Quantum-dot biosensor for hybridization and detection of R3500Q mutation of apolipoprotein B-100 gene

• A new QD biosensor was introduced for detection of R3500Q Mutation of ApoB-100 gene.
• Nucleotide can efficiently adsorb on carboxylic acid-functionalized quantum dots.
• CdS quantum dots can effectively enhance the sensitivity of biosensor.
• The biosensor showed a low detection limit of 3.4×10−17 M for apoB-100.
• The biosensor showed acceptable selectivity, reproducibility and stability.

A quantum-dot electrode system was developed as a transducer surface for covalent immobilization of a designed synthetic ApoB-100 specific probe, DNA hybridization and monitoring of DNA synthesis for the sensitive detection of R3500Q mutation of apolipoprotein B-100 (ApoB-100) gene. CdS-QDs cause an improvement in the fundamental characteristics of the electrode interface, such as its electroactive surface area, diffusion coefficient and electron transfer kinetics. The sensing characteristics of this biosensor offer a suitable potential for detection of target oligonucleotide with a detection limit of 3.4×10−17 M. Also, the electrochemical responses of single-stranded DNA (ssDNA), DNA hybridization and DNA synthesis were investigated using electrochemical impedance spectroscopy (EIS). The extracted genomic DNA was detected based on changes in the charge transfer resistance (RCT) with [Fe(CN)6]3−/4− as a redox probe. The proposed biosensor can distinguish between the normal sequence and the mutant sequence of ApoB-100 gene, promising a possibility to apply the QD-based biosensor for clinical investigations.