In this Feature Article, we examine recent advances in chemical analyte detection and optical imaging applications using gold and silver nanoparticles, with a primary focus on our own work. Noble metal nanoparticles have exciting physical and chemical properties that are entirely different from the bulk. For chemical sensing and imaging, the optical properties of metallic nanoparticles provide a wide range of opportunities, all of which ultimately arise from the collective oscillations of conduction band electrons ("plasmons") in response to external electromagnetic radiation. Nanorods have multiple plasmon bands compared to nanospheres. We identify four optical sensing and imaging modalities for metallic nanoparticles: (1) aggregation-dependent shifts in plasmon frequency; (2) local refractive index-dependent shifts in plasmon frequency; (3) inelastic (surface-enhanced Raman) light scattering; and (4) elastic (Rayleigh) light scattering. The surface chemistry of the nanoparticles must be tunable to create chemical specificity, and is a key requirement for successful sensing and imaging platforms.

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Background: Crowdsourcing is increasingly being used in medical research to obtain the opinion of laypeople. The investigators hypothesized that a layperson’s perception of a primary maxillary deficiency (PMD) dentofacial deformity (DFD) patient is more favorable after orthognathic surgery with regard to perceived personality traits and emotional facial expressions. Methods: The investigators implemented a survey, distributed through Amazon.com’s Mechanical Turk crowdsourcing platform, to compare 6 perceived personality traits and 6 perceived emotional traits before and >6 months after orthognathic surgery in subjects through standardized facial photographs. The sample was composed of 20 subjects randomly selected from a PMD DFD database, treated by 1 surgeon all having undergone bimaxillary and chin orthognathic surgery. The outcome variable was change in each of 6 perceived personality and 6 emotional expression traits studied. Descriptive and bivariate statistics were computed. P -value of <0.05 was considered significant. Results: Five hundred respondents (raters) completed the survey. A majority of respondent raters were male (59%) and White (71%), ranging in age between 25 and 34 years (52%). After bimaxillary and chin orthognathic surgery, PMD subjects as a group were perceived to be significantly more dominant, more trustworthy, more friendly, more intelligent, more attractive, and less threatening. They were also perceived as happier and less angry, less surprised, less sad, less afraid, and less disgusted than before surgery ( P < 0.05). Conclusions: We confirmed that laypeople consistently report positive changes in a PMD DFD subject’s perceived personality traits and perceived emotional expressions after bimaxillary and chin orthognathic surgery.

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