Photonic crystal based immunosensor for clinical diagnosis

Transcription

1 1,4 ID: nd year of the PhD in Electronic Devices Official Tutors: Prof. M. De Vittorio 1,2,3, Ing. Tiziana Stomeo 1, Prof. Fabrizio Pirri 4, Prof. Carlo Ricciardi 4 Collaborators: A. Qualtieri 1, M. Grande 5, A. D Orazio 5, N. Voelcker 6, B. Prieto-Simon 6 1 Center for Bio-Molecular Nanotechnology, Istituto Italiano di Tecnologia (IIT), Via Barsanti, Arnesano (Lecce) Italy 2 Dipartimento di Ingegneria dell'innovazione, Università del Salento, Via Arnesano, Lecce - Italy 3 National Nanotechnology Laboratory, Istituto Nanoscienze-CNR, Via Arnesano, Lecce Italy 4 Politecnico di Torino, Scuola di Dottorato, Corso Duca degli Abruzzi n. 24, Torino - Italy 5 Dipartimento di Ingegneria Elettrica e dell'informazione, Politecnico di Bari, Via Re David, Bari - Italy 6 Mawson Institute, University of South Australia, GPO Box 2471, Adelaide, South Australia

2 Outline Attended Classes ITEM project (PONa3_00077) Research context and motivations Nanophotonics for immunosensing Addressed research questions/problems Technological optimization and experimental results Novel contributions A device for early and fast diagnosis Adopted methodologies Design Numerical Simulations Fabrication process Preliminary Experimental Results Submitted and published conference/journal papers Future work Conclusions 2

3 Attended Classes ITEM project (PONa3_00077) from 01 March 2013 to 31 December 2014 Total of academic courses: 930 hours in distance learning (From the call for the "PONa3_00077, Infrastructure Project for bio-mems Technologies for Advanced Sensing of Environmental and Food Monitoring and Diagnostics ) 3

4 Research context and motivations - Nanophotonics for immunosensing Biomarkers are measurable products of biological processes which play an important role in the diagnosing and monitoring of relevant pathologies Label-free optical immunosensors are powerful tools in the medical sensing, offering a fast and portable detection of an analyte in solution and avoiding the use of radioactive or fluorescent tags 2D photonic crystal structures are suitable as building block for the realization of innovative optical biosensors, thanks to their optical properties making them good candidate as sensitive devices Sensitive devices fabricated on free-standing membranes are characterized by a good light confinement in the vertical direction due to the high index contrast and high sensitivity to the variation of filling material refractive index The proposed immunosensor has been tested in the detection of the IL-6 protein, a biomarker related with complex diseases, such as cancer, congestive heart failure and Alzheimer s, representing a significant socioeconomic burden in ageing societies 4

5 Addressed research questions/problems Technological optimization and experimental results Main step in the design and fabrication of the photonic crystal immunosensor: Choice of a suitable structure and material Choice of geometrical parameters to have a sharp resonance peak in the visible range useful for sensing measurements Fabrication of a 1 mm x 1 mm membrane device Optimization of the fabrication process Preliminary experimental results using Interleukin-6 (IL-6) protein 5

6 Novel Contributions A device for early and fast diagnosis The sensing block of the immunosensor consists of a large PhC freestanding membrane and the signal is collected from the entire surface by means of a simple and cost-effective read-out system The immunosensor has the strong potential to become an important diagnostic component for home-based care 6

7 Adopted methodologies - Design Impinging light Antibodies For a bio-specific recognition p d Reflected light 2D-PhC on Si 3 N 4 membrane biocompatibility high refractive index good mechanical properties absence of absorption in the visible spectrum Si substrate t = 300 nm Good mechanical properties Good optical properties 7

8 Adopted methodologies Numerical simulations A systematic analysis has been performed on the geometrical parameters by means of numerical simulations to identify peaks of Fano resonance in the VIS-NIR range Numerical simulations of the reflectivity for period 460 nm and varying the radious 8

9 Adopted methodologies Fabrication process How can we get a high quality large photonic crystal membrane (1 mm 2 )? Our approach: The large membrane is composed by a series of 100 µm 100 µm square lattice PhC membranes arranged in a matrix pattern of

