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Abstract: Exosomes are very small vesicles that are shed from a variety of cell types. They are present in body fluids comprising blood, urine and ascites, and they hold the potential to serve as indicators in the diagnosis, prognosis and surveillance of a variety of health conditions. In consideration of this, there is broad interest worldwide in deriving and understanding their biochemical composition. Here, small drops of solutions containing exosomes, isolated from either healthy (CCD841-CoN) or tumor (HCT116) colon cells, were manipulated using super-hydrophobic surfaces (SHSs) decorated with nano-geometry based photonics structures. SHSs are surfaces with superior properties, including a reduced friction coefficient, on account of which they can be used to control diluted solutions of biological or medical interest. The combination of this technology with optical resonance phenomena, open up terrific opportunities in the detection, analysis or characterization of biological compounds. Therefore, exosomes were conveniently concentrated and conveyed onto the Surface Enhanced Raman Spectroscopy (SERS) active areas of the substrate, whereby they were analyzed and characterized with extreme precision. Results indicate a difference in the concentration of some biological compounds, and namely: exosomes derived from healthy cells exhibit higher intensities of the peaks corresponding to lipids vibrations, while exosomes extracted from tumor cell lines exhibit a richer RNA content. [Copyright &y& Elsevier]

The detection of a few molecules in a highly diluted solution is of paramount interest in fields including biomedicine, safety and eco-pollution in relation to rare and dangerous chemicals. Nanosensors based on plasmonics are promising devices in this regard, in that they combine the features of high sensitivity, label-free detection and miniaturization. However, plasmonic-based nanosensors, in common with general sensors with sensitive areas on the scale of nanometres, cannot be used directly to detect molecules dissolved in femto- or attomolar solutions. In other words, they are diffusion-limited and their detection times become impractical at such concentrations. In this Article, we demonstrate, by combining super-hydrophobic artificial surfaces and nanoplasmonic structures, that few molecules can be localized and detected even at attomolar (10?18 mol l?1) concentration. Moreover, the detection can be combined with fluorescence and Raman spectroscopy, such that the chemical signature of the molecules can be clearly determined. [ABSTRACT FROM AUTHOR]

Abstract: Super-hydrophobic surfaces were designed and micro-fabricated. These comprise micro-pillars combined to form a regular hexagonal motif; the pillars were conveniently modified to incorporate nanoporous silicon films. Silver nanoparticles were dispersed into the pores to guarantee superior SERS (surface enhanced Raman scattering) capabilities. On account of its multiscale nature, the substrate exhibits an increased hydrophobicity and a reduced friction coefficient. This device is multiplexed in the sense that features different functions or abilities, including (i) the concentration of diluted solutions, (ii) the separation of ‘small’ molecules basing on an exclusion principle and (iii) the SERS measurement of these molecules with extreme accuracy. In consideration of the properties above, the device may be employed for investigating systematically the blood serum, and extracting from this the low molecular weight content, that discloses precious information about the ongoing status of tumors or other diseases. Here, analytes were separated and detected in the femto molar (10−15 M) range. [Copyright &y& Elsevier]

Abstract: Micro and nano-patterned devices were fabricated which disclose the possibility of concentrating, localizing, detecting and thus analyzing with unprecedented accuracy few molecules (at the limit a single molecule) of biological and medical interest. Important applications are envisioned where proteins poorly concentrated in blood are detected thus (early) revealing the appearance of diseases. The major advance of the paper is that it combines micro/nano-fabrication and spectroscopical nano-optics based techniques to study and individualize the biomolecules at study. Super hydrophobic surface would concentrate the diluted solution into a small area whereas spectroscopical nano-optics techniques would gather the molecular/chemical information of the residual solute. Fluorescence and SERS techniques were used to analyze Rhodamine molecules initially highly diluted (10−18 M). [Copyright &y& Elsevier]