TY  - GEN
A1  - Ciuciu, Adina I.
A1  - Cywiński, Piotr J.
T1  - Two-photon polymerization of hydrogels – versatile solutions to fabricate well-defined 3D structures
N2  - Hydrogels are cross-linked water-containing polymer networks that are formed by physical, ionic or covalent interactions. In recent years, they have attracted significant attention because of their unique physical properties, which make them promising materials for numerous applications in food and cosmetic processing, as well as in drug delivery and tissue engineering. Hydrogels are highly water-swellable materials, which can considerably increase in volume without losing cohesion, are biocompatible and possess excellent tissue-like physical properties, which can mimic in vivo conditions. When combined with highly precise manufacturing technologies, such as two-photon polymerization (2PP), well-defined three-dimensional structures can be obtained. These structures can become scaffolds for selective cell-entrapping, cell/drug delivery, sensing and prosthetic implants in regenerative medicine. 2PP has been distinguished from other rapid prototyping methods because it is a non-invasive and efficient approach for hydrogel cross-linking. This review discusses the 2PP-based fabrication of 3D hydrogel structures and their potential applications in biotechnology. A brief overview regarding the 2PP methodology and hydrogel properties relevant to biomedical applications is given together with a review of the most important recent achievements in the field.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 286 
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-99450
ER  - 
TY  - JOUR
A1  - Cywinski, Piotr J.
A1  - Hammann, Tommy
A1  - Huehn, Dominik
A1  - Parak, Wolfgang J.
A1  - Hildebrandt, Niko
A1  - Löhmannsröben, Hans-Gerd
T1  - Europium-quantum dot nanobioconjugates as luminescent probes for time-gated biosensing
JF  - Journal of biomedical optics
N2  - Nanobioconjugates have been synthesized using cadmium selenide quantum dots (QDs), europium complexes (EuCs), and biotin. In those conjugates, long-lived photoluminescence (PL) is provided by the europium complexes, which efficiently transfer energy via Forster resonance energy transfer (FRET) to the QDs in close spatial proximity. As a result, the conjugates have a PL emission spectrum characteristic for QDs combined with the long PL decay time characteristic for EuCs. The nanobioconjugates synthesis strategy and photo-physical properties are described as well as their performance in a time-resolved streptavidin-biotin PL assay. In order to prepare the QD-EuC-biotin conjugates, first an amphiphilic polymer has been functionalized with the EuC and biotin. Then, the polymer has been brought onto the surface of the QDs (either QD655 or QD705) to provide functionality and to make the QDs water dispersible. Due to a short distance between EuC and QD, an efficient FRET can be observed. Additionally, the QD-EuC-biotin conjugates' functionality has been demonstrated in a PL assay yielding good signal discrimination, both from autofluorescence and directly excited QDs. These newly designed QD-EuC-biotin conjugates expand the class of highly sensitive tools for bioanalytical optical detection methods for diagnostic and imaging applications. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)
KW  - quantum dots
KW  - europium complex
KW  - amphiphilic polymer assembly
KW  - nanobioconjugate
KW  - biosensor
KW  - time-resolved fluorescence
Y1  - 2014
U6  - https://doi.org/10.1117/1.JBO.19.10.101506
SN  - 1083-3668
SN  - 1560-2281
VL  - 19
IS  - 10
PB  - SPIE
CY  - Bellingham
ER  - 
TY  - JOUR
A1  - Cywinski, Piotr J.
A1  - Idzik, Krzysztof R.
A1  - Cranfield, Charles G.
A1  - Beckert, Rainer
A1  - Mohr, Gerhard J.
T1  - Synthesis and sensing properties of a new carbazole fluorosensor for detection of abacavir
N2  - An abacavir-targeted fluorosensor based on the carbazole moiety has been synthesised and characterised. Recognition of abacavir is by base pairing between a uracil moiety present in the fluorosensor and the guanine moiety of abacavir. The fluorosensor exhibits five-fold quenching in the presence of 50M abacavir. Its sensitivity to abacavir is superior to that of other reverse transcriptase inhibitors: zidovudine, lamivudine and didanosine. Due to its high sensitivity, this fluorosensor has the potential to be used in multi-analyte array-based detection platforms as well as in microfluidics systems.
Y1  - 2010
UR  - http://www.informaworld.com/openurl?genre=journal&issn=1061-0278
U6  - https://doi.org/10.1080/10610278.2010.506541
SN  - 1061-0278
ER  - 
TY  - JOUR
A1  - Cywinski, Piotr J.