10 Adopted methodologies Fabrication process To realize the immunosensor a high standard fabrication protocol has been developed exploiting top-down techniques such as electron beam lithography and wet/dry etching techniques Si 3 N 4 (300nm) Si 3 N 4 (300nm) ZEP520A (400nm) Si 3 N 4 (300nm) ZEP520A (400nm) Si Si Si 1. Unprocessed sample 2. Electronic resist deposition 3. Resist exposure by e-beam lithography and development Antibodies Si 3 N 4 (300nm) Si 3 N 4 (300nm) Si 3 N 4 (300nm) Si Si Si 4. Inductively coupled plasma etching to pattern Si 3 N 4 layer 5. Wet etching to release the membrane by removing silicon under it 6. Antibodies functionalization 10

11 Adopted methodologies Fabrication process An optimazed ICP dry etching process has been used to drill round holes in Si 3 N 4 with vertical side wall and diameter equal to the simulated ones, achieving a high quality photonic crystal in membrane configuration Pl Si 3 N 4 Si 1 µm Inductively Coupled Plasma Etching Process (FIB crosssection. A previous platinum deposition is used to protect the structure surface during the FIB milling) 2 µm SEM cross-section image of a PhC Si 3 N 4 membrane after the wet etching process 4 µm SEM in-plane image of the PhC membrane fabricated with p = 460 nm and d = 230 nm 11

12 Adopted methodologies Preliminary Experimental Results The sample has been perpendicularly illuminated by means of a white light source, while the reflected light has been collected by an aspherical fiber and sent to an optical spectrometer White light source (400 nm 750 nm) Measured reflectivity for the PhC immunosensor with p460 r025 in IPA and the simulated one in Phosphate Buffer Saline (PBS) solution Optimized fabrication process Good agreement between experimental and numerical results! Preliminary test in different solutions (IPA n=1,3776 and ethanol n=1,3616) to verify the shift of the resonance peak with the refractive index of the background It works as a sensor! 12

13 Adopted methodologies Preliminary Experimental Results The biosensor has been tested to characterize the amount of the resonant frequency shift related to different concentrations of interleukin 6 protein (IL-6) in a PBS solution 3000 Air Buffer 2,2 2,0 1,8 First peak (lower ) Second peak (higher ) Relative intensity Normalised red-shift (nm) 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0, , Wavelength (nm) [IL-6] (pg/ml) Measured reflectivity for the PhC biosensors p = 460 nm r = 025*p in air and PBS before the functionalization Calibration curve of normalized red-shift vs IL-6 in buffer solution based on the displacement of the two resonant peak Test in reflectivity for the detection of IL-6 protein in order to assess its sensing performance Limit of Detection 1pg/ml 13

14 Submitted and published conference/journal papers Conferences: Poster presentation at the International School on Physics and Technologies of Matter, Otranto (Italy), September 16 20, 2013 Oral presentation at the Third Mediterranean Photonics Conference, Trani (Italy), May 7 9, 2014 Poster presentation at the FOTONICA 2014 Conference, Napoli (Italy), May 12 14, 2014 Poster presentation at the MNE 2014 Conference, Lousanne (Switzerland) September 22 26, 2014 Conference and journal papers: D. Zecca, A. Qualtieri, G. Magno, M. Grande, V. Petruzzelli, B. Prieto-Simon, A. D Orazio, M. De Vittorio, N.H. Voelcker, T. Stomeo, Photonic crystal based immunosensor for clinical diagnosis, Photonics Conference, 2014 Third Mediterranean, IEEE, pp. 1-3, 2014 D. Zecca, A. Qualtieri, T. Stomeo, M. De Vittorio, G. Magno, M. Grande, V. Petruzzelli, A. D Orazio, B. Prieto-Simon, N.H. Voelcker, 2D photonic crystal membranes for optical biosensors, Photonics Technologies, 2014 Fotonica AEIT Italian Conference on., IEEE, pp. 1-3, 2014 D. Zecca, A. Qualtieri, G. Magno, M. Grande, V. Petruzzelli, B. Prieto-Simon, A. D'Orazio, M. De Vittorio, N.H. Voelcker, T. Stomeo, Label-free Si3N4 photonic crystal based immunosensors for diagnostic applications, Photonics Journal, IEEE, 2014 ( /JPHOT ) 14

15 Future work - Conclusions Large PhC free-standing membrane is a powerful platform for realizing an immunosensor working in the visible range High standard fabrication protocol for the nano-pattern has been achieved with geometrical features comparable with those designed and simulated Test in reflectivity for the detection of IL-6 protein in order to assess its sensing performance 1pg/ml Proof-of-concept for the realization of highly sensitive immunosensors for proteins of interest in clinical diagnosis Further Developments: Test with other biomarkers of interest in clinical diagnosis Design of package and microfluidic system for real-time response 15