Full-Color "Off-On" Thermochromic Fluorescent Fibers for Customizable Smart Wearable Displays in Personal Health Monitoring.

Responsive thermochromic fiber materials capable of miniaturization and integrating comfortably and compliantly onto the soft and dynamically deforming human body are promising materials for visualized personal health monitoring. However, their development is hindered by monotonous colors, low-contrast color changes, and poor reversibility. Herein, full-color "off-on" thermochromic fluorescent fibers are prepared based on self-crystallinity phase change and Förster resonance energy transfer for long-term and passive body-temperature monitoring, especially for various personalized customization purposes. The off-on switching luminescence characteristic is derived from the reversible conversion of the dispersion state and fluorescent emission by fluorophores and quencher molecules, which are embedded in the matrix of a phase-change material, during the crystallizing/melting processes. The achievement of full-color fluorescence is attributed to the large modulation range of fluorescence colors according to primary color additive theory. These thermochromic fluorescent fibers exhibit good mechanical properties, fluorescent emission contrast, and reversibility, showing their great potential in flexible smart display devices. Moreover, the response temperature of the thermochromic fibers is controllable by adjusting the phase-change material, enabling body-temperature-triggered luminescence; this property highlights their potential for human body-temperature monitoring and personalized customization. This work presents a new strategy for designing and exploring flexible sensors with higher comprehensive performances.

Electro-Thermochromic Luminescent Fibers Controlled by Self-Crystallinity Phase Change for Advanced Smart Textiles.

Smart textiles with tunable luminescence have received special attention due to their great potential in various advanced photonic applications. Particularly, the development of one-dimensional, on-demand, responsive fluorescence fibers with excellent adaptability is of great significance. Herein, we propose electro-thermochromic fluorescence fibers regulated by a self-crystallinity phase change; that is, their tunable luminescence properties are derived from the reversible conversion of the dispersion state and fluorescence emission of fluorophore molecules during the crystallization/melting processes of phase-change materials. First results obtained with an alginate wet-spinning system demonstrate that the self-crystallinity phase change can produce polymeric fibers with thermochromic fluorescence behavior, which are prepared using microemulsion particles containing a phase-change fatty acid and coumarin fluorescent dyes. These thermochromic fluorescence fibers possess a fast response speed, high emission contrast, and good reversibility (>100 cycles). Particularly, the thermochromic fluorescent fibers can gain an electrotriggered capability by means of electric heating materials, and their great potential in precision operation applications is demonstrated. It is easy to adjust the switching point of the electro-thermochromic fluorescence fibers, highlighting their potential use in a diverse range of applications, the designs of which can be personalized. This work offers a simple yet versatile strategy for constructing electro-thermochromic fluorescence fibers for advanced smart textiles.

Tailoring Broad-Band-Absorbed Thermoplasmonic 1D Nanochains for Smart Windows with Adaptive Solar Modulation.

Controlling solar transmission through windows promises to reduce building energy consumption. A new smart window for adaptive solar modulation is presented in this work proposing the combination of the photothermal one-dimensional (1D) Au nanochains and thermochromic hydrogel. In this adaptive solar modulation system, the Au nanochains act as photoresponsive nanoheaters to stimulate the optical switching of the thermochromic hydrogel. By carefully adjusting the electrostatic interactions between nanoparticles, different chain morphologies and plateau-like broad-band absorption in the NIR region are achieved. Such broad-band-absorbed 1D nanochains possess excellent thermoplasmonic effect and enable the solar modulation with compelling features of improved NIR light shielding, high initial visible transmittance, and fast response speed. The designed smart window based on 1D Au nanochains is capable of shielding 94.1% of the solar irradiation from 300 to 2500 nm and permitting 71.2% of visible light before the optical switching for indoor visual comfort. In addition, outdoor cooling tests in model house under continuous natural solar irradiation reveal the remarkable passive cooling performance up to ∼7.8 °C for the smart window based on 1D Au nanochains, showing its potential in the practical application of building energy saving.

Construction of a high fidelity epidermis-on-a-chip for scalable in vitro irritation evaluation.

