George TsekenisAcademy of Athens · Biomedical Research Foundation
George Tsekenis
BSc Hons, PhD
Head of Applied Biophysics and Surface Science Group, BRFAA
About
53
Publications
8,743
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Citations
Introduction
A biochemist by training, since my PhD studies I have focused on assay development along with robust, innovative surface functionalization techniques and their integration into biosensors and LoCs. I am currently heading the ABISS Group at BRFAA, which works on a variety of topics from biosensor fabrication to drug delivery and cell culturing on structured surfaces, with a special focus on aptamers and the optimization of universal surface modification techniques
Additional affiliations
January 2021 - June 2021
Position
- Senior Researcher
Description
- Development of a microfluidic biosensing device, based on aptazymes and metal nanoparticles for the detection of heavy metals in water that will be integrated into a portable IoT hardware platform
April 2020 - April 2024
Position
- Senior Researcher
Description
- NextGenMicrofluidics (H2020) - establishment of an Open Innovation Test Bed for the development and production of lab-on-a-foil systems.
March 2020 - June 2021
Position
- Senior Researcher
Description
- COMPLEX-CELLS (NSRF-funded project on a COMbinatorial aPprorach on Laser Engineered and Chemically Structured surfaces for CELL Co-culture Systems)
Education
September 2004 - September 2007
September 2001 - September 2004
Publications
Publications (53)
The emergence of the novel coronavirus, SARS-CoV-2, has highlighted the need for rapid, accurate, and point-of-care diagnostic testing. Lab-on-a-Chip (LoC) devices offer the possibility to run such tests at a low cost while at the same time permitting the multiplexed detection of several viruses when coupled with microarray detection of the amplifi...
Antibiotics are often used in human and veterinary medicine for the treatment of bacterial diseases. However, extensive use of antibiotics in agriculture can result in the contamination of common food staples such as milk. Consumption of contaminated products can cause serious illness and a rise in antibiotic resistance. Conventional methods of ant...
Enzyme-based electrochemical biosensors have been widely deployed for the detection of a range of contaminants in different food products due to their significant advantages over other (bio)sensing techniques. Nevertheless, their performance is greatly affected by the sample matrix itself or by the matrix they are presented with in pretreated sampl...
A hybrid noble nanoparticle/DNAzyme electrochemical biosensor is proposed for the detection of Pb2+, Cd2+, and Cr3+. The sensor takes advantage of a well-studied material that is known for its selective interaction with heavy metal ions (i.e., DNAzymes), which is combined with metallic nanoparticles. The double-helix structure of DNAzymes is known...
Due to rapid industrialization, novel water-quality monitoring techniques for the detection of highly toxic and hazardous heavy metal ions are essential. Herein, a hybrid noble nanoparticle/DNAzyme electrochemical biosensor is proposed for the simultaneous and label-free detection of Pb2+ and Cr3+ in aqueous solutions. The sensor is based on the co...
Immune checkpoint inhibitors (ICIs) exhibit remarkable antitumor activity and immune-related cardiotoxicity of unknown pathomechanism. The aim of the study was to investigate the ICI class-dependent cardiotoxicity in vitro and pembrolizumab’s (Pem’s) cardiotoxicity in vivo, seeking for translational prevention means. Cytotoxicity was investigated i...
![Study of the milk matrix effect. [OTC] (µg/L) ME](publication/376698133/figure/tbl1/AS:11431281213764127@1703163257774/Study-of-the-milk-matrix-effect-OTC-g-L-ME_Q320.jpg)
Introduction
Advances in oncology have led to the discovery of immune checkpoint inhibitors (ICIs) that exhibit remarkable results in cancer patients’ survival and tumour regression. Despite their antitumor potential, some life-threatening immune-related adverse effects (AEs) including cardiotoxicity have been reported, while the pathomechanism of...
To date, numerous aptamer-based biosensing platforms have been developed for sensitive and selective monitoring of target analytes, relying on analyte-induced conformational changes in the aptamer for the quantification of the analyte and the conversion of the binding event into a measurable signal. Despite the impact of these conformational rearra...
The presence of heavy metal ions in soil, air and water constitutes an important global environmental threat, as these ions accumulate throughout the food chain, contributing to the rise of chronic diseases, including, amongst others, cancer and kidney failure. To date, many efforts have been made for their detection, but there is still a need for...
In this work, a biosensor for heavy metal-ion detection, based on platinum nanoparticles (Pt NPs) and DNAzymes, is presented. Two chemical modification groups were utilized for the DNAzymes' immobilization on the Pt NPs film. The biosensors were characterized concerning their ability to detect Lead (Pb 2+) ions in buffer solutions. Both immobilizat...
Breast cancer is the most common type of cancer observed in women. Communication with the tumor microenvironment allows invading breast cancer cells, such as triple negative breast cancer cells, to adapt to specific substrates. The substrate topography modulates the cellular behavior, among other factors. A number of different materials and micro/n...
