@article{FudickarRoderListeketal.2021,
  author    = {Fudickar, Werner and Roder, Phillip and Listek, Martin and Hanack, Katja and Linker, Torsten},
  title     = {Pyridinium alkynylanthracenes as sensitizers for photodynamic therapy},
  series = {Photochemistry and photobiology},
  volume    = {98},
  journal   = {Photochemistry and photobiology},
  number    = {1},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0031-8655},
  doi       = {10.1111/php.13554},
  pages     = {193 -- 201},
  year      = {2021},
  abstract  = {Photodynamic therapy (PDT) is a mild but effective method to treat certain types of cancer upon irradiation with visible light. Here, three isomeric methylpyridinium alkynylanthracenes 1op were evaluated as sensitizers for PDT. Upon irradiation with blue or green light, all three compounds show the ability to initiate strand breaks of plasmid DNA. The mayor species responsible for cleavage is singlet oxygen (O-1(2)) as confirmed by scavenging reagents. Only isomers 1m and 1p can be incorporated into HeLa cells, whereas isomer 1o cannot permeate through the membrane. While isomer 1m targets the cell nucleus, isomer 1p assembles in the cellular cytoplasm and impacts the cellular integrity. This is in accordance with a moderate toxicity of 1p in the dark, whereas 1m exhibits no dark toxicity. Both isomers are suitable as PDT reagents, with a CC50 of 3 mu m and 75 nm, for 1p and 1m, respectively. Thus, derivative 1m, which can be easily synthesized, becomes an interesting candidate for cancer therapy.},
  language  = {en}
}
@article{BalkBehlLendlein2019,
  author    = {Balk, Maria and Behl, Marc and Lendlein, Andreas},
  title     = {Quadruple-shape hydrogels},
  series = {Smart materials and structures},
  volume    = {28},
  journal   = {Smart materials and structures},
  number    = {5},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0964-1726},
  doi       = {10.1088/1361-665X/ab0e91},
  pages     = {10},
  year      = {2019},
  abstract  = {The capability of directed movements by two subsequent shape changes could be implemented in shape-memory hydrogels by incorporation of two types of crystallizable side chains While in non-swollen polymer networks even more directed movements could be realized, the creation of multi-shape hydrogels is still a challenge. We hypothesize that a quadruple-shape effect in hydrogels can be realized, when a swelling capacity almost independent of temperature is generated, whereby directed movements could be enabled, which are not related to swelling. In this case, entropy elastic recovery could be realized by hydrophilic segments and the fixation of different macroscopic shapes by means of three semi-crystalline side chains generating temporary crosslinks. Monomethacrylated semi-crystalline oligomers were connected as side chains in a hydrophilic polymer network via radical copolymerization. Computer assisted modelling was utilized to design a demonstrator capable of complex shape shifts by creating a casting mold via 3D printing from polyvinyl alcohol. The demonstrator was obtained after copolymerization of polymer network forming components within the mold, which was subsequently dissolved in water. A thermally-induced quadruple-shape effect was realized after equilibrium swelling of the polymer network in water. Three directed movements were successfully obtained when the temperature was continuously increased from 5 degrees C to 90 degrees C with a recovery ratio of the original shape above 90\%. Hence, a thermally-induced quadruple-shape effect as new record for hydrogels was realized. Here, the temperature range for the multi-shape effect was limited by water as swelling media (0 degrees C-100 degrees C), simultaneously distinctly separated thermal transitions were required, and the overall elasticity indispensable for successive deformations was reduced as result of partially chain segment orientation induced by swelling in water. Conclusively the challenges for penta- or hexa-shape gels are the design of systems enabling higher elastic deformability and covering a larger temperature range by switching to a different solvent.},
  language  = {en}
}
@article{WanjikuYamamotoKlosseketal.2019,