3D skin equivalents have been increasingly used in the pharmaceutical and cosmetic industries, but the troublesome operation procedure and low throughput restricted their applications as in vitro safety evaluation models. Organ-on-a-chip, an emerging powerful tool in tissue/organ modeling, could be utilized to improve the function of the skin model compared with that of traditional static skin models, as well as innovate an automatic and modular way for construction or detection. In this research, we grew and differentiated human keratinocytes within a microfluidic chip to construct an integrated epidermis-on-a-chip (iEOC) system, which is specially designed to integrate multi-culture units with integrated bubble removal structures as well as trans-epithelial electrical resistance (TEER) electrodes for barrier function detection in situ. After 14 days of culture at the air-liquid interface (ALI), the constructed epidermis-on-a-chip demonstrated histological features similar to those observed in normal human epidermis: a proliferating basal layer and differentiating spinous, granular, and cornified layers, especially the TEER value reached 3 kΩ cm2 and prevented more than 99% of Cascade Blue-607 Da permeation owing to the enhanced barrier function. Further immunofluorescence analysis also indicated typical keratin expression including keratin-14, keratin-10, loricrin, involucrin, and filaggrin. With the TEER monitoring integration in the chip, it could be convenient for scale-up high-quality epidermis-on-chip fabrication and correlated investigation. Additionally, the iEOC can distinguish all the 10 known toxins and non-toxins in irritation measurement by MTT assay, which is consistent with animal testing according to the OECD. Preliminarily detection of irritation responses like inflammatory cytokines also predicted different irritation reactions. This high fidelity epidermis-on-a-chip could be a potential alternative in in vitro skin irritation evaluation. This microchip and automated microfluidic systems also pave the way for scalable testing in multidisciplinary industrial applications.

Development and characterization of antioxidant active packaging and intelligent Al3+-sensing films based on carboxymethyl chitosan and quercetin.

Different amounts of quercetin were mixed with carboxymethyl chitosan (CMCS) to develop novel antioxidant active packaging and intelligent Al3+-sensing films. The physical properties, structure, antioxidant and Al3+-sensing abilities of CMCS-quercetin composite films were investigated. Results showed CMCS-quercetin composite films presented a dark yellowish color. When compared with CMCS film, CMCS-quercetin composite films containing 5 and 7.5 wt% of quercetin on CMCS basis exhibited higher thicknesses, opacity and thermal stability; however, presented lower moisture contents, UV-vis light transmittance and elongation at break. Besides, the incorporation of quercetin could not significantly change the water solubility and water vapor barrier property of CMCS film. Morphological observation showed the surface of CMCS-quercetin composite film became coarse when 7.5 wt% of quercetin was incorporated. Infrared spectra and X-ray diffraction patterns of CMCS-quercetin composite films further indicated quercetin was compatible with CMCS. Importantly, CMCS-quercetin composite films could sustainably release antioxidant ability into aqueous and fatty food stimulants. Moreover, CMCS-quercetin composite films were sensitive to Al3+. The color and UV-vis absorption patterns of CMCS-quercetin composite films were changed by the addition of Al3+. Results suggested that CMCS-quercetin composite films could be used as novel antioxidant and intelligent Al3+-sensing materials in food packaging.

Structural and physicochemical properties of chemically modified Chinese water chestnut [Eleocharis dulcis (Burm. f.) Trin. ex Hensch] starches.

Chinese water chestnut [Eleocharis dulcis (Burm.f.) Trin. ex Hensch] is a starch-rich aquatic plant widely consumed throughout the oriental countries. In this study, different chemically modified Chinese water chestnut starches including acetylated starch (AS), succinylated starch (SS) and carboxymethylated starch (CMS) were prepared. The structural and physicochemical properties of native starch and chemically modified Chinese water chestnut starches were compared for the first time. The degrees of substitution for AS, SS and CMS were 0.087, 0.575 and 0.972, respectively. Results of powder X-ray diffractometry, small-angle X-ray scattering and scanning electron microscopy indicated the crystalline regions and morphology of native starch were destroyed by chemical modification. Notably, carboxymethylation completely destroyed the original morphology of native starch and thus CMS exhibited an amorphous state. Besides, AS and SS showed significantly lower gelatinization properties than native starch. The thermal stability decreased in the order of CMS > AS > native starch > SS, whereas viscoelastic properties decreased in the order of SS > CMS > native starch > AS pastes. Notably, CMS exhibited the highest swelling power, solubility, paste clarity and resistant starch content, implying CMS might have wide applications in food industry.

Comparison of the structural characterization and physicochemical properties of starches from seven purple sweet potato varieties cultivated in China.

In this study, the structural characterization and physicochemical properties of starches from seven purple sweet potato varieties (Fuzi No. 1, Guang No. 161, Jihei No. 1, Ningzi No. 1, Ningzi No. 2, Xuzi No. 6 and Xuzi No. 8) cultivated in China were compared. Starch granules of purple sweet potatoes all exhibited round, polygonal and hemispherical shapes with granule sizes ranging from 4.3 to 23.6 µm. X-ray powder diffraction patterns and 13C nuclear magnetic resonance spectra revealed purple sweet potato starches were CA-type with relative crystallinity varying from 34.0% to 37.3%. Small-angle X-ray scattering spectra indicated the lamellar repeat distances of starch granules were in the range of 9.962-10.137 nm. Ratios of 1045/1022 cm-1 and 1022/995 cm-1 of Fourier transform infrared spectra varied in the range of 0.689-0.887 and 0.850-0.974, respectively. Amylose contents of purple sweet potato starches differed from 18.2 to 27.2%. Purple sweet potato starches exhibited different gelatinization properties but similar thermal stability. Moreover, resistant starch contents varied from 29.25% to 43.50%. Our study indicated the granule size, relative crystallinity, the degree of short-range order, amylose content, gelatinization property and in vitro digestibility of purple sweet potato starches were greatly influenced by the variety of purple sweet potato.

Recent advances in flavonoid-grafted polysaccharides: Synthesis, structural characterization, bioactivities and potential applications.

Plant derived flavonoids have been demonstrated to possess many valuable biological functions. In recent years, flavonoids have been successfully conjugated with polysaccharides through different graft copolymerization methods including chemical coupling, enzyme catalysis, free radical mediated grafting, and acid catalyzed condensation reactions. The successful grafting of flavonoids onto polysaccharides can be confirmed by several instrumental methods. The conjugation of flavonoids can significantly improve the antioxidant, antimicrobial, antitumor, hepatoprotective and enzyme inhibition properties of polysaccharides. Moreover, the applications of polysaccharides in food and pharmaceutical industries can be greatly broadened by grafting with flavonoids. Flavonoid-grafted polysaccharides can be developed as films for active packaging, hydrogels for controlled drug release, micelles for oral drug delivery, and emulsions for nutraceutical delivery. In general, the bioactivities and applications of conjugates are closely related to the type of flavonoid grafted, the grafting method used as well as the grafting efficiency. Recent advances in the synthesis, structural characterization, bioactivities and potential applications of flavonoid-grafted polysaccharides are summarized in this review.

Preparation, characterization, digestibility and antioxidant activity of quercetin grafted Cynanchum auriculatum starch.

In this study, a novel method was developed to conjugate quercetin with Cynanchum auriculatum starch. Quercetin was first succinylized and then grafted onto C. auriculatum starch through a N,N'­carbonyldiimidazole mediated reaction. The obtained water soluble quercetin grafted starch (quercetin-g-starch) was characterized by several instrumental methods. UV-vis spectrum of quercetin-g-starch aqueous solution exhibited two absorption bands at around 300 and 430nm. Fourier-transform infrared spectrum of quercetin-g-starch showed characteristic bands at 1731 and 1568cm-1, assigning to CO stretching of esterified carboxyl group and CC stretching of aromatic ring, respectively. Proton nuclear magnetic resonance spectrum of quercetin-g-starch showed partial proton signals of starch (3.30-5.47ppm) and quercetin (6.19-7.68ppm). All above results suggested quercetin was successfully grafted onto C. auriculatum starch. Besides, quercetin-g-starch particles were irregular in shape and were in an amorphous state. Notably, the thermal stability, resistant starch content as well as antioxidant activity of C. auriculatum starch was greatly enhanced by grafting with quercetin. This indicated the potential of quercetin-g-starch in the development of a novel resistant starch with antioxidant activity.

Recent advances in endophytic exopolysaccharides: Production, structural characterization, physiological role and biological activity.