A1  - Moro, Artur J.
A1  - Löhmannsröben, Hans-Gerd
T1  - Cyclic GMP recognition using ratiometric QD-fluorophore conjugate nanosensors
JF  - Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics
KW  - Quantum dots
KW  - Naphthyridines
KW  - Cyclic GMP
KW  - Base pairing
KW  - Fluorescent nanoconjugate
KW  - Nanosensor
Y1  - 2014
U6  - https://doi.org/10.1016/j.bios.2013.09.002
SN  - 0956-5663
SN  - 1873-4235
VL  - 52
SP  - 288
EP  - 292
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Cywinski, Piotr J.
A1  - Moro, Artur J.
A1  - Ritschel, Thomas
A1  - Hildebrandt, Niko
A1  - Löhmannsröben, Hans-Gerd
T1  - Sensitive and selective fluorescence detection of guanosine nucleotides by nanoparticles conjugated with a naphthyridine receptor
JF  - Analytical & bioanalytical chemistry
N2  - Novel fluorescent nanosensors, based on a naphthyridine receptor, have been developed for the detection of guanosine nucleotides, and both their sensitivity and selectivity to various nucleotides were evaluated. The nanosensors were constructed from polystyrene nanoparticles functionalized by (N-(7-((3-aminophenyl) ethynyl)-1,8-naphthyridin- 2-yl) acetamide) via carbodiimide ester activation. We show that this naphthyridine nanosensor binds guanosine nucleotides preferentially over adenine, cytosine, and thymidine nucleotides. Upon interaction with nucleotides, the fluorescence of the nanosensor is gradually quenched yielding Stern-Volmer constants in the range of 2.1 to 35.9mM(-1). For all the studied quenchers, limits of detection (LOD) and tolerance levels for the nanosensors were also determined. The lowest (3 sigma) LOD was found for guanosine 3',5'-cyclic monophosphate (cGMP) and it was as low as 150 ng/ml. In addition, we demonstrated that the spatial arrangement of bound analytes on the nanosensors' surfaces is what is responsible for their selectivity to different guanosine nucleotides. We found a correlation between the changes of the fluorescence signal and the number of phosphate groups of a nucleotide. Results of molecular modeling and zeta-potential measurements confirm that the arrangement of analytes on the surface provides for the selectivity of the nanosensors. These fluorescent nanosensors have the potential to be applied in multi-analyte, array-based detection platforms, as well as in multiplexed microfluidic systems.
KW  - Naphthyridine receptor
KW  - cGMP
KW  - Base pairing
KW  - Nucleotide nanosensor
KW  - Fluorescence spectroscopy
Y1  - 2011
U6  - https://doi.org/10.1007/s00216-010-4420-2
SN  - 1618-2642
VL  - 399
IS  - 3
SP  - 1215
EP  - 1222
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Cywinski, Piotr J.
A1  - Nono, Katia Nchimi
A1  - Charbonniere, Loic J.
A1  - Hammann, Tommy
A1  - Löhmannsröben, Hans-Gerd
T1  - Photophysical evaluation of a new functional terbium complex in FRET-based time-resolved homogenous fluoroassays
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - A new functional luminescent lanthanide complex (LLC) has been synthesized with terbium as a central lanthanide ion and biotin as a functional moiety. Unlike in typical lanthanide complexes assembled via carboxylic moieties, in the presented complex, four phosphate groups are chelating the central lanthanide ion. This special chemical assembly enhances the complex stability in phosphate buffers conventionally used in biochemistry. The complex synthesis strategy and photophysical properties are described as well as the performance in time-resolved Forster Resonance Energy Transfer (FRET) assays. In those assays, this biotin-LLC transferred energy either to acceptor organic dyes (Cy5 or AF680) labelled on streptavidin or to quantum dots (QD655 or QD705) surfacefunctionalised with streptavidins. The permanent spatial donor-acceptor proximity is assured through strong and stable biotin-streptavidin binding. The energy transfer is evidenced from the quenching observed in donor emission and from a decrease in donor luminescence decay, both associated with simultaneous increase in acceptor intensity and in the decay time. The dye-based assays are realised in TRIS and in PBS, whereas QD-based systems are studied in borate buffer. The delayed emission analysis allows for quantifying the recognition process and for auto-fluorescence-free detection, which is particularly relevant for application in bioanalysis. In accordance with Forster theory, Forsterradii (R0) were found to be around 60 angstrom for organic dyes and around 105 angstrom for QDs. The FRET efficiency (Z) reached 80% and 25% for dye and QD acceptors, respectively. Physical donor-acceptor distances (r) have been determined in the range 45-60 angstrom for organic dye acceptors, while for acceptor QDs between 120 angstrom and 145 angstrom. This newly synthesised biotin-LLC extends the class of highly sensitive analytical tools to be applied in the bioanalytical methods such as time-resolved fluoroimmunoassays (TR-FIA), luminescent imaging and biosensing.