  author    = {Wanjiku, Barbara and Yamamoto, Kenji and Klossek, Andre and Schumacher, Fabian and Pischon, Hannah and Mundhenk, Lars and Rancan, Fiorenza and Judd, Martyna M. and Ahmed, Muniruddin and Zoschke, Christian and Kleuser, Burkhard and R{\"u}hl, Eckart and Sch{\"a}fer-Korting, Monika},
  title     = {Qualifying X-ray and Stimulated Raman Spectromicroscopy for Mapping Cutaneous Drug Penetration},
  series = {Analytical chemistry},
  volume    = {91},
  journal   = {Analytical chemistry},
  number    = {11},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0003-2700},
  doi       = {10.1021/acs.analchem.9b00519},
  pages     = {7208 -- 7214},
  year      = {2019},
  abstract  = {Research on topical drug delivery relies on reconstructed human skin (RHS) in addition to ex vivo human and animal skin, each with specific physiological features. Here, we compared the penetration of dexamethasone from an ethanolic hydroxyethyl cellulose gel into ex vivo human skin, murine skin, and RHS. For comprehensive insights into skin morphology and penetration enhancing mechanisms, scanning transmission X-ray microscopy (STXM), liquid chromatography tandem mass spectrometry (LC-MS/MS), and stimulated Raman spectromicroscopy (SRS) were combined. STXM offers high spatial resolution with label-free drug detection and is therefore sensitive to tissue damage. Despite differences in sample preparation and data analysis, the amounts of dexamethasone in RHS, detected and quantified by STXM and LC-MS/MS, were very similar and increased during the first 100 min of exposure. SRS revealed interactions between the gel and the stratum corneum or, more specifically, its protein and lipid structures. Similar to both types of ex vivo skin, higher protein-to-lipid ratios within the stratum corneum of RHS indicated reduced lipid amounts after 30 min of ethanol exposure. Extended ethanol exposure led to a continued reduction of lipids in the ex vivo matrixes, while protein integrity appeared to be compromised in RHS, which led to declining protein signals. In conclusion, LC-MS/MS proved the predictive capability of STXM for label-free drug detection. Combining STXM with SRS precisely dissected the penetration enhancing effects of ethanol. Further studies on topical drug delivery should consider the potential of these complementary techniques.},
  language  = {en}
}
@article{StarkeHolzbergerKammetal.2000,
  author    = {Starke, Ines and Holzberger, Anja and Kamm, Birgit and Kleinpeter, Erich},
  title     = {Qualitative and quantitative analysis of carbohydrates in green juices (wild mix grass and alfalfa) from a green biorefinery by gas chromatography/mass spectrometry},
  year      = {2000},
  language  = {en}
}
@phdthesis{Klaumuenzer2012,
  author    = {Klaum{\"u}nzer, Bastian},
  title     = {Quantenchemische und molekulardynamische Untersuchungen zur Photoanregung von Riboflavin},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-63171},
  school      = {Universit{\"a}t Potsdam},
  year      = {2012},
  abstract  = {Die Photophysik und Photochemie von Flavinen sind aufgrund ihrer biologischen Funktion, inbesondere von Flavoproteinen, von großen Interesse. Flavoproteine spielen eine große Rolle in einer Vielzahl von biologischen Prozessen, z.B. Biolumineszenz, Entfernung von Radikalen, die bei oxidativem Stress entstehen, Photosynthese und DNA-Reparatur. Die spektroskopischen Eigenschaften des Flavin-Cofaktors machen diesen zu einem nat{\"u}rlichen Reporter f{\"u}r Ver{\"a}nderungen innerhalb des aktiven Zentrums. Deshalb sind die Flavoproteine eine der am meisten untersuchten Enzymfamilien. Eine biologische Aktivit{\"a}t des Flavins f{\"u}hrt {\"u}ber einen elektronisch angeregten Zustand, wo dann, abh{\"a}ngig von der Aminos{\"a}ureumgebung, ein bestimmter Mechanismus zu einem biologischen Prozess f{\"u}hrt (Photozyklus). Ein wichtiges Analysetool zum Verst{\"a}ndnis des anf{\"a}nglichen Photoanregungsschritts der Flavine sind die elektronische und die Schwingungsspektroskopie. In dieser Arbeit wurden die Prozesse von Riboflavin (RF) w{\"a}hrend und nach optischer Anregung mit theoretischen Mitteln beleuchtet. Dazu wurden quantenchemische Berechnungen f{\"u}r Schwingungsspektren (vibratorische) von Riboflavin, auch Laktoflavin oder Vitamin B2 genannt, dem