Breast cancer is the most common type of cancer observed in women. Communication with the tumor microenvironment allows invading breast cancer cells, such as triple negative breast cancer cells, to adapt to specific substrates. The substrate topography modulates the cellular behavior among other factors. Several different materials and micro/nanofa...
In this paper, we present the development of a photonic biosensor device for cancer treatment monitoring as a complementary diagnostics tool. The proposed device combines multidisciplinary concepts from the photonic, nano-biochemical, micro-fluidic and reader/packaging platforms aiming to overcome limitations related to detection reliability, sensi...
Despite the fact that a considerable amount of effort has been invested in the development of biosensors for the detection of pesticides, there is still a lack of a simple and low-cost platform that can reliably and sensitively detect their presence in real samples. Herein, an enzyme-based biosensor for the determination of both carbamate and organ...
Immunosensor sensitivity and stability depend on a number of parameters such as the orientation, the surface density, and the antigen-binding efficiency of antibodies following their immobilization onto functionalized surfaces. A number of techniques have been developed to improve the performance of an immunosensor that targets one or both of the p...
Surface bio-functionalization plays a critical role in the performance of a biosensor and numerous techniques for the enhancement of a biosensor’s surface coverage with oriented capture biomolecules have been developed with the ultimate goal of optimizing a sensor’s performance in terms of its sensitivity and linear response over a wide dynamic ran...
p>BIOFOS aims to further develop and validate a reusable and high-added value Lab-on-Chip (LoC) based, micro-biophotonic sensor platform for in situ monitoring of food contaminants. The Lab-on-Chip was tested on milk (aflatoxin M1, antibiotics and lactose), olive oil (pesticides and metals), nuts (aflatoxin B1) and dehydrated fruits (ochratoxin A)....
An impedimetric label-free aptasensor for the simultaneous and highly selective detection of two pesticides is presented. The sensor is based on the combination of self-assembled platinum nanoparticle two-dimensional films (produced in room temperature via the magnetron sputtering technique) and target specific nucleic acids (a.k.a. aptamers). The...
A novel impedimetric biosensor was developed for the detection of the two extensively used pesticides, acetamiprid and atrazine. By employing the sputtering and e-beam lithography techniques, platinum nanoparticles (Pt NPs) were deposited in a bridge-like arrangement, in between interdigitated electrodes (IDEs). The resulting Pt NP microwires were...
We extend the simulations for sensors with micro-ring resonators and FFT-based processing of the measurement data. We experimentally demonstrate a system with low Q-factor resonators and coarse scanning steps, achieving limit of detection 8.5·10-7 RIU.
We extend our previous simulation study and we present experimental results regarding our Fast Fourier Transform method for the calculation of the resonance shifts in biosensors based on micro-ring resonators (MRRs). For the simulation study, we use a system model with a tunable laser at 850 nm, an MRR with 1.5∙10⁴ quality factor, and a detection s...
Considering both cancer's serious impact on public health and the side effects of cancer treatments, strategies towards targeted cancer therapy have lately gained considerable interest. Employment of gold nanoparticles (GNPs), in combination with ionizing and non-ionizing radiations, has been shown to improve the effect of radiation treatment signi...
In this paper we present the immobilization of thiol-modified aptamers on alkyne- or alkene-terminated silicon nitride surfaces, by laser-initiated "click chemistry" reactions. The aptamers are printed onto the surface by Laser Induced Forward Transfer (LIFT), which initiates the covalent bonding of the aptamers by thiol-ene or thiol-yne reactions...
In this article novel approaches for the improvement of the recorded signal coupled with the feasibility of multiple analyte detection, irrespective of the biosensor platform are being presented. The techniques that have been developed address commonly encountered issues that have traditionally hindered the commercialization of biosensors, such as...
A novel nanoparticle based biosensor for the fast and simple detection of DNA hybridization events is presented. The sensor utilizes hybridized DNA's charge transport properties, combining them with metallic nanoparticle networks that act as nano-gapped electrodes. The DNA hybridization events can be detected by a significant reduction in the senso...
Utilizing the sputtering technique, platinum nanoparticles of 5 nm in diameter have been deposited on top of oxidized silicon substrates. The nanoparticle layer has been subsequently functionalized with DNAzymes that are known to self-cleave in the presence of lead (Pb2+) ions. The resulting device has proven to operate as an environmental monitori...
In this article novel approaches for the improvement of the recorded signal coupled with the feasibility of multiple analyte detection, irrespective of the biosensor platform are being presented. The techniques that have been developed address commonly encountered issues that have traditionally hindered the commercialization of biosensors, such as...