Y1  - 2014
U6  - https://doi.org/10.1039/c3cp54883j
SN  - 1463-9076
SN  - 1463-9084
VL  - 16
IS  - 13
SP  - 6060
EP  - 6067
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Cywinski, Piotr J.
A1  - Olejko, Lydia
A1  - Löhmannsröben, Hans-Gerd
T1  - A time-resolved luminescent competitive assay to detect L-selectin using aptamers as recognition elements
JF  - Analytica chimica acta : an international journal devoted to all branches of analytical chemistry
N2  - L-selectin is a protein with potential importance for numerous diseases and clinical disorders. In this paper, we present a new aptamer-based luminescent assay developed to detect L-selectin. The sensing system working principle is based on Forster Resonance Energy Transfer (FRET) from a donor terbium complex (TbC) to an acceptor cyanine dye (Cy5). In the present approach, the biotinylated aptamer is combined with Cy5-labelled streptavidin (Cy5-Strep) to yield an aptamer-based acceptor construct (Apta-Cy5-Strep), while L-selectin is conjugated using luminescent TbC. Upon aptamer binding to the TbC-labelled L-selectin (L-selectin-TbC), permanent donor-acceptor proximity is established which allows for radiationless energy transfer to occur. However, when unlabelled L-selectin is added, it competes with the L-selectin-TbC and the FRET signal decreases as the L-selectin concentration increases. FRET from the TbC to Cy5 was observed with time-gated time-resolved luminescence spectroscopy. A significant change in the corrected luminescence signal was observed in the dynamic range of 10 -500 ng/mL L-selectin, the concentration range relevant for accelerated cognitive decline of Alzheimer's disease, with a limit of detection (LOD) equal to 10 ng/mL. The aptasensor-based assay is homogeneous and can be realized within one hour. Therefore, this method has the potential to become an alternative to tedious heterogeneous analytical methods, e.g. based on enzyme-linked immunosorbent assay (ELISA). (C) 2015 Elsevier B.V. All rights reserved.
KW  - Aptamer
KW  - FRET
KW  - L-selectin
KW  - Luminescence spectroscopy
KW  - Fluoroassay
KW  - Lanthanide
Y1  - 2015
U6  - https://doi.org/10.1016/j.aca.2015.06.045
SN  - 0003-2670
SN  - 1873-4324
VL  - 887
SP  - 209
EP  - 215
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Cywinski, Piotr J.
A1  - Pietraszkiewicz, Marek
A1  - Maciejczyk, Michal
A1  - Gorski, Krzysztof
A1  - Hammann, Tommy
A1  - Liermann, Konstanze
A1  - Paulke, Bernd-Reiner
A1  - Löhmannsröben, Hans-Gerd
T1  - Total protein concentration quantification using nanobeads with a new highly luminescent terbium(III) complex
JF  - RSC Advances
N2  - Total protein concentration (TPC) is a key parameter in many biochemical experiments and its quantification is often necessary for isolation, separation, and analysis of proteins. A sensitive and rapid nanobead-based TPC quantification assay based on Forster Resonance Energy Transfer (FRET) has been developed. A new, highly luminescent Tb(III) complex has been synthesised and applied as donor in this FRET assay with an organic dye (Cy5) as acceptor. FRET-induced changes in luminescence have been investigated both at donor and acceptor emission wavelength using time-resolved luminescence spectroscopy with time-gated detection. In the assay, the Tb(III) complex and fine-tuned polyglycidyl methacrylate (PGMA) nanobeads ensure that an improvement in sensitivity and background reduction is achieved. Using 40 nm large PGMA nanobeads loaded with the Tb(III) complex, it is possible to determine TPC down to 50 ng mL(-1) in just 10 minutes. Through specific assay components the sensitivity has been improved when compared to existing nanobead-based assays and to currently known commercial methods. Additionally, the assay is relatively insensitive to the presence of contaminants, such as non-ionic detergents commonly found in biological samples. Due to no need for any centrifugal steps, this mix-and-measure bioassay can easily be implemented into routine TPC quantification protocols in biochemical laboratories.
