Voltage-tunable elastomer composites that use shape instabilities for rapid structural color changes.

Structurally colored materials can switch colors in response to external stimuli, which makes them potentially useful as colorimetric sensors, dynamic displays, and camouflage. However, their applications are limited by the angular dependence, slow response, and absence of synchronous control in time and space. In addition, out-of-plane deformation from shape instability easily occurs in photonic films, leading to inhomogeneous colors in photonic-crystal materials. To address these challenges, we combine structurally colored photonic glasses and dielectric elastomer actuators. We use an external voltage signal to tune color changes quickly (much less than 0.1 s). The photonic glassses produce colors with low angular dependence, so that their colors are homogeneous even when they become curved due to voltage-triggered instabilities (buckling or wrinkling). As proof of concept, we present a pixelated display in which segments can be independently and rapidly turned on and off. This wide-angle, instability-tolerant, color-changing platform could be used in next-generation soft and curved color displays, camouflage with both shape and color changes, and multifunctional sensors.

Performance status (PS) as a predictor of poor response to immune checkpoint inhibitors (ICI) in recurrent/metastatic head and neck cancer (RMHNSCC) patients.

BACKGROUND: Anti-PD1 checkpoint inhibitors (ICI) represent an established standard-of-care for patients with recurrent/metastatic head and neck squamous cell carcinoma (RMHNSCC). Landmark studies excluded patients with ECOG performance status (PS) ≥2; the benefit of ICI in this population is therefore unknown. METHODS: We retrospectively reviewed RMHNSCC patients who received 1+ dose of ICI at our institution between 2013 and 2019. Demographic and clinical data were obtained; the latter included objective response (ORR), toxicity, and any unplanned hospitalization (UH). Associations were explored using uni- and multivariate analysis. Overall survival (OS) was estimated using a Cox proportional hazards model; ORR, toxicity, and UH were evaluated with logistic regression. RESULTS: Of the 152 patients, 29 (19%) had an ECOG PS ≥2. Sixty-six (44%) experienced toxicity; 54 (36%) had a UH. A multivariate model for OS containing PS, smoking status, and HPV status demonstrated a strong association between ECOG ≥2 and shorter OS (p < 0.001; HR = 3.30, CI = 2.01-5.41). An association between OS and former (vs. never) smoking was also seen (p < 0.001; HR = 2.17, CI = 1.41-3.35); current smoking did not reach statistical significance. On univariate analysis, poor PS was associated with inferior ORR (p = 0.03; OR = 0.25, CI = 0.06-0.77) and increased UH (p = 0.04; OR = 2.43, CI = 1.05-5.71). There was no significant association between toxicity and any patient characteristic. CONCLUSIONS: We observed inferior OS, ORR, and rates of UH among ICI-treated RMHNSCC patients with ECOG 2/3. Our findings help frame discussion of therapeutic options in this poor-risk population.

High End-of-Life Health Care Utilization in a Contemporary Cohort of Head and Neck Cancer Patients Treated with Immune Checkpoint Inhibitors.

Background/Objective: End-of-life health care utilization (EOLHCU) is largely uncharacterized among patients with recurrent/metastatic head and neck squamous cell carcinomas (RMHNSCC), particularly now that immune checkpoint inhibitors (ICI) have been introduced to the treatment landscape. We examined this in a single-institution, retrospective study. Design/Settings: We utilized a database of deceased, ICI-treated RMHNSCC patients to obtain demographic and EOLHCU data, the latter of which included advanced care plan documentation (ACPD) and systemic therapy or emergency room (ER)/hospital/intensive care unit (ICU) admission within 30 days of death (DOD). This was compared with a cohort of deceased thoracic malignancy (TM) patients in an exploratory analysis. Multivariate analysis was performed to examine for association between patient factors (such as age, Eastern Cooperative Oncology Group (ECOG) performance status, or smoking status) and overall survival (OS); associations between the said patient factors and EOLHCU were also evaluated. This study was conducted at an academic, tertiary center in the United States. Results: The RMHNSCC patients (n = 74) were more likely to have ACPD (p < 0.01), an emergency department visit (p < 0.01), and/or hospital admission (p < 0.01) within 30 DOD relative to the TM group. There was no difference in ICU admissions, ICU deaths, or systemic therapy at end of life (EOL). The OS declined in association with ECOG performance status (PS) and smoking. No association was observed between patient factors and any EOLHCU metric. Conclusions: At our center, patients with ICI-treated RMHNSCC have higher rates of both ACPD and EOLHCU, suggesting high symptom burden and representing opportunities for further study into supportive care augmentation.

Investigating the trade-off between color saturation and angle-independence in photonic glasses.

Photonic glasses-isotropic structures with short-range correlations-can produce structural colors with little angle-dependence, making them an alternative to dyes in applications such as cosmetics, coatings, and displays. However, the low angle-dependence is often accompanied by low color saturation. To investigate how the short-range correlations affect the trade-off between saturation and angle-independence, we vary the structure factor and use a Monte Carlo model of multiple scattering to investigate the resulting optical properties. We use structure factors derived from analytical models and calculated from simulations of disordered sphere packings. We show that the trade-off is controlled by the first peak of the structure factor. It is possible to break the trade-off by tuning the width of this peak and controlling the sample thickness. Practically, this result shows that the protocol used to pack particles into a photonic glass is important to the optical properties.

