Recent Advances of the Polymer Micro/Nanofiber Fluorescence Waveguide

Highly fluorescent hybrid nanofibers as potential nanofibrous scaffolds for studying cell-fiber interactions

In this study, we report on the fabrication of hybrid nanofibers for labeling and bioimaging applications. Our approach is involved for developing highly fluorescent nanofibers using a blend of polylactic acid, polyethyleneglycol, and perylenediimide dyes, through the solution blow spinning technique. The nanofibers are exhibited diameters ranging from 330 nm to 420 nm. Nanofibers showed excellent red and near-infrared fluorescence emissive properties in fluorescent spectroscopy. Moreover, the strong two-photon absorption phenomenon was observed for nanofibers under confocal microscopy. To assess the applicability of these fluorescent nanofibers in bioimaging settings, we employ two types of mammalian cells B16F1 melanoma cells and J774.A1 macrophages. Both cell types exhibit negligible cytotoxicity after 24 h incubation with the nanofibers, indicating the suitability of nanofibers for cell-based experiments. We also observe strong interactions between the nanofibers and cells, as evidenced by two major events: a) the acquisition of an elongated cellular morphology with the major cellular axis parallel to the nanofibers and b) the accumulation of actin filaments along the points of contact of the cells with the fibers. Our findings demonstrate the suitability of these newly developed fluorescent nanofibers in cell-based applications for guiding cellular behavior. We expect that these fluorescent nanofibers have the potential to serve as scaffold materials for long-time tracking of cell-fiber interactions in fluorescence microscopy.

Enhancing Photoluminescence Intensity and Spectral Bandwidth of Hybrid Nanofiber/Thin-Film Multilayer Tm3+-Doped SiO2-HfO2

Multilayering of optical thin films is widely used for a range of purposes in photonic technology, but the development of nanofiber structures that can outperform thin films and nanoparticles in optical applications cannot simply be disregarded. Hybrid structures composed of Tm³⁺-doped SiO₂-HfO₂ in the form of nanofibers (NFs) and thin films (TFs) are deposited on a single substrate using the electrospinning and dip-coating methods, respectively. Ultrafine nanofiber strands with a diameter of 10-60 nm were fabricated in both single and multilayer samples. Enhanced photoluminescence emission intensity of about 10 times was attained at wavelengths of around 457, 512 and 634 nm under an excitation of 350 nm for NF-TF-NF* hybrid structures when compared with single-layered NF and TF structures. The arrangement of nanofibers and thin films in a multilayer structure influenced the luminescence intensity and spectral bandwidth. High transparency in the range of 75-95% transparency across the wavelength of 200-2000 nm was achieved, making it ideal for photonic application. Theoretical findings obtained through IMD software were compared with experimental results, and they were found to be in good agreement.

Single Polylactic Acid Nanowire for Highly Sensitive and Multifunctional Optical Biosensing

Nanowire-based optical biosensors with high sensitivity are highly desired for the detection of biological microenvironments and analysis of cellular processes. However, the current nanowire biosensors are mostly fabricated with metal and semiconductor materials, which are not suitable for long-term use in biological environments due to their incompatible and nondegradable properties. Biosensors based on biofriendly materials (e.g., spider silk) often do not have high enough sensitivity due to high losses or micron sizes. Here, polylactic acid (PLA), a polymer with high optical transparency, good biocompatibility, biodegradability, and flexibility, is used to fabricate nanowires using a directly drawing method for the first time. Because of the strong evanescent wave and abundant carboxyl groups on the surface of nanowires, an ultralow concentration sensing of cytochrome c is achieved with a limit of detection of 1.38 × 10^-17 M, which is much lower than other detection results using semiconductor/metal-based nanosensors (10^-6 to 10^-12 M). On this basis, a label-free and real-time monitoring of cell apoptosis is realized. In addition, by doping quantum dots, the functionalized PLA nanowires can also sense a change in pH. These results are suggestive of the potential for PLA nanowires applied in multifunctional biosensing and biodetection, pushing forward the photomedicine field.

Teleproctoring for Neurovascular Procedures: Demonstration of Concept Using Optical See-Through Head-Mounted Display, Interactive Mixed Reality, and Virtual Space Sharing-A Critical Need Highlighted by the COVID-19 Pandemic

BACKGROUND AND PURPOSE

Physician training and onsite proctoring are critical for safely introducing new biomedical devices, a process that has been disrupted by the pandemic. A teleproctoring concept using optical see-through head-mounted displays with a proctor's ability to see and, more important, virtually interact in the operator's visual field is presented.

MATERIALS AND METHODS

Test conditions were created for simulated proctoring using a bifurcation aneurysm flow model for WEB device deployment. The operator in the angiography suite wore a Magic Leap-1 optical see-through head-mounted display to livestream his or her FOV to a proctor's computer in an adjacent building. A Web-based application (Spatial) was used for the proctor to virtually interact in the operator's visual space. Tested elements included the quality of the livestream, communication, and the proctor's ability to interact in the operator's environment using mixed reality. A hotspot and a Wi-Fi-based network were tested.