Y1  - 2016
U6  - https://doi.org/10.1039/c6ra23207h
SN  - 2046-2069
VL  - 6
SP  - 115068
EP  - 115073
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - GEN
A1  - Cywiński, Piotr J.
A1  - Nono, Katia Nchimi
A1  - Charbonnière, Loïc J.
A1  - Hammann, Tommy
A1  - Löhmannsröben, Hans-Gerd
T1  - Photophysical evaluation of a new functional terbium complex in FRET-based time-resolved homogenous fluoroassays
N2  - A new functional luminescent lanthanide complex (LLC) has been synthesized with terbium as a central lanthanide ion and biotin as a functional moiety. Unlike in typical lanthanide complexes assembled via carboxylic moieties, in the presented complex, four phosphate groups are chelating the central lanthanide ion. This special chemical assembly enhances the complex stability in phosphate buffers conventionally used in biochemistry. The complex synthesis strategy and photophysical properties are described as well as the performance in time-resolved Förster Resonance Energy Transfer (FRET) assays. In those assays, this biotin-LLC transferred energy either to acceptor organic dyes (Cy5 or AF680) labelled on streptavidin or to quantum dots (QD655 or QD705) surface-functionalised with streptavidins. The permanent spatial donor–acceptor proximity is assured through strong and stable biotin–streptavidin binding. The energy transfer is evidenced from the quenching observed in donor emission and from a decrease in donor luminescence decay, both associated with simultaneous increase in acceptor intensity and in the decay time. The dye-based assays are realised in TRIS and in PBS, whereas QD-based systems are studied in borate buffer. The delayed emission analysis allows for quantifying the recognition process and for auto-fluorescence-free detection, which is particularly relevant for application in bioanalysis. In accordance with Förster theory, Förster-radii (R0) were found to be around 60 Å for organic dyes and around 105 Å for QDs. The FRET efficiency (η) reached 80% and 25% for dye and QD acceptors, respectively. Physical donor–acceptor distances (r) have been determined in the range 45–60 Å for organic dye acceptors, while for acceptor QDs between 120 Å and 145 Å. This newly synthesised biotin-LLC extends the class of highly sensitive analytical tools to be applied in the bioanalytical methods such as time-resolved fluoroimmunoassays (TR-FIA), luminescent imaging and biosensing.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 252 
KW  - acceptors
KW  - bioanalysis
KW  - contrast agents
KW  - europium
KW  - fluoroimmunoassay
KW  - labels
KW  - lanthanide luminescence
KW  - quantum dots
KW  - resonance energy-transfer
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-95390
SP  - 6060
EP  - 6067
ER  - 
TY  - JOUR
A1  - Harma, Harri
A1  - Pihlasalo, Sari
A1  - Cywinski, Piotr J.
A1  - Mikkonen, Piia
A1  - Hammann, Tommy
A1  - Löhmannsröben, Hans-Gerd
A1  - Hanninen, Pekka
T1  - Protein quantification using resonance energy transfer between donor nanoparticles and acceptor quantum dots
JF  - Analytical chemistry
N2  - A homogeneous time-resolved luminescence resonance energy transfer (TR-LRET) assay has been developed to quantify proteins. The competitive assay is based on resonance energy transfer (RET) between two luminescent nanosized particles. Polystyrene nanoparticles loaded with Eu3+ chelates (EuNPs) act as donors, while protein-coated quantum dots (QDs), either CdSe/ZnS emitting at 655 nm (QD655-strep) or CdSeTe/ZnS with emission wavelength at 705 nm (QD705-strep), are acceptors. In the absence of analyte protein, in our case bovine serum albumin (BSA), the protein-coated QDs bind nonspecifically to the EuNPs, leading to RET. In the presence of analyte proteins, the binding of the QDs to the EuNPs is prevented and the RET signal decreases. RET from the EuNPs to the QDs was confirmed and characterized with steady-state and time-resolved luminescence spectroscopy. In accordance with the Forster theory, the approximate average donor acceptor distance is around 15 nm at RET efficiencies, equal to 15% for QD655 and 13% for QD705 acceptor, respectively. The limits of detection are below 10 ng of BSA with less than a 10% average coefficient of variation. The assay sensitivity is improved, when compared to the most sensitive commercial methods. The presented mix-and-measure method has potential to be implemented into routine protein quantification in biological laboratories.
Y1  - 2013
U6  - https://doi.org/10.1021/ac303586n
SN  - 0003-2700
VL  - 85
IS  - 5
SP  - 2921
EP  - 2926
PB  - American Chemical Society
CY  - Washington
ER  -