Grundmolek{\"u}l der Chromophore biologischer Blaulichtrezeptoren, in dessen elektronischem Grundzustand und dessen niedrigsten angeregten Zustand durchgef{\"u}hrt. Weiterhin wurden vibronische (vibratorische+elektronische) Absorptionsspektren und ein vibronisches Emissionsspektrum berechnet. Die so berechneten Schwingungs- und elektronischen Spektren sind in guter qualitativer wie quantitativer {\"U}bereinstimmung mit gemessenen Werten, und helfen so, die experimentellen Signale der Photoanregung von Flavinen zuzuweisen. Unmittelbar nach der Photoanregung wurde ein Verlust des Doppelbindungscharakters im polaren Bereich des Ringssystems beobachtet, was zu der vibronischen Feinstruktur im elektronischen Absorptions- und Emissionsspektrum f{\"u}hrte. Hier zeigte sich zudem, dass neben den vibronischen Effekten auch die L{\"o}sungsmitteleffekte wichtig f{\"u}r das quantitative Verst{\"a}ndnis der Photophysik der Flavine in L{\"o}sung sind. Um Details des optischen Anregungsprozesses als initialen, elementaren Schritt zur Signalweiterleitung zu entschl{\"u}sseln, wurden ultraschnelle (femtosekundenaufgel{\"o}ste) Experimente durchgef{\"u}hrt, die die Photoaktivierung des Flavins untersuchen. Diese Arbeit soll zu einem weiteren Verst{\"a}ndnis und der Interpretation dieser Experimente durch das Studium der Post-Anregungsschwingungsdynamik von Riboflavin und mikrosolvatisiertem Riboflavin beitragen. Dazu wurde eine 200 fs lange Molekulardynamik in angeregten Zust{\"a}nden betrachtet. Durch die Analyse charakteristischer Atombewegungen und durch die Berechnungen zeitaufgel{\"o}ster Emissionsspektren fand man heraus, dass nach der optischen Anregung Schwingungen im Ringssystem des Riboflavins einsetzen. Mit Hilfe dieser Berechnungen kann die Umverteilung der Energie im angeregten Zustand beobachtet werden. Neben den theoretischen Untersuchungen zu Riboflavin in der Gasphase und auch in L{\"o}sung wurde ein Modell f{\"u}r eine BLUF (Blue-Light Photoreceptor Using Flavin) Dom{\"a}ne, ein Flavin benutzender Photorezeptor, erstellt. Hierbei zeigt sich, dass man die in dieser Arbeit angewendeten Analysemethoden auch auf biologisch relevante Systeme anwenden kann.},
  language  = {de}
}
@phdthesis{Koch2001,
  author    = {Koch, Andreas},
  title     = {Quantenchemische Untersuchungen von Tautomeriegleichgewichten und von Rotationsbarrieren um partielle C,N- Doppelbindungen},
  pages     = {115 S.},
  year      = {2001},
  language  = {de}
}
@phdthesis{Morgner2012,
  author    = {Morgner, Frank},
  title     = {Quantenpunktbasiertes spektroskopisches Lineal mit Terbium-Komplexen als Donoren f{\"u}r optische FRET-Multiplexmessungen},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-63576},
  school      = {Universit{\"a}t Potsdam},
  year      = {2012},
  abstract  = {Der F{\"o}rster-Resonanzenergietransfer (FRET) liefert einen wichtigen Beitrag bei der Untersuchung kleinskaliger biologischer Systeme und Prozesse. M{\"o}glich wird dies durch die r-6-Abh{\"a}ngigkeit des FRET, die es erlaubt Abst{\"a}nde und strukturelle {\"A}nderungen weit unterhalb der Beugungsgrenze des Lichts mit hoher Sensitivit{\"a}t und geringem Aufwand zu bestimmen. Die besonderen photophysikalischen Eigenschaften von Terbiumkomplexen (LTC) und Quantenpunkten (QD) machen sie zu geeigneten Kandidaten f{\"u}r hochsensitive und st{\"o}rungsarme Multiplex-Abstandsmessungen in biologischen Systemen und Prozessen. Die Abstandsbestimmungen setzen jedoch eine genaueste Kenntnis des Mechanismus des Energietransfers von LTC auf QD ebenso voraus, wie das Wissen um Gr{\"o}ße und Gestalt letzterer. Quantenpunkte haben im Vergleich zu biologischen Strukturen {\"a}hnliche Dimensionen und k{\"o}nnen nicht als punktf{\"o}rmig betrachtet werden, wie es bei einfacheren Farbstoffen m{\"o}glich ist. Durch ihre Form kommt es zu einer Abstandsverteilung innerhalb des Donor-Akzeptorsystems. Dies beeinflusst den Energietransfer und damit die experimentellen Ergebnisse. In dieser Arbeit wurde der Energietransfer von LTC auf QD untersucht, um zu einer Aussage hinsichtlich des Mechanismus der Energie{\"u}bertragung und der dabei zu ber{\"u}cksichtigenden photophysikalischen und strukturellen Parameter von LTC und QD zu gelangen. Mit der Annahme einer Abstandsverteilung