RESULTS

The operator successfully livestreamed the angiography room environment and his FOV of the monitor to the remotely located proctor. The proctor communicated and guided the operator through the procedure over the optical see-through head-mounted displays, a process that was repeated several times. The proctor used mixed reality and virtual space sharing to successfully project images, annotations, and data in the operator's FOV for highlighting any device or procedural aspects. The livestream latency was 0.71 (SD, 0.03) seconds for Wi-Fi and 0.86 (SD, 0.3) seconds for the hotspot (P = .02). The livestream quality was subjectively better over the Wi-Fi.

CONCLUSIONS

New technologies using head-mounted displays and virtual space sharing could offer solutions applicable to remote proctoring in the neurointerventional space.

Intelligent Polymers, Fibers and Applications

Intelligent materials, also known as smart materials, are capable of reacting to various external stimuli or environmental changes by rearranging their structure at a molecular level and adapting functionality accordingly. The initial concept of the intelligence of a material originated from the natural biological system, following the sensing–reacting–learning mechanism. The dynamic and adaptive nature, along with the immediate responsiveness, of the polymer- and fiber-based smart materials have increased their global demand in both academia and industry. In this manuscript, the most recent progress in smart materials with various features is reviewed with a focus on their applications in diverse fields. Moreover, their performance and working mechanisms, based on different physical, chemical and biological stimuli, such as temperature, electric and magnetic field, deformation, pH and enzymes, are summarized. Finally, the study is concluded by highlighting the existing challenges and future opportunities in the field of intelligent materials.

Nano-Micro Dimensional Structures of Fiber-Shaped Luminous Halide Perovskite Composites for Photonic and Optoelectronic Applications

Perovskite nanomaterials have been revealed as highly luminescent structures regarding their dimensional confinement. In particular, their promising potential lies behind remarkable luminescent properties, including color tunability, high photoluminescence quantum yield, and the narrow emission band of halide perovskite (HP) nanostructures for optoelectronic and photonic applications such as lightning and displaying operations. However, HP nanomaterials possess such drawbacks, including oxygen, moisture, temperature, or UV lights, which limit their practical applications. Recently, HP-containing polymer composite fibers have gained much attention owing to the spatial distribution and alignment of HPs with high mechanical strength and ambient stability in addition to their remarkable optical properties comparable to that of nanocrystals. In this review, the fabrication methods for preparing nano-microdimensional HP composite fiber structures are described. Various advantages of the luminescent composite nanofibers are also described, followed by their applications for photonic and optoelectronic devices including sensors, polarizers, waveguides, lasers, light-down converters, light-emitting diode operations, etc. Finally, future directions and remaining challenges of HP-based nanofibers are presented.

The Relationships between the Working Fluids, Process Characteristics and Products from the Modified Coaxial Electrospinning of Zein

The accurate prediction and manipulation of nanoscale product sizes is a major challenge in material processing. In this investigation, two process characteristics were explored during the modified coaxial electrospinning of zein, with the aim of understanding how this impacts the products formed. The characteristics studied were the spreading angle at the unstable region (θ) and the length of the straight fluid jet (L). An electrospinnable zein core solution was prepared and processed with a sheath comprising ethanolic solutions of LiCl. The width of the zein nanoribbons formed (W) was found to be more closely correlated with the spreading angle and straight fluid jet length than with the experimental parameters (the electrolyte concentrations and conductivity of the shell fluids). Linear equations W = 546.44L - 666.04 and W = 2255.3θ - 22.7 could be developed with correlation coefficients of Rwl2 = 0.9845 and Rwθ2 = 0.9924, respectively. These highly linear relationships reveal that the process characteristics can be very useful tools for both predicting the quality of the electrospun products, and manipulating their sizes for functional applications. This arises because any changes in the experimental parameters would have an influence on both the process characteristics and the solid products' properties.

Light waveguiding in bioinspired peptide nanostructures

Basic optical properties of bioinspired peptide nanostructures are deeply modified by thermally mediated refolding of peptide secondary structure from α-helical to β-sheet. This conformational transition is followed by the appearance in the β-sheet structures of a wideband optical absorption and fluorescence in the visible region. We demonstrate that a new biophotonic effect of optical waveguiding recently observed in peptide/protein nanoensembles is a structure-sensitive bimodal phenomenon. In the primary α-helical structure input, light propagates via optical transmission window demonstrating conventional passive waveguiding, based on classical optics. In the β-sheet structure, fluorescent (active) light waveguiding is revealed. The latter can be attributed to completely different physical mechanism of exciton-polariton propagation, characterized by high effective refractive index, and can be observed in nanoscale fibers below diffraction limit. It has been shown that peptide material requirements for passive and active waveguiding are dissimilar. Original biocompatibility and biodegradability indicate high potential future applications of these bioinspired waveguiding materials in precise photobiomedicine towards advanced highly selective bioimaging, photon diagnostics, and optogenetics.