title: Synthesis and label free characterization of a bimolecular PNA homo quadruplex.
abstract: G-quadruplex DNA is involved in many physiological and pathological processes. Both clinical and experimental studies on DNA G-quadruplexes are slowed down by their enzymatic instability. In this frame, more stable chemically modified analogs are needed.
  
  
  
  The bis-end-linked-(gggt)2PNA molecule (BEL-PNA) was synthesized using in solution and solid phase synthetic approaches. Quadruplex formation was assessed by circular dichroism (CD) and surface enhanced Raman scattering (SERS).
  
  
  
  An unprecedented bimolecular PNA homo quadruplex is here reported. To achieve this goal, we developed a bifunctional linker that once functionalized with gggt PNA strands and annealed in K+buffer allowed the obtainment of a PNA homo quadruplex. The identification of the strong SERS band at ~1481cm-1, attributable to vibrations involving the quadruplex diagnostic Hoogsteen type hydrogen bonds, confirmed the formation of the PNA homo quadruplex.
  
  
  
  By tethering two G-rich PNA strands to the two ends of a suitable bifunctional linker it is possible to obtain bimolecular PNA homo quadruplexes after annealing in K+-containing buffers. The formation of such CD-unfriendly complexes can be monitored, even at low concentrations, by using the SERS technique.
  
  
  
  Given the importance of DNA G-quadruplexes in medicine and nanotechnology, the obtainment of G-quadruplex analogs provided with enhanced enzymatic stability, and their monitoring by highly sensitive label-free techniques are of the highest importance. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
authors.affiliation: Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy.
authors.forename: Brunella
authors.initials: B
authors.lastname: Pinto
authors.affiliation: Dipartimento di Scienze Fisiche, Università degli Studi di Napoli Federico II, 80126 Napoli, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Rusciano
authors.affiliation: Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: D'Errico
authors.affiliation: Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Borbone
authors.affiliation: Dipartimento di Scienze Fisiche, Università degli Studi di Napoli Federico II, 80126 Napoli, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Sasso
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, 80126 Napoli, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Piccialli
authors.affiliation: Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Mayol
authors.affiliation: Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy. Electronic address: giorgia.oliviero@unina.it.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Oliviero
authors.affiliation: Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy; CNR, Institute of Protein Biochemistry, 80131 Napoli, Italy. Electronic address: gennaro.piccialli@unina.it.
authors.forename: Gennaro
authors.initials: G
authors.lastname: Piccialli
mesh_terms: D001483:Base Sequence; D002942:Circular Dichroism; D054856:G-Quadruplexes; D006147:Guanine / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D020135:Peptide Nucleic Acids / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013329:Structure-Activity Relationship
chemical_list: D020135:Peptide Nucleic Acids; D006147:Guanine
keywords: G-quadruplex; Label free monitoring; PNA; SERS; Surface enhanced Raman scattering