Optical nano-printing provides a versatile platform to print various nanoparticles into arbitrary configurations. Optical printing, the use of light to direct the formation of a desired structure, has been of significant interest in the last two decades. For particles much smaller than the laser wavelength, optical forces can be well described in the dipole approximation. For a focused laser beam, two main optical force components are identified: the gradient force, which attracts particles toward the high-intensity focal spot, and the scattering force, which tends to push particles along the beam propagation direction. When the wavelength light is close to the particle localized surface plasmons resonance, a scattering force is dominant and can be used to efficiently push nanoparticles along the beam optical axis onto a substrate. In this context, optical forces can be applied to optically print nanoparticles into patterns aggregated on surfaces such as glass. Here, we report on use optical nanoprinting of plasmonic nanoparticles to create an active aggregate in a solution containing dyes or nanoplastics. The active aggregate, produced by optical forces, serves as a sensitive sensor which is used to detect dyes in concentrations below the limit of detection for Raman spectroscopy and/or to detection of plastic nanoparticles.
We report on the development of a set of Raman based techniques to monitor a large variety of biological and chemical analytes, such as various microorganisms, gels of hyaluronic acid and selected halogenated hydrocarbons using Raman spectroscopy, Raman tweezers and surface-enhanced Raman spectroscopy (SERS). We analyzed individual microbial cells with Raman tweezers to provide solutions for fast and label-free identification of specific bacterial or yeast species. We designed an optofluidic SERS platform for quantification of sub-millimolar concentrations of halogenated environmental pollutants such as 1,2,3-trichloropropane and chloroform. We also examined the gel structure of hyaluronic acid by Raman spectroscopy.
We developed an optofluidic device containing a nanostructured substrate for surface enhanced Raman spectroscopy (SERS). The device is based on a silicon chip, on which structures were fabricated using electron lithography and wet etching to achieve a pattern of inverted pyramids on the surface, which was then covered by gold layer of defined thickness and roughness. The geometry of the surface allows localized plasmon oscillations to give rise to the SERS effect, in which the Raman spectral lines are intensified by the interaction of the plasmonic field with the electrons in the molecular bonds. The SERS substrate was enclosed in a microfluidic system from silicone polymer and glass, which allowed transport and precise mixing of fluids entering the chip, while preventing contamination or abrasion of the highly sensitive substrate. We used this device as a platform for quantitative detection of halogenated hydrocarbons such as 1,2,3-trichloropropane (TCP) in water in submillimolar concentrations. TCP is used in industry and it is a persistent environmental pollutant. The presented sensor allows fast and simple quantification of such molecules and it could contribute to environmental monitoring disciplines as well as enzymologic experiments with genetically engineered dehalogenases, which are potentially useful for bioremediation. This research is supported by Czech Science Foundation (CSF) 16-07965S, infrastructure was supported by MEYS (LO1212, LM2015055) and EC (CZ.1.05/2.1.00/01.0017).
Optofluidics, a research discipline combining optics and microfluidics, currently aspires to revolutionize the analysis of biological and chemical samples, e.g. for medicine, pharmacology, or molecular biology. In order to detect low concentrations of analytes in water, we have developed an optofluidic device containing a nanostructured substrate for surface enhanced Raman spectroscopy (SERS). The geometry of the gold surface allows localized plasmon oscillations to give rise to the SERS effect, in which the Raman spectral lines are intensified by the interaction of the plasmonic field with the electrons in the molecular bonds. The SERS substrate was enclosed in a microfluidic system, which allowed transport and precise mixing of the analyzed fluids, while preventing contamination or abrasion of the highly sensitive substrate. To illustrate its practical use, we employed the device for quantitative detection of persistent environmental pollutant 1,2,3-trichloropropane in water in submillimolar concentrations. The developed sensor allows fast and simple quantification of halogenated compounds and it will contribute towards the environmental monitoring and enzymology experiments with engineered haloalkane dehalogenase enzymes.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.