Heavy metal ions are major contaminants in present day water supply. In this work the fabrication and evaluation of a DNAzyme functionalized capacitive micromechanical sensor array for the detection of lead ions is presented. The catalytic strand of a “8-17” DNAzyme can cleave a substrate DNA strand that has one ribonucleotide base, in the presence...
This work presents the direct laser printing of thiol-modified oligonucleotides onto the surface of 3-glycidoxypropyltrimethoxysilane (GOPTS)-functionalized ultra-thin Low temperature oxide (LTO)/Si membranes for the fabrication of a label-free capacitive biosensor. During the hybridization of the target oligonucleotides with their immobilized comp...
Responding to an increasing demand for LoC devices to perform bioanalytical protocols for disease diagnostics, the development of an integrated LoC device consisting of a μPCR module integrated with resistive microheaters and a biosensor array for disease diagnostics is presented. The LoC is built on a Printed Circuit Board (PCB) platform, implemen...
This work presents a comparative study between two functionalization techniques, gold (Au) and 3-glycidoxypropyl-tri-methoxy silane (GOPTS) that were used to immobilize thiol-modified oligonucleotides on low temperature oxide (LTO) on silicon (Si) surfaces toward the fabrication of a micromembrane array capacitive DNA biosensor. In the effort to in...
A label-free micromechanical, capacitive type, biosensor is presented and evaluated. The sensor is integrated together with a continuous flow μPCR on a common printed circuit board (PCB) platform. In this scheme, the sensor is placed into a cavity formed on the PCB to provide the hybridization chamber, while the μPCR channel is implemented in thin...
This work presents the direct laser printing of thiol-modified oligonucleotides onto the surface of 3-glycidoxypropyltrimethoxysilane (GOPTS)-functionalized LTO on Si planar substrates and onto (GOPTS)functionalized capacitive sensor membranes. The (GOPTS)-functionalized planar LTO on Si surfaces have been used to select the optimum deposition cond...
We report the fabrication of microbiosensors by Laser Induced Forward Transfer. Two kinds of biosensors are discussed: capacitive biosensors and polyaniline amperometric biosensors. Laser fabrication allows for low-cost, maskless patterning with the potential of miniaturization.
This paper describes the construction of a labeless immunosensor for the antibiotic ciprofloxacin in milk and its interrogation using an ac impedance protocol. Commercial screen-printed carbon electrodes were used as the basis for the sensor. Polyaniline was electrodeposited onto the sensors and then utilized to immobilize a biotinylated antibody f...
This paper describes the development and characterisation of labeless immunosensors for (a) the cardiac drug digoxin and (b) bovine serum albumin (BSA). Commercial screen-printed carbon electrodes were used as the basis for the sensors. Two methods were used to immobilise antibodies at the electrode surface. Aniline was electropolymerised onto thes...
This paper describes the development and characterization of a label-less immunosensor for myelin basic protein (MBP) and its interrogation using an ac impedance protocol. Commercial screen-printed carbon electrodes were used as the basis for the sensor. Polyaniline was electrodeposited onto the sensors, and this modified surface then utilized to i...
11 pages, 6 figures. This paper describes the construction of a labeless immunosensor for the antibiotic ciprofloxacin and its interrogation using an AC impedance protocol. Commercial screen-printed carbon electrodes were used as the basis for the sensor. Polyaniline was electrodeposited onto the sensors and then utilized to immobilize a biotinylat...
Questions
Questions (3)
We have linked aminobenzoic acid dissolved in PBS 1x with SPDP (succinimidyl 3-(2-pyridyldithio)propionate) dissovled first in a small volume of DMSO (3% of the total reacton volume). We want to isolate the linked reaction product from the reactants by thin layer chromatography.
1. Do we have to perform an extractive workup first or can we apply to reaction mixture directly on TLC platess?
2. What would be the best solvent choice for elution?
Thank you
Dear all,
I have commercially available screeen printed gold (220BT) and carbon electrodes (110) by Dropsens. The reference electrode is made of silver in both of them. What is the best way to chlorinate it so as to achieve a Ag/AgCl reference electrode. I have tried the method with FeCl3 (1% solution for 1 minute). The surface did not get darker and no significant differences were observed when the 'chlorinated' electrodes were interrogated by CV in a ferri/ferro buffer (not really sure whether I should expect any differences). Do you have any other suggestions?
And further to this how different is the behaviour of the silver and silver/silver chloride as reference electrodes? Most publications state applied potentials vs Ag/AgCl. Does that mean I can still apply the same potentials with a silver reference without chlorinating it and get comparable results?
With regards to refractive indeces of organic compounds like methanol, ethanol etc how can one be certain with a great degree of accuracy (say 4th or 5th decimal point) about the refractive index of each compound? It seems that, although close, figures differ depending on the publication or database used (at the same temperature and wavelength). Any suggestions as to what the most reliable way to find this info is?