Endophytes are microorganisms that colonize living, internal tissues of plants without causing any immediate, overt negative effects. In recent years, both endophytic bacteria and fungi have been demonstrated to be excellent exopolysaccharides (EPS) producers. This review focuses on the recent advances in EPS produced by endophytes, including its production, isolation and purification, structural characterization, physiological role and biological activity. In general, EPS production is influenced by media components and cultivation conditions. The structures of purified EPS range from linear homopolysaccharides to highly branched heteropolysaccharides. These structurally novel EPS not only play important roles in plant-endophyte interactions; but also exhibit several biological functions, such as antioxidant, antitumor, anti-inflammatory, anti-allergic and prebiotic activities. In order to utilize endophytic EPS on an industrial scale, both yield and productivity enhancement strategies are required at several levels. Besides, the exact mechanisms on the physiological roles and biological functions of EPS should be elucidated in future.

Effect of acid hydrolysis on morphology, structure and digestion property of starch from Cynanchum auriculatum Royle ex Wight.

Effect of acid hydrolysis on the morphology, structure and digestion property of starch from Cynanchum auriculatum Royle ex Wight was investigated in this study. The hydrolysis degree of C. auriculatum starch rapidly increased to 63.69% after 4days and reached 78.67% at the end of 9days. Morphology observation showed that the starch granules remained intact during the first 4days of hydrolysis. However, serious erosion phenomenon was observed after 5days and starch granules completely fell into pieces after 7days. During acid hydrolysis process, the crystal type of hydrolyzed starch changed from original CB-type to final A-type. Small-angle X-ray scattering patterns showed the semi-crystalline growth rings started to be hydrolyzed after 4days. The proportions of single helix and amorphous components as well as amylose content in starch gradually decreased, whereas the proportion of double helix components continuously increased during acid hydrolysis. However, the contents of rapidly digestible starch, slowly digestible starch and resistant starch were almost constant during acid hydrolysis process, indicating the in vitro digestion property of C. auriculatum starch was not affected by acid hydrolysis. Our results provided novel information on the inner structure of C. auriculatum starch granules.

Morphology, structural and physicochemical properties of starch from the root of Cynanchum auriculatum Royle ex Wight.

The root of Cynanchum auriculatum Royle ex Wight is a traditional Chinese herbal medicine and healthy food. Although C. auriculatum has already been processed into starch for human consumption in China, the structural characterizations of C. auriculatum starch is still unknown. Therefore, the morphology, structural and physicochemical properties of C. auriculatum starch were investigated in this study. C. auriculatum starch exhibited both spherical and polygonal shapes with granule size ranging from 2 to 12µm. Some void cavities and serpentine channels were observed in the inner of starch granules. X-ray powder diffraction pattern revealed that C. auriculatum starch was a CB-type with relative crystallinity of 25.19%. Small-angle X-ray scattering spectrum indicated C. auriculatum starch had a lamellar repeat distance of 9.21nm. The proportions of single helix, double helix and amorphous components in C. auriculatum starch were 3.42%, 27.11% and 69.47%, respectively. The amylose content of C. auriculatum starch was 28.0% with the gelatinization temperature ranging from 59.3 to 70.1°C. The maximum weight loss rate of C. auriculatum starch appeared at 309°C. In addition, C. auriculatum starch showed higher swelling power than other starches tested. Our results suggest C. auriculatum starch will have wide applications in food industry.

Effect of Protocatechuic Acid-Grafted-Chitosan Coating on the Postharvest Quality of Pleurotus eryngii.

Protocatechuic acid-grafted-chitosan (PA-g-CS) solution with antioxidant activity was developed as a novel edible coating material for Pleurotus eryngii postharvest storage. The effect of PA-g-CS coating on the postharvest quality of P. eryngii was investigated by determination of various physicochemical parameters and enzyme activities. Results showed that the antioxidant capacity and viscosity of PA-g-CS solutions were closely related to the grafting degree and were much higher than that of chitosan (CS) solution. At the end of 15 days of storage, serious mushroom browning was observed in the control and CS coating groups. By contrast, PA-g-CS coating groups with medium and high grafting degrees maintained better physical appearance. Among all of the treatment groups, P. eryngii in PA-g-CS III coating group exhibited the highest firmness and the lowest weight loss, browning degree, respiration rate, malondialdehyde content, electrolyte leakage rate, superoxide anion production rate, and hydrogen peroxide content. Moreover, P. eryngii in PA-g-CS III coating group maintained relatively higher antioxidant enzyme activities but lower polyphenol oxidase activity than other treatment groups. Therefore, PA-g-CS III is a promising preservation agent for P. eryngii.