TY - JOUR A1 - Zutta Villate, J. M. A1 - Hahn, Marc Benjamin T1 - Radioactive gold nanoparticles for cancer treatment JF - European physical journal D N2 - Dose enhancement by gold nanoparticles (AuNP) was shown to increase the biological effectiveness of radiation damage in biomolecules and tissue. Most of the current studies focus on external beam therapy on combination with AuNP. Here we present a Monte-Carlo study (Geant4) to characterise radioactive AuNP. Radioactive 198 Au emits beta and gamma rays and is considered for applications with solid tumours. To effectively apply 198 AuNP their energy deposit characteristics have to be determined in terms of intrinsic and extrinsic properties e.g. AuNP diameter, AuNP density, and their clustering behaviour. After each decay process, the energy deposit, inelastic scattering events, kinetic energy spectrum of secondary particles within the AuNP themselves and in a spherical target volume of water up to 1 μm radius were determined. Simulations were performed for AuNP radii ranging from 2.5 nm to 20 nm radius, different cluster sizes and densities. The results show an increase of the energy deposit in the vicinity of the AuNP up to 150 nm. This effect nearly vanishes for distances up to one micron. For the case of AuNP clusters and the same activity, the enhancement of the energy deposit increases with the relative gold mass percentage and therefore can be adjusted by changing AuNP radius or clustering behaviour. KW - Gold KW - Nanoparticle KW - Cancer KW - Monte-Carlo KW - Simulation KW - Cluster PY - 2019 DO - https://doi.org/10.1140/epjd/e2019-90707-x SN - 1434-6060 SN - 1434-6079 VL - 73 IS - 95 SP - 1 EP - 7 PB - Springer CY - Berlin AN - OPUS4-47964 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin A1 - Smales, Glen Jacob A1 - Seitz, H. A1 - Solomun, Tihomir A1 - Sturm, Heinz T1 - Ectoine interaction with DNA: Influence on ultraviolet radiation damage JF - Physical Chemistry Chemical Physics N2 - Ectoine is a small zwitterionic osmolyte and compatible solute, which does not interfere with cell metabolism even at molar concentrations. Plasmid DNA (pUC19) was irradiated with ultraviolet radiation (UV-C at 266 nm) under quasi physiological conditions (PBS) and in pure water in the presence and absence of ectoine (THP(B)) and hydroxyectoine (THP(A)). Different types of UV induced DNA damage were analysed: DNA single-strand breaks (SSBs), abasic sites and cyclobutane pyrimidine dimers (CPDs). A complex interplay between these factors was observed with respect to the nature and occurrence of DNA damage with 266 nm photons. In PBS, the cosolutes showed efficient protection against base damage, whilst in pure water, a dramatic shift from SSB damage to base damage was observed when cosolutes were added. To test whether these effects are caused by ectoine binding to DNA, further experiments were conducted: small-angle X-ray scattering (SAXS), surface-plasmon resonance (SPR) measurements and Raman spectroscopy. The results show, for the first time, a close interaction between ectoine and DNA. This is in stark contrast to the assumption made by preferential exclusion models, which are often used to interpret the behaviour of compatible solutes within cells and with biomolecules. It is tentatively proposed that the alterations of UV damage to DNA are attributed to ectoine influence on nucleobases through the direct interaction between ectoine and DNA. KW - Ectoine KW - DNA KW - Radiation damage KW - Radiation protection KW - SSB KW - DNA damage KW - DNA protection KW - Compatible solute KW - Zwitterion KW - Hydroxyectoine KW - Salt KW - PBS KW - UV absorption KW - DNA strand-break KW - DNA base damage KW - Ectoine UV absorption KW - Ectoine DNA protection KW - Excited states KW - UV irradiation KW - UV-A KW - UV-B KW - UV-C KW - 266nm KW - UV photons KW - Ectoine-DNA binding KW - Raman spectroscopy KW - UV-Vis KW - Radical scavenger KW - OH scavenger KW - Hydroxyl radicals KW - CPD KW - Abasic site KW - Agarose gel electrophorese KW - SYBR gold KW - DNA melting temperature KW - Counterions KW - Preferential exclusion KW - Cancer KW - Therapy KW - UV protection KW - Sunscreen PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505772 DO - https://doi.org/10.1039/d0cp00092b SN - 1463-9076 SN - 1463-9084 VL - 22 IS - 13 SP - 6984 EP - 6992 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-50577 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin A1 - Susann, Meyer A1 - Schröter, Maria-Astrid A1 - Kunte, Hans-Jörg A1 - Solomun, Tihomir A1 - Sturm, Heinz T1 - DNA protection by ectoine from ionizing radiation: molecular mechanisms JF - Physical Chemistry Chemical Physics N2 - Ectoine, a compatible solute and osmolyte, is known to be an effective protectant of biomolecules and whole cells against heating, freezing and extreme salinity. Protection of cells (human keratinocytes) by ectoine against ultraviolet radiation has also been reported by various authors, although the underlying mechanism is not yet understood. We present the first electron irradiation of DNA in a fully aqueous environment in the presence of ectoine and at high salt concentrations. The results demonstrate effective protection of DNA by ectoine against the induction of single-strand breaks by ionizing radiation. The effect is explained by an increase in low-energy electron scattering at the enhanced free-vibrational density of states of water due to ectoine, as well as the use of ectoine as an ˙OH-radical scavenger. This was demonstrated by Raman spectroscopy and electron paramagnetic resonance (EPR). KW - Ectoine KW - DNA KW - Radiation protection KW - Ionizing radiation KW - Compatible solute KW - Biomolecules KW - Sodium chloride KW - Aqueous solution KW - Hydroxyectoine KW - Raman spectroscopy KW - Electron irradiation KW - Cancer KW - Radical scavenger KW - Low energy electrons KW - Hydroxyl radical KW - OH-radical KW - Ectoin KW - UV radiation KW - Sun KW - Salt KW - Radiation therapy PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-419332 UR - http://pubs.rsc.org/en/content/articlehtml/2017/cp/c7cp02860a DO - https://doi.org/10.1039/C7CP02860A SN - 1463-9076 VL - 19 IS - 37 SP - 25717 EP - 25722 PB - Royal Society of Chemistry CY - United Kingdom AN - OPUS4-41933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Direct electron irradiation of DNA in fully aqueous environment: Microscopic dose determination in combination with Monte-Carlo simulations N2 - Introduction: Ionizing radiation & DNA damage Experimental setup: Direct electron irradiation of DNA in liquid Monte-Carlo simulations: Electron scattering & diffusion Application: Radiation protection by compatible solutes T2 - Seminarvortrag im Joint Ultrafast Dynamics Laboratory in Solution and at Interfaces CY - Helmholtz-Zentrum Berlin, Germany DA - 14.06.2017 KW - DNA KW - Ectoine KW - Microdosimetry KW - Dosimetry KW - Radiation damage KW - Compatible solutes KW - Low energy electrons KW - Ionizing radiation KW - OH radical KW - Hydroxyl radicals KW - Prehydrated electrons KW - Radiation therapy KW - Cancer KW - Cancer therapy KW - Radiation protection KW - Proteins KW - Monte carlo simulations KW - Geant4 KW - Electron scattering PY - 2017 AN - OPUS4-42620 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -