Bio-Inspired Nano Technologies for the Early Detection of Cancer

Treatment of cancer patients is greatly facilitated by detection of the cancer prior to metastasis;  nevertheless, the effective early detection of precancerous and neoplastic lesions remains an elusive goal. Advanced clinical cancer imaging technologies, including MRI (magnetic resonance imaging), PET (positron emission tomography), C-T (computerized tomography) scans, or medical ultrasonography, do not possess sufficient spatial resolution for early detection based on lesion anatomy and are, besides, very expensive, and thus not accessible to large scale. To date, and rather surprisingly, surgical biopsy remains the gold standard for the clinical assessment of the pathologic basis of disease, where the quality of diagnoses is still entrusted with the pathologists experience. Accurate, non-subjective, identification of malignancies may be addressed basing on their molecular expression profiles. Single, exclusive markers, or rather biomarker patterns, integrated to each other, express a high sensitivity and specifity, and may be employed to discriminate diseases and especially cancers.
Despite this understanding, a number of challenges wait to be faced before blood serum may be used as a routinely screening procedure, including the severe dilution of the peptides of interest, and the interference of abundant proteins. Nanotechnology offers a realistic tool to face these challenges. Nanotechnology is a new science concerned with the study and the fabrication of devices whose size is, in at least a dimension, comprised in the nanometer range. These systems deliver the promise of changing the way biomedical sciences are practiced, in that they feature characteristic length scales that are of the same order of magnitude of biological objects and can accordingly interact with these in a fashion that new physical/biological laws, strategies or possibilities emerge. In this research line, we pursue the integration of super-hydrophobic surfaces (SHSs) with nano geometrical bio-sensors to overcome the diffusion limit and secure unprecedented benefits to the analysis of very diluted molecules of medical interest. Super hydrophobic surfaces (SHSs) are artificial, micro- or nano- fabricated surfaces, with a texture that typically is given by a regular array of cylindrical micro pillars.
The top of pillars can be conveniently modified to incorporate features at the nano scales. In sight of a dramatically low friction coefficient, this innovative family of devices delivers the ability of manipulating biological solutions. Inspired by the lotus effect, we develop super-hydrophobic surfaces that mimic the morphology of the lotus leaf. We create such a superhydrophobic surface from arrays of silicon micropillars. We optimize the size, periodicity and aspect ratio of the pillars to enable a large contact angle and low-friction forces that are independent of the sample droplet radius. In doing so, we provide a new tool for biomolecular detection by combining super-hydrophobic and plasmonic structures to efficiently bring molecules in an ultralow-concentration droplet to a nanosensor[1-3]. The droplet evaporation time, which takes from a few seconds to several minutes depending on its size, dramatically shortens the long waiting time of hours or even days for the traditional diffusion process. The usage of the device is simple: we allow a water droplet containing the molecules of interest to evaporate and slide on the superhydrophobic surface, leaving very little solution behind.
As it evaporated, the solution becomes increasingly concentrated until the droplet finally collapses onto one of the pillars, thus confining the solute to a suspended region of a few square micrometres. This simple drop and dry scheme provides good localization and immobilization of molecules for fluorescent and Raman spectroscopic measurements. To boost the Raman signal further, a range of plasmonic structures is integrated into super-hydrophobic silicon pillars. These metal structures serve as hot spots that intensify the local electric fields and consequently enhance the Raman signal by several orders of magnitude. This concept was developed even further. Polymer based SHSs and X-ray spectroscopy were used to probe the crystal structure of proteins[4]; SH surfaces and nanoporous silicon matrices were combined to yield devices with the capability of concentrating and harvesting small molecules, where the cut-off size can be adequately controlled[5-7]. In, Limongi et collegues demonstrated that silicon nano-patterned SH devices stimulate primary neurons to build three dimensional networks[8]. We reported on the direct imaging of double stranded (ds) λ-DNA in the A conformation, obtained by combining a novel sample preparation method based on super hydrophobic DNA molecules self-aggregation process with transmission electron microscopy (TEM)[9].  

