What You Should Know:
- Recently, researchers from Chung-Ang University developed an electrochemical DNA biosensor with enhanced sensitivity for effective HPV detection with high specificity.
- They achieved this feat using a graphitic nano-onion/molybdenum disulfide nanosheet composite with improved conductive electron transfer compared to the nanosheet alone. Their breakthrough can open doors to the development of electrochemical biosensors for early diagnosis of various ailments.
Effective HPV Detection Using High-Specificity Biosensors
Molybdenum disulfide (MoS2) has recently captured the interest of materials science researchers due to its capacity to form two-dimensional nanosheets, akin to graphene. These nanosheets emerge from the stacking of S–Mo–S layers, connected by Van der Waals interactions. Furthermore, MoS2 boasts distinctive structural, optical, thermal, and electrochemical attributes, opening diverse research paths in fields such as biomolecule sensing, chemical detection, optoelectronics, supercapacitors, and batteries.
Traditionally, carbon nanostructures have served as DNA immobilization platforms. To replace carbon with MoS2 as an efficient electrochemical DNA sensor, it’s essential to significantly enhance MoS2’s electrical conductivity. In response to this challenge, Associate Professor Eunah Kang and Mr. Youngjun Kim from Chung-Ang University’s School of Chemical Engineering and Material Science in Korea have devised an ingenious solution. They’ve engineered an electrochemical DNA biosensor employing a composite of graphitic nano-onions and molybdenum disulfide (MoS2) nanosheets, effectively detecting human papillomavirus (HPV)-16 and HPV-18, offering early cervical cancer diagnosis.
To enable DNA chemisorption probing on the novel electrode surface, the research duo achieved chemical conjugation between two functional groups: acyl bonds on functionalized nano-onion surfaces and amine groups on modified MoS2 nanosheets. Cyclic voltammetry experiments unveiled that a 1:1 composite electrode exhibited an improved rectangular shape in contrast to a MoS2 nanosheet electrode. Dr. Kang underscores, “This indicates the amorphous nature of the nano-onions with curved carbon layers, enhancing electronic conductivity compared to MoS2 nanosheets alone.”
Additionally, the duo measured the sensitivity of their novel electrochemical DNA biosensor device towards HPV-16 and HPV-18 by employing differential pulse voltammetry (DPV) technique in the presence of methylene blue (MB) as a redox indicator. Dr. Kang elaborates: “The DPV current peak was lowered after probe DNA chemisorption and target DNA hybridization. Since the hybridized DNA was double-stranded, it induced less effective MB electrostatic intercalation, resulting in a lower oxidation peak.”
The duo found that, compared to the MoS2 nanosheet electrode, the nano-onion/MoS2 nanosheet composite electrode attained higher current peaks, indicating a greater change in the differential peak. This was attributed to an enhanced conductive electron transfer owing to the nano-onion.
