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Achilleas Tsortos (Staff Scientist - Gizeli Lab)

Achilleas Tsortos (Staff Scientist - Gizeli Lab)

Principal Staff Scientist
Email address
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Phone
+30-2810-4075
Fax
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Lab web page
 

I am a Biophysicist, with current research interests (experimental & theoretical) in the areas of
•    Biosensors/Biointerfaces: adsorption and detection mechanisms, viscoelasticity of ultrathin films
•    Conformation analysis of DNA (-ss, -ds, -ts, Holliday, intercalation, etc.)
•    Conformation of Proteins at the solid/liquid interface
•    Structure of Lipid Membranes and interaction with antimicrobial Peptides (Liposomes, SLBs)
•    DNA/protein interactions at interfaces     
•    DNA hydrodynamics
Earlier work was done in the fields of            
•    Biomaterials:  calcium phosphate mineralization (e.g. apatite), in vitro crystal growth, kinetics, promotion-inhibition, nucleation at organic surfaces,   
      influence of protein or biopolymer structure in (bio)mineralization
•    Protein Structure: stability, heat-induced denaturation, folding/unfolding
•    Molecular Recognition: guest/host & self-assembly systems (SAMs, cyclodextrins, drugs, liposomes)

A variety of techniques is employed such as:
Acoustic Resonators (QCM-D), Ellipsometry, SPR, microCalorimetry (DSC, ITC), ATR-InfraRed, Circular Dichroism, UV, Microscopy (SEM-w/EDX), Zeta Potential,  Potentiometric Titrations, Adsorption Isotherms, Viscometry, Constant-Composition (for inorganic crystal growth) and Computer Modelling (numerical methods)

Mansfield ML, Tsortos A, Douglas JF. (2015) Persistent draining crossover in DNA and other semi-flexible polymers: evidence from hydrodynamic models and extensive measurements on DNA solutions. J Chem Phys. 143:124903.

Papadakis G, Tsortos A, Gizeli E. (2010) Acoustic characterization of nanoswitch structures: application to the DNA Holliday junction. Nano Lett. 10:5093-5097.

Tsortos A, Papadakis G, Mitsakakis K, Melzak KA, Gizeli E. (2008) Quantitative determination of size and shape of surface-bound DNA using an acoustic wave sensor. Biophys J. 94:2706-2715.   

Pyrpassopoulos S, Vlassi M, Tsortos A, Papanikolau Y, Petratos K, Vorgias CE, Nounesis G. (2006) Equilibrium heat-induced denaturation of Chitinase 40 from Streptomyces thermoviolaceus. Proteins. 64:513-523.  

Tsortos A, Ohki S, Zieba A, Baier RE, Nancollas GH. (1996) The dual role of fibrinogen as inhibitor and nucleator of calcium phosphate phases: The importance of structure. J Colloid Interface Sci. 177:257-262.

see  GoogleScholar

•    A.G. Samarentsis, A.K. Pantazis, A. Tsortos, J.M. Friedt, E. Gizeli “Hybrid sensor device for simultaneous surface plasmon resonance and surface acoustic wave measurements” Sensors 20: Article Number 6177 (2020)

•    A. Vazquez-Quesada, M. Melendez-Schofield, A. Tsortos, P. Mateos-Gil, D. Milioni, E. Gizeli, R. Delgado-Buscalioni “Hydrodynamics of quartz-crystal-microbalance DNA sensors based on liposome amplifiers” Physical Review Applied 13: Article Number 064059 (2020)

•    D. Milioni, P. Mateos-Gil, G. Papadakis, A. Tsortos, O. Sarlidou, E. Gizeli “Acoustic methodology for selecting highly dissipative probes for ultra-sensitive DNA detection" Analytical Chemistry 92: 8186-8193 (2020)

•    V. Raptis, A. Tsortos, E. Gizeli “Theoretical aspects of a discrete-binding approach in quartz-crystal microbalance acoustic biosensing” Physical Review Applied 11: Article Number 034031 (2019)

•    G. Papadakis, P. Palladino, D. Chronaki, A. Tsortos, E. Gizeli “Sample-to-answer acoustic detection of DNA in complex samples” Chemical Communications 53: 8058-8061 (2017)

•    D. Milioni, A. Tsortoss, M. Velez, E. Gizeli “Extracting the shape and size of biomolecules attached to a surface as suspended discrete nano-particles” Analytical Chemistry 89: 4198-4203 (2017)

•    D. Chronaki, D. I. Stratiotis, A. Tsortos, E. Anastasiadou, E. Gizeli “Screening between normal and cancer human thyroid cells through comparative adhesion studies using the Quartz Crystal Microbalance” Sensing and Biosensing Research 11: 99-106 (2016)

•    A. Tsortos, G. Papadakis, E. Gizeli “On the hydrodynamic nature of DNA acoustic sensing” Analytical Chemistry 88: 6472-6478 (2016)

•    P. Mateos Gil, A. Tsortos, M. Velez, E. Gizeli “Monitoring structural changes in intrinsically disordered proteins with QCM-D: application to the bacterial cell division protein ZipA” Chemical Communications 52: 6541-6544 (2016)

•    M.L. Mansfield, A. Tsortos, J.F. Douglas “Persistent draining crossover in DNA and other semi-flexible polymers: evidence from hydrodynamic models and extensive measurements on DNA solutions” Journal of Chemical Physics 143: Article Number 124903 (2015)

•    A. Tsortos, A. Grammoustianou, R. Lymbouridou, G. Papadakis, E. Gizeli “Detection of multiple DNA targets with a single probe using a conformation-sensitive acoustic sensor” Chemical Communications 51: 11504-11507 (2015)

•    T. Tsiavos, N.E. Ioannidis, A. Tsortos, E. Gizeli, K. Kotzabasis “Spermine is a potent modulator of proton transport through LHC-II” Journal of Plant Physiology 177: 44-50 (2015)

•    K. Mitsakakis, A. Tsortos, E. Gizeli “Quantitative determination of protein molecular weight with an acoustic sensor; significance of specific versus non-specific binding” Analyst 139: 3918-3925 (2014)

•    G. Papadakis, A. Tsortos, A. Kordas, I. Tiniakou, E. Morou, J. Vontas, D. Kardassis, E. Gizeli “Acoustic detection of DNA conformation in genetic assays combined with PCR”
Scientific Reports 3: Article Number 2033 (2013)

•    G. Papadakis, A. Tsortos, F. Bender, E.E. Ferapontova, E. Gizeli “Direct detection of DNA conformation in hybridization processes” Analytical Chemistry 84: 1854-1861 (2012)

•    A. Tsortos, G. Papadakis, E. Gizeli “The intrinsic viscosity of linear DNA” Biopolymers 95: 824-832 (2011)

•    G. Papadakis, A. Tsortos, E. Gizeli “Acoustic characterization of nanoswitch structures: application to the DNA Holliday junction” Nano Letters 10: 5093-5097 (2010)

•    G. Papadakis, A. Tsortos, K. Mitsakakis, E. Gizeli “Characterization of DNA-Hv1 histone interactions; discrimination of DNA size and shape” FEBS Letters 584: 935-940 (2010)

•    M. Saitakis, A. Tsortos, E. Gizeli “Probing the interaction of a membrane receptor with a surface-attached ligand using whole cells on acoustic biosensors” Biosensors and Bioelectronics 25: 1688-1693 (2010)

•    K. Melzak, A. Tsortos, E. Gizeli “Use of acoustic sensors to probe the mechanical properties of liposomes” Methods in Enzymology 465: 21-41 (2009)

•    G. Papadakis, A. Tsortos, E. Gizeli “Triple-helix DNA structural studies using a Love wave acoustic biosensor” Biosensors and Bioelectronics 25: 702-707 (2009)

•    F. Bender, P. Roach, A. Tsortos, G. Papadakis, M.I. Newton, G. McHale, E. Gizeli “Development of a combined surface plasmon resonance/surface acoustic wave (SPR/SAW) device for characterization of biomolecules” Measurement  Science and Technology 20: Article Number 124011 (2009)

•    K. Mitsakakis, A. Tsortos, J. Kondoh, E. Gizeli “Parametric study of SH-SAW device response to various types of surface perturbations” Sensors and Actuators B (-Chemical) 138: 408-416 (2009)

•    A. Tsortos, G. Papadakis, E. Gizeli “Acoustic wave biosensor for detecting DNA conformation; a study with QCM-D” in «Proceedings, the IEEE International Frequency Control Symposium», (DOI: 10.1109/FREQ.2008.4623017), Article Number 4623017, pp. 346-349 (2008)

•    A. Tsortos, G. Papadakis, E. Gizeli “Shear acoustic wave biosensor for detecting DNA intrinsic viscosity and conformation; a study with QCM-D” Biosensors and Bioelectronics 24: 836-841 (2008)

•    K.A. Melzak, F. Bender, A. Tsortos, E. Gizeli “Probing mechanical properties of liposomes using acoustic sensors” Langmuir 24: 9172-9180 (2008)

•    A. Tsortos, G. Papadakis, K. Mitsakakis, K.A. Melzak, E. Gizeli “Quantitative determination of size and shape of surface-bound DNA using an acoustic wave sensor” Biophysical Journal 94: 2706-2715 (2008)

•    S. Pyrpassopoulos, M. Vlassi, A. Tsortos, Y. Papanikolau, K. Petratos, C.E. Vorgias, G. Nounesis “Equilibrium heat-induced denaturation of Chitinase 40 from Streptomyces thermoviolaceus” Proteins (-Structure Function Bioinformatics) 64: 513-523 (2006)

