The implementation of our acoustic methodology in real samples is a strong indicator that the method can be readily applied in routine DNA analysis. Its potential has been demonstrated in three different cases:
- Detection of an insecticide-resistant mutation in the ace-1 gene of Anopheles gambiae, the major malaria vector (Sci Rep 2013)
- Quantification of the change in the expression levels of the ABCA1 gene in the liver of mice which was induced by a synthetic ligand (Sci Rep 2013)
- Detection of 4 different mutations in BRCA1 and BRCA2 genes that could serve as a focused genetic screening test for breast cancer (Anal Meth 2013)
Our intention is to combine for the first time the detection power of our acoustic methodology with the advantages of on-chip polymerase chain reaction to develop an integrated platform for label-free DNA diagnostics. In the on-chip PCR, a reaction mixture is loaded on a microchip and is driven through different microchannels, which are constantly held at three different temperatures. This feature combined with the reduced thermal capacity of the chip leads to rapid thermal equilibrium of the PCR mixture allowing for fast thermocycling with low power consumption.
In comparison to the hours required to run a PCR with most bench-scale thermocyclers due to their high thermal mass and low heating and cooling rates, the chip-based microscale PCR can perform the job within minutes. The ultimate goal of this work is to develop a fully integrated and autonomous system for DNA analysis, where DNA amplification and detection is performed on a single platform and in a fast and label free manner. Such a system is currently under development for the detection of foodborne pathogen bacteria in milk and other samples in a total time of less than 4 hrs (as opposed to the 1-3 days normally required with current techniques). This ambitious work, funded by the EC in two follow up projects (Love Food and LoveFood2Market) is carried out in collaboration with several partners in academia (Dr A.Tserepi and Dr E.Gogolides from NCSR-Demokritos, Dr B. Depuy from Pasteur Inst. and Dr Z. Bilkova from Pardubice Un.) and industry (Jobst Technologies and Senseor).
Our ultimate goal is to develop integrated biosensing platforms that could be used directly in real human, food or environmental samples, such as blood, urine, milk, meat, soil etc. To achieve this, we are working towards the development of biocompatible surfaces that could selectively and with high sensitivity detect the amplified DNA in a complex medium. Such an example is a surface coated with the co-polymer PEG-polylysine and is used for the selective binding of amplified DNA in the presence of lysed cells, proteins and the PCR amplification medium (i.e., primers, enzymes and Triton).
Our strong interest and commitment towards the technology transfer of acoustic biosystems to clinical diagnostics is also illustrated in our involvement in the development of a platform for the detection of circulating DNAs and their mutations in blood samples. The LiqBiopSens project, also funded by the EC through a Horizon2020-Innovation program, promises the delivery of a fast, direct, real time and inexpensive instrument that has the potential to save thousands of lives through the early and accurate colorectal cancer detection.