Biosensors & Bioelectronics

Recent Techniques for the Detection of β-Thalassemia: A Review

Abstract

Gourav Mishra, Rupali Saxena, Amit Mishra and Archana Tiwari

β-thalassemias are very heterogeneous in nature, with respect to the molecular basis of the disease. This type of disorder is caused by extensive deletions occurring within the β-globin gene locus, present on chromosome number 11. Due to point mutations, stop codons in the β-globin mRNA is introduced, thus curbing its normal function. This paper reviews conventional and latest β-thalassemia detection techniques. Amongst the conventional techniques, the DNA-based piezoelectric biosensors were based on the observation of distinguishable frequency shifts, resulting from the hybridisation between an oligonucleotide probe which was immobilized on a gold electrode of a quartz crystal and the complementary strand; present in solution. Q-primer real time PCR (Q-PCR) system utilises
the 5’>3’ exonuclease activity of a DNA polymerase, which cleaves the nucleotides and results in fluorescence. Amongst the latest detection methods, the capacitive micro-membrane and surface stress based biosensors require flexible structures, microcantilevers or membranes, where one of their surfaces is functionalized with the probe biomolecules. The interaction with the appropriate target molecules induces surface stress variations and finally changes in the deflection of the structure. In bead based biosensors, the natural immobilization of the beads into the polyacrylamide gel pads allows the beads to acquire unique spatial addresses that is recorded via image, and thus helps in avoiding labeling or color encoding steps. These techniques are more efficient and overcome the disadvantages of conventional techniques that were costly, less sensitive and complex too.