•    A. Tsortos, S. Pyrpassopoulos, Y. Papanikolaou, A. Zees, K. Petratos, C.E. Vorgias, P. Pissis, G. Nounesis
“The thermal unfolding of proteins Chitinase A and Chitinase 40” (in Greek) in
«Proceedings, the 1st Hellenic Conference on Thermal Analysis», M. Lalia-Kantouri (ed.) ZITI Publ./Thessaloniki, (ISBN 960-431-810-1),  pp. 147-152 (2002)

•    H. Maswadeh, C. Demetzos, I. Daliani, I. Kyrikou, T. Mavromoustakos, A. Tsortos, G. Nounesis
“A molecular basis explanation of the dynamic and thermal effects of vinblastine sulfate upon dipalmitoylphosphatidylcholine bilayer membranes” Biochimica et Biophysica Acta (BBA-Biomembranes) 1567: 49-55 (2002)

•    H. Maswadeh, C. Demetzos, I. Daliani, T. Mavromoustakos, G. Nounesis, A. Tsortos “The effects of vinblastine sulfate on dipalmytoylphosphatidylcholine single and multiple bilayer membranes” in «Drug Discovery & Design: Medical Aspects», J. Matsoukas & T. Mavromoustakos (eds.), IOS Press/Amsterdam, (ISBN 1-58603-261-5) Biomedical and Health Research 55: 125-130 (2002)

•    A. Tsortos, G.H. Nancollas “The role of polycarboxylic acids in calcium phosphate mineralization” Journal of Colloid and Interface Science 250: 159-167 (2002)

•    Z. Sideratou, D. Tsiourvas, A. Tsortos, S. Pyrpassopoulos, G. Nounesis, C.M. Paleos “Interaction of phosphatidyl choline based liposomes functionalized at the interface with adenine and barbituric acid moieties” Langmuir 18: 829-835 (2002)

•    A. Tsortos, K. Yannakopoulou, K. Eliadou, I.M. Mavridis, G. Nounesis “Partial thermal dethreading of [3]pseudorotaxanes of α-cyclodextrin with linear aliphatic α,ω-aminoacids in aqueous solution” Journal of Physical Chemistry -B 105: 2664-2671 (2001)

•    Z. Sideratou, D. Tsiourvas, A. Tsortos, G. Nounesis, C.M. Paleos “Molecular recognition of complementary liposomes: the enhancing role of cholesterol” Langmuir 16: 9186-9191 (2000)

•    B. Nock, T. Maina, A. Tsortos, M. Pelecanou, C.P. Raptopoulou, M. Papadopoulos, H.J. Pietzsch, C.I. Stassinopoulou, A. Terzis, H. Spies, G. Nounesis, E. Chiotellis “Glutathione interaction with SNS/S mixed-ligand complexes of oxorhenium(V): kinetic aspects and characterization of the products” Inorganic Chemistry 39: 4433-4441 (2000)

•    A. Tsortos, G.H. Nancollas “The adsorption of polyelectrolytes on hydroxyapatite crystals” Journal of Colloid and Interface Science 209: 109-115 (1999)

•    A. Tsortos, A. Zieba, G.H. Nancollas “The nucleation and growth of calcium phosphate crystals at protein and phosphatidylserine liposome surfaces” Scanning Microscopy 10: 499-507 (1996)

•    A. Tsortos, S. Ohki, A. Zieba, R.E. Baier, G.H. Nancollas “The dual role of fibrinogen as inhibitor and nucleator of calcium phosphate phases: the importance of structure” Journal of Colloid and Interface Science 177: 257-262 (1996)

•    G.H. Nancollas, A. Tsortos, Y. Liu, J. Zhang “The mechanisms of biomineralization and demineralization” in «Fundamentals of Biomineralization», D. Allemand & J.P. Cuif (eds.), Musée Océanographique, Monaco (ISBN 2-7260-0168-8) Bulletin de l’ Institut Oceanographique 14: 65-73 (1994)


Theses:
•    A. Tsortos “The role of macromolecules as inhibitors and nucleators of calcium phosphate phases: a physico-chemical study” Ph.D Thesis  Dept. of Biophysics, University at Buffalo, New York, U.S.A (1993)

•    A. Tsortos “Measurement of the magnetic susceptibility of the 99mTc organic complexes using the method of 1H-NMR” BSc. Thesis,  Dept. of Physics, University of Athens, Greece (1987)

Software:
•    A. Tsortos, M. Lanza, M. Anbar, J. Loonsk “Object-oriented programming and databases in an integrated learning environment for medical informatics” in «Proceedings, Meeting of the AAMC», Section: Innovations in Medical Education, software, source code manuscript pp. 1-11, (1989)

Patent:
•    A. Tsortos, G. Papadakis, E. Gizeli “Molecular Conformation Biosensing” WO2008/155692 (2008), US8429953 (2013), EP2171083 (2014)