REFERENCES

1) De Angelis, F., F. Gentile, F. Mecarini, G. Das, M. Moretti, P. Candeloro, M. Coluccio, G. Cojoc, A. Accardo, C. Liberale, R. Zaccaria, G. Perozziello, L. Tirinato, A. Toma, G. Cuda, R. Cingolani, and E. Di Fabrizio, Breaking the diffusion limit with super hydrophobic delivery of few molecules to plasmonic nanofocusing structures. Nature Photonics, 2011. 5: p. 682.
2) Gentile, F., M. Coluccio, N. Coppedè, F. Mecarini, G. Das, C. Liberale, L. Tirinato, M. Leoncini, G. Perozziello, P. Candeloro, F. De Angelis, and E. Di Fabrizio, Superhydrophobic Surfaces as Smart Platforms for the Analysis of Diluted Biological Solutions. ACS Applied Materials and Interfaces, 2012. 4(6): p. 3213–3224.

3) Gentile, F., G. Das, M. Coluccio, F. Mecarini, A. Accardo, L. Tirinato, R. Tallerico, G. Cojoc, C. Liberale, P. Candeloro, P. Decuzzi, F. De Angelis, and E. Di Fabrizio, Ultra low concentrated molecular detection using super hydrophobic surface based biophotonic devices. Microelectronic Engineering, 2010. 87 p. 798-801.
4) Accardo, A., F. Gentile, F. Mecarini, F. De Angelis, M. Burghammer, E. Di Fabrizio, and C. Riekel, Ultrahydrophobic PMMA micro- and nano- textured surfaces fabricated by optical lithography and plasma etching for X-Ray diffraction studies. Microelectronic Engineering, 2011. 88 p. 1660-1663.
5) Gentile, F., A. Accardo, M. Coluccio, M. Asande, G. Cojoc, F. Mecarini, G. Das, C. Liberale, F. De Angelis, P. Candeloro, P. Decuzzi, and E. Di Fabrizio, NanoPorous- MicroPatterned- SuperHydrophobic Surfaces as Harvesting Agents For Low Molecolar Weight Molecules. Microelectronic Engineering, 2011. 88 p. 1749-1752.
6) Gentile, F., E. Battista, A. Accardo, M. Coluccio, M. Asande, G. Perozziello, G. Das, C. Liberale, F. De Angelis, P. Candeloro, P. Decuzzi, and E. Di Fabrizio, Fractal Structure Can Explain the Increased Hydrophobicity of NanoPorous Silicon Films. Microelectronic Engineering, 2011. 88: p. 2537-2540.
7) Gentile, F., M. Coluccio, A. Accardo, G. Marinaro, E. Rondanina, S. Santoriello, S. Marras, G. Das, L. Tirinato, G. Perozziello, F. De Angelis, C. Dorigoni, P. Candeloro, and E. Di Fabrizio, Tailored Ag nanoparticles/nanoporous superhydrophobic surfaces hybrid devices for the detection of single molecule. Microelectronic Engineering, 2012. 97: p. 349–352.
8) Limongi, T., F. Cesca, F. Gentile, R. Marotta, R. Ruffilli, A. Barberis, M.D. Maschio, E.M. Petrini, S. Santoriello, F. Benfenati, and E. Di Fabrizio, Nanostructured Superhydrophobic Substrates Trigger the Development of 3D Neuronal Networks. Small, 2013. 9(3): p. 402–412.
9) Gentile, F., M. Moretti, T. Limongi, A. Falqui, G. Bertoni, A. Scarpellini, S. Santoriello, L. Maragliano, R.P. Zaccaria, and E. Di Fabrizio, Direct Imaging of DNA Fibers: The Visage of Double Helix. Nano Letters, 2012. 12: p. 6453−6458.