and Au-SNA was optimized. Additionally, we explored using the SynSed technique (synergistic sedimentation of Brownian motion suppression and dehydration transfer) as an alternative particle transfer method in DFM imaging to traditional electrostatic deposition. This addresses the issue of inconsistent deposition efficiency of Ag-Au satellites and their disassembly due to their size and charge differences. The sensor achieved a remarkable limit of detection (LOD) of 10 fM, lowered by 9-fold compared to traditional electrostatic deposition methods. Clinical testing in DNA extractions from 10 human cervical swabs demonstrated significant response differences between the positive and negative samples. Our sensor offers a promising solution for sensitive and specific HPV-16 detection, with implications for cancer screening and management.

Nucleic acid-based electrochemical biosensors

Colorectal cancer, breast cancer, oxidative DNA damage, and viral infections are all significant and major health threats to human health, presenting substantial challenges in early diagnosis. In this regard, a wide range of nucleic acid-based electrochemical platforms have been widely employed as point-of-care diagnostics in health care and biosensing technologies. This review focuses on biosensor design strategies, underlying principles involved in the development of advanced electrochemical genosensing devices, approaches for immobilizing DNA on electrode surfaces, as well as their utility in early disease diagnosis, with a particular emphasis on cancer, leukaemia, oxidative DNA damage, and viral pathogen detection. Notably, the role of biorecognition elements and nanointerfaces employed in the design and development of advanced electrochemical genosensors for recognizing biomarkers related to colorectal cancer, breast cancer, leukaemia, oxidative DNA damage, and viral pathogens has been extensively reviewed. Finally, challenges associated with the fabrication of nucleic acid-based biosensors to achieve high sensitivity, selectivity, a wide detection range, and a low detection limit have been addressed. We believe that this review will provide valuable information for scientists and bioengineers interested in gaining a deeper understanding of the fabrication and functionality of nucleic acid-based electrochemical biosensors for biomedical diagnostic applications.

Detection of high-risk HPV 16 genotypes in cervical cancers using isothermal DNA amplification with electrochemical genosensor

Cervical cancer emerges as the third most prevalent types of malignancy among women on a global scale. Cervical cancer is significantly associated with the persistent infection of human papillomavirus (HPV) type 16. The process of diagnosing is crucial in order to prevent the progression of a condition into a malignant state. The early detection of cervical cancer through initial stage screening is of the utmost significance in both the prevention and effective management of this disease. The present detection methodology is dependent on quantitative polymerase chain reaction (qPCR), which necessitates the use of a costly heat cycler instrument. In this study, we report the development of an electrochemical DNA biosensor integrated with an isothermal recombinase polymerase amplification (RPA) reaction for the detection and identification of the high-risk HPV-16 genotype. The electrochemical biosensor exhibited a high degree of specificity and sensitivity, as evidenced by its limit of detection (LOD) of 0.23 copies/μL of HPV-16 DNA. The validity of this electrochemical platform was confirmed through the analysis of 40 cervical tissues samples, and the findings were consistent with those obtained through polymerase chain reaction (PCR) testing. Our straightforward electrochemical detection technology and quick turnaround time at 75 min make the assay suitable for point-of-care testing in low-resource settings.

Point-of-care tests for human papillomavirus detection in uterine cervical samples: A review of advances in resource-constrained settings

Incidence of cervical cancer and associated mortality are still high in resource-constrained countries due to the lack of infrastructural facilities and trained workforce. Human papillomavirus (HPV)-based screening tests offer a better sensitivity (>90%) for the detection of cervical high-grade lesions. However, these tests usually require an extensive laboratory set-up and trained technical staff. Moreover, the high cost of the currently available and approved HPV tests precludes their use in the cervical cancer screening programmes in resource-limited settings. Hence, there is a felt need for a low-cost point-of-care (POC) HPV test with good performance characteristics to help augment cervical cancer screening in such settings. A recent meta-analysis demonstrated a good sensitivity and specificity for two of the commercially available POC HPV tests. The present review discusses the merits and limitations of the current commercially available POC and near-POC devices for HPV-based cervical cancer screening. The technologies that have the potential to be developed into low-cost POC tests and newer promising modalities for HPV-based POC or near POC have also been highlighted. This review underscores the need for collaborative and coordinated research for development of POC or near-POC HPV-based tests to be used in cervical cancer screening. Efforts need to be focussed on technologies that offer ease of performance without the requirement of sophisticated equipment or extensive sample pre-processing coupled with a good sensitivity and cost-effectiveness.

Electrochemical bioplatform for the determination of the most common and carcinogenic human papillomavirus DNA

Nucleic acid-based analytical bioplatforms have gained importance as diagnostic tests for genomics and as early detection tools for diseases such as cancer. In this context, we report the development of an amperometric bioplatform for the determination of a specific human papillomavirus type 16 (HPV16) sequence. The bioplatform utilizes an immune-nucleic acid hybrid-sandwich assay. A biotinylated RNA capture probe (RNAbCp), complementary to the selected HPV16 target DNA sequence, was immobilised on the surface of streptavidin coated magnetic microbeads (Strep-MBs). The RNA/DNA heteroduplex resulting from the hybridization of the RNAbCP and the HPV16 target sequence was recognised by a commercial antibody that specifically bound to the heteroduplex (Ab_DNA-RNA). A horseradish-peroxide labeled secondary antibody (antiIgG-HRP) was used for the detection of Ab_DNA-RNA. Relying on amperometric detection of the resulting HRP-labeled magnetic bioconjugates captured on screen-printed electrodes (SPCEs) in the presence of H₂O₂ and hydroquinone (HQ), the biotool achieved a low limit of detection (0.5 pM) for the synthetic HPV16 target DNA. In addition, the developed bioplatform was able to discriminate between HPV16 positive and negative human cancer cells using only 25 ng of amplified DNA in a test time of 45 min.