sollten die Gr{\"o}ßen der Quantenpunkte bestimmt und der Einfluss von Form und Gestalt auf den Energietransfer betrachtet werden. Die notwendigen theoretischen und praktischen Grundlagen wurden eingangs dargestellt. Daran schlossen sich Messungen zur photophysikalischen Charakterisierung der Donoren und Akzeptoren an, die Grundlage der Berechnung der FRET-Parameter waren. Die F{\"o}rster-Radien zeigten die f{\"u}r den FRET von LTC auf QD typischen extrem hohen Werte von bis zu 11 nm. Zeitaufgel{\"o}ste Messungen der FRET-induzierten Lumineszenz der Donoren und Akzeptoren in den beiden biomolekularen Modellsystemen Zink-Histidin und Biotin-Streptavidin beschlossen den praktischen Teil. Als Donor wurde Lumi4Tb gebunden an ein Peptid bzw. Streptavidin genutzt, Akzeptoren waren f{\"u}nf verschiedene, kommerziell erh{\"a}ltliche Quantenpunkte mit Carboxyl- bzw. Biotinfunktionalisierung. Bei allen Donor-Akzeptor-Paarungen konnte FRET beobachtet und ausgewertet werden. Es konnte gezeigt werden, dass die gesamte Emission des Terbiums zum Energietransfer beitr{\"a}gt und der Orientierungsfaktor ² den Wert 2/3 annimmt. Die Charakterisierung der Bindungsverh{\"a}ltnisse innerhalb der FRET-Paare von LTC und QD {\"u}ber Verteilungsfunktionen bietet {\"u}ber die Form der Verteilungskurve die M{\"o}glichkeit Aussagen {\"u}ber die Gestalt der FRET-Partner zu treffen. So war es m{\"o}glich, die mittlere Form der Quantenpunkte als Sph{\"a}re zu bestimmen. Dies entsprach, insbesondere bei den in z-Richtung des Kristallgitters elongierten Quantenpunkten, nicht den Erwartungen. Dieser Befund erm{\"o}glicht daher bei zuk{\"u}nftigen Messungen eine Verbesserung der Genauigkeit bei Abstandsbestimmungen mit Quantenpunkten. Neben der Ermittlung der die FRET-Verteilung bestimmenden Gestalt der Quantenpunkte konnte im Rahmen dieser Arbeit anhand vergleichender Messungen die Dicke der Polymerh{\"u}lle der QD bestimmt und so gezeigt werden, dass FRET-Paare aus lumineszenten Terbiumkomplexen und Quantenpunkten in der Lage sind, Abst{\"a}nde im Nano- bis Sub-Nanometerbereich aufzul{\"o}sen.},
  language  = {de}
}
@misc{Kleinpeter2014,
  author    = {Kleinpeter, Erich},
  title     = {Quantification and visualization of the anisotropy effect in NMR spectroscopy by through-space NMR shieldings},
  series = {Annual reports on NMR spectroscopy},
  volume    = {82},
  journal   = {Annual reports on NMR spectroscopy},
  editor    = {Webb, GA},
  publisher = {Elsevier},
  address   = {San Diego},
  isbn      = {978-0-12-800184-4},
  issn      = {0066-4103},
  doi       = {10.1016/B978-0-12-800184-4.00003-5},
  pages     = {115 -- 166},
  year      = {2014},
  abstract  = {The anisotropy effect of functional groups (respectively the ring-current effect of aryl moieties) in H-1 NMR spectra has been computed as spatial NICS (through-space NMR chemical shieldings) and visualized by iso-chemical-shielding surfaces of various size and low(high) field direction. Hereby, the anisotropy/ring-current effect, which proves to be the molecular response property of spatial NICS, can be quantified and can be readily employed for assignment purposes in proton NMR spectroscopy-characteristic examples of stereochemistry and position assignments (the latter in supramolecular structures) will be given. In addition, anisotropy/ring-current effects in H-1 NMR spectra can be quantitatively separated from the second dominant structural effect in proton NMR spectra, the steric compression effect, pointing into the reverse direction, and the ring-current effect, by far the strongest anisotropy effect, can be impressively employed to visualize and quantify (anti) aromaticity and to clear up standing physical-organic phenomena as are pseudo-, spherical, captodative, homo-and chelatoaromaticity, to characterize the pi-electronic structure of, for example, fulvenes, fulvalenes, annulenes or fullerenes and to differentiate aromatic and quinonoid structures.},
  language  = {en}
}
@phdthesis{Ebel2021,
  author    = {Ebel, Kenny},
  title     = {Quantification of low-energy electron induced single and double strand breaks in well-defined DNA sequences using DNA origami nanostructures},
  doi       = {10.25932/publishup-50449},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-504499},
