An atomic force microscopy investigation on self-assembled peptide nucleic acid structures on gold(111) surface

Superparamagnetic iron oxide nanoparticles functionalized by peptide nucleic acids

“…4 is constituted by the presence in the lower trace of a series of relatively weak absorptions in the 1100-1400 cm À1 region, due to the C-N stretching modes of the nucleobases and of the PNA amide skeleton. 28 The nucleobases and the amide CO groups of PNA also contribute to the broad absorption at ca. 1660 cm À1 , which is more intense and slightly shied with respect to the spectrum of the SPION@DMSA precursor.…”

Fischer carbene mediated covalent grafting of a peptide nucleic acid on gold surfaces and IR optical detection of DNA hybridization with a transition metalcarbonyl label

“…Formation of monolayers of PNA strands onto gold surfaces has been previously achieved by introducing a cysteine residue (i.e. a sulfhydryl functionality) at one extremity of the sequence (generally the pseudo 5' end or N-terminus) during solid-phase synthesis followed by direct chemisorption to the surface [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Alternatively, PNA strands have been immobilized by affinity via the biotin / avidin system [36,[38][39][40][41] or by conjugation to carboxyl-terminated SAMs [42,43].…”

“…The first band can only belong to the PNA since dA 10 does not contain any C=O group. Therefore, its presence might be due to a reorientation of the PNA molecules upon hybridization with complementary DNA or to an increased rigidity of the PNA-DNA heteroduplex [27,31,33]. Indeed, the RAIRS technique is highly sensitive to vibrator orientation with respect to the surface.…”

Nucleic Acid Sensing onto Peptide Nucleic Acid (PNA) Modified Solid Surfaces

“…Motivated by the previous reports that PNA can potentially be a better alternative for on-surface nucleic acid detection technologies compared to DNA probes, the Mukhopadhyay group developed a sensitive and robust bio-active self assembled PNA sensor layer, which is capable of efficient and specific target detection. The formation of close association of ssPNA strands was found to be relatively straightforward, and compact self-assembled PNA films could be readily generated on solid substrates like gold (111) surface by a simple immersion method [25]. In such films, the immobilized ssPNA strands could be oriented away from the surface, as elicited from reflection absorption infrared spectroscopy (RAIRS) experiments [25], and nonspecific interactions with the underlying gold substrate could be largely avoided, creating an ideal situation for the target nucleic acid strands to access the immobilized sensor PNA probes.…”

“…The formation of close association of ssPNA strands was found to be relatively straightforward, and compact self-assembled PNA films could be readily generated on solid substrates like gold (111) surface by a simple immersion method [25]. In such films, the immobilized ssPNA strands could be oriented away from the surface, as elicited from reflection absorption infrared spectroscopy (RAIRS) experiments [25], and nonspecific interactions with the underlying gold substrate could be largely avoided, creating an ideal situation for the target nucleic acid strands to access the immobilized sensor PNA probes. On the contrary, the DNA films comprising the negatively charged ssDNA strands have been found to be mostly disordered/poorly ordered [26], where nonspecific DNA−surface interactions could occur through the relatively exposed nucleobases, resulting in reduced bioactivity of the film [27].…”