Ewelina Zabost

Substantial difference between temperature dependencies of dsDNA predenaturation process obtained by voltammetry and spectroscopy.

The electrooxidation of double stranded DNA has been studied in a wide temperature range by cyclic and square wave voltammetries and the results were compared with UV-Vis and CD spectroscopies. A twofold increase of dsDNA voltammetric peaks related to the conformation changes preceding the denaturation process was found to begin at a temperature lower than the well known increase of dsDNA absorbance upon denaturation (the melting point) by circa 20 degrees C. Since the dsDNA voltammetric peaks are related directly to the electrooxidation of guanine and adenine, early conformational changes in guanine-cytosine (G-C) and adenine-thymine (A-T) pairs in dsDNA are possible reasons for the increase of the voltammetric peaks. The above observations prove that the voltammetric methods are much more sensitive to the changes in guanine and adenine base-pairs conformations and indicate increased exposition of guanine and adenine in the reversible stages that precede the denaturation process of dsDNA. Interestingly, two distinct ranges of change in ellipticity in CD spectra correlate well to the changes obtained by voltammetry and UV spectroscopy, respectively. We also checked the influence of an intercalator on the dsDNA denaturation (temperature) plots. The spectroscopic measurements indicated an increase in the stability of the structure of the double stranded helix upon the addition of the intercalator, while voltammetry showed also that the exposition of guanine and adenine for the electrooxidation drops substantially in the region preceding the denaturation process.

Hydrogel Nanofilaments via Core-Shell Electrospinning.

Recent biomedical hydrogels applications require the development of nanostructures with controlled diameter and adjustable mechanical properties. Here we present a technique for the production of flexible nanofilaments to be used as drug carriers or in microfluidics, with deformability and elasticity resembling those of long DNA chains. The fabrication method is based on the core-shell electrospinning technique with core solution polymerisation post electrospinning. Produced from the nanofibers highly deformable hydrogel nanofilaments are characterised by their Brownian motion and bending dynamics. The evaluated mechanical properties are compared with AFM nanoindentation tests.

A degradable nanogel drug carrier crosslinked with three-oligonucleotide hybrids for two-way drug release in mild and high hyperthermia treatment

Three-segment oligonucleotide hybrids were introduced as crosslinkers to a PNIPA-AAc nanonetwork. The obtained nanogels could be specifically transformed and degraded. The specific architecture of the presented carrier aims at achieving effective cancer treatment with reduced side toxicity. As a result, compared to the gels with regular crosslinkers, the drug release could be independently realized by (a) changing the structure of the gel net and conformation of DNA hybrids in an oscillating way and (b) degradation of DNA crosslinkers by denaturation. The hydrodynamic diameter and zeta potential of the nanogels were examined as a function of T and pH. The presence of a DNA helix in the nanogels led to a substantial increase, of nearly three times, in the storing efficiency of the selected anticancer drug compared to the nanogels with regular crosslinkers. Moreover, the nanogels allowed 98% drug release efficiency at high hyperthermic and 70% at mild hyperthermic conditions. The effectiveness of cytotoxicity of insulinoma cells was better compared to free doxorubicin. Since in the proposed approach, in addition to the drug, the third DNA strand can be also liberated, this opens new possibilities in development of gene therapies. This novel biocompatible carrier exhibits enhanced drug loading, possesses tunable and degradable properties under hyperthermic conditions and offers controlled release of the drug.

Electrochemical examination of ability of dsDNA/PAM composites for storing and releasing of doxorubicin.

Composites consisting of ss- and ds-DNA strands and polyacrylamide (PAM) hydrogel have been synthesized. DNA was entrapped non-covalently. The obtained DNA biomaterial exhibited a strong increase in guanine and adenine anodic currents when temperature reached the physiological level. This increase was related to the unique oligonucleotide structural changes in the composite. The structural alterations in the PAM lattices were employed for the release of the drug accumulated in the composite. Doxorubicin (Dox) was selected as the drug; it was accumulated by intercalation to dsDNA and was slowly released from the dsDNA/PAM system by using a minor temperature increase (up to 40÷45 °C) as it is routinely done in hyperthermia. The applied release temperature was either constant or oscillating. The binding strength, the rate of Dox release and the properties of the composite were examined using voltammetry, SEM and ICP-MS.

Environmentally sensitive nanohydrogels decorated with a three-strand oligonucleotide helix for controlled loading and prolonged release of intercalators

Two different short DNA strands were attached to the surface of a gel nanoparticle. The third DNA strand that was 50:50 complementary to those strands allowed the formation of a three-strand hybrid. The gel nanoparticles were synthetized from N-isopropyloacrylamide (NIPA), N,N′-methylenebisacrylamide (BIS) and acrylic acid (AA) by employing the free radical polymerization reaction. The physicochemical parameters of this novel nanogel stimulated its penetration of selected cancer tissues (Hela and Insulinoma cells) and allowed effective delivery of the anticancer drug doxorubicin (Dox). Since the three-strand oligonucleotide hybrid sites were located at the surface of the nanogel, this allowed effective storing of Dox by its intercalation to the double stranded DNA. The binding through intercalation resulted in prolonged release of the drug. The release of Dox at selected temperatures was a consequence of oligo1-2-3 hybrid conformational change, the shrinking of the hydrogel and zeta-potential change.

Correction: Hydrogel Nanofilaments via Core-Shell Electrospinning

The images for Figs ​Figs66 and ​and77 are incorrectly switched. The image that appears as Fig 6 should be Fig 7 and the image that appears as Fig 7 should be Fig 6. The figure captions appear in the correct order. Please view the correct figures below. Fig 6 Fluorescence images showing bending dynamics of a nanofilament (Table 1, nanofilament no. 1). Fig 7 a) Plot of the mean square displacement of a filament of contour length 21.5 μm as a function of lag time. The upper two plots are MSDs along the a and b axes in terms of μm2, whereas the bottom one is the angular MSD in terms of mrad ... The fifth sentence in the second paragraph of the Results subsection titled “Mechanical properties of hydrogel nanofilaments” should reference Fig 7b instead of Fig 6b. The tenth sentence in the second paragraph of the Results subsection titled “Mechanical properties of hydrogel nanofilaments” should reference Fig 7c instead of Fig 6c.