Designing angle-independent structural colors using Monte Carlo simulations of multiple scattering.

Disordered nanostructures with correlations on the scale of visible wavelengths can show angle-independent structural colors. These materials could replace dyes in some applications because the color is tunable and resists photobleaching. However, designing nanostructures with a prescribed color is difficult, especially when the application-cosmetics or displays, for example-requires specific component materials. A general approach to solving this constrained design problem is modeling and optimization: Using a model that predicts the color of a given system, one optimizes the model parameters under constraints to achieve a target color. For this approach to work, the model must make accurate predictions, which is challenging because disordered nanostructures have multiple scattering. To address this challenge, we develop a Monte Carlo model that simulates multiple scattering of light in disordered arrangements of spherical particles or voids. The model produces quantitative agreement with measurements when we account for roughness on the surface of the film, particle polydispersity, and wavelength-dependent absorption in the components. Unlike discrete numerical simulations, our model is parameterized in terms of experimental variables, simplifying the connection between simulation and fabrication. To demonstrate this approach, we reproduce the color of the male mountain bluebird (Sialia currucoides) in an experimental system, using prescribed components and a microstructure that is easy to fabricate. Finally, we use the model to find the limits of angle-independent structural colors for a given system. These results enable an engineering design approach to structural color for many different applications.

Effects of multiple scattering on angle-independent structural color in disordered colloidal materials.

Disordered packings of colloidal spheres show angle-independent structural color when the particles are on the scale of the wavelength of visible light. Previous work has shown that the positions of the peaks in the reflectance spectra can be predicted accurately from a single-scattering model that accounts for the effective refractive index of the material. This agreement shows that the main color peak arises from short-range correlations between particles. However, the single-scattering model does not quantitatively reproduce the observed color: the main peak in the reflectance spectrum is much broader and the reflectance at low wavelengths is much larger than predicted by the model. We use a combination of experiment and theory to understand these features. We find that one significant contribution to the breadth of the main peak is light that is scattered, totally internally reflected from the boundary of the sample, and then scattered again. The high reflectance at low wavelengths also results from multiple scattering but can be traced to the increase in the scattering cross section of individual particles with decreasing wavelength. Both of these effects tend to reduce the saturation of the structural color, which limits the use of these materials in applications. We show that while the single-scattering model cannot reproduce the observed saturations, it can be used as a design tool to reduce the amount of multiple scattering and increase the color saturation of materials, even in the absence of absorbing components.

Solution-Processable Photonic Inks of Mie-Resonant Hollow Carbon-Silica Nanospheres.

Hollow carbon-silica nanospheres that exhibit angle-independent structural color with high saturation and minimal absorption are made. Through scattering calculations, it is shown that the structural color arises from Mie resonances that are tuned precisely by varying the thickness of the shells. Since the color does not depend on the spatial arrangement of the particles, the coloration is angle independent and vibrant in powders and liquid suspensions. These properties make hollow carbon-silica nanospheres ideal for applications, and their potential in making flexible, angle-independent films and 3D printed films is explored.

Wound Complications in Head and Neck Squamous Cell Carcinomas After Anti-PD-1 Therapy.

Immune checkpoint inhibitors have demonstrated activity in recurrent/metastatic head and neck squamous cell cancer, but less is known regarding their long-term sequelae. We describe four patients who, after complete responses to anti-PD-1 therapy, developed complications requiring surgical intervention. Patient 1 is a 57-year-old female whose marked tumor regression exposed some mandibular hardware. Patient 2 is a 39-year-old male who developed an ulcerated buccal lesion with exposed mandible. Patient 3 is a 66-year-old male with craniofacial osteoradionecrosis. Patient 4 is a 71-year-old male who developed an exposed and fractured mandible. All patients successfully underwent surgical intervention and remain disease free. Laryngoscope, 129:E428-E433, 2019.

Adsorption characteristics of charged and nonionic small molecules to colloidal alumina.

Dense fluorescent pigments used for inkjet printing of UV and IR-readable non-photobleaching security features require stabilizers to prevent aggregation/sedimentation and inkjet head clogging at high resolution. A study of small molecule adsorption to α-alumina, a model system for security pigments, is presented. Alumina is dispersed by two methods yielding different zeta potentials but identical isoelectric points. Essentially complete dispersion is obtained in water at pH 3 but aggregation occurs at pH 6 where the surface charging is lower. Adsorption studies focus on the naphthyl-phosphate, -sulfate, and hydroxyl (triethylene glycol) groups. Phosphate adsorption was strongest with a 1.2 molecules/nm2 plateau, close to the titratable exchange capacity of 1.3 OH groups/nm2 on the alumina surface with ΔHadsorption=-7.58±1.63kJ/mol determined by calorimetry. Sulfate adsorption was weaker with a more linear adsorption isotherm. The adsorption/exchange process yields a rise in pH that is correlated with the binding strength. Hydroxyl binding is weakest, being driven by hydrogen bonding, and showed no rise in pH during adsorption. A polyphosphate-poly(ethylene glycol) block copolymer is expected to be advantageous for the dispersion of such inkjet colloids.