Surface enhanced Raman spectroscopy (SERS) and spatial characterization of quartz-bound Au nanoparticle substrates
has been used to assist the improvement of analytical sensitivity and limits of detection. SERS enhancement is
significantly affected not only by a substrate's surface morphology but also laser-analyte orientation as well as matrix
effects caused by non-analyte and non-metal substrate compounds. The use of Au hydrosols to fabricate better
performing SERS substrates to detect chemical and/or biological agents has been an area of active and widespread
research, but to date, the impact of matrix effects from spectral interferers introduced during fabrication on analytical
sensitivity and limits of detection is not well understood. Experiments varying the depth of collection (observation)
volume with respect to R6G on the substrate show high variability in analyte signal to noise ratios (S/N) well as high
variability in background due to matrix effects from varying influences of the substrate non-metal components. Of the
many post-fabrication design factors affecting SERS substrate sensitivity, characterization of matrix effects caused by
vertical changes in observation volume near the analyte-substrate interface will improve analytical sensitivity and limits
of detection.
Visible extinction and Surface Enhanced Raman Scattering (SERS) spectra using quartz-bound Au nanoparticle substrates are used to identify substrate production-related sources of spectral variability. Hydrosol Au nanoparticle size distributions are known to affect SERS enhancement, but the effect of spatial orientation and nanoparticle physiosorption during substrate preparation on spectral reproducibility and performance are not well understood. Experiments varying quartz slide orientation and Au nanoparticle delivery method show significant concentrationgradient and physiosorption-related aggregation effects in the substrate extinction spectra and SERS spectra of R6G applied to spatially mapped substrate regions. Additionally, applying multiple Au hydrosol treatments to functionalized quartz substrates reveals interesting relationships between Au nanoparticle thickness and substrate extinction and SERS spectra. Of the many factors affecting substrate spectral reproducibility, minimizing concentration gradients and optimizing the rate of Au nanoparticle-quartz physiosorption allow improvements in SERS active substrate spectral reproducibility.
This research reviews common implant materials and suggests smart materials that may be used as substitutes. Current prosthetic technology, including artificial limbs, joints, and soft and hard tissue, falls short in comprehensive characterization of the chemo-mechanics and materials relationships of the natural tissues and their prosthetic materials counterparts. Many of these unknown chemo-mechanical properties in natural tissue systems maintain cooperative function that allows for optimum efficiency in performance and healing. Traditional prosthetic devices have not taken into account the naturally occurring electro-chemo-mechanical stress- strain relationships that normally exist in a tissue system. Direct mechanical deformation of tissue and cell membrane as a possible use of smart materials may lead to improved prosthetic devices once the mechanosensory systems in living tissues are identified and understood. Smart materials may aid in avoiding interfacial atrophy which is a common cause of prosthetic failure. Finally, we note that advanced composite materials have not received sufficient attention, they should be more widely used in prosthetics. Their structural efficiency allows design and construction of truly efficient bionic devices.
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