Nanostructures on a Vector : Enzymatic Oligo Production for DNA Nanotechnology

The technique of DNA origami utilizes the specific and limited bonding properties of DNA to fold single stranded DNA sequences of various lengths to form a predesigned structure. One longer sequence is used as a scaffold and numerous shorter sequences called staples, which are all complementary to the scaffold sequence, are used to fold the scaffold into intricate shapes. The most commonly used scaffold is derived by extracting the genome of the M13 phage and the staples are usually chemically synthesized oligonucleotides. Longer single stranded sequences are difficult to synthesize with high specificity, which limits the choices of scaffold sequences available. In this project two main methods of single stranded amplification, Rolling Circle Amplification (RCA) and the usage of helper phages, were explored with the goal to produce both a 378 nt scaffold and staple sequences needed for folding a DNA origami structure. To facilitate imaging by Transmission Electron Microscopy (TEM) of this small structure, the DNA origami structure was created to form a polymer structure. Production of the scaffold sequence in high yield was unsuccessful and no well-defined polymers were found in the folded samples, though a few results showed promise for further studies and optimizations. Due to time constraints of this project, only production of the scaffold sequence was tested. Unfortunately the scaffold produced by the helper phages was of the complementary strand to that used to design the DNA origami structure, and could therefore not be used for folding. The correct strand was produced by the RCA where the yield was too low when using Phi29 DNA polymerase for proper folding to take place, though small scale RCA by Bst DNA polymerase on the other hand showed promising results. These results indicate that the scaffold production may not be far off but still more experience in producing intermediate size oligonucleotides may be necessary before succeeding in high yield production of this 378 nt long sequence. The promise given by this production is to enable high yield, high purity, low cost and also an easily scalable process set-up. This would be an important step in future DNA nanotechnology research when moving from small scale laboratory research to large scale applications such as targeted drug delivery systems

Liposomes as nanoreactors for the photochemical synthesis of gold nanoparticles

A simple and novel method for the photochemical synthesis of AuNPs in liposomes is described. Gold salt is co-encapsulated with the photoinitiator Irgacure-2959 in POPC liposomes prepared via traditional thin-film hydration technique. UVA irradiation for 15 min results in encapsulated AuNPs of 2.8 +/- 1.6 nm in diameter that are primarily dispersed in the aqueous interior of the liposomes. (C) 2015 Elsevier Inc. All rights reserved.Funding Agencies|Swedish Foundation for Strategic Research (SSF); Center for Integrative Regenerative Medicine (IGEN) at Linkoping University</p

Antibacterial effects of Lactobacillus and bacteriocin PLNC8 alpha beta on the periodontal pathogen Porphyromonas gingivalis

Background: The complications in healthcare systems associated with antibiotic-resistant microorganisms have resulted in an intense search for new effective antimicrobials. Attractive substances from which novel antibiotics may be developed are the bacteriocins. These naturally occurring peptides are generally considered to be safe and efficient at eliminating pathogenic bacteria. Among specific keystone pathogens in periodontitis, Porphyromonas gingivalis is considered to be the most important pathogen in the development and progression of chronic inflammatory disease. The aim of the present study was to investigate the antimicrobial effects of different Lactobacillus species and the two-peptide bacteriocin PLNC8 alpha beta on P. gingivalis. Results: Growth inhibition of P. gingivalis was obtained by viable Lactobacillus and culture media from L. plantarum NC8 and 44048, but not L. brevis 30670. The two-peptide bacteriocin from L. plantarum NC8 (PLNC8 alpha beta) was found to be efficient against P. gingivalis through binding followed by permeabilization of the membranes, using Surface plasmon resonance analysis and DNA staining with Sytox Green. Liposomal systems were acquired to verify membrane permeabilization by PLNC8 alpha beta. The antimicrobial activity of PLNC8 alpha beta was found to be rapid (1 min) and visualized by TEM to cause cellular distortion through detachment of the outer membrane and bacterial lysis. Conclusion: Soluble or immobilized PLNC8 alpha beta bacteriocins may be used to prevent P. gingivalis colonization and subsequent pathogenicity, and thus supplement the host immune system against invading pathogens associated with periodontitis.Funding Agencies|Swedish Heart-Lung Foundation; Foundation of Magnus Bergvall; Foundation of Olle Engkvist; Knowledge Foundation, Sweden</p

Additional file 1: Figure S1. of Antibacterial effects of Lactobacillus and bacteriocin PLNC8 αβ on the periodontal pathogen Porphyromonas gingivalis

Hydropathy scores of PLNC8 α and β. The amino acid sequence of PLNC8 α (A) and PLNC8 β (B) and their corresponding hydropathy score [46]. (TIF 369 kb