“…Only a few recent papers have explored so far the possible applications of HNTs in photonics and spectroscopy. , Among these, the immobilization of metal nanoparticles over the external surface of HNTs results in better surface-enhanced Raman scattering, and second harmonic generation from HNTs under 800 nm femtosecond laser radiation has been recently demonstrated by Fidecka et al, paving the way to bioimaging applications . Interestingly, due to their relatively large sizes in the order of hundreds of nm, HNTs are rather strong light scatterers despite the refractive index of halloysite materials (1.54) being lower than other common scatterers such as TiO 2 (2.5–2.8).…”
Naturally occurring halloysite nanotubes (HNTs) have
attracted
significant scientific interest due to their multifunctional behavior
and biocompatibility. However, the application of HNTs in photonics
is still unexplored. Here, natural HNTs with different lengths and
diameters have been employed as passive scatterers for the generation
of random laser (RL) emission from rhodamine B (RhB) in a colloidal
phase. Upon pumping at 532 nm, mixed HNT-RhB disordered colloidal
systems are shown to yield orange RL emission with a linewidth as
small as ∼4 nm. Moreover, a statistical analysis of shot-to-shot
correlations among RL modes reveals an obvious photonic paramagnetic
to spin-glass transition with increasing pump energy, which is a unique
statistical fingerprint of RL. Interestingly, besides acting as scatterers,
the HNTs are also found to improve the photostability of RhB molecules.
Indeed, HNTs help to better dissipate the excess energy deposited
in the gain medium, thus protecting the dye from photodegradation
and facilitating the achievement of RL. The results contribute to
the theoretical understanding and technical development of low-cost
RL devices based on widely available sources in view of multiple prospective
applications in photonics.
“…Only a few recent papers have explored so far the possible applications of HNTs in photonics and spectroscopy. , Among these, the immobilization of metal nanoparticles over the external surface of HNTs results in better surface-enhanced Raman scattering, and second harmonic generation from HNTs under 800 nm femtosecond laser radiation has been recently demonstrated by Fidecka et al, paving the way to bioimaging applications . Interestingly, due to their relatively large sizes in the order of hundreds of nm, HNTs are rather strong light scatterers despite the refractive index of halloysite materials (1.54) being lower than other common scatterers such as TiO 2 (2.5–2.8).…”
Naturally occurring halloysite nanotubes (HNTs) have
attracted
significant scientific interest due to their multifunctional behavior
and biocompatibility. However, the application of HNTs in photonics
is still unexplored. Here, natural HNTs with different lengths and
diameters have been employed as passive scatterers for the generation
of random laser (RL) emission from rhodamine B (RhB) in a colloidal
phase. Upon pumping at 532 nm, mixed HNT-RhB disordered colloidal
systems are shown to yield orange RL emission with a linewidth as
small as ∼4 nm. Moreover, a statistical analysis of shot-to-shot
correlations among RL modes reveals an obvious photonic paramagnetic
to spin-glass transition with increasing pump energy, which is a unique
statistical fingerprint of RL. Interestingly, besides acting as scatterers,
the HNTs are also found to improve the photostability of RhB molecules.
Indeed, HNTs help to better dissipate the excess energy deposited
in the gain medium, thus protecting the dye from photodegradation
and facilitating the achievement of RL. The results contribute to
the theoretical understanding and technical development of low-cost
RL devices based on widely available sources in view of multiple prospective
applications in photonics.
“…The HNTs pattern not only can guide the cell growth but also can capture tumor cells from physiological medium, Figure 3 . The pattern was conjugated with anti-EpCAM, which leads to the capture yield of MCF-7 cells reaching 92% within 3 h. HNTs pattern can capture eight MCF-7 cells from 1 mL artificial blood samples with 10 cells, showing the promising applications in clinical tumor cell capture for early diagnosis and monitoring of cancer patients [ 26 ]. Figure 3.…”
Section: Halloysite Nanotube Orientation In Cell Capturing Patternsmentioning
confidence: 99%
“…Recently, these clay nanotubes were arranged in an orderly manner along the optical fiber surface to form slit-like patterned layers to enhance the interaction with tumor cells, resulting in more effective capture of the cells in real time [ 26 ]. The sensor consists of a tilted fiber Bragg grating inscribed in the fiber core and specially designed HNTs coat.…”
Section: Halloysite Nanotube Orientation In Cell Capturing Patternsmentioning
Micropatterning of biological surfaces performed via assembly of nano-blocks is an efficient design method for functional materials with complex organic–inorganic architecture. Halloysite clay nanotubes with high aspect ratios and empty lumens have attracted widespread interest for aligned biocompatible composite production. Here, we give our vision of advances in interfacial self-assembly techniques for these natural nanotubes. Highly ordered micropatterns of halloysite, such as coffee rings, regular strips, and concentric circles, can be obtained through high-temperature evaporation-induced self-assembly in a confined space and shear-force brush-induced orientation. Assembly of these clay nanotubes on biological surfaces, including the coating of human or animal hair, wool, and cotton, was generalized with the indication of common features. Halloysite-coated microfibers promise new approaches in cotton and hair dyeing, medical hemostasis, and flame-retardant tissue applications. An interfacial halloysite assembly on oil microdroplets (Pickering emulsion) and its core–shell structure (functionalization with quantum dots) was described in comparison with microfiber nanoclay coatings. In addition to being abundantly available in nature, halloysite is also biosafe, which makes its spontaneous surface micropatterning prospective for high-performance materials, and it is a promising technique with potential for an industrial scale-up.
“…(d) Spectrum and fluorescence images of cells demonstrate that HNTs assembled on optical fibers can integrate with microfluidic chips to capture and detect tumor cells. Reprinted with permission from ref . Copyright 2023 Elsevier.…”
Section: Biomedical Applicationsmentioning
confidence: 99%
“…To increase the capture speed and accurately quantify the number of tumor cells, we assembled HNTs on optical fibers and integrated them with a microfluidic chip to design a multiresonant optical fiber sensor. The sensor could quickly and sensitively distinguish between normal and tumor cells with a detection limit of 10 cells/mL (Figure d) …”
Medical mineralogy explores the interactions between natural minerals and living organisms such as cells, tissues, and organs and develops therapeutic and diagnostic applications in drug delivery, medical devices, and healthcare materials. Many minerals (especially clays) have been recognized for pharmacological activities and therapeutic potential. Halloysite clay (Chinese medicine name: Chishizhi), manifested as onedimensional aluminum silicate nanotubes (halloysite nanotubes, HNTs), has gained applications in hemostasis, wound repair, gastrointestinal diseases, tissue engineering, detection and sensing, cosmetics, and daily chemicals formulations. Various biomedical applications of HNTs are derived from hollow tubular structures, high mechanical strength, good biocompatibility, bioactivity, and unique surface characteristics. This natural nanomaterial is safe, abundantly available, and may be processed with environmentally safe green chemistry methods. This review describes the structure and physicochemical properties of HNTs relative to bioactivity. We discuss surface area, porosity and surface defects, hydrophilicity, heterogeneity and charge of external and internal surfaces, as well as biosafety. The paper provides comprehensive guidance for the development of this tubule nanoclay and its advanced biomedical applications for clinical diagnosis and therapy.
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