Çetin Lab.

Optical Biosensing for Diagnotistics


The process of developing biosensors requires fundamental research on plasmonics so that new functionalities can be achieved that are not available with the conventional approaches. In Nanophotonics and Biodetection Systems Laboratory, we utilize nano-plasmonics to develop ultra-sensitive spectroscopy and sensing technologies for real-time, label-free and high-throughput detection and analysis of very low quantities of biomolecules. In order to achieve large sensitivities, high-quality factor plasmonic structures supporting extremely sharp spectral features with strong nearfield responses are explored. The sensing platforms utilizing these plasmonic structures allows stronger analyte-field overlap, which leads strong spectroscopy and sensing signals, easily distinguishable by detectors.

Cetin Lab

Cetin et al. Optics Express, Vol. 19, Iss. 23, pp. 22607-22618 (2011).
Cetin et al. ACS Nano, Vol. 6, No 11, pp. 9989-9995 (2012).
Yilmaz et al. ACS Nano, Vol. 8, No 5, pp. 4547-4558 (2014).


In the conventional spectrometer-based read-out schemes utilize refractive index sensing, where the presence of biomolecules is measured by monitoring spectral shifts within the optical response of the plasmonic structures. These platforms can enable analyte sensing i.e., viruses or bacteria, from biological media at clinically relevant concentrations with little to no sample preparation. Multiplexing and high-throughput capability of the biosensors can be improved via integrating large scale and highly dense plasmonic chips to imaging based platforms, i.e., CCD/CMOS cameras. These biosensors can be portable to be employed in the resource-poor settings by integrating plasmonic chip technology with lensfree telemedicine technology. This handheld design can be integrated with portable read-out-devices, e.g., a laptop or a cell-phone, which enables detection of biomolecules with a multiplexed manner in any environment lack of medical infrastructure. This system can also enable parallel detection of different biomolecules with ultra-thin layers as well as quantitative analyses of single-type biomolecules with large variety of concentrations.

Cetin Lab

Cetin et al. Light: Science & Applications, 3, e122 (2014).
Yanik et al. PNAS, 108, 11784 (2011).

We also study on vibrational spectroscopy which is an important technique allowing analysis of wide range of molecules through detecting their molecular fingerprints. Integrating nano-technology to this technique, we achieved much stronger sensing information compared to the conventional spectroscopy methods. We developed surface enhanced infra-red absorption spectroscopy (SEIRA) platforms, utilizing nano-antennas concentrating light on antenna surfaces such that molecules introduced on the same surface interacts effectively with light in the form of plasmons. Therefore, sensing information of materials with weak vibrational modes or the modes of materials with extreme low quantities can be identified.

Cetin Lab

Cetin et al. Applied Physics B, 118, 29 (2015).
Cetin et al. Advanced Optical Materials, 2, 866 (2014).
Cetin et al. Advanced Optical Materials, 4, 1274 (2016).
Cetin et al. IEEE Transactions on Nanotechnology, 11, 208 (2011).
Cetin et al. Jrl. Elect. Waves App. 29, 1686 (2015).
Aksu et al. Advanced Optical Materials, 1, 798 (2013).
Turkmen et al. Optics Express, 19, 7921 (2011).

We investigate fluidic systems integrated with plasmonic chip technology for efficient analyte-delivery, yielding ultra-fast sensor response compared to the conventional fluidic systems based on a flow-over scheme. Integrating microfluidics with plasmonic handheld technology, we also demonstrate real-time analyses of protein-protein interaction kinetics in a cost-effective and high-throughput manner. Utilizing robust algorithms, the microfluidic technology allows to monitor biomolecular binding interactions at pMolar levels.

Cetin Lab

Cetin et al. ACS Photonics, 2, 1167 (2015).
Coskun et al. Scientific Reports, 4, 6789, (2014).
Huang, et al. Lab on a Chip, 13, 4842 (2013).

Toward a new route to application of plasmonics to ultra-sensitive cancer immunotherapy, we introduced a platform for adoptive cell transfer (ACT). Cancer immunotheraphy has emerged in the last decades as an alternative treatment for cancer, especially in metastatic and advanced stages. Efficiency of ACT therapy relies on exceptional ability of T-cells to target and kill cancer cells. T-cell recognition of cancer occurs when T-cell receptor (TCR) specifically interact with the peptide major histocompatibility complex (pMHC) of antigen-presenting cells. Our technology exploits plasmonic nanohole sensors that can evaluate TCR-pMHC interaction affinity and kinetics at clonal level. Spectral variations for the plasmonic response corresponding to the stained T-cell are clearly distinct from those of non-stained ones (cells without biotinylated pMHC), due to the capture of the pMHC disassociated from T-cells. This platform could be an alternative for ex-vivo cellular analysis and an ideal candidate for adoptive ACT immunotherapy.

Cetin Lab