Abstract
Peptide nucleic acid (PNA) is a synthetic DNA mimic that outperforms the properties of traditional oligonucleotides (ONs). On account of its outstanding features, such as remarkable binding affinity towards complementary DNA or RNA as well as high thermal and chemical stability, PNA has been proposed as a valuable alternative to the ON probe in gene-sensor design. In this study, a hybrid transducer made-up of graphene oxide (GO) nano-sheets covalently grafted onto a porous silicon (PSi) matrix has been investigated for the early detection of a genetic cardiac disorder, the Brugada syndrome (BS). A functionalization strategy towards the realization of a potential PNA-based device is described. A PNA, able to detect the SCN5A gene associated with the BS, has been properly synthesized and used as a bioprobe for the realization of a proof-of-concept label-free optical PNA-biosensor. PSi reflectance and GO photoluminescence signals were simultaneously exploited for the monitoring of the device functionalization and response.
Highlights
Nucleic acid analogues have been recognized as powerful tools in DNA biosensor design as functional bioprobes
Since porous silicon (PSi) optical biosensors are strongly limited by the oxidation and degradation of its porous matrix under ambient conditions [30,38,41], a passivation process was required before the graphene oxide (GO) infiltration
The interaction between the synthesized peptide nucleic acid (PNA) and the DNA target through heteroduplexes formation has been investigated in solution by Circular Dichroism (CD), CD melting, and Polyacrylamide Gel Electrophoresis (PAGE) analyses
Summary
Nucleic acid analogues have been recognized as powerful tools in DNA biosensor design as functional bioprobes. PNA is a synthetic DNA analogue whose backbone is formed of N–(2-aminoethyl)glycine motifs linked by peptide bonds [1]. This molecule is considered a better probe traditional oligonucleotide (ON) sequence in DNA and RNA targeting. The neutral charge nature of the amide backbone enables the PNA hybridization to the target sequence on exposure to a low-salt environment In this case, the salt positive ions are not necessary for neutralizing the inter-strand repulsion that hampers the duplex formation between two negatively charged ONs [4,5,6,7,8]. The PNA is a powerful probe to detect single-base mismatches in DNA and a suitable tool for the development of a biosensor (i.e., gene-sensor) for the diagnosis of point mutation-related genetic diseases, such as the Brugada syndrome (BS)
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