  school      = {Universit{\"a}t Potsdam},
  pages     = {111},
  year      = {2021},
  abstract  = {Ionizing radiation is used in cancer radiation therapy to effectively damage the DNA of tumors leading to cell death and reduction of the tumor tissue. The main damage is due to generation of highly reactive secondary species such as low-energy electrons (LEE) with the most probable energy around 10 eV through ionization of water molecules in the cells. A simulation of the dose distribution in the patient is required to optimize the irradiation modality in cancer radiation therapy, which must be based on the fundamental physical processes of high-energy radiation with the tissue. In the present work the accurate quantification of DNA radiation damage in the form of absolute cross sections for LEE-induced DNA strand breaks (SBs) between 5 and 20 eV is done by using the DNA origami technique. This method is based on the analysis of well-defined DNA target sequences attached to DNA origami triangles with atomic force microscopy (AFM) on the single molecule level. The present work focuses on poly-adenine sequences (5'-d(A4), 5'-d(A8), 5'-d(A12), 5'-d(A16), and 5'- d(A20)) irradiated with 5.0, 7.0, 8.4, and 10 eV electrons. Independent of the DNA length, the strand break cross section shows a maximum around 7.0 eV electron energy for all investigated oligonucleotides confirming that strand breakage occurs through the initial formation of negative ion resonances. Additionally, DNA double strand breaks from a DNA hairpin 5'-d(CAC)4T(Bt-dT)T2(GTG)4 are examined for the first time and are compared with those of DNA single strands 5'-d(CAC)4 and 5'- d(GTG)4. The irradiation is made in the most likely energy range of 5 to 20 eV with an anionic resonance maximum around 10 eV independently of the DNA sequence. There is a clear difference between σSSB and σDSB of DNA single and double strands, where the strand break for ssDNA are always higher in all electron energies compared to dsDNA by the factor 3. A further part of this work deals with the characterization and analysis of new types of radiosensitizers used in chemoradiotherapy, which selectively increases the DNA damage upon radiation. Fluorinated DNA sequences with 2'-fluoro-2'-deoxycytidine (dFC) show an increased sensitivity at 7 and 10 eV compared to the unmodified DNA sequences by an enhancement factor between 2.1 and 2.5. In addition, light-induced oxidative damage of 5'-d(GTG)4 and 5'-d((CAC)4T(Bt-dT)T2(GTG)4) modified DNA origami triangles by singlet oxygen 1O2 generated from three photoexcited DNA groove binders [ANT994], [ANT1083] and [Cr(ddpd)2][BF4]3 illuminated in different experiments with UV-Vis light at 430, 435 and 530 nm wavelength is demonstrated. The singlet oxygen induced generation of DNA damage could be detected in both aqueous and dry environments for [ANT1083] and [Cr(ddpd)2][BF4]3.},
  language  = {en}
}
@article{KleinpeterKoch2021,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Quantification of sigma-acceptor and pi-donor stabilization in O, S and Hal analogues of N-heterocyclic carbenes (NHCs) on the magnetic criterion},
  series = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory},
  volume    = {125},
  journal   = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory},
  number    = {33},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1089-5639},
  doi       = {10.1021/acs.jpca.1c05257},
  pages     = {7235 -- 7245},
  year      = {2021},
  abstract  = {The spatial magnetic properties, through-space NMR shieldings (TSNMRSs), of stable O, S and Hal analogues of N-heterocyclic carbenes (NHCs) have been calculated using the GIAO perturbation method employing the nucleus-independent chemical shift (NICS) concept and the results visualized as iso-chemical-shielding surfaces (ICSSs) of various sizes and directions. The TSNMRS values (actually the anisotropy effects measurable in H-1 NMR spectroscopy) are employed to qualify and quantify the position of the present mesomeric equilibria (carbenes <-> ylides). The results are confirmed by geometry (bond angles and bond lengths), IR spectra, UV spectra, and C-13 chemical shifts of the electron-deficient carbon centers.},
  language  = {en}
}