Overview

Our work is very multidisciplinary, lying at the interface of molecular biology, biophysics, micro-engineering and nano-biotechnology. We are using acoustic wave devices as the means to study biological molecules and their interactions. We are also employing scientific curiosity and innovation. The former in order to elucidate basic biological issues such as the structure of biomolecules and its significance in biological processes or the mechanism of cells’ interaction with inorganic substrates; the latter in order to provide useful clinical and diagnostic tools for improving people’s healthcare. Currently, we are actively engaged in the technology transfer of our novel findings to commercial products through the creation of a spin-off company dedicated to biosensors and point-of-care diagnostics.

Research and medical laboratories normally rely on real-time PCR and solid phase hybridization assays to answer biological problems regarding gene expression profiling, determination of viral load in clinical samples, DNA and RNA quantification, bacterial identification, SNP genotyping and pharmaco-genomics. Both techniques are based either on non-specific or sequence-specific fluorescent reporters that generate a signal reflecting on the amount of the PCR product; detection and quantification of fluorescently labeled targets require expensive instrumentation and sophisticated algorithms in some cases. In other cases, the combination of DNA amplification with visual detection was demonstrated to be a simple and cost-effective method, but results are qualitative, which is a clear drawback for many clinical applications. In our lab, we are developing new approaches for genetic testing which retain the high sensitivity and quantitative nature of PCR combined with simple detection methodologies.

Biophysical Studies

Funding agents: Horizon2020, HFSP, FP7

A major focus of our research is the elucidation of the way by which acoustic waves interact with biological molecules attached to the device surface and specifically, the molecular mechanisms involved in the interaction processes leading to acoustic energy dissipation. In our analysis, we consider that biomolecules attached to the device surface via an anchor are subject to a surface perturbation as a result of the wave propagation in the underlying substrate. We, therefore, imagine individual biomolecules being forced to oscillation which in turn produces a drag force between the moving biomolecule and the surrounding liquid.

Cellular
Studies

Funding agents: FP7, GSRT, Ministry of Education

Despite the widespread use of biosensors with soluble analytes, limited data exist on the detection of whole cells and cell-bound membrane receptor interactions. Acoustic wave biosensors have an important advantage over optical biosensors as they can offer analysis of cell-surface interactions at the molecular level (Cell Mol Life Sci 2012). Due to the confinement of the wave close to the interface (~100 nm), the sensor can focus on the protein-protein binding that mediates cell-substrate interactions; the bulk cell mass does not affect the acoustic signal so that non-specific adsorption of cells can be distinguished from specific interactions of interest. The observed sensitivity of acoustic damping to the number of cell/surface specific bonds provides a unique sensing mechanism for investigating membrane interactions (Biophys J 2008Biosens Bioelectron 2010). Moreover, the acoustic signal change, together with a modified 3D kinetic analysis, can be used to measure detailed kinetics and derive both two-dimensional association and dissociation rate constants in a fast and simple way.

Cell adhesion of malignant cells on surfaces

Cancer is a wide spread devastating condition where tools for high precision determination of the malign phenotype of cells and metastatic potential is crucial for treatment. Cell adhesion properties are of particular interest for cancer diagnosis since they are able to reflect the progressive state of cell-matrix and cell-cell loosening interactions. We are investigating differences in cell adhesion during the interaction of benign and malignant cells on inorganic surfaces and protein-modified Au; typical proteins used to cover the surface include collagen, fibrinogen and fibronectin. Our aim is to follow acoustically cell adhesion and correlate physicochemical parameters with the degree of cancer differentiation. Recently we demonstrated the ability to screen between normal and cancer thyroid cells through comparative acoustic adhesions studies on two different surfaces (Sensing Bio-Sensing Research 2016). This work was performed in collaboration with Dr E. Anastasiadou from the BRFAA, Greece.

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Funding agents:

GSRT, FP7

Acoustic waves have a typical wavelength of few tenths of micrometers. The study of the intrinsic properties of nano-entities attached to the device surface is carried out in our lab using acoustic wave devices operating at several frequencies, i.e., from 35 to 300 MHz. In order to have spatial control of the immobilized molecules, the latter are bound through a single anchor (normally a PEG, thiol or DNA) to specific attachment points separated from each other by a certain distance. Through this single point attachment, biomolecules are presented to the surface in a suspended way as discrete particles, allowing the preservation of their native conformation. The above methodology is used for the immobilization of proteins and DNA molecules and subsequent study of dynamic changes of their conformation under well-controlled conditions.

Funding agents:

Horizon2020, FP7, GSRT

Biosensors group has extensive know-how and experience in laboratory research with acoustic wave sensors (Surface Acoustic Wave (SAW) and QCM). The Love wave biosensor, a SAW-based waveguide device originally developed by Prof. E. Gizeli (Sensor Actuat 1992, Patent WO9201931), is a system routinely used for the propagation and detection of shear acoustic waves in a frequency range of 100 to 300 MHz. Today, the lab is also using a plethora of different commercially available or home-made devices to test novel concepts on acoustic sensing and develop integrated platforms. An ongoing research interest involves the design and manufacturing of acoustic wave devices both in a single and multi-channel array format. Devices in an array format are desirable since they will require low volumes of consumables, thus, creating the potential for multiple testing. Acoustic SAW-type biochips are currently developed in collaboration with Dr JM. Friedt from Femto-ST Institute and the Franche-Comté University, France and our industrial